[7] - IISER Tirupati · 2018-01-05 · e-onspectus: ISAMP-T 7, Tirupati, 6—8 January 2018 iii Welcome note: Director, IIT Tirupati I am very happy that our two new institutions

6th to 8th January 2018Tirupati, Andhra Pradesh, India

e-Conspectus: ISAMP-TC7, Tirupati, 6—8 January 2018

Table of Contents

Welcome notes:

Director, IISER Tirupati

Director, IIT Tirupati

President, ISAMP

Conveners, ISAMP-TC7

.......................................................

.......................................................

.......................................................

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ii

iii

iv

v

ISAMP: History, Objectives, Executive Committee ....................................................... vi

Conferences organised by ISAMP ....................................................... vii

Advisory Committee ....................................................... viii

Scientific Advisory Committee ....................................................... viii

Organising Committees ....................................................... ix

Program Schedule ....................................................... xi

List of Abstracts ....................................................... xiii

Abstracts:

Keynote Addresses

Invited Speakers

Contributed Speakers

Posters

.......................................................

.......................................................

.......................................................

.......................................................

2

5

48

60

About Tirupati, IISER & IIT Tirupati ....................................................... b

Maps of Tirupati with important contacts ....................................................... e


ii

Welcome note: Director, IISER Tirupati

The 7th Topical Conference of the Indian Society of Atomic and Molecular Physics is being jointly

hosted by the IISER Tirupati and the IIT Tirupati. Both these institutions began functioning with the

first batch of students admitted from August 2015. It is thus a matter of great pride that in just a very

few years, we are able to jointly organize a major conference of the ISAMP in our institutions. It is most

appropriate that our first joint conference is in the very fundamental field of atomic and molecular

physics which developed hand-in-hand with the quantum theory in the 20th century. This field

continues to provide an arch over all of the basic sciences. Developments in this field continue to

provide breakthroughs in both basic and applied sciences. Atoms and molecules provide the basic

building blocks of all inorganic and even biological species. The physics of these constituents is very

challenging since all fundamental processes are governed by quantum theory and relativistic

mechanics. Studies in these areas have also led to major breakthroughs in new materials, including

new states of matter such as the Bose-Einstein Condensates. Advanced topics in the quantum collision

physics and spectroscopy will be dealt with at the ISAMP-TC7. Among many advanced topics, the

conference will also address fundamental ultrafast processes including at the attosecond time-scale.

It is heartening that experts from near and far parts of India, and also from many other parts of the

world from the far East, to the far West, will be presenting their research works. A very good number

of young researchers are also at this conference presenting their results. They will take home new

ideas and provide leadership in the years and decades to come. This symposium jointly organised by

IISER and IIT at Tirupati will be prelude to jointly organising meetings in other areas as well. I wish the

conference every success.

Professor K. N. Ganesh

Director, Indian Institute of Science Education and Research Tirupati


iii

Welcome note: Director, IIT Tirupati

I am very happy that our two new institutions – IISER Tirupati and IIT Tirupati are jointly hosting the

7th edition of the Topical Conference of the Indian Society of Atomic and Molecular Physics. Both our

institutions have the great advantage of leveraging each other’s strengths and resources with the

shared legacy that we have including – co-location (permanent campuses located 3 km apart),

common foundation stone ceremony, launch of academic programs in August 2015 etc. Tirupati is

developing as an education hub, and as a smart city. It is most appropriate that the two leading science

and technology institutions in the region have come together to jointly host the Conference.

Breakthroughs in technology can come only from innovative engineering, which in turn can only be

enabled by advances in fundamental sciences. Computing, networking, data storage and retrieval,

communication engineering, as well as the necessity to have sustainable environment friendly

ecosystem requires new engineering materials, and also new processes. These can only be discovered

and invented in the research laboratories in the field of basic sciences. The field of atomic and

molecular physics provides the fundamental laboratory from which many innovations have been

made, and tested, before new materials and processes could be scaled up for fruitful technology.

The response that this conference has got is awesome. It has attracted distinguished scientists from

within India and from many countries in the world. These include many world leaders in the field

working in frontier research areas. Many young researchers from all parts of the country are coming

for this conference, and they will present their own research, and also take back new ideas to work on.

Some of these may provide important breakthroughs for engineering and technology.

I join the organizing committee members in welcoming the conference delegates to Tirupati and our

institutions. I wish the conference a great success.

Professor K. N. Satyanarayana

Director, Indian Institute of Technology Tirupati


iv

Welcome note: President, ISAMP

Dear Members of the Society and Delegates,

It is with great pleasure that I welcome you all to the seventh Topical Conference of the Society. The

topical conferences began as small affairs, with a somewhat regional flavour, and over the years have

grown in popularity, and have also seen participation of delegates from abroad. I trust that the current

conference will meet or exceed your expectations as to the quality of the contributions and the

spectrum of colleagues that you will be meeting. The topics of this conference are a good reflection

of the gradual change in the focus of atomic and molecular physics research. You will also notice that

participants in this conference are a healthy mix of junior and senior colleagues. We have tried our

best to support the participation of students in this conference.

IISER Tirupati and IIT Tirupati came to be the choice of venue for this meeting largely thanks to the

initiative of Prof P C Deshmukh, who first proposed the plan. My own close association with IISER

Tirupati bolstered it and the proposal got a decisive boost with the financial and Institutional support

from Director, IISER Tirupati, Prof K N Ganesh, and Director, IIT Tirupati, Prof K N Satyanarayana. This

conference happens to be the first national conference to be held here, and will therefore occupy a

special place in the history of IISER Tirupati and IIT Tirupati. On behalf of the Society I thank both

Directors and the faculty and staff of these Institutions for their whole-hearted support to the

organisation of the conference.

Welcome once again, and enjoy the conference!

Bhas Bapat

President, ISAMP


v

Welcome note: Conveners, ISAMP-TC7

We are delighted that the ISAMP TC7 has come to our sister institutions, the IISER and the IIT, at

Tirupati. Thank you very much for coming from all over India, and also for coming from distant parts

of the world. We are really extremely happy to have you here. We shall have 53 talks at the conference,

but some of these will be in parallel sessions, so we urge you to go through the program schedule in

advance and plan which talks you wish to attend. On each of the three days of the meeting, we shall

have a poster session between lunch break and the tea break. This provides for extended periods for

the poster sessions, overlapping with the lunch and the tea break. It will be great if delegates go back

refreshed from this conference with some new research ideas which we hope will come out of the

discussions. In order that the research work you would present at the conference gets into scientific

literature, we have arranged for the proceedings of ISAMP-TC7 to be published as SPRINGER

CONFERENCE PROCEEDINGS. Publishing in this special volume will make your work accessible to

researchers in the years come. ISAMP-TC7 has become possible because of the generous support and

guidance from Professor K. N. Ganesh (Director, IISER T) and from Professor K. N. Satyanarayana

(Director, IIT T). Very many staff and faculty members at the IISER-T and the IIT-T have put in huge

effort in organizing fine details with regard to various arrangements. Lapses however will be found,

and these can be easily traced to the two of us. The members of the organizing committee are listed

in this e-Book, and we have no words to thank them. Even if it will be unfair to mention only one of

them, we wish to place on record our gratitude and admiration to Dr. S. Sunil Kumar, the Conference

Secretary, for superb coordination of all activities. We are also very grateful to NPTEL for video-

recording the two keynote addresses, by Professor Anatoli Kheifets (Theory) and Professor E.

Krishnakumar (Experiment). These talks will remain accessible from the NPTEL web archives. Thank

you all very much, and wish you all happy times in Tirupati.

Pranawa C. Deshmukh and Bhas Bapat

Joint Conveners, ISAMP-TC7


vi

Indian Society of Atomic & Molecular Physics (ISAMP)

A brief history & objectives

In 1981, a group of Scientists working in Atomic and Molecular Physics in India convened a meeting in

Gandhinagar, Gujarat with an aim to form a registered society with the objectives as stated below:

• To encourage the study of all aspects of Atomic and Molecular Physics and help towards

the advancement, dissemination and application of the knowledge of Atomic and

Molecular Physics.

• To promote active interaction among all persons, bodies, educational and research

institutions and industries interested.

• To issue such publications (e.g. newsletters, reports, bulletins, journals incorporating

research and teaching ideas, reviews, new developments etc.) from time to time.

• To hold periodic scientific meetings in Atomic and Molecular Physics in different parts of

the Country.

• To hold and sponsor topical meetings along with similar organizations and also to

participate in holding International Meetings in India.

• To encourage coordinated research programmes among Atomic and Molecular Physicists

in India and Exchange of research personnel between research institutions and

Universities in India.

• To keep liaison with other atomic and molecular physics societies of the world.

• To institute lectures, prizes and fellowships.

• To secure grants, funds and endowments and administer the same for the furtherance of

the above any or all aims and objectives.

Executive Committee of the ISAMP

President: B. Bapat, IISER Pune

Vice-president: B. N. Rajashekhar, BARC, Mumbai

Secretary: M. Vinodkumar, VP & RPTP Science College, Vallabh Vidyanagar

Treasurer: S. B. Banerjee, PRL, Ahmedabad

Ex-officio member: L. C. Tribedi, TIFR, Mumbai

Members: A. Shastri, BARC, Mumbai

T. Ahmed, AMU, Aligarh

C. P. Safvan, IUAC, New Delhi

T. K. Mukherjee, Narula Institiute of Technology, Kolkata

Detailed information about the ISAMP can be found at the website: https://www.prl.res.in/~isamp/.


vii

Conferences Organized by ISAMP

National Conferences on Atomic and Molecular Physics (NCAMP)

(Known as Workshops till 1993 BARC conference)

Year Hosted by

1976 PRL, Ahmedabad

1978 Visva-Bharati, Santiniketan

1980 CCSU, Meerut

1982 Dec IACS, Kolkata

1984 Dec TIFR, Mumbai

1986 Dec BHU, Varanasi

1988 AMU, Aligarh

1990 University of Hyderabad

1993 Mar BARC, Mumbai

1995 Mar CCSU, Meerut

1996 IIT Madras, Chennai

1998 MLSU, Udaipur

2000 IACS, Kolkata

2003 Feb Visva-Bharati, Santiniketan

2004 Dec PRL, Ahmedabad

2007 Jan TIFR, Mumbai

2009 Feb IUAC, New Delhi

2011 Feb Karnatak University, Dharwad

2012 Dec IISER Kolkata

2014 Dec IIST, Thiruvananthapuram

2017 Jan PRL, Ahmedabad

ISAMP Topical Conferences

2005 Dec IACS, Kolkata Electron Processes in Atoms and Molecules

2008 Jan SP University, Vallabh Vidyanagar Electron Collisions in Atoms and Molecules

2010 Feb RRCAT, Indore Synchrotrons for AMP

2012 Feb University of Hyderabad Lasers in AMP

2013 Nov IPR, Gandhinagar (St Laurn Hotel) Atomic Processes in Plasmas

2016 Jan ISM Dhanbad Charged Particle Collisions and Electronic

Processes in Atoms, Molecules and Materials


viii

Conveners

• Deshmukh, P. C. (IIT Tirupati & IISER Tirupati)

• Bapat, Bhas (IISER Pune & IISER Tirupati)

Conference Secretary

• Sunil Kumar, S. (IISER Tirupati)

Advisory Committee

• Ganesh, Krishna N. (IISER Pune & IISER Tirupati)

• Krishnakumar, E. (TIFR, Mumbai)

• Rajashekhar, B. N. (BARC, Mumbai)

• Satyanarayana, K. N. (IIT Tirupati)

• Srivastava, Rajesh (IIT Roorkee)

• Subramanian, K. P. (PRL, Ahmedabad)

• Tribedi, Lokesh (TIFR, Mumbai)

Scientific Advisory Committee

• Bapat, Bhas (IISER Pune)

• Bhatt, Pragya (IUAC, New Delhi)

• Deshmukh, P. C. (IIT Tirupati)

• Mukherjee, Tapan Kumar (Narula Institute of Technology, Kolkata)

• Rajashekhar, B. N. (BARC, Mumbai)

• Rangwala, Sadiq (RRI, Bengaluru)

• Safvan, C. P. (IUAC, New Delhi)

• Satyajit, K. T. (Amrita University, Coimbatore)

• Shastri, Aparna (BARC, Mumbai)

• Singh, Angom D. K. (PRL, Ahmedabad)

• Subramanian, K. P. (PRL, Ahmedabad)

• Sunil Kumar, S. (IISER Tirupati)

• Vinodkumar, Minaxi (VP & RPTP Science College, Vallabh Vidyanagar)

7th Topical Conference of the ISAMP (ISAMP-TC7)


ix

Organising Committees

Sl. No. Name of the Committee Members / Coordinators Institute

1 Reception 1. Jessy Jose (Coordinator)

2. Raghunath Ramabhadran (Coordinator)

3. Rajib Biswas (Coordinator)

Members

1. Chaman Mehta

2. V. Nikhilasri

3. Salvi M.

4. Veena P.

5. Deepu Damodar

6. Bharathi K.

7. Mohana

8. Poornashri

IISER

IISER

IIT

IISER

IISER

IISER

IISER

IISER

IISER

IIT

IIT

2 Hall Management 1. Shibdas Banerjee (Coordinator)

2. Pankaj Kumar (Coordinator)

3. Arun Manna (Coordinator)

4. Rudra Sekhar Manna (Coordinator)

Members

1. Chaman Mehta

2. Antony Joe

3. V. Srikanth

4. K. Sivakumar

5. Satish Jadhav

6. Sureshkumar C.

7. Jagadeesh

8. Senthil

9. Ramesh Krishnan

10. T. T. Mani

IISER

IISER

IIT

IIT

IISER

IISER

IISER

IISER

IISER

IISER

IIT

IIT

IIT

IIT

3 Poster Sessions 1. Ankur Mandal (Coordinator)

2. Raghunath Ramabhadran (Coordinator)

3. Debasish Mondal (Coordinator)


5. Poornasri (Coordinator)

Members

1. Chaman Mehta

2. Deepu Damodar

3. V. Nikhilasri

4. Salvi M.

5. Sureshkumar C.

6. Udayakumar

7. Sanyasi Naidu

IISER

IISER

IIT

IIT

IIT

IISER

IISER

IISER

IISER

IISER

IIT

IIT


x

4 Transport 1. Lakshmana Rao (Coordinator)

2. Gopinath Purushothaman (Coordinator)

3. Koteswara Rao (Coordinator)

Members

1. Inderpreet Singh Kohli

2. Kolli V. V. Nagarjun

3. Ramesh Yadav

4. N. Dileep Kumar

5. Midhun Kumar

IISER

IISER

IIT

IISER

IISER

IISER

IISER

IIT

5 Accommodation 1. Pankaj Kumar (Coordinator)

2. Shibdas Banerjee (Coordinator)

Members

1. Inderpreet Singh Kohli

2. Dattaprasad Gavde

3. P. M. Azad

IISER

IISER

IISER

IISER

IISER

6 Catering services and

House Keeping

1. Soloman Raju (Coordinator)

2. Raju Mukherjee (Coordinator)


4. Debasish Mondal (Coordinator)

5. Koteswara Rao (Coordinator)

Members

1. Dattaprasad

2. K. Ramesh

3. M. Vamsidhar

4. Ramji

5. Gopal

IISER

IISER

IIT

IIT

IIT

IISER

IISER

IISER

IIT

IIT

7 Computer support and

WiFi services

1. Chitrasen Jena (Coordinator)

2. Ankur Mandal (Coordinator)

Members

1. V. Srikanth

2. Satish Jadhav

3. T. T. Mani

4. Senthil

5. Lokesh

IISER

IISER

IISER

IISER

IIT

IIT

IIT

8 Medical

Support

1. Suchi Goel (Coordinator)

2. Arunima Banerjee (Coordinator)

3. Kalpana (Coordinator)

Members

1. Nimmy K. Prasad

2. Pushpa

IISER

IISER

IIT

IISER

IIT

9 Finance / Budget 1. S. Sunil Kumar (Coordinator)


IISER

IIT

10 Program Committee 1. S. Sunil Kumar (Coordinator)

2. Ankur Mandal (Coordinator)

IISER

IISER


xi


xii


xiii

List of Abstracts

Keynote Addresses

Authors Title of the Abstract ID Page

A. Kheifets Attosecond-Time resolved studies of atomic

and molecular photoionization: What have we

learned from them?

IB004 2

E. Krishnakumar Electron-Molecule Resonances IA016 3

Invited Talks


R. Srivastava Characterization of inert gas plasma through

relativistic electron excitation cross-sections

IA001 5

C.C. Montanari* &

J.E. Miraglia

The shellwise local plasma approximation, a

many electron model for ion-matter inelastic

collisions

IA002 6

T. Nandi Influence of strong force on electromagnetic

interactions

IA003 7

H. Tanuma*,

N. Numadate,

K. Shimada et al.

Laboratory Experiments of Solar Wind

Charge Exchange and Related Atomic

Processes

IA004E 8

M.N.R. Ashfold*,

M. Bain,

C.S. Hansen et al.

лσ*-state mediated bond fission:

Determining absolute branching fractions for

competing photoinduced bond fission

processes

IA005F 9

A. Dubey,

S. Agrawal,

T.R. Rao & J. Jose*

Elastic Scattering of H Atom by C60 and

Kr@C60: Calculation of Total Cross Section

and Time-Delay

IA006B 10

R.K. Kushawaha Photoionization of polyatomic molecules:

multi-slits type interferences, molecular

fragmentation and ultrafast dynamics

IA007E 11


xiv


L. Natarajan Probing quantum effects via X-ray

spectroscopy

IA008 12

H. Chakraborty The Fullerene molecule: a super-attractive

object for new spectroscopy

IA009B 13

R. Gopal, A. Sen, …,

V. Sharma*

A three-dimensional ion imaging

spectrometer for studying photo-induced

fragmentation in small molecules

IA010 14

G. Aravind* &

R. Chacko

Collision-induced dissociation of anions of

astrophysical interest

IA011 15

T. Rajagopala Rao Quantum symmetry effects and isotopic

effects in oxygen exchange reactions

IA012 16

S. Gordon, J. Zhou,

S. Tanteri,

N. Gkogkoglou, &

A. Osterwalder*

Merging, splitting, orienting – towards

ultracold stereodynamics

IA013 17

S. Fritzsche Excitation and ionization of atoms by twisted

light

IA014 18

J. Tennyson Low temperature chemistry using the R-

matrix method

IA015 19

D. Nandi Dissociative electron attachment and dipolar

dissociation dynamics probed by velocity

slice imaging

IA017 20

S. Krishnan Electron dynamics in small atomic

aggregates at He nanodroplets:

multicoincidence spectroscopy

IA018 21

J.A. Lopez-Domınguez*,

M. Klinker,

C. Marante et al.

Multichannel photoionization of polyatomic

non-linear targets within the XCHEM

approach: the H2O case study

IA019 22

L.C. Tribedi Angular asymmetry of electron emission and

ionization dynamics

IA020 23


xv


Y. Azuma Post Collision Interaction (PCI) Recapture of

Photoelectrons into Rydberg Orbitals:

Electrons Playing Tag at Threshold

IA021 24

C. Christophe Dosimetry of ionizing radiations in

biological tissues: Importance of calculations

at a microscopic scale

IA022 25

Y. Khajuria Spectroscopic studies and quantum chemical

investigations of (3,

4−dimethoxybenzylidene) propanedinitrile

IA023 26

M. Krishnamurthy Acceleration of neutral atoms in laser

produced plasmas

IA024 27

K.P. Subramanian*,

B.G Patel & P. Kumar

LTE condition validation by plume

characterization in laser produced plasmas

IA025E 28

M.F. Ciappina Attosecond Physics at the Nanoscale IB001 29

H.R. Varma Wigner photoionization time delay studies of

the neon 2s → np autoionization resonances

IB002 30

R. Lucchese Aspects of single-photon ionization of

molecules with implications for Wigner time

delay and high-harmonic generation

IB004 31

G. Dixit*,

Á. Jiménez-Galán,

L. Medišauskas et al.

Control of helicity of high-harmonic

radiation using bichromatic circularly

polarized laser fields

IB005 32

R. Bai,

S. Bandopadhyay, ...,

D. Angom

Quantum Hall states in optical lattices IC001 33

J. Bera, & U. Roy* Long Time Evaluation of Bose-Einstein

Condensate in a Toroidal Trap

IC002 34

M. Mukherjee*,

D. Yum & T. Dutta

Precision measurements with trapped ions IC003D 35


xvi


R.Sawant,

S. Dutta, ..., &

S. A. Rangwala*

Atoms, molecules and ions in cavities ID001 36

V. Sudhir*,

D. Wilson,

S. Fedorov et al.

Quantum measurement and control of a

mechanical oscillator

ID002 37

P. Chakraborty Ion-beam synthesis of metal quantum dots in

glasses for nonlinear photonic Applications

ID003 38

T. Azuma Recurrent fluorescence observed with an ion

storage ring

ID004 39

A. Bhowmik &

S. Majumder*

Tunable magic wavelengths of cooling and

trapping with focused LG beam

ID005 40

A. Wolf Fast Ion Beams in a Cryogenic Storage Ring:

Collisions and Internal Excitations

IE001 41

M. Schmidt* &

G. Zschornack

Elaborated Electron Beam Ion Sources for

AMO Physics and Laboratory Astrophysics

IE002 42

B.N. Rajasekhar* &

Asim Kumar Das

Design of an experimental facility for

Molecular Science research using UV-VUV

and soft X-ray photons

IE003 43

C.P. Safvan Molecular Physics facilities at IUAC IE004 44

U.R. Kadhane Plasma and beam diagnostics for electric

propulsion research

IE005 45

S. Son Ultrafast ionization and fragmentation

dynamics of molecules at high x-ray

intensity

IF001 46


xvii

Contributed Talks


S. Kumar*,

S. Prajapati,

B. Singh, et al.

Dissociation dynamics of N2n+ cations (n=1-

2) and kinetic energy release study in the

collision of 3.5 keV electron with nitrogen

molecule

CA001 48

K. Saha,

V. Chandrasekaran,

O. Heber et al.

Ultraslow isomerization in photoexcited gas

phase C10-

CA003 49

H. Kumar,

P. Bhatt,

C.P. Safvan et al

Fragmentation dynamics of multiply charged

OCS

CA006 50

S. Mandal,

R. Gopal,

S. Krishnan et al

Isomerization of Acetylene doped in He

nanodroplets by EUV synchrotron radiation

CA035 51

A. Shastri*,

A.K. Das &

B.N. Raja Sekhar

Vacuum ultraviolet photoabsorption

spectroscopy of anisole

CA049 52

S. Soumyashree*,

P. Kumar,

R.K. Kushawaha et al.

Elemental analysis using Laser Induced

Breakdown Spectroscopy

CA051E 53

V. Pramod Majety* &

A. Scrinzi

Multielectron effects in strong field

ionization of few electron molecules

CB003 54

U. S. Sainadh*, H. Xu,

X. Wang et al.

Tunneling delays in strong field ionization of

atomic hydrogen

CB005 55

A. Acharya*,

R. B. Reddy,

M. Bajaj et al

PC based Acousto Optic Modulator Driver

for Cold Atom Interferometer

CC001 56

N. Kundu* & U. Roy Two Components Bose-Einstein Condensate

in a Frustrated Optical Lattice

CC004 57

P. Rajauria* &

T. S. Raju

Non-autonomous matter-waves in a quasi-

one-dimensional waveguide geometry

CC007 58


xviii

Posters


B. Singh, S. Prajapati,

S. Kumar et al.

Measurement of the angular distributions of

thick target bremsstrahlung produced by 10-

25 keV electrons incident on thick Ti & Cu

pure elements.

CA002 60

Priti, L. Sharma &

R. Srivastava

Xenon Plasma Modeling with Relativistic

Fine Structure Cross Sections

CA004 61

A. Mandal &

P.C. Deshmukh

SOIAIC effect on Wigner-Eisenbud-Smith

time delay: Xe 4d photoionization

CA005B 62

A. Husan, S. Jabeen &

A. Wajid

Study of the excited even configuration of Cs

VII

CA007A 63

S.Gupta, L. Sharma &

R. Srivastava

Electron-impact excitation of Xe+ ion and

polarization of subsequent emissions

CA008 64

A. Mandal &

P. C. Deshmukh

Wigner-Eisenbud-Smith time delay in

photoionization of n f subshell: angle and

spin resolved study

CA009B 65

A. Dora & J. Tennyson Potential energy curves of the higher lying

resonances in electron-CO scattering

CA010 66

B. Bapat, D. Sharma,

A. Kumar et al

Orientation effects in ionisation of CO by

proton and ion impact

CA011 67

C. C. Montanari &

P. Dimitriou

The IAEA database for stopping power,

trends in the energy loss experimental

research

CA012 68

C. C. Montanari &

J. E. Miraglia

Energy loss of low energy protons and

antiprotons in metals

CA013 69

R. Bhavsar, Y. Thakar, &

C. Limbachiya

Electron interaction scattering cross sections

of Astromolecules

CA014 70

Y. Thakar, R. Bhavsar, &

C. Limbachiya

Electron interaction scattering cross sections

of Biologically relevant molecule

CA015 71


xix


D. Prajapati, H. Yadav, &

M. Vinodkumar

Electron Induced chemistry of

Chlorobenzene

CA016 72

S. K. Kumar,

B. N. Rajasekhar &

A. K. Das

Optical breath gas sensing using UV-VUV

absorption spectroscopy

CA017 73

A.M.P. Mendez,

D.M. Mitnik, &

C. C. Montanari,

Fully relativistic structure calculations of

heavy targets for inelastic collisions

CA018 74

M. Kumar, R. Singh &

S. Pal

Kinetic energy release distribution in

electron dissociative ionization of CO2

CA019 75

A. K. Das,

S. Krishnakumar &

B. N. Rajasekhar

VUV Spectroscopy of Diethyl Carbonate CA020 76

R. Bala, H. S. Nataraj &

M. Abe

Ab initio calculations of spectroscopic

parameters of HfH+ and PtH+

CA021 77

M. R. Parida &

O. F. Mohammed

Ultrafast spectroscopy of perovskite

interfaces

CA022 78

D. Chakraborty, P. Nag,

& D. Nandi

Absolute dissociative electron attachment

cross section measurement studies for

difluoromethane

CA023 79

A. Rashid &

A. Tauheed

The spectrum of quadruply ionized mercury:

Hg V

CA024 80

A. Ganesan,

G.B. Pradhan,

P.C. Deshmukh

Xe 5s Photoionization near the Second

Cooper Minimum using RMCTD

CA025 81

S.Singh, P. Verma, &

V. Singh

Positron collision dynamics for C2-C3

hydrocarbons

CA026 82

M. Vinodkumar,

H. Yadav, &

P.C. Vinodkumar

Dissociative electron attachment study of di

& tri atomic molecule

CA027 83


xx


H. Yadav,

M. Vinodkumar,

C. Limbachiya et al.

Electron impact scattering studies of

Halomethane (CH3X, X = F, Cl, Br, I)

CA028 84

S. Bharti, P. Malkar,

L. Sharma et al.

Electron scattering from endohedrally

confined Ca atoms

CA029D 85

K. Chakraborty,

R. Gupta,

Ch.V. Ahmad et al.

Molecular effects in L shell ionization of Au

and Bi by slow Ag ions

CA030 86

K.K Gorai,

P.J. Singh,

A. Shastri et al

VUV Spectroscopy of Dodecane Molecule

using synchrotron radiation

CA031 87

R. Gupta,

Ch. V. Ahmad,

K. Chakraborty et al

Detecting the elemental constitution of

environmental samples of Delhi and

surrounding regions using XRF spectroscopy

CA032 88

S. Kumar, S. Kumar,

D. K. Swami et al

Characterization of thin aluminized

polypropylene backed atomic targets using 2

MeV He+ Ions

CA033 89

S. Kumar, S. Kumar,

D. K. Swami et al.

L shell x-ray production in ultra-thin 76Os

using 4-6 MeV/u fluorine ions.

CA034 90

P. Modak, V. Patel,

H. Tomer et al.

Ionization cross section of water clusters

((H2O)n,n=1-4) by electron impact

CA036 91

P. Sharma & T. Nandi Disentangling charge exchange processes in

bulk from surface

CA037 92

R. Singh, M. Kumar,

N. Kumar & S. Pal

Determination of energy and angle

dependent electron ionization cross sections

for methylamines

CA038 93

A. Naratajan &

L. Natarajan

Kα X-Rays from Variously Ionized Iodine CA039 94

S. Ankita &

A. Tauheed

The Spectrum of Doubly Ionized Silver: Ag

III

CA040 95


xxi


A. Sen,

A.S. Venkatachalam,

S. R. Sahu et al.

Study Molecular Dissociation Dynamics

using Velocity Map Imaging

CA041 96

P.J. Singh, A.K. Das,

K.K. Gorai et al.

Synchrotron based VUV spectroscopy of

dimethylacetamide

CA042 97

N. Sinha, D. Patel &

B. Antony

Positron Scattering Cross Sections for

Methyl Halides

CA043 98

A. Zainab &

A. Tauheed

Energy levels and classified lines in the third

spectrum of gold: Au III

CA044 99

S. Ghosh, B. Halder &

U. Roy

Phase Space Structures and Isotope

Separation of Bromine Molecules

CA045 100

A. Wajid, S. Jabeen &

A.Husain

Isoelectronic Energy Levels of Xe-like Ions:

La IV- Ce V

CA046 101

S. Mukund, S.

Bhattacharyya &

S.G. Nakhate

Laser-induced fluorescence spectroscopy of

jet-cooled LaNH: Observation of (0,0) C2∏ -

Χ2Σ+ transition

CA047 102

J. Singh, M. Khamesian

& V. Kokoouline

Theoretical method to study electron-impact

rotational excitation of molecular ions

CA048 103

N. B. Ram, S. G. Walt,

M. Atala et al

Imaging electron-nuclear dynamics in strong

field rescattering

CA050B 104

N. Uddin, P. Verma &

B. Antony

Electron scattering total ionization cross

section of H2CCCC: A cumulene carbene

detected in interstellar medium

CA052 105

P. K. Najeeb,

M. V. Vinitha,

A. Kala et al

Structural stability of polycyclic aromatic

hydrocarbons and polycyclic nitrogen

heterocycles under charged particle

collisions

CA053 106

M.V. Vinitha,

P.K. Najeeb,

K. Anudit et al

Collisional isomerisation between

naphthalene and azulene due to energetic

proton

CA054 107


xxii


M. Nrisimhamurty,

L.C. Tribedi & D. Misra

Two- and three-body dissociation dynamics

of H2O2

CA055 108

S. Banerjee,

H.R. Varma &

P.C. Deshmukh

Effects of interchannel coupling on angular

distribution of photoelectrons and on time

delay in the autoionization regions of Neon

2s → np resonance series

CB001 109

A. Jain, R. Heider,

M. Wagner et al

Attosecond-Streaking Spectroscopy on a

Liquid-Water Microjet

CB002E 110

S. Banerjee,

A. Thuppilakkadan,

H. R. Varma et al

Photoionization dynamics of Ar@C 540 CB004 111

S. Saha, J. Jose &

P.C. Deshmukh

Shape resonance induced Wigner time delay

in atomic photoeffects

CB006 112

S. Saha, J. Jose &

P.C. Deshmukh

Influence of SOIAIC in photodetachment

and photoionization time delays near the

centrifugal barrier shape resonance

CB007 113

A. Thuppilakkadan,

S. Saha, J. Jose et al

Effect of model potentials (smooth Vs hard)

on the Wigner time delay of H@C60

Photoionization

CB008 114

S. Bhushan &

R.K. Easwaran

A Two Dimensional Magneto Optical Trap

with High and Tunable Optical Depth for

Slow Light Applications

CC002 115

S. Modak, P. Das, &

P. K. Panigrahi

Quantum State Transfer through Coherent

Atom-Molecule Conversion in Bose-Einstein

Condensate

CC003 116

J. Bera, A.Q. Batin,

S. Ghosh et al

Breathing Dynamics of Ultracold Atoms in a

Vibrated Optical Lattice

CC005 117

V. U. Kumar &

P. C. Deshmukh

A pedagogical simulation of the Aharonov-

Bohm effect

CC006D 118

mailto:Ar@C

mailto:Ar@C540


xxiii


S. Dutta &

S. A. Rangwala

Cooling of trapped ions with a tiny cloud of

ultracold atoms: the role of resonant charge

exchange

CD001 119

D.K. Bayen &

S. Mandal

Quantum dynamics and frequency shift of a

Driven multi-photon anharmonic oscillator

CD002 120

S. Kumar, S. Ringleb,

N. Stallkamp et al

High-intensity laser ion experiments in

Penning Trap

CD003 121

Prakash, D. Datar,

B.M. Dyavappa et al

Non-linear Axial Oscillations of an Electron

plasma in a Penning Trap

CD004 122

R. K. Gangwar,

K. Saha, O. Heber et al

A Novel Cooling Process Using

Autoresonance in an Electrostatic Ion Beam

Trap

CD005 123

R. Chacko,

P. C. Deshmukh &

G. Aravind

Development of a 22-pole radio-frequency

ion-trap experimental set-up to study ion-

atom and ion-photon collisions of

astrophysical interests

CE001 124

A.Sharma, M. Leyser,

A.V. Viatkina et al

Towards a search for Dark Matter candidates

using atomic Dysprosium

CE002 125

U. Momeen & J. Hu Development of nanoscale magnetometry

using nitrogen-vacancy center in diamond

CF001 126

J. Hu & U. Momeen Novel tunable near field broadband

microwave antenna designs for nitrogen-

vacancy center in diamond

CF002 127

Abstractsof

Keynote Addresses

Attosecond-Time resolved studies of atomic and molecular photoionization: What have we learned from them?

Anatoli Kheifets∗ 1

∗ Research School of Physics and Engineering, The Australian National University, Canberra ACT 0200,

Australia

Time resolved studies of atomic photoioniza-tion with various pump-probe techniques such as attosecond streaking [1] or RABBITT [2], or self-referencing techniques like attoclock [3] opened up a new and rapidly developing area of research collectively termed attosecond chronoscopy [4]. The attosecond streaking and RABBITT measurements return the photoelectron group delay which is related to the photoelectron phase and its energy derivative known as the Wigner time delay [5]. These studies bring one step closer what had been dreamed of as a complete pho-toionization experiment. The attoclock mea-surement can be related to the tunneling time, i.e. the time photoelectron spends under thebarrier in a classically inaccessible region. Thenew measurements reopened decades-longdebate about a finite tunneling time [6].

In this presentation, the recent theoreticaladvances in evaluating the Wigner and tunnel-ing times in atomic and molecular photoioniza-tion will be reviewed in connection with ongoingexperimental activities. The following topics willbe highlighted.

1. Wigner time delay in photoionization offree and encapsulated noble gas atoms. Thistopic includes the relativistic effects and angu-lar dependent time delay. Connection with therecent measurements in heavy noble gas atoms[7] will be made.

2. Wigner time delay in molecular photoion-ization [8] including the stereoscopic time delayin heteronuclear molecules [9]

3. Tunneling time measurements [10] and cal-culations [11] in atomic hydrogen and their im-plications for the finite tunneling time problem

In conclusion, directions of the future time re-solved studies of atomic photoionization, includ-ing threshold effects [12] will be discussed.

References

[1] M. Schultze et al. Science, 328 1658, 2010.

[2] K. Klunder et al. Phys. Rev. Lett.,106 143002, 2011.

[3] P. Eckle et al. Science, 322 1525, 2008.

[4] R. Pazourek, S. Nagele, and J. Burgdorfer. Rev.Mod. Phys., 87 765, 2015.

[5] J.M. Dahlstrom, D. Guenot, K. Klunder, M. Gis-selbrecht, J. Mauritsson, A. L Huillier, A. Ma-quet, and R. Taıeb. Chem. Phys., 414 53, 2012.

[6] Alexandra S. Landsman and Ursula Keller. At-tosecond science and the tunneling time problem,Physics Reports, 547 1, 2015.

[7] I. Jordan, M. Huppert, S. Pabst, A. S. Kheifets,D. Baykusheva, and H. J. Worner. Phys. Rev.A, 95 013404, 2017.

[8] M. Huppert, I. Jordan, D. Baykusheva, A. vonConta, and H. J. Worner. Phys. Rev. Lett.,117 093001, 2016.

[9] J. Vos, L. Cattaneo, S. Patchkovskii,T. Zimmermann, C. Cirelli, M. Luc-chini, A. Kheifets, A. S. Landsman, , andU. Keller. Orientation-dependent stereoWigner time delay in a small molecule. InICOMP 14 , Budapest, Hungary, 2017.

[10] U. S. Sainadh, H. Xu, X. Wang, Atia-Tul-Noor, W. C. Wallace, N. Douguet,A. W. Bray, I. Ivanov, K. Bartschat,A. Kheifets, R. T. Sang, and I. V. Litvinyuk.ArXiv e-prints 1707.05445, July 2017.

[11] Lisa Torlina, Felipe Morales, Jivesh Kaushal,Igor Ivanov, Anatoli Kheifets, Alejandro Zielin-ski, Armin Scrinzi, Harm Geert Muller, SurenSukiasyan, Misha Ivanov, and Olga Smirnova.Nat. Phys., 11 503, 2015.

[12] A. S. Kheifets, A. W. Bray, and Igor Bray. Phys.Rev. Lett., 117 143202, 2016.

1E-mail: [email protected]

ISAMP TC-7, 6−8 January, 2018, Tirupati IB004 Kheifets

2

Electron-Molecule Resonances

E. Krishnakumar∗1

∗ Dept. of Nuclear and Atomic Physics, Tata Institue of Fundamental Research,Homi Bhabha Road, Mumbai -400 005, India

Electron-molecule resonances, which are short-lived excited states of molecular negative ions, haveattracted increasing attention in recent times due totheir complex dynamics as well as their role in widevariety of practical applications. Formation and de-cay of the resonance is the most efficient way ofconverting kinetic energy into chemical energy in amedium through the creation of vibrationally or elec-tronically excited states, radicals and negative ions -all of which are chemically very active. It has been

found that the energy specificity of this process al-lows chemical control by bond selective fragmenta-tion of organic molecules. Though diverse experi-mental techniques have been used to study the res-onances over the last few decades, recent advanceshave provided several new insights into the dynamicsof these species. This talk would provide an introduc-tion to negative ion resonances and a short overviewof their importance followed by some of the signifi-cant findings in recent times.


ISAMP TC-7, 6−8 January, 2018, Tirupati IA016 Krishnakumar

3

Abstractsof

Invited Talks

CHARACTERIZATION OF INERT GAS PLASMA THROUGH

RELATIVISTIC ELECTRON EXCITATION CROSS-SECTIONS

Rajesh Srivastava*

* Department of Physics, IIT Roorkee, Roorkee –247667 Uttarakhand, India

Topic: A- Quantum collisions and spectroscopy of atoms, molecules, clusters and ions.

There is need to develop reliable collisional

radiative (CR) models for inert gas plasma at

low temperature. Dominant processes involved

in the plasma modeling are the electron impact

processes. Despite the large body of literature

on inert gases, there is in general serious lack of

excitation cross section data for their various

fine-structure transitions [1-3]. Also the grow-

ing demand of electron-atom/ion collision data

can’t be met solely through experimental meas-

urements. Due to the complexity involved in

dealing with the fine-structure transitions the

theoretical data used for plasma modeling have

been obtained from empirical or simple classi-

cal methods which are not reliable. Consequent-

ly, reliable fine-structure cross sections should

be obtained and then incorporated into the CR

model for low temperature plasmas [3]. A re-

view on our CR models that we have recently

developed for inert gas plasmas viz. considering

Kr and Ar as well as their mixture with molecu-

lar gases like O2 and N2 will be discussed [2-5].

The required electron impact fine-structure

excitation cross-sections of the considered inert

gases are obtained from the accurate fully rela-

tivistic distorted wave (RDW) theory [4-7] and

these are incorporated in the CR model. The

model considers several electron impact fine

structure transitions from the ground as well as

excited fine structure states. The model incorpo-

rates various population transfer mechanisms

among fine structure levels such as electron im-

pact excitation, ionization, radiative decay

along with their reverse processes such as elec-

tron impact de-excitation, three body recombi-

nation. Rate equations for all fine structure lev-

els are solved simultaneously to obtain the pop-

ulation of the levels through which intensities of

different transitions are calculated and com-

pared with the experimentally measured intensi-

ties to fix the electron density and temperature

of the plasma. Our detailed results for Kr and

Ar as well as Ar-O2 and Ar-N2 plasma will be

presented discussed [2-5].

References

[1] S. Wang, A. E. Wendt, J. B. Boffard, C. C. Lin,

S. Radovanov, and H. Persing, 2013 J. Vac. Sci.

Technol. A, 31 021303

[2] R. A. Dressler, Y. Chiu, O. Zatsarinny, K.

Bartschat, R. Srivastava, and L. Sharma, 2009

J. Phys. D. Appl. Phys., 42 185203

[3] R. K. Gangwar, L. Sharma, R. Srivastava, and

A. D. Stauffer, 2012 J. Appl. Phys., 111 053307

[4] Dipti, R. K. Gangwar, R. Srivastava, and A. D.

Stauffer, 2013 Eur. Phys. J. D, 67 40244

[5] R. K. Gangwar, Dipti, L. Stafford and R.

Srivastava, 2016 Plasma Sources Sci. Technol. 25 035025


A. D. Stauffer, 2010 Phys. Rev. A, 82 032710


A. D. Stauffer, 2010 Phys. Rev. A, 81 052707

E-mail: [email protected]

ISAMP TC-7, 6−8 January, 2018, Tirupati IA001 Srivastava

5

The shellwise local plasma approximation, a many electron model for ion-matter inelastic collisions

C. C. Montanari 1, J. E. Miraglia 2

Instituto de Astronomía y Física del Espacio, CONICET and Universidad de Buenos Aires, Argentina Facultad de Ciencias Exactas y Naturales, Univerisdad de Buenos Aires, Buenos Aires, Argentina

Topic A: We present and discuss here the possibilities and ranges of validity of the shellwise local plasma approximation to deal with the inelastic collisions. This model describes the response of target bound electrons collectively by means of the dielectric formalism, considering the different subshells and binding energies. We present here our results for ionization cross sections, energy loss of ions in matter and also energy los straggling. A wide spec-trum of collisions of ions with gases and solids, atomic or molecular targets is covered, with. special attention to multielectronic relativistic targets.

The shellwise local plasma approximation (SLPA) [1] is an ab-initio model to deal with the inelastic collisions. It is a many-electron model within the frame of the dielectric formal-ism, especially suitable for multi-electronic tar-gets and intermediate to high energy collisions, in which target deep shells are involved. The SLPA describes the electronic response of each sub-shell of target electrons as a whole, includ-ing screening among electrons. This is of par-ticular interest when describing many-electron sub-shells such as 4f or 3d. The main character-istics of the SLPA are the independent-shell ap-proximation (a dielectric function for each sub-shell of target electrons, i.e. only the electrons of the same binding energy respond collectively to the ion perturbation and screen among them) and the inclusion of the binding energy explic-itly (not free-electron gas, but electron gas with an energy threshold). The inputs are the elec-tronic densities of the different sub-shells and the corresponding binding energies. For these reason, the model is suitable for describing atomic or molecular targets (see for example the results for water in [2] and for ZnO in [3].

We will present details of this model such as the inclusion of the charge state of the ion, the separate treatment for conduction and bound electrons in metals, or the description of relativ-istic targets.

In Fig. 1 the SLPA curve for the energy loss of protons in gold is displayed. All experimental data is included by using the compilation by Paul at the IAEA [4].

In Fig. 2 we display the results for ionization of the Li subshells (2s, 2p1/2, 2p3/2). The rela-tivistic description of Pb including the spin-orbit split is considered.

Figure 1. Energy loss of protons in solid gold. Ex-perimental data from IAEA database [4].

Figure 2. L-shell ionization cross sections of alphas in solid lead. Experimental data by Hardt [5].

References

[1] Montanari et al. (2013), Advances in Quantum Chem-istry, ed. Dz. Belkic (Elsevier), Chap. 7, pp. 165-201. [2] Montanari et al. (2014), J. Phys. B 47, 015201. [3] Fadanelli et al (2016), Eur. Phys. J. D 70, 178. [4] https://www-nds.iaea.org/stopping/ [5] Hardt et al (1976) Phys Rev A 14, 137.

1 E-mail: [email protected] 2 E-mail: [email protected]

ISAMP TC-7, 6−8 January, 2018, Tirupati IA002 Montanari

6

[Type here]

Influence of strong force on electromagnetic interactions

T. Nandi*1

*Inter-University Accelerator Centre, JNU Campus, New Delhi110067, India.

Topic: A

The well-known disparity between the in-

teraction range and coupling constant for the elec-

tromagnetic and strong force suggests independent

treatment of the atomic and nuclear phenomena.

However, some distinct processes viz. bound-state

β-decay [1], nuclear excitation by electron capture

[2] etc., occurring at the borderline between the

atomic and nuclear physics, provide a possibility to

explore the interference between such interactions.

Similarly, Coulomb barrier region also may provide

an opportunity to study the interplay between the

atomic and nuclear processes [3]. Nevertheless, no

effort has been invested yet to study the influence

of the nuclear interaction on the atomic processes at

the barrier energies during the ion-atom interaction.

We have investigated the above mentioned,

atomic phenomena in the interface of atomic and

nuclear physics through experimental as well as

theoretical routes. Earlier works in this laboratory

indicate clearly that the shakeoff ionization is one

of the major phenomena important in this regime.

Accordingly, in the first step we have put certain

efforts to establish the theoretical frame works [4].

Side by side we develop experimental setup incor-

porating both atomic and nuclear tools. Next chal-

lenge is to utilize the x-ray spectra in finding the

charge changing phenomenon in the bulk of the

target foil [5] and then proceed to monitor the sur-

face effects through the radiative electron capture

processes [6]. Further, thorough analysis enables us

to establish the fact that the beam-foil interaction is

indeed a high density localized plasma [7]. These

preparatory grounds lead us to proceed for the ma-

jor goal. We measure the projectile K x-ray spectra

as a function of the beam energies in small steps

around the Coulomb barrier in different collision

systems and notice an unusual increase in x-ray en-

ergy near the interaction barrier energies. The un-

derlying process is found, theoretically in the sud-

den approximation limit, to be shakeoff of L-shell

electrons of the projectile due to the sudden nuclear

recoil. This fact finally leads to discover the fact

that the strong nuclear force does influence on the

atomic processes [8]. Interestingly, such phenome-

non finds significant implications in dark matter

search experiments [9] and atomic physics research

at the nuclear regimes.

I shall introduce the foundation of this unu-

sual topic and then the various steps in achieving

the present goal. Finally, highlight the important

results and then possible impacst in future applica-

tions.

References

[1] J. N. Bahcall, 1961 Phys. Rev. 124 495

[2] A. Palffy et al., 2006 Phys. Rev. A 73 012715

[3] M. S. Freedman 1974 Ann. Rev. Nucl. Sci. 24 209

[4] P. Sharma et al. 2015 Nucl. Phys. A 941 265

[5] P. Sharma et al. 2016 Phys. Lett. A 380 182

[6] P. Sharma et al. 2017 submitted to Euro Phys. Lett.

[7] P. Sharma et al. 2016 Phys. Plas. 23 083102

[8] P. Sharma et at. 2017 Phys. Rev. Lett. (in Press).

[9] H. Ejiri et al. 2006 Phys. Lett. B 639 218


ISAMP TC-7, 6−8 January, 2018, Tirupati IA003 Nandi

7

Laboratory Experiments of Solar Wind Charge Exchange andRelated Atomic Processes

Hajime Tanuma1, Naoki Numadate, Kento Shimada, Hirofumi Shimaya, Takuya Ishida,Takuma Kanda, Nobuyuki Nakamura∗, Kunihiro Okada†, Ling Liu‡, and Jianguo Wang‡

Department of Physics, Tokyo Metropolitan University, Hachioji, Tokyo 192-0397, Japan∗ Institute of Laser Science, The University of Electro-Communications, Chofu, Tokyo 182-0021, Japan

† Department of Physics, Sophia University, Chiyoda, Tokyo 102-8554, Japan‡ Institute of Applied Physics and Computational Mathematics, Beijing 100088, Republic of China

Topic: A & E

The soft X-ray emission observed with theROSAT all-sky survey in the 1990s found anintensity fluctuating in cycles of 1–2 days du-ration [1]. It was difficult to understand thisphenomenon before the mechanism of the softX-ray emissions from comets has been revealed.In 1996, the ROSAT also observed the soft X-ray emission from the comet C/Hyakutake 1996B2 approaching to Earth [2]. According toCravens’ suggestion, it has been recognized thatthe soft X-ray emission stems from charge ex-change collisions between the solar wind ionsand the neutrals among the comet, and thisphenomenon is called “Solar Wind Charge eX-change” (SWCX) [3]. In analogy to this, it wasproposed that the soft X-ray background radia-tion with fluctuating intensity is due to a charge-excange of the highly charged ions in the solarwind with thin neutral matter within the helio-sphere [4].

In order to analyze soft X-ray emission spec-tra observed with X-ray observatory satellitesquantitatively, accurate emission cross sectionsin collisions of multiply charged ions with neu-tral atoms are required by astrophysicists. Wehave a 14.25 GHz electron cyclotron resonanceion source (ECRIS) which can produce variousmultiply charged ions (for example, bare, H-like,and He-like ions of C, N, and O atoms etc.) in aplasma of about 106 K and beam lines for colli-sion experiments between multiply charged ionsand neutral gases with solar wind speed of 300–800 km/s which corresponds to a kinetic energyrange of 0.5–3.3 keV/u.

Using this multiply charged ion beam facil-ity, we have been performing the following ex-periments in this decade:1) Total charge exchange cross sections:

Charge state distribution after passing

through a collision cell filled with a neutral gashas been analyzed by a electrostatic deflector toobtain total charge changing cross sections.

2) Emission spectra and emission cross sections:

Soft X-ray and extreme ultra-violet (EUV)emissions following charge exchange collisionshave been observed at magic angles by a silicondrift detector and a grazing incident spectrome-ter with a cooled CCD camera, respectively [5, 6].

3) Observation of forbidden transitions:

He-like ions produced in collisions of H-likeions with neutral gas targets are in both sin-glet and triplet states. Most of triplet stateswill transfer to the 1s2s 3S, which has a longlifetime, via cascade transitions. To observe theforbidden transition directly, we have developeda Kingdon ion trap and have measured a purespectrum of the forbidden transition of 1s2–1s2ssuccessfully [7, 8].

4) Soft X-ray emissions from 1s2snp states:

Recently, we have observed the soft X-rayemissions corresponding to 1s22s–1s2snp (n = 2and 3) transitions of Li-like ions in collisions ofmeta-stable He-like ions, which are produced bythe ECRIS, with neutral gases [9].

References

[1] Snowden S L et al. 1994 Astrophys J. 424 714

[2] Lisse C M et al. 1996 Science 274 205

[3] Cravens T E 2000 Astrophys. J. 532 L153

[4] Fujimoto R 2007 Publ. Astron. Soc. Japan 59S133

[5] Kanda T et al. 2011 Phys. Scr. T144 014025

[6] Shimaya H et al. 2013 Phys. Scr. T156 014002

[7] Numadate N et al. 2014 Rev. Sci. Instrum. 85103119

[8] Numadate N et al. 2017 Nucl. Instrum. Meth. B408 114

[9] Numadate N et al. to be submitted


ISAMP TC-7, 6−8 January, 2018, Tirupati IA004E Tanuma

8

σ*-state mediated bond fission: Determining absolute branching fractions

for competing photoinduced bond fission processes.

Michael N.R. Ashfold,1 Matthew Bain, Christopher S. Hansen and Rebecca A. Ingle

School of Chemistry, University of Bristol, Bristol, U.K. BS8 1TS

Topic: A (or F)

Heterocycles are common chromophores in

the nucleobases and the aromatic amino-acids

that dominate the near ultraviolet (UV) absorp-

tion spectra of many biological molecules.

* excitations are responsible for the strong

UV absorptions, but such molecules also pos-

sess excited states formed from * electron

promotions. The * states typically have much

smaller absorption cross-sections, but can have

profound photophysical importance. We have

used photofragment translational spectroscopy

(PTS) methods and complementary ab initio

calculations to explore *-state mediated bond

fission following UV excitation of many such

heteroatom containing molecules in the gas

phase, and ultrafast pump-probe studies to in-

vestigate analogous processes in a number of

different solvents [1].

This presentation will address near UV pho-

toinduced S–H and S–C bond fissions in thio-

phenols, thioanisoles and thiophenes. We will:

1. Summarize the extent to which photophys-

ical insights gained from collision-free gas

phase photolysis studies of thiophenols and thi-

oanisoles can guide our interpretation of ultra-

fast pump-probe transient absorption studies of

the UV photofragmentation dynamics of similar

molecules in solution and vice versa [2];

2. Show how such solution phase studies of-

fer a route to exploring *-state mediated ring-

opening of heterocycles like thiophenes [3,4];

3. Review recent attempts to study the dy-

namics of photoinduced ring-opening processes

in the gas phase, using both traditional (Fig. 1)

[5] and novel multimass-detection, universal-

ionization, velocity-map imaging [6] methods.

4. Demonstrate how these recent advances in

photofragment ion imaging can be used to de-

termine absolute branching fractions for com-

peting bond fission processes, e.g. of the rival

C–S bonds in tert-butylmethylthioether.

Figure 1. Images of the Br(2P3/2) atoms formed by

photolysis of gas phase 2-bromothiophene molecules

at 266.6 nm (above) and 244.9 nm (below). The

electric vector of the photolysis laser radiation is

aligned vertically, and the image radii are propor-

tional to the fragment recoil velocity. The use of

more energetic photons yields slower Br atoms [4].

References

[1] M.N.R. Ashfold, et al., 2010, Phys. Chem.

Chem. Phys. 12, 1218.

[2] S.J. Harris, et al., 2013, Phys. Chem. Chem.

Phys. 15, 6567.

[3] M.N.R. Ashfold, et al., 2017, Annu. Rev. Phys.

Chem. 68, 63.

[4] M.N.R. Ashfold, et al., 2017, J. Phys. Chem. Letts.,

8, 3440.

[5] B. Marchetti, et al., 2015, J. Chem. Phys. 142,

224303.

[6] R.A. Ingle, et al., 2017, J. Chem. Phys. 147, 013914.

1 [email protected]

ISAMP TC-7, 6−8 January, 2018, Tirupati IA005F Ashfold

9

Elastic Scattering of H Atom by C60 and Kr@C60 : Calculation of Total Cross-Section and Time-Delay

KM. AKANKSHA DUBEY*, SHWETA AGRAWAL†, T. RAJGOPALA RAO†, JOBIN JOSE*1

* Department of Physics, Indian Institute of Technology Patna, Bihta – 801106, Bihar, India † Department of Chemistry, Indian Institute of Technology Patna, Bihta – 801106, Bihar, India

Top: A, B

Total scattering cross-section and time-delay for elastic collision of H atom with C60 and Kr@C60 have been studied theoretically in this work. We have taken primarily two cases-(a) H atom passing through hexagonal and (b) H atom passing through pentagonal ring of C60. Both the cases are compared and contrasted. We have thus tried to illustrate the contribution of con-fined Kr by analyzing the results of H+C60 and H+Kr@C60 scattering in each cases. Interaction-potential for H+Kr@C60 and H+C60 are computed in each case using DFT (B3LYP) method employing-631g*-basis set of GAUSSIAN16 set of codes [1]. This potential exhibits a double-humped barrier in the region of the boundary of C60 [2]. The barrier height is distinctively more for the case (b) than that for the case (a). This result in differences in the scattering parameters of our interest: cross-section and time-delay.

Time-independent Schrodinger equation has been solved numerically, using Numerov’s technique [3]. Corresponding partial phase-shifts (l(E)) are determined using partial wave-analysis of scattering theory in order to obtain the total cross-section. The total scattering cross-section for a particular value of l shows glory oscillations and two distinct resonances [4]. The origin of these resonances lies in the trapping of H atom by the C60 barrier [5]. Fig. 1 shows partial cross section of scattering for H+Kr@C60 collision for l=0. For case (a), the resonances are observed for energies lying between 0.14 to 0.15 a. u. Interestingly, these resonances fall on maxima or minima of glory oscillations depending on even or odd values of l. Consequently, this will determine the shape of the resonances. For case

(b), the resonance energies are shifted further. The energy range for resonances here is between 0.17 to 0.19 a. u.

Further, time-delay calculations have been performed based on Wigner-Eisenbud time-delay theory [6]. We observe that l=0 partial wave of the projectile experiences a maximum time-delay of 31.0 and 23.0 pico-seconds for case (a) and (b) respectively.

Figure1 Cross-section vs Energy curve for H+Kr@C60 collision for case (a) (Top axis) and case (b) (Bottom axis).

References

[1] M. J. Frisch et al. 2016 Gaussian 16 Revision A.03 [2]T.T.Vehvilainen et al. 2011 Phys. Rev. Lett. B 84 085447 [3]J. M. Thijssen, Computational Physics 2012 (Ox-ford Univ. Press) [4] S. Yu. Ovchinnikov et al. 2006 Phys. Rev. Lett. A 74 042706 [5] J. Peter Toennies et al. 1979 A. I. P. 71 614 [6] Wigner P. Eugene 1955 Phys. Rev. Lett. 98 145


ISAMP TC-7, 6−8 January, 2018, Tirupati IA006B Jose

10

Photoionization of polyatomic molecules: multi-slits type interferences, molecu-

lar fragmentation and ultrafast dynamics

R. K. Kushawaha*, 1

* Physical Research Laboratory, Ahmedabad – 380009, Gujarat, India

Topic: A (or E)

In this talk, the core- and inner-valence pho-

toionization of molecular systems will be dis-

cussed and recent findings on the Young’s dou-

ble-slit type oscillations in cross sections will be

reported. The signature of beyond the double-

slit type oscillation in cross section of butane

will be presented. A new method for estimating

the butane and anti-butane conformal equilibria

will be discussed.

Recent finding on isomer-dependent fragmenta-

tion dynamics of inner-shell photoionized

Difluoroiodobenzene based on coincidence im-

aging techniques will be covered in this presen-

tation. In this study, we conclude that the charg-

es on the di- and tri-cation delocalize on an ul-

trafast timescale, and in some fragmentation

channels of the tri-cation involve step-wise

fragmentation with a delay between the two

steps ranging from a few hundred femtoseconds

to picoseconds or longer. Finally, the molecular

alignment and probing the electronic and nucle-

ar wave packets by pump-probe scheme [3] will

be discussed in detail.

In PRL, we are developing a femtosecond laser

lab for studying the ultrafast processes in

atomic and molecular systems. In talk, I will be

explaining the details about planned

experiments.

References [1] Maria Novella Piancastelli et al., 2014 Journal

of Physics B: Atomic, Molecular and Optical Phys-

ics, 47, 124031

[2] Rajesh Kumar Kushawaha et al., 2013, PNAS.,

110 15201-15206.

[3] Artem Rudenko et al, 2016, Faraday Discuss.,

194, 463-478


ISAMP TC-7, 6−8 January, 2018, Tirupati IA007E Kushawaha

11

Probing quantum effects via X-ray spectroscopy

L.Natarajan

Department of Physics, University of Mumbai, Mumbai-400098

Topic A

In this talk, two extreme cases of atomic

configurations and the resulting radiative decay

are considered: a) only two electrons knocked

out and b) only two electrons present. In the

first case, an empty K shell with an otherwise

normal atomic configuration (hollow atoms) is

studied. The structureof the KαX-ray spectrum

from hollow atoms is the onlytesting ground

to prove LS,intermediate and JJ coupling

schemes. The effects of correlation that

influence the angular momentum coupling

scheme will be investigated by analyzing the

resonant and non-resonant transitions to empty

K shell from L subshells [1,2]. In the second

case, He-like ions with empty K shell and only

two electrons in the L shell are investigated. In

principle, the estimated reliable atomic data

should be independent of the choice of the

optimization approach, whether one uses relaxed

or frozen spin orbitals. This gets violated in

some unconventional non-resonant transitions

and shows a strong dependence of the estimated

line intensities of X-ray photons on the nature

of orthogonalization of the spin orbitals [3]. The

calculations are based on Multiconfiguaration

Dirac-Fock methods with the inclusion of finite

nuclear size and higher order corrections [4].

References [1] L.Natarajan 2008 Phys. Rev. A 78 052505

[2] Riddhi Kadrekar and L.Natarajan ,2010 J.Phys. B Atomic ,mol. and Opt.Phy 43 155001

[3] L.Natarajan, , 2014 Phy. Rev.A 90 032509

[4]P.Jonsson etal , 2013 Comp.Phys.Commun 184 2197

____________________________________________________________________________________________

Email: [email protected]

ISAMP TC-7, 6−8 January, 2018, Tirupati IA008 Natarajan

12

The Fullerene molecule: a super-attractive object for new spectroscopy

Himadri Chakraborty

Department of Natural Sciences, D.L. Hubbard Center for Innovation and Entrepreneurship, Northwest Missouri State

University, Maryville, Missouri 64468, USA

Topic: A, B

Empty fullerenes and atom-encaging

endofullerenes are quintessential symmetric

molecules exhibiting stability in the room tem-

perature. This property endows them with the

quality of being tested for spectroscopic infor-

mation which are otherwise inaccessible using

regular atoms or molecules. Probing the response

of these systems to radiations is one classic way

to access the dynamics in which the photoelec-

tron count as a function of energy predicts varie-

ties of resonances. These resonances from the

plasmonic electron motions [1] or the molecule’s

structural symmetry inducing diffractions [2] or

the mixing of both these effects in tandem. An

exotic genre of these resonances includes photo-

excitation at one site in the molecule and its sub-

sequent decay at a different location [3], the in-

ter-Coulombic decay (ICD). A coherent admix-

ing of the ICD mechanism with localized Auger

processes is a commonplace outcome [3,4].

Another contemporary form of spectroscopy

is the determination of the attosecond time-of-

flight of the photoelectron from its production-

site in the molecule to the detector. This may uti-

lize a Wigner clock based on the knowledge of

the energy-dependent quantum phase of bound-

continuum transitions. The Wigner time is abun-

dantly sensitive to the underlying electron correl-

ative dynamics, both at the energy region of the

giant plasmon resonance [5] and at generic

Cooper [6] and cavity [7] minima anti-reso-

nances.

By supporting the coherent and collective

electron motion, fullerenes are great candidates

for ion-impact studies as well. If the projectiles

are completely stripped off the bound electrons,

their interactions with a fullerene target can un-

leash pure plasmonic dynamics driven by the ion

field. Since the ion impact can render the target’s

non-dipole response significant, this method can

allow access to strong collective motions in

mono- and quadrupole ionization channels.

Finally, a brand new spectroscopic direction

emerges via the positronium (Ps) formation with

fullerenes as targets. Straddling the line between

atoms and condensed matters, Fullerenes support

quasi-free electron gas within a finite region of

well-defined boundary, as opposed to a longer-

range, highly diffused Coulomb-type boundary

characteristic of atoms and molecules. This en-

sures predominant electron capture from local-

ized regions in space spawning novel resonant

diffractions in Ps formation as a function of the

recoil momentum [8]. Impacting positrons can

also provide enough energy to excite fullerene

plasmons. Since these plasmon energies are de-

generate with the molecular ionization continua,

a large number of electrons will be resonantly

knocked out directly or via the endohedral

atomic emissions and thereby facilitating en-

hanced capture rates.

A selection of the results will be presented

which are computed by the density functional

method where the fullerene ion-core is jelli-

umized. The ground state of the molecule has

been described in a local density approximation

(LDA) framework where a linear-response vari-

ant of LDA, the time-dependent LDA (TDLDA),

is utilized to describe the interaction with the

field of external stimulus [9]. Results can probe

versatile territories of research applied to molec-

ular nanomaterials with novel experimental in-

terests.

The research is funded by the US National

Science Foundation.

References

[1] Madjet et al, 2007 Phys. Rev. Lett. 99, 243003

[2] McCune et al, 2009 Phys. Rev. A 80, 011201(R)

[3] De et al, 2016 J. Phys. B Letter 49, 11LT01

[4] Javani et al, 2014 Phys. Rev. A 89, 063420

[5] Barillot et al, 2015 Phys. Rev. A 91, 033413

[6] Dixit et al, 2013 Phys. Rev. Lett. 111, 203003

[7] Magrakvelidze et al, 2015 Phys. Rev. A 91,

053407

[8] Hervieux et al, 2017 Phys. Rev. A 95, 020701(R)

[9] Choi et al, 2017 Phys. Rev. A 95, 023404


ISAMP TC-7, 6−8 January, 2018, Tirupati IA009B Chakraborty

13

A three-dimensional ion imaging spectrometer for studying photo-induced

fragmentation in small molecules

R. Gopal1, A. Sen2, Anbu S. Venkatachalam3, Shilpa R. Sahu3, M. Anand1, V. Sharma3*

1Tata Institute of Fundamental Research, Sy. No 36/P, Gopanpally Village,Hyderabad 500107, India

2Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pashan, Pune 411008, India 3Department of Physics, Indian Institute of Technology, Hyderabad, 502285, India

Topic: A

We indigenously designed and constructed an ion

imaging spectrometer [1] to study photo-induced

fragmentation dynamics of molecules using

femtosecond laser pulses. The imaging spectrom-

eter is capable of recording three-dimensional ion

momentum and we illustrated capabilities of spec-

trometer through the momentum spectra of O+ ion

resulting from fragmentation of O2 in moderately

strong (~1013 W/cm2) femtosecond laser fields.

During presentation we also will present a recipe

for self-consistent calibration of kinetic energy

(KE) spectra by operating the spectrometer in a

non-imaging time-of flight mode. Consequently,

we can correlate KE spectra obtained in 2D imag-

ing mode to KE distributions extracted from time-

of-flight spectra to calibrate the images. The KE

distributions along with the angular distributions

allow us to assign pathways to the distribution for

even a complex molecule such as O2 which is

emphasized by the capability of distinguishing

vibrational levels.

References

[1] André T. J. B. Eppink and David H. Parker, Rev. Sci.

Inst, 68, 3477 (1997)

*E-mail: [email protected]

ISAMP TC-7, 6−8 January, 2018, Tirupati IA010 Sharma

14

Collision-induced dissociation of anions of astrophysical interest

G. Aravind* 1 and Roby Chacko*

2

* Department of Physics, IIT Madras, Chennai – 600036, Tamil Nadu, India

Topic: A

Anions have been only recently detected

in the interstellar medium (ISM) although E.

Herbst [1] predicted their presence more than

three decades earlier. Recent identification of

six carbon-containing anions such as

C6H¯(McCarthy et al. [2], C4H¯(Cernicharo et

al. [3], Gupta et al.[4]), C8H¯(Gupta et al. [4]),

and CnN ¯ (n= 1,3,5) (Agundez et al. [5]) moti-

vates the study of their stability and search for

other carbon containing anions in the astrophys-

ical environment.

Anion resonances are electronic states that

are embedded in the detachment continuum.

They play a vital role in the Astrochemistry.

ISM anions could be excited via photon or col-

lisional excitation under extreme situations

thereby accessing the resonances. The reso-

nances in polyatomic anions are complex poten-

tial energy surface leading to various dissocia-

tion pathways. The resonances thus determine

the formation and stability of anions in the ISM.

In this talk, we will discuss our experimental

results on collision induced dissociation of ISM

anions such FeO¯, FeC¯[6], CnN¯. Fast moving

ISM anions were made to collide with Argon

target resulting in collisional excitation to reso-

nance states. From these resonance states,

which are short-lived, forms the negatively

charged fragment ions. We have measured the

kinetic energy distributions of the fragments

and deduced the potential energy curves of the

resonances in case of the diatomic anions. The

resonances in CnN¯ show rich dissociation dy-

namics. We have employed the kinetic energy

distributions to identify the dissociation path-

ways. In this talk we shall discuss the im-

portance of our results on resonances in deter-

mining abundances of ISM anions and their sta-

bility.

References

[1] Herbst, E. 1981, Natur, 289, 656

[2] McCarthy et al. 2006 ApJ, 652, L141

[3] Cernicharo, J., et al. 2007, A&A, 467, L37

[4] Gupta et al. 2007, ApJ, 655, L57

[5] Agundez et al., 2010, A&A, 517, L2

[6] Nrisimhamurthy M., et al., 2016, ApJ, 833,

269

1 E-mail: [email protected]


ISAMP TC-7, 6−8 January, 2018, Tirupati IA011 Aravind

15

Quantum symmetry effects and isotopic effects in oxygen exchangereactions

T. Rajagopala Rao∗ 1,

∗ Department of Chemistry, IIT Patna, Bihta –801103 , Bihar, India

Topic: A

The O + O2 collision is now known to play akey role in the formation of atmospheric ozone,because it is closely related to the ozone forma-tion, O + O2 + M → O3 + M [1, 2, 3, 4, 5]. In-deed they proceed through the same O∗

3 interme-diate complex (excited ozone). An in-depth un-derstanding of the bimolecular isotope exchangereactions will therefore not only advance ourknowledge of complex-forming reactions in gen-eral, but also shed light on the mass independentfractionation of ozone.

We will show the results of an extremely com-putational intensive full-quantum investigationof the dynamics of the 16O + 32O2 collision andits isotopic variants, on a recent accurate globalpotential energy surface for the ground state ofozone [6]. Our study takes into account the indis-tinguishability of the three identical atoms andyield accurate cross sections and rate constants[7, 8, 9].

References

[1] K. Mauersberger 1981 Geophys. Res. Lett. 8, 935-937

[2] M. H. Thiemens and J. E. Heidenreich III 1983Science 219 1073-1075

[3] K. Mauersberger, B. Erbacher, D. Krankowsky, J.Gunther and R. Nickel 1999 Science 283 370-372

[4] Y. Q. Gao and R. A. Marcus 2001 Science 293259-263

[5] R. A. Marcus 2013 Proc. Natl. Acad. Sci. USA110 17703-17707

[6] R. Dawes, P. Lolur, A. Li, B. Jiang and H. Guo,2013 J Chem Phys 139 201103

[7] T. Rajagopala Rao, G. Guillon, S. Mahapatra andP. Honvault 2015 J. Phys. Chem. Lett. 6 633-636

[8] T. Rajagopala Rao, G. Guillon, S. Mahapatra andP. Honvault 2015 J. Chem. Phys. 142 174311

[9] T. Rajagopala Rao, G. Guillon, S. Mahapatra andP. Honvault 2015 J. Phys. Chem. A 119 11432-11439


ISAMP TC-7, 6−8 January, 2018, Tirupati IA012 Rao

16

Merging, splitting, orienting – towards ultracold stereodynamics

Sean Gordon, Junwen Zhou, Silvia Tanteri, Nikolaos Gkogkoglou, and Andreas Osterwalder1

Institute for Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), Switzerland

Topic: A

Merged neutral beams have enabled the investiga-tion of sub-Kelvin chemical reactions in molecular beams. In the past years we have conducted several Penning ionization studies of polyatomic molecules, targeting characteristics that arise from the presence of multiple rotational degrees of freedom and from the anisotropic shape of such systems are accessi-ble. Here I will give an overview of our recent ex-periments,[1] both in crossed and in merged beams, on stereo dynamical aspects where we orient, e.g., the angular momentum of a meta-stable rare gas atom prior to reaction. Strong orientation-dependent changes in the branching ratio between different reaction channels permit the determination of state-specific reaction cross sections for levels that differ only by their magnetic quantum number, and to do so in an energy range from 0.1 K to several 100 K.

I will also present a new method to produce electrically conductive structures for, e.g., high-voltage applications inside high-vacuum: the 3D printing of a plastic structure, followed by

electroplating. This approach opens many possi-bilities for the generation of scientific appa-ratus, and it will greatly simplify and accelerate the design, production, testing, and exchange of experimental components. We have recently used this method for the first time by printing the beam splitter for neutral polar molecules shown in figure 1.[2] With this device a single supersonic expansion is split, using electrostatic guides, into two nearly identical components. This permits, for example, differential measure-ments with correlated probe and reference beams.

Figure 1. Photograph of our 3D printed, electroplated beam splitter for molecular beams.[2]

References [1] Phys. Rev. Lett. 119, 053001 (2017). [2] Phys.Rev.Applied 7, 044022(2017).


ISAMP TC-7, 6−8 January, 2018, Tirupati IA013 Osterwalder

17

Excitation and ionization of atoms by twisted light

Stephan Fritzsche∗† 1

∗ Helmholtz-Institut Jena, 07743 Jena, Germany† Theoretisch-Physikalisches Institut, Universitat Jena, 07743 Jena, Germany

Topic: A

Optical vortex beams, often referred to astwisted light, have attracted much interest dur-ing the past 20 years. In particular, the spinand orbital angular momentum distributions ofsuch vortex beams have been explored theoreti-cally in good detail. Much less is known howeverabout their interaction with (clouds of) atomsand molecules, and how the orbital angular mo-mentum (OAL) of the incident light affects thephotoelectron emission or the subsequent fluo-rescence. In this work, I shall review and dis-cuss recent results from our group on the exci-tation and ionization of atoms by twisted light[1,2]. Emphasis will be placed especially on theinteraction of localized atomic targets and with(Bessel) beams of various intensity [3–5]

For weak vortex fields, the excitation ofatoms and ions is described most naturallywithin the framework of the density matrix the-ory [6,7]. General expressions were derived forthe alignment of the (excited) states as well asthe angular distribution of the subsequent flu-orescence emission, if excited by a Laguerre-Gaussian beam, a Bessel beam, or the coherentsuperposition of several such beams. For thesebeams, we have shown that, both, the relativepopulation of the magnetic substates as well asthe angular distribution of the fluorescence radi-ation, are sensitive to the transverse momentumand the (projection of the) total angular momen-tum of the incident radiation [8]. This agrees

nicely with recent observation [9], in which theexcitation of atoms, placed upon the axis of anincident Laguerre-Gaussian beam, was seen to bedetermined by the OAM of the beam. – A similarbehaviour has been found also for the scatteringof twisted electrons, although with a quite differ-ent physics behind.

References

[1] A. Surzhykov et al., 2015, Phys. Rev. A 91,013403.

[2] O. Matula, A. G. Hayrapetyan, V. G. Serbo,A. Surzhykov and S. Fritzsche, 2013, J. Phys. B46, 205002.

[3] A. Surzhykov, D. Seipt and S. Fritzsche, 2016,Phys. Rev. A 94, 033420.

[4] R. A. Muller et al., 2016, Phys. Rev. A 94,041402(R).

[5] B. Boning et al., 2017, Phys. Rev. A 96, 043423.

[6] V. V. Balashov, A. N. Grum-Grzhimailo andN. M. Kabachnik, Polarization and CorrelationPhenomena in Atomic Collisions (Kluwer Aca-demic/Plenum Publishers, New York, 2000).

[7] A. A. Peshkov et al., 2016, Phys. Scr. 91, 064001.

[8] A. A. Peshkov, D. Seipt, A. Surzhykov andS. Fritzsche, 2017, Phys. Rev. A 96, 023407.

[9] C.T. Schmiegelow et al., 2016 Nat. Commun. 712998.


ISAMP TC-7, 6−8 January, 2018, Tirupati IA014 Fritzsche

18

Low temperature chemistry using the R-matrix method

Jonathan Tennyson 1

Department of Physics and Astronomy, University College London, London WC1E 6BT, UK

Topic: A

A quiet revolution is occuring at the borderbetween atomic physics and experimental quan-tum chemistry. Techniques for producing coldand ultracold molecules are enabling the studyof chemical reactions and heavy-particle scatter-ing at the quantum scattering limit with onlya few partial waves contributing to the incidentchannel leading to the observation and even fullcontrol of state-to-state collisions in this regime.

We have developed a new R-matrix-based for-malism for tackling problems involving low- andultra-low energy collisions between heavy par-ticles [1]. This formalism is completely generaland could prove transformative in its scope. It isparticularly appropriate for slow collisions occur-ing over deep potential energy wells which sup-port many bound ro-vibrational states. Thesesystems support many quasibound or resonancestates. These resonances make such systems hardto treat theoretically but offer the best prospectsfor novel physics: resonances are being widelyused to control diatomic systems and should pro-vide the route to steering ultracold reactions.

The R-matrix method [2] involves divid-ing space into an inner and outer region. Inour method, the inner region exploits codesfor performing high-accuracy variational nuclear-motion calculations of molecular spectra whichhave bee developed over many years in my group[3, 4, 5]. The codes have already be used to com-pute wavefunctions up to [6] and above [7] dis-sociation, revealing interesting and unexpectedbehaviours [7, 8]. These variational nuclear mo-

tion methods are used to provide wavefunctions(both bound and continuum) for the whole sys-tem at short internuclear distances only. Thesecollision-energy-independent, inner-region wave-functions are then used to construct collision-energy-dependent R-matrices which can then bepropagated to asymptotia.

Progress on the project will be described in-cluding results of a series of test calculations onvarious systems including ultra-low energy Ar –Ar collisions.

References

[1] Tennyson J., McKemmish L.K., Rivlin T., 2016,Faraday Discuss, 195, 31.

[2] Burke P.G., 2011, R-Matrix Theory of AtomicCollisions: Application to Atomic, Molecular andOptical Processes, Springer.

[3] Yurchenko S.N., Lodi L., Tennyson J., StolyarovA.V., 2016, Computer Phys. Comm, 202, 262.

[4] Tennyson J. et al., 2004, Computer Phys. Comm,163, 85.

[5] Yurchenko S.N., Thiel W., Jensen P., 2007, J.Mol. Spectrosc., 245, 126.

[6] Mussa H.Y., Tennyson J., 1998, J. Chem. Phys,109, 10885.

[7] Zobov N.F. et al., 2011, Chem. Phys. Letts, 507,48.

[8] Munro J.J., Ramanlal J., Tennyson J., 2005, NewJ. Phys, 7, 196.


ISAMP TC-7, 6−8 January, 2018, Tirupati IA015 Tennyson

19

Dissociative electron attachment and dipolar dissociation dynamicsprobed by velocity slice imaging

Dhananjay Nandi 1

Department of Physical Sciences, IISER Kolkata, Mohanpur – 741246, West Bengal, India

Topic: A.

Electron collisions with gas phase moleculesleading to dissociative electron attachment(DEA) and dipolar dissociation (DD) have fun-damental as well as applications in variousbranches of science. DEA is a resonant processwhereas DD is a non-resonant process, however,the detecting particle(s) is/are anion(s) in boththe cases. Moreover, the associated particle af-ter the reaction is a neutral and a cation for DEAand DD process, respectively.

We developed a velocity slice imaging tech-nique to study detailed dynamics in the DEAand DD process at IISER Kolkata recently. Fewsimple molecules have been studied and obtainedvery interesting results that will be present inthe conference. The representative graphs showDEA and DD to carbon monoxide.

Detailed dynamical studies on DEAto CO showed that the involvement oftwo temporary negative ion (TNI) states.

Figure 1. (a) Velocity slice image of O− ion at 11

eV incident electron and (b) angular distribution of

the ions at 11 eV with the fitted curves.

The dynamics in the DD process hasbeen explained in the light of direct and in-direct excitation to the ion-pair states thateventually dissociate into anion and cation.

Figure 2. Fragmentation dynamics of ion-pair

states of carbon monoxide in electron collisions

through direct and indirect excitation.

References

[1] P. Nag et al. 2015 Phys. Chem. Chem. Phys. 177130

[2] S. X. Tian et al. 2013 Phys. Rev. A 88 012708

[3] K. Gope et al. 2016 Eur. Phys. J. D 70 134

[4] D. Chakraborty et al. 2016 Phys. Chem. Chem.Phys. 18 32973


ISAMP TC-7, 6−8 January, 2018, Tirupati IA017 Nandi

20

Electron dynamics in small atomic aggregates at He nanodroplets: multi-

coincidence spectroscopy

Sivarama Krishnan* 1

* Department of Physics, Indian Institute of Technology Madras, Chennai 600036, India

Topic: A.

We will present representative results from

our investigations of small atomic and molecu-

lar clusters attached to He nanodroplets interro-

gated by coincident photoelectron-photoion

spectroscopy at the Elettra synchrotron. When

photoexcited between 20…30eV across the

atomic ionization threshold of He, we find intri-

guing behaviour of the systems attached to the

host He droplets both by Penning transfer of

energy from the single-photon excited He ma-

trix to the dopant system, as well as by charge-

transfer from He to the dopant system when

photon energies were sufficient to directly ion-

ize the droplet [1, 2]. Using alkali, alkaline

earth [3] and rare gas dopant clusters as well as

small molecules attached to these droplets, we

explore the fascinating dynamics of these com-

plex atomic systems.

References

1) D Buchta, S R Krishnan, et al., The

Journal of chemical physics 139 (8), 084301

(2013).

2) ibid., The Journal of Physical Chemistry

A 117 (21), 4394-4403 (2013)

3) A C LaForge et al., Physical review let-

ters 116 (20), 203001.

ISAMP TC-7, 6−8 January, 2018, Tirupati IA018 Krishnan

21

Multichannel photoionization of polyatomic non-linear targetswithin the XCHEM approach: the H2O case study.

Jesus A. Lopez-Domınguez,† 1 Markus Klinker,† Carlos Marante,† Luca Argenti,†,‡ JesusGonzalez-Vazquez,† Fernando Martın†,§,∗ 2

† Departamento de Quımica, Modulo 13, Universidad Autonoma de Madrid, 28049 Madrid, Spain, EU‡ Department of Physics and CREOL College of Optics & Photonics, University of Central Florida, Orlando,

Florida 32816, USA§ Instituto Madrileno de Estudios Avanzados en Nanociencia (IMDEA-Nanociencia), Cantoblanco, 28049

Madrid, Spain, EU∗ Condensed Matter Physics Center (IFIMAC), Universidad Autonoma de Madrid, Spain, EU

Topic: A.

From a theoretical point of view, themain challenge when studying ionizing phe-nomena, is to obtain an accurate (and not-so-computationally expensive) representation of thesystem’s electronic continua. So far, most com-mercially available quantum chemistry packages(QCP) have excelled, to a very reasonable level,in implementing and refining methods to repre-sent bound molecular electronic states. Withthis in mind, efforts in our group to providea feasible and flexible enough method to de-scribe ionizing electronic continua for a widerange of systems has led to the developmentof a Hybrid Gaussian-B-spline basis (GABS) [1]which interfaces QCP, and altogether with close-coupling scattering methods have already provensuccessful in treating a variety of ionizing prob-lems, ranging from the photoionization of atomic[1] and molecular [2] hydrogen to polyelectronicatoms, He [2] and Ne [3], and even for the di-atomic N2 [4].

Following the aforementioned success in ac-counting for the electron correlation in the con-tinuum for different ionizing phenomena in poly-electronic atoms and even diatomic molecules,the subsequent natural pursue has been to trythe feasibility in terms of computational effortand physical accuracy of the method in describ-ing a polyatomic non-linear molecule, where thereduced symmetry, and thus, added angular de-pendencies play a major role in the correlationand exchange effects that shapes the continuumin, for example, a photoionization experiment.

The very nature of the GABS basis contain-ing, a large enough, pure Gaussian representa-tion of the electronic wave function in the ra-

dial region, allows for the use of QCP to de-scribe neutral and parent-ion states, and a setof added and pure B splines over the mid- andlong-range respectively, permits the accurate de-scription of scattering or photoionization observ-ables [1]. In the present work, we applied thismethod to theoretically study the multichannelphotoionization of H2O, including the (1b1)

−1,(4a1)

−1 and (2b2)−1 channels. Looking at the

total cross sections below the highest ionizationthreshold under consideration, several resonantfeatures are apparent, which are usually over-looked, and by looking at the cross sections for in-dividual channels and scattering symmetries, wewere able to determine the importance of inter-channel effects too. Although a continued effortexists on our side to improve current capabilitiesof our code, we expect that the results hereinshown, will suffice to convince of the usefulnessand potential of the XCHEM code approach tostudy such multichannel ionizing processes bothin atoms and molecules, providing the neededtools to study, among other things, the dynami-cal effects in photoionization.

References

[1] Marante C, Argenti L and Martın F 2014 Phys.Rev. A 90 102506

[2] Marante C, Klinker M, Corral I, Gonzalez-Vazquez J, Argenti L and Martın F 2017 J. Chem.Theory Comput. 13 499

[3] Marante C, Klinker M, Kjellsson T, Lindroth E,Gonzalez-Vazquez J, Argenti L and Martın F 2017Phys. Rev. A 96 022507

[4] To be published.

1E-mail: [email protected]: [email protected]

ISAMP TC-7, 6−8 January, 2018, Tirupati IA019 Lopez

22

Angular asymmetry of electron emission and ionization dynamics

Lokesh C Tribedi 1

Tata Institute of Fundamental Research, Colaba, Mumbai 400005, India

Topic: A

Ejected electron double differential distribu-

tions in collisions with atoms and molecules

carry the signature of different features of colli-

sion dynamics [1-15]. The angular distributions

for simple atoms can be described by some of

the Coulomb ionization models, such as, con-

tinuum distorted wave approximation etc. In

addition, the derived quantity such as forward

backward asymmetry which is to some extent

termed as angular anisotropy has been shown to

be sensitive to the collisional features, such as,

binary nature, post-collisional two center-

interaction, in atoms and small molecules in-

cluding water, Young type electron interference

in case of di-atomic molecules, collective exci-

tation in case of mesoscopic objects, fullerenes

or PAH-molecules, or size-effect in case of

DNA/RNA -bases The collision physics involv-

ing large molecules is closely related to inter-

disciplinary science whereas that involving

smallest di-atomic molecules, e.g. H2, N2 or O2

closely deals with fundamental quantum me-

chanical Cohen-Fano interference effect in a

molecular double-slit. The latest advances in

some of these features using electrons, photons

and ions will be emphasized will be presented.

References

[1] S. Biswas et al. 2015 Phys Rev A 92, 060701 (R)

[2] A. Kelkar et al, 2015 Phys Rev A 92 052708

[3] S. Bhattacharjee et al, 2016 J Phys B 49 065202

[4] A. Agnihotri et al, 2013 Phys Rev A 87 032716

[5] A. Agnihotri et al, 2012 Phys Rev A 85, 032711

[6] S. Kasthurirangan et al, 2013 PRL 111, 243201

[7] U Kadhane et al. 2003 PRL 90, 093401

[8] D. Misra et al. 2004 Phys Rev Letts. 92 153201

[9] D. Misra et al 2005, Phys. Rev Letts 95, 079302

[10] Ilchen et al.2014 Phys. Rev. Letts 112, 023001

[11] M. Roy Chowdhury et al 2016 PRA 94 052703

[12] M. Roy Chowdhury et al 2017 JPB 55, 155201

[13] M. Roy Chowdhuri et al 2017, EPJ D71, 218

[14] S. Bhattacharjee et al 2017 Euro P J D (in press)

[15] S. Bhattacharjee et al, 2017 PRA 96, 052707


ISAMP TC-7, 6−8 January, 2018, Tirupati IA020 Tribedi

23

Post Collision Interaction (PCI) Recapture of Photoelectrons in-

to Rydberg Orbitals: Electrons Playing Tag at Threshold

Yoshiro Azuma

* Faculty of Materials and Life Sciences, Sophia University, Chiyoda-Ku, Tokyo, JAPAN 102-8554

Topic: A

Inner-shell photoionization and photo-

excitation of atoms can be followed by further

ejection of electrons due to Auger effects. The

interaction of photoelectrons and Auger elec-

trons upon this process, the Post Collision Inter-

action (PCI) effects can provide fertile ground

for research on multi-electron dynamics involv-

ing multi-electron effects involving the continua.

The PCI effect is particularly prominent in the

photon energy region close to the photoioniza-

tion threshold. It is interesting to trace the com-

ing and going of PCI effects in various forms as

one varies the photon energy from way above

the photoionization threshold to well below. We

find it useful to define four photon energy re-

gions from above to below the photoionization

threshold as follows.

Region 0:

Way above photoionization threshold

where the photoelectron is much faster than the

Auger electrons. There is little chance for inter-

action between the photoelectron and the Auger

electron. The Auger electron peak exhibits the

Lorenzian line-shape manifesting the Auger

lifetime width.

Region 1:

Post Collision Interaction (PCI) effects ap-

pear as the shift and continuous tailing of the

photoelectron peak toward lower energy as well

as the shift and tailing of the Auger electron

peaks toward higher energy.

Region 2:

Then, as the photon energy is tuned lower,

very close above the threshold, photoelectrons

may return back and get recaptured into one of

the Rydberg orbitals of the final ionic state. Due

to energy conservation, this process manifests

as the Rydberg series structure of the ionic final

state imprinted exactly as narrow fine structures

in the wide Auger electron peak.

Region 3.

As the photon energy is made even lower,

going below threshold, the process will turn into

the resonant Auger process, i.e.photoexcitation

followed by a spectator Auger process which

can induce shakeup and or shakedown of the

photoexcited electron.

It is important to note that the above four

regions, distinct as they are in terms of physical

processes, nevertheless connect seamlessly

from one to another as the photon energy is var-

ied continuously.

The current status of research in each of

the above regions will be reviewed. In particu-

lar, new results on the photoelectron recapture

processes in region 2 show unexpected effects

due to dynamic correlation. Most of the previ-

ous research explained PCI processes in terms

of radial correlation between the photo- and

Auger electron. Nevertheless, our results on Kr

3d photoionization is dominated by prominent

conjugate processes due to the exchange of an-

gular momentum. For Xe 4d photionization,

Angular distributions of the Auger electrons

were measured, and variation of the patterns

were found not only depending on the angular

momentum state of the recaptured electron, but

the angular momentum state dependence itself

depended on the principal quantum number.

In recent years, quantum entanglement has

been found to be more and more ubiquitous in

various atomic processes. Nevertheless, some

unique type of manifestations in the photoelec-

tron recapture processes are worth pointing out.

References

[1] H. Aksela, M. Kivilompolo, E. Nommiste and S.

Aksela, Phys. Rev. Lett. 79, 4970 (1997).

[2] S. Kosugi, M. Iizawa, Y. Kawarai, Y. Kuriyama,

A.L.D. Kilcoyne, F. Koike, N. Kuze, D.S. Slaughter

and Y. Azuma, J. Phys. B 48, 115003 (2015).


ISAMP TC-7, 6−8 January, 2018, Tirupati IA021 AzumaY

24

Dosimetry of ionizing radiations in biological tissues: Importance of calculations at a microscopic scale

Champion Christophe* 1

* Centre Lasers Intenses et Applications, Université de Bordeaux, Bordeaux, France

Topic: A.

When biological matter is irradiated by charged particles, a wide variety of interactions occur, which leads to a deep modification of the cellular environment. To understand the fine structure of the microscopic distribution of en-ergy deposits, the Monte Carlo event-by-event simulations are particularly suitable. However, the development of these track structure codes requires a large set of accurate multiple differ-ential and total cross sections for describing all the collision processes including the ionization, the electronic excitation, the elastic scattering and the Positronium (Ps) formation event when incident positrons are considered.

In this context, we have recently developed a Monte Carlo code for electron and positron tracking in water. All the processes are studied in detail via theoretical differential and total cross section calculations performed within the quantum mechanical framework. Comparisons with existing theoretical and experimental data in terms of stopping powers, mean energy trans-fers and ranges have shown a very good agree-ment. Moreover, thanks to the theoretical de-scription of Ps formation, we access to the complete kinematics of the electron capture process [1-2]. Then, the current Monte Carlo code is able to describe the detailed Ps history, what provides useful information for medical imaging (like Positron Emission Tomography) where improvements are needed to define with the best accuracy the tumor volumes [3-4].

Besides, recent quantum mechanical models for treating the electron-induced ionization pro-cess in a realistic biological medium have been implemented into the code in order to extend its applications. Thus, an accurate description of biological volumes of interest - including the nucleobases as well as the sugar phosphate backbone - may be considered in the current version [5,6].

A detailed overview of the code will be ex-posed along this talk with in particular its relat-ed version - called CELLDOSE - devoted to absorbed dose calculation in nanometer-size volumes for radio-isotopes of medical interest [7-8] providing accurate quantities such as dose point kernel (DPK) functions and S-values that are commonly used in radiopharmaceutical do-simetry (see Figure).

Figure 1. Dose profile (S-value) within concentric shells of 10-µm thickness.

References [1] Champion C et al. Phys. Med. Biol. 51 1707 (2006). [2] Champion C et al. Phys. Med. Biol. 52 6605 (2007). [3] Champion C et al. J. Nucl. Med. 49 151 (2008). [4] Zanotti-Fregonara P et al. J. Nucl. Med. 49 679 (2008). [5] Champion C et al. Int. J. Radiat. Biol. 88 No.1-2 62 (2012). [6] Champion C J. Chem. Phys. 138 184306 (2013). [7] Champion C et al. J. Nucl. Med. 49 151-157 (2008). [8] Zanotti-Fregonara P et al. Health Phys. 97(1) 82-85 (2009).

1 e-mail: [email protected]

ISAMP TC-7, 6−8 January, 2018, Tirupati IA022 Champion

25

Spectroscopic studies and quantum chemical investigationsof (3, 4−dimethoxybenzylidene) propanedinitrile

Yugal Khajuria∗1

∗ School of Physics, Shri Mata Vaishno Devi University, Kakryal,Katra−182320, Jammu & Kashmir, India

Topic: A

The Fourier Transform Infrared (FTIR),Ultra-Violet Visible (UV-Vis) spectroscopy andThermogravimetric (TG) analysis of (3, 4-dimethoxybenzylidene) propanedinitrile have beencarried out and investigated using quantum chemi-cal calculations. The molecular geometry, harmonicvibrational frequencies, Mulliken charges, naturalatomic charges and thermodynamic properties in theground state have been investigated by using HartreeFock Theory (HF) and Density Functional Theory(DFT) using B3LYP functional with 6-311G(d,p)basis set. Both HF and DFT methods yield goodagreement with the experimental data. Vibrationalmodes are assigned with the help of Vibrational en-

ergy distribution analysis (VEDA) program. UV-Visible spectrum was recorded in the spectral rangeof 190-800 nm and the results are compared with thecalculated values using TD-DFT approach. Stabilityof the molecule arising from hyperconjugative in-teractions, charge delocalization have been analyzedusing natural bond orbital (NBO) analysis. The re-sults obtained from the studies of Highest OccupiedMolecular Orbital (HOMO) and Lowest Unoccu-pied Molecular Orbital (LUMO) are used to calcu-late molecular parameters like ionization potential,electron affinity, global hardness, electron chemicalpotential and global electrophilicity.


ISAMP TC-7, 6−8 January, 2018, Tirupati IA023 Yugal

26

Acceleration of neutral atoms in laser produced plasmas

M. Krishnamurthy1

Tata Institute of Fundamental research. Homi Bhabha Road, Mumbai - 400 005

TIFR center for inter-disciplinary sciences, Narasinghi, Hyderabad - 500 107

Topic: A.

Intense laser pulse focused on solid sub-

strate are well known to generate high density

high temperature plasma. Electron and ion

emission to a few MeV with laser intensities

close to the relativistic intensities are well stud-

ied. The question we ask is about the possibility

of tuning the compact charge particle accelera-

tion schemes to generate neutral atoms beam of

the energy same as that of ions As intense laser-

produced plasmas have been demonstrated to

produce high-brightness-low-emittance beams,

it is therefore possible to envisage generation of

high-flux, low-emittance, high energy neutral

atom beams in length scales of less than a mil-

limeter. Feasibility of such a high energy neu-

tral atom accelerator could significantly impact

applications in neutral atom lithography and

diagnostics. We demonstrate [1] in this talk that

it is possible to device a scheme where in nearly

80% of the accelerated ions of heavy atoms like

Cu generated at the target front can be reduced

to neutral atoms. We find that adjusting the la-

ser focal waist provides an optimal control of

the pre-plasma and can be tuned to alter the

neutralisation efficiency.

Generating and analysing a beam of high en-

ergy neutral atoms is a challenge that is im-

portant for many technological application. In

lithographic applications, high energy neutral

atoms result in higher finesse structures than

those produced with charged particle beams.

High energy hydrogen atom beams play an im-

portant role in Tokamak diagnostics. A 15 de-

gree conical emission of neutral atoms with en-

ergy as large as MeV is likely impact the possi-

ble neutral atom beam applications.

References

[1] Compact acceleration of energetic neutral atoms

using high intensity laser-solid interaction, Malay

Dalui, T. Madhu Trivikram, James Colgan, John

Pasley, and M. Krishnamurthy Sci. Rep. (2017)


ISAMP TC-7, 6−8 January, 2018, Tirupati IA024 Krishnamurthy

27

LTE condition validation by plume characterization in laser produced plasmas

K P Subramanian* 1, B G Patel†, and Prashant Kumar*

* Physical Research Laboratory, Ahmedabad – 380009, Gujarat, India † Institute for Plasma Research, Bhat, Gandhinagar – 382428, Gujarat, India

Topic: E & A

The laser produced plasmas (LPP) are exten-

sively been studied for past many decades, and

its application ranges from realization of table-

top accelerators to fabrication of thin films,

nano-tubes etc. Another area which has received

a lot of contribution from LPP studies is the la-

ser induced breakdown spectroscopy (LIBS).

LIBS is now emerging as an important diagnos-

tic tool for the quantitative estimation of ele-

mental concentrations in a sample.

In LIBS, the line emissions from the LPP are

analyzed to identify the elements present in a

sample as well as their concentration fraction.

In the LIBS technique, the existence of LTE is

the essential requisite for the application of

Boltzmann and Saha equations that relate

fundamental plasma parameters and

concentration of sample species. The most

popular criterion reported in the literature

dealing with plasma diagnostics, and usually

invoked as a proof of the existence of LTE in

the plasma, is the McWhirter criterion [1]. Ac-

cording to this criterion, the collisional depopu-

lation rates for all electronic levels of the atom

are to be at least ten times larger than the radia-

tive depopulation rate. In this way, it could be

established that collisional processes prevail

over radiative processes and deviations from

LTE are negligible.

Plume homogenization by the way of ambi-

ent gas mixing give certain vital information

regarding the LTE validity regime. In an exper-

iment, the LPP and laser blow-off (LBO) plume

evolutions are studied in detail. Attempts are

made to check the validity of invoking the Ray-

leigh-Taylor instability for the rupture of evolv-

ing plume boundary in an ambient gas [2].

Figure 1. Shock wave to drag model change-over

exhibited by Al, Cu and Pb LPP plumes. Black curve

is the distance of the plume front from the target and

red curve is the time when the change-over happens.

Further, studies are conducted to investigate the

transition of the evolving plume from the descrip-

tion of shock wave to drag model. It is found that

the length of the evolved plume boundary (from

target) and time (measured from the laser firing) at

which the plume-model switch-over is happening,

are dependent on the atomic mass of the evolving

plasma species (see Figure 1). This gives us a clue

that the 'delay' and 'gate' used in LIBS experiment

may be dependent of the atomic mass of the sample.

Details of the studies will be presented in the

conference.

References

[1] R.W.P. McWhirter, in: "Plasma Diagnostic

Techniques", (Eds. R.H. Huddlestone, S.L. Leonard)

1965 Academic Press, New York 201–64.

[2] Ajai Kumar et. al 2006 J. Phys. D: Appl. Phys.

39 4860–66

.


ISAMP TC-7, 6−8 January, 2018, Tirupati IA025E Subramanian

28

Attosecond Physics at the Nanoscale

M. F. Ciappina∗ 1

∗ Institute of Physics of the ASCR, ELI-Beamlines project, Na Slovance 2, 182 21 Prague, Czech Republic

Topic: B

Recently two emerging areas of research, at-tosecond and nanoscale physics, have startedto come together. Attosecond physics dealswith phenomena occurring when ultrashort laserpulses, with duration on the femto- and sub-femtosecond time scales, interact with atoms,molecules or solids. The laser-induced electrondynamics occurs natively on a timescale down toa few hundred or even tens of attoseconds (1 at-tosecond = 1 as = 10−18 s), which is comparablewith the optical field. For comparison, the revo-lution of an electron on a 1s orbital of a hydrogenatom is ∼ 152 as.

On the other hand, the second branch in-volves the manipulation and engineering of meso-scopic systems, such as solids, metals and di-electrics, with nanometric precision. Althoughnano-engineering is a vast and well-establishedresearch field on its own, the merger with intenselaser physics is relatively recent.

We present in this talk a comprehensive ex-perimental and theoretical overview of physicsthat takes place when short and intense laserpulses interact with nanosystems, such as metal-lic and dielectric nanostructures. In particularwe elucidate how the spatially inhomogeneouslaser induced fields at a nanometer scale modifythe laser-driven electron dynamics (see Fig. 1 fora sketch of conventional and plasmonic-enhancedstrong field processes).

Consequently, this field characteristic has im-portant impact on pivotal processes such asabove-threshold ionization (ATI) and high-orderharmonic generation (HHG). The deep under-standing of the coupled dynamics between thesespatially inhomogeneous fields and matter config-ures a promising way to new avenues of researchand applications. Thanks to the maturity that

attosecond physics has reached, together withthe tremendous advance in material engineeringand manipulation techniques, the age of atto-nano physics has begun, but it is in the initialstage. We present thus some of the open ques-tions, challenges and prospects for experimentalconfirmation of theoretical predictions, as well asexperiments aimed at characterizing the inducedfields and the unique electron dynamics initiatedby them with high temporal and spatial resolu-tion [1].

(a)

(b)

input pulse

1013—1014 W/m2

Detector

e–

xuv

Detector

interaction region [µm]

gas jet

input pulse

1010—1011 W/m2 interaction region [nm]

xuv

metal nanostructure

Detector

Detector

e–

enhanced laser field

gas atoms

Figure 1. Sketch of conventional (a) and

plasmonic-enhanced (b) strong field processes.

References

[1] M. F. Ciappina et al. 2017 Rep. Prog. Phys. 80,054401


ISAMP TC-7, 6−8 January, 2018, Tirupati IB001 Ciappina

29

Wigner photoionization time delay studies of the neon 2s → np autoionization resonances

Hari R. Varma

School of Basic Sciences, IIT Mandi, Mandi –175005, Himachal Pradesh, India

Topic: B

Recent developments in attosecond science have enabled study of electron correlation in the time domain. A deeper understanding of electron correlation and relativistic interactions can be extracted from the time delay studies[1]. Time-delay associated with the photoionization dynamics is directly related to the energy deriv-ative of the phase of the transition matrix ele-ment. Hence significant modulation in time de-lay is expected in regions where phase varies rapidly (e.g. Cooper minimum, autoionization resonances, shape resonances and confinement resonances etc ). Many of the previous work have reported time delay studies in the region of Cooper minimum while studies in the region of autoionization resonances are scanty[2, 3].

The present study report the intrinsic Wigner-Eisenbud-Smith time delay in the 2s → np au-toionization resonance region of atomic Neon. Here we report the results using an ingenious combination of relativistic random phase ap-proximation (RRPA) and relativistic multichan-nel quantum defect theory(RMQDT). The cal-culations are performed at two different levels of truncation of the RRPA which enable an ex-amination of the role of various ionization/exci-tation channels in the dynamics. Following trun-cation levels are employed:

(i) 7 relativistic channels from 2p and 2s: 2p3/2

→ εd5/2, εd3/2, εs1/2; 2p1/2 → εd3/2, εs1/2; 2s1/2 → kp3/2, kp1/2;(ii) 3 relativistic channels from 2p and 2s: 2p3/2

→ εd5/2; 2s1/2 → kp3/2, kp1/2;

In Figure 1 shown the time delay obtained across the 2s → 3p autoionization resonance re-gion using RRPA and RMQDT with 7 channel calculation. It shows that photoionization time delay across the resonance region takes both positive and negative values; initially positive and then changes to negative. It is to be noted that the magnitude of time delay in the reso-

nance region (~pico seconds) is several order higher compared to the non-resonance region (~atto seconds). It is further found that, the min-imal correlation required to produce the nega-tive time delay is the presence of at least two continuum channels. The flip in the sign of time delay disappears when the calculations are performed at a 3 channel level where only one continuum channel 2p3/2 → εd5/2 is present. The contrast in the behavior of time delay profile in 7channel and 3 channel calculations indicate the importance of including all of the relevant chan-nels in dealing with the resonance region.

Figure 1. Phase shift and time delay for the 7ch calculation for Ne 2s → 3p resonance region

An attempt is made to suggest an empirical for-mula for time delay in resonance region using the powerful Fano parametrisation techniques . The result obtained using Fano analysis is also shown in the figure (red curve) which nearly re-produce the qualitative and quantitative aspects of the RRPA+RMQDT curve. The results ob-tained for the higher members of resonat series and its detailed analysis will also be presented.

References[1] Pazourek et al. 2015. Rev. Mod. Phy. 87, 765 [2] Saha et al. 2014, Phys. Rev. A 90 053406 [3] Gruson et al. 2016, Science 354 734


ISAMP TC-7, 6−8 January, 2018, Tirupati IB002 Varma

30

Aspects of single-photon ionization of molecules with implications for Wigner time delay and high-harmonic generation

Robert Lucchese* 1

* Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA

Topic: B. Wigner time delay in collisions and photoionization

The relative phases of photoionization ma-trix elements contributing to the same process are important in determining a number of as-pects of the photoionization process. In molec-ular photoionization, the relative phases of dif-ferent partial waves contributing to the same ionization process determine the molecular-frame photoelectron angular distributions (MFPADs). The energy dependence of such phases can be related to the Wigner time delay. General features of the molecular photoioni-zation and their effects on the phase will be giv-en, including shape-resonances, autoionization resonances, and geometry dependence of the matrix elements. Additionally, the effects of correlation and the strong energy dependence of the Coulomb phase will be discussed. In Fig. 1 we see the effects of a shape reso-nance on the phase and magnitude of the pho-toionization matrix of N2 for ionization form the 3σg orbital. These matrix elements have been used to interpret measured group delays in the photoionization of N2. [1]. Beyond single-photon ionization, the dipole matrix elements in photoionization can be used to understand strong field processes. In particu-lar high-harmonic generation (HHG) can be modeled using the quantitative rescattering (QRS) model, in which one essential element is the matrix elements for photo-recombination of an electron scattering from a molecular ion. The photo-recombination elements can be computed using the same computational tools as are used to compute photoionization matrix el-ements. In particular, the photorecombina-tion matrix elements can be obtained from pho-toionization matrix elements by time reversal. Thus features found in photoionization, will al-so affect high-harmonic yields. A discussion of shape resonances and inter-channel coupling in the high-harmonic genera-tion by SF6 [2] will be discussed where the three highest occupied orbitals all contribute to the HHG signal.

-6

-4

-2

0

2

Phas

e of

Mat

rix E

lem

ent

10080604020

Photon Energy (eV)

0° 15° 30° 45° 60° 75° 90°

4

3

2

1

0

Mag

nitu

de o

f Mat

rix E

lem

ent

10080604020Photon Energy (eV)

0° 15° 30° 45° 60° 75° '90°

Figure 1. Phase and magnitude of photoionization ma-trix elements for N2 in the direction of the polarization of the ionizing radiation.

References [1] Schoun S B, Camper A, Salières P, Lucchese R R, Agostini P and DiMauro L F 2017 Phys. Rev. Lett. 118 033201 [2] Wilson B P, Fulfer K D, Mondal S, Ren X, Tross J, Poliakoff E D, et al 2016 J. Chem. Phys. 145 224305


ISAMP TC-7, 6−8 January, 2018, Tirupati IB004 Lucchese

31

Control of helicity of high-harmonic radiation using bichromatic circularly po-larized laser fields

Gopal Dixit* 1, Álvaro Jiménez-Galán†, Lukas Medišauskas#, and Misha Ivanov†

* Department of Physics, Indian Institute of Technology Bombay Mumbai 400076 India † Max-Born-Institute, Max-Born Strasse 2A, 12489 Berlin, Germany

# Max-Planck Institute for the Physics of Complex Systems, Noethnitzer Strase 38, 01187 Dresden, Germany

Topic: B. Wigner time-delay in collisions and photoionization

High harmonic generation in two-color (ω-2ω) counter-rotating circularly polarized laser fields opens the path to generate isolated attosecond puls-es and attosecond pulse trains with controlled ellip-ticity. Microscopically, to achieve high ellipticity, it is advantageous to generate the harmonics from atoms with p-type ground state over s-type ground state. Indeed, for the s-type state successive har-monics have equal amplitude but opposite helicity, yielding isolated attosecond pulses and attosecond pulse trains with linear polarisation, rotated by 120 degree from pulse to pulse.

In this work, we suggest a solution to over-come the limitation associated with the s-type ground state. It is based on modifying the three propensity rules associated with the three steps of the harmonic generation process: ionization, propagation, and recombination. We control the first step by seeding high harmonic generation with XUV light tuned below the ionization threshold, which populates bound states that co-rotate with the ω-field. We control the propagation step by increasing the intensity of the ω-field relative to the 2ω-field, further enhancing the chance of the ω-field being absorbed versus the 2ω-field, thus favoring the emission co-rotating with the seed and the ω-fields. If, on the other had, we seed with the radiation that co-rotates with the 2ω-field, we have a conflict between the ionization and the propagation steps, decreasing the contrast in the intensity of successive high harmonics. We demonstrate our proposed control scheme using Helium atom as a target and solving time-dependent Schroedinger equation in two and three-dimensions. 1 E-mail: [email protected]

ISAMP TC-7, 6−8 January, 2018, Tirupati IB005 Dixit

32

Quantum Hall states in optical lattices

Rukmani Bai∗† 1, Soumik Bandopadhyay∗† 2, Sukla Pal∗ 3, Kuldeep Suthar∗ 4, DilipAngom∗ 5,

∗ Physical Research Laboratory, Ahmedabad-38009, India, † Indian Institute of Technology, Palaj,

Gandhinagar-382355, India

Topic: C

The observation of quantum Hall states inBose-Einstein condensates is close to experimen-tal realization with the recent developments of in-troducing synthetic magnetic field in optical lat-tices. In this work we examine the quantum Hallstates in parameter domains close to the Mottlobes and between the Mott lobes. Earlier workshave focused on the quantum Hall states in opti-cal lattices and close to the Mott lobes. However,

experiments with optical lattices are performedwith a background confining potential. So, it isessential to incorporate it in the theoretical de-scriptions of the experimental results, or to studythe expected signatures of quantum Hall statesin optical lattices. In our studies we have con-sidered a harmonic confining potential, and ourresults show what are the expected signatures ofquantum Hall states in these systems.

1E-mail: [email protected]: [email protected]: [email protected]: [email protected]: [email protected]

ISAMP TC-7, 6−8 January, 2018, Tirupati IC001 Angom

33

Long Time Evaluation of Bose-Einstein Condensate in a Toroidal Trap

Jayanta Bera1 † and Utpal Roy1 *

1 Indian Institute of Technology of Patna, Bihta, Patna, Bihar- 801103 Topic: C In recent times, experimental observations of vari-ous novel phenomena in the system of Bose-Einstein condensate (BEC) with long coherence time have established it as one of the most appro-priate candidates to observe and apply towards quantum technology. Theoretical developments, although nontrivial due to the nonlinear nature of the dynamical equation, are of huge importance to understand the physics of formation and dynamics of the system in a transparent manner. There have been continuous emphasizes to the applications of BEC towards quantum optics, quantum informa-tion, weak measurement, higher harmonic genera-tion, frustrated optical lattices etc. The dynamical equation for this quantum system, namely, Gross-Pitäevskii equation (GPE), is widely used for weak interatomic interactions. Incorporating various ex-ternal confinements, further makes the dynamics richer and tunable to achieve coherent control. In this work, we consider two condensates formed in the opposite corners of a toroidal trap. Our ap-proach is to solve the corresponding dynamical eq-uation, numerically. Ultraclod atoms in a ring shaped trap is already been observed [1]. Two con-densates at diametrically opposite points of a to-roidal potential radially expand along their curva-ture. After certain time during their course of ex-pansion, the clockwise and anti-clockwise probabil-ities start merging each other, bringing out quantum interference structures [fig. (1)]. Similar interfe-rences due to expended condensate is also studied for some situations [2]. Explanation of the dynamics and splitting of the consensate into several parts becomes possible us-ing the theory of superposition, only till the two components get completely mixedup. However, it becomes quite nontrivial to understand the splitting in a later time. It is observed that the dynamics re-peat after a certain time, which is designated as re-vival time (Trev). We have also studied the auto-correlation function and the corresponding position space 2D probability densities at various important time intervals. The nonlinear nature of the system starts contributing and the dynamics shows revival and fractional revivals.

Figure 1: Two condensates start merging (t = 5.85) after evolving from the initial positions at two diagonally op-posite points.

Figure 2: Autocorrelation function for longer evolution time where t = 187.3 is the revival time. The autocorrelation function is investigated for the whole revival time period [fig. (2)]. It is apparent that the peaks at regular intervals are clear signa-tures of nonlinearity in the energy spectrum. The formation of the regular peaks are similar to the pure quantum system, where a wave packet is visu-alized as a combination of several eigen states and the dynamics is governed by nonlinear enery spec-trum. However, ultracold atomic cloud is a many body system modeled by an order parameter, where understanding long time evolution of a condensate becomes quite nontrivial and our analysis paves the way to reveal the same.

References: [1] S. gupta et al., (2005), Phys. Rev. Lett,. 95, 143201; W. Rooijakk-ers, (2004), Appl. Phys. B: Laser Opt. 78, 719; L. Amico et al., (2005), Phys. Rev. Lett., 95, 063201. [2] T. A. Bell et al., (2016), New J. Phys., 18, 035003. * E-mail: [email protected] † E-mail: [email protected]

ISAMP TC-7, 6−8 January, 2018, Tirupati IC002 Roy

34

Precision measurements with trapped ions

Manas Mukherjee*12, Dahyun Yum1 and Tarun Dutta1

1 Department of Physics, NUS, Singapore – 117551, Singapore 2 Centre for Quantum Technologies, Science drive 2, NUS, Singapore – 117543, Singapore

Topic: C D

Trapped and laser cooled barium ion is a system of choice for atomic weak interaction studies. The presence of large number of neu-tron and protons provides an amplification of parity mixing of the electronic states due to electro-weak interaction. Based on the original proposal of N. Fortson to measure the atomic parity violation (APV), we have developed a method of enhancing the effect by using corre-lated atomic states using an entangled pair of ions. However from the experimental point of view the APV measurement still needs some precursor measurements to be performed. One of them is to measure the involved dipole ma-trix elements with a precision comparable to the seminal Cs experiment [1]. We have developed and measured the most sig-nificant matrix elements in barium ion with a precision surpassing the cesium results for the same matrix elements. As observed in figure 1, our measured values for the transition probabili-ties clearly differentiate between the theory val-ues. This allows different theoretical results to benchmark against experiment with a precision well below one percent. This work is based on the development of a barium ion qubit setup which is also used for quantum information processing.

Figure 1. The measured values of transition proba-bilities as well as the theoretical values calculated by different groups are shown. The references are as in [1].

In this talk, the experimental setup will be dis-cussed in details along with the recent results and some outlook for the ongoing or future ex-periments.

References [1] T. Dutta et al. 2016 Sci. Rep. 6, 29772 * E-mail: [email protected]

ISAMP TC-7, 6−8 January, 2018, Tirupati IC003D Mukherjee

35

Atoms, molecules and ions in cavities

Rahul Sawant, Sourav Dutta, Tridib Ray, S. Jyothi, Arijit Sharma and S. A. Rangwala* 1

* Raman Research Institute, C. V. Raman Avenue, Sadashivanagar, Bangalore 560080, Karnataka, India

Topic: D

The coupling between light and matter can be

manipulated over a range from the very weak to

the very strong. In quantum optics such a range

of atom-light coupling is engineered at low light

intensities. This is done in part by tuning the

light on atomic resonance or slightly detuning it

with respect to the appropriate atomic reso-

nance. Further enhancement of atom-light cou-

pling is enabled by interacting station-

ary/trapped atoms with a single mode of light,

in a Fabry-Perot cavity. In such experiments,

which allow very precise control, multiple as-

pects of atom-light interactions can be investi-

gated.

It is then tempting to ask how far we can push

the cavity coupled systems in order to tease the

answer to experimentally difficult questions.

We present several instances in which a cavity

can be used to measure elusive properties of

light coupled with atoms, ions, molecules and

interactions between them. Specifically we are

interested in the non-destructive measurements

of interactions between cavity coupled atoms

and cotrapped ions/molecules and the non-

destructive detection of state selected mole-

cules.

For our experimental system, by construction

we cannot put a single atom in collective strong

coupling with a cavity mode. Instead what we

routinely do is attain collective strong coupling

of laser cooled atoms with the FP cavity. In

such a system we see vacuum Rabi splitting of

externally scanned probe light through the cavi-

ty, when probing on a closed transition. When

the coupling is probed in an open transition, the

VRS disappears as the atoms are optically

pumped out of the cavity coupled transition [1].

This is a serious problem when one wants to

probe a multiple level molecule using the same

technique.

In the above experiment the atoms were optical-

ly pumped into a particular ground state before

probing, and then released from the trap while

probing. A more effective way is to construct a

dark MOT. Such a MOT has all the trapped at-

oms optically pumped into a specific atomic

ground state. The trapped atoms can then be

continuously probed and VRS can be observed

once again [2]. This VRS can now be used as a

means to non-destructively detect ions co-

trapped with the cold atoms. The ions by virtue

of being more energetic than the atoms will de-

plete the atoms and affect the collective strong

coupling of the atoms to the cavity. The meas-

ure of the atom depletion is directly related to

the ion-atom collision rate and this allows the

determination of the density of the trapped ions

in the cavity mode [3].

The challenge of detecting complex multi-level

atoms and molecules is then taken up. In our

previous experiment [1] this was not possible

without repopulating the cavity coupled ground

state, This deficiency can be overcome by a

suitable choice of cavity and system parameters,

which should allow the measurement of a VRS

signal for complex atoms and molecules so that

the range of the cavity coupled system as a ge-

neric measurement tool is greatly extended [4].

Finally we examine what happens when bright

atoms are coupled to the cavity. In such a case,

as the cavity length is scanned, for each spatial

mode, two spectrally proximate peaks are ob-

served. It is then found that one of these two

peaks is a laser and the mechanism for this is

discussed. In such a system the population of

the system does not invert [5].

References [1] T. Ray, A. Sharma, S. Jyothi, and S. A. Rangwala, Phys.

Rev. A 87, 033832 (2013). [2] S Dutta, SA Rangwala, Applied Physics Letters 110 (12),

121107

[3] S Dutta, SA Rangwala, Physical Review A 94 (5), 053841

[4] Rahul Sawant, Olivier Dulieu and SA Rangwala,

Under preparation

[5] Rahul Sawant, SA Rangwala. Scientific Reports 7,

Article number: 11432 (2017)

1.E-mail: [email protected]

ISAMP TC-7, 6−8 January, 2018, Tirupati ID001 Rangwala

36

Quantum measurement and control of a mechanical oscillator

V. Sudhir∗ 1, D. Wilson, S. Fedorov, H. Schutz, R. Schilling, T. J. Kippenberg†

∗ LIGO Laboratory, Massachusetts Institute of Technology, Cambridge, USA† Institute of Physics, Ecole Polytechnique Federale de Lausanne, Switzerland

Topic: D. Trapping and manipulation of quantum systems

Over the past decade, it has become possi-ble to measure and control solid-state mechan-ical oscillators with a precision that allows towitness their zero-point motion. This advancehas been predicated by the ability to tightly in-tegrate nano-scale mechanical oscillators withhigh-finesse optical micro-cavities, so that themotion of the oscillator can be interferometri-cally measured. In our group at EPFL, we havepioneered some of these advances, and have usedthe technology to investigate the predictions ofquantum theory on a macroscopic object [1].

We couple the motion of a glass nanostring tothe frequency of a high-finesse whispering-gallerymode of an optical microdisk cavity. The motionof the string causes frequency fluctuations of thecavity mode which we readout using a quantum-noise-limited laser locked on cavity resonance.By operating the system at cryogenic temper-atures down to 1 K, we have been able to sup-press all extraneous sources of classical frequencyfluctuations. This enables us to resolve the zero-point motion of the string with a imprecision thatis 4 orders of magnitude smaller than its zero-point motion. Heisenberg’s uncertainty principlepredicts that such a measurement would lead to adisturbance of the string’s momentum – an effectcalled quantum measurement back-action. Weobserve quantum back-action on the nanostring,consistent with Heisenberg’s predictions [2]. Wethen demonstrate a technique whereby the recordof the measurement is used to perform feedbackto cancel the disturbance due to quantum back-action.

Another prediction of quantum theory is thatin addition to the subject of a measurement un-

dergoing random changes, the state of the mea-suring instrument also undergoes changes. In ourexperiment, we observe this as a change in thestate of the light used to measure the motionof the string: the coherent state of the laser istransmuted into a non-classical squeezed state af-ter the measurement. We use feedback to studyvarious manifestations of this property, includinga direct measurement of the magnitude of theposition-momentum commutation relation [3].

Finally, we demonstrate that the same phe-nomena can be observed when the oscillator isat room-temperature. In this case, we are ableto observe the effect of the quantum correlationsdeveloped in the light field due to its interactionwith the string. We then show how these corre-lations can be harnessed to improve the abilityto estimate weak forces applied on the string [4].

These experiments verify long-standing pre-dictions of quantum theory and have deep rele-vance to the operation of state of the art opticalinterferometers such as the Laser InterferometricGravitational-wave Detectors (LIGO). Progressis currently underway to translate some of thetechniques demonstrated on a table-top to thekm-scale interferometers of LIGO.

References

[1] V. Sudhir, Ph.D. thesis, EPFL (2016)

[2] D. Wilson, V. Sudhir et al., Nature 524, 325(2015)

[3] V. Sudhir, D. Wilson et al., Phys. Rev. X 7,011001 (2017)

[4] V. Sudhir, R. Schilling et al., Phys. Rev. X 7,031055 (2017)


ISAMP TC-7, 6−8 January, 2018, Tirupati ID002 Sudhir

37

Ion-beam synthesis of metal quantum dots in glasses for nonlinear photonic

Applications

Purushottam Chakraborty*

Saha Institute of Nuclear Physics

Surface Physics and Materials Science Division

Kolkata

Topic: D

Although electronics technologies have

made great advances in device speed, optical devic-

es can function in the time domain inaccessible to

electronics. In the time domain less than 1 ps, opti-

cal devices have no competition. Photonic or optical

devices are designed to switch and process light

signals without converting them to electronic form.

The major advantages that these devices offer are

speed and preservation of bandwidth. The switching

is accomplished through changes in refractive index

of the material that are proportional to the light in-

tensity. The third-order optical susceptibility, (3)

known as the ‘optical Kerr susceptibility’, which is

related to the non-linear portion of the total refrac-

tive index, is the non-linearity which provides this

particular feature. Future opportunities in photonic

switching and information processing will depend

critically on the development of improved photonic

materials with enhanced Kerr susceptibilities, as

these materials are still in a relatively early stage of

development.

Optically isotropic materials, e.g. glasses

that have inversion symmetry, inherently possess

some third-order optical non-linearities. Although

this is quite small for silica-glasses at = 1.06 m,

the absorption coefficient is extremely low, thereby

allowing all-optical switching between two wave-

guides, embedded in a silica fibre, simply by con-

trolling the optical pulse intensity. Different glass

systems are under investigation to increase their

non-linearity by introducing a variety of modifiers

into the glass-network. The incorporation of semi-

conductor micro-crystallites enhances the third-

order optical response. Metal colloids or nanoclus-

ters, embedded in glasses, have also been found to

introduce desired third-order optical non-linearities

in the composite at wavelengths very close to that

of the characteristic ‘surface-plasmon resonance

(SPR)’ of the metal clusters.

_________________________________________

*[email protected]

Ion implantation is found to be an attractive

method for inducing colloid formation at a high

local concentration unattainable by ‘melt-glass fab-

rication process’ and for confining the non-

linearities to specific patterned regions in a variety

of host matrices. Our recent works on metal-ion

implanted colloid generation in bulk silica glasses

have shown that these nanoclus ter–glass compo-

sites under favourable circumstances have signifi-

cant enhancement of (3) with picoseconds to

femtosecond temporal responses. The remarkable

achievements in developing such novel photonic

materials seem to open the way for advances in all-

optical switching devices, e.g. in inducing metal-

colloids into coupled waveguides acting as a direc-

tional coupler.

These ion-beam synthesized metal

nanocluster-glass composites have been imaged

using transmission electron microscopy (TEM), and

confirmed using linear optical absorption (UV-Vis)

and Rutherford backscattering spectrometry (RBS).

Nonlinear refractive index and two-photon absorp-

tion of these nanocomposites have been observed

using Z-scan, Degenerate Four-Wave Mixing

(DFWM) and Anti-resonant Interferometric Nonlin-

ear Spectroscopy (ARINS) in the close proximity of

SPR wavelength of these metal nanoclusters. Both

sign and value of the nonlinear parameters have

been determined, and the third-order optical suscep-

tibility of the composites has been found to be sig-

nificant. Such metal- glass nanocomposites having

appreciable (3) with temporal responses in picosec-

ond to femtosecond time domain have great rele-

vance to futuristic switching materials in nanopho-

tonics.

ISAMP TC-7, 6−8 January, 2018, Tirupati ID003 Chakraborty

38

Recurrent fluorescence observed with an ion storage ring

Toshiyuki Azuma*† 1

* AMO Physics Laboratory, RIKEN, Wako, Saitama 351-0198, Japan † Department of Physics, Tokyo Metropolitan University, Hachioji, Tokyo 192-0397, Japan

Topic: D

For the last decade our understanding of the cooling process of the isolated system in vacu-um has been deepened dramatically. Especially, the critical role of visible or near-IR photon emission from the electronic excited states after thermalization (not prompt fluorescence) has been clarified experimentally. Historically, this mechanism has been recognized by a variety of fields (sometimes independently) for a long time. It is called by technical terms, like inverse electronic relaxation, Douglas effect, recurrent fluorescence (RF), or Poincaré fluorescence. However, fluorescence from the thermally pop-ulated electronic excited state is an appropriate concept in the statistical treatment rather than a picture of recurrence.

The RF process indeed reflects electronic re-sponse and property of molecules, while vibra-tional cooling emitting IR photons is deter-mined mainly by the size and structure of the molecules. The RF rates are often orders of magnitude higher than rates corresponding to IR vibrational transitions, and this fact has been used for an experimental indication or evidence of the RF process. The first example is semi-conductor cluster [1] of Sin

+ and metal cluster [2] of Aun

+. However, a drawback of such ob-servation for detailed discussion is the fact that the property of the electronic excited level is not well understood. The case of Al4

- is also not ful-ly understood although a theoretical prediction of very low-lying excited state for Al4

- was re-ported [3]. The second one is polycyclic aro-matic hydrocarbon (PAH) cations of anthracene, naphthalene and pyrene [4], and the third one is carbon anion cluster [5,6] of C4

- and C6-, where

their electronic property is available both from theory and experiment. A necessary condition for the RF process is the large thermal popula-tion of the low-lying electronic excited state and the large oscillator strength. It is noted that cooling of C60

- has been explained by introduc-ing collective electronic de-excitation [7], which may be in the similar concept of the RF process.

The criteria between the RF and black body radiation (BBR) is also one of major concerns.

From this viewpoint, recent detection of re-current fluorescence visible photons [8] from C4

- and C6- stored in an electrostatic ion storage

ring (TMU E-ring) is a milestone for the “RF photon spectroscopy”. Improvement of energy resolution in near future will give rich infor-mation on transitions from the initial vibronic state to other states accompanying the vibra-tional excitation or de-excitation for several modes. Furthermore, our group is now planning an experiment for cold negative carbon cluster ions stored in a newly developed cryogenic electrostatic ion storage ring, RICE (RIken Cryogenic Electrostatic ring) [9]. This device will provide the initial condition of the electron-ically and vibrationally ground state for the stored ions, and allows us to control their inter-nal energy precisely by introducing energy-tunable lasers.

References [1] P. Ferrari et al 2015 J. Chem. Phys. 143 224313 [2] K. Hansen et al 2017 J. Phys. Chem. C 121 10663 [3] B. Kafle et al 2015 Phys. Rev. A 92 052503 and ref-erences therein; T. Sommerfeld 2010 J. Chem. Phys. 132 124305 [4] S. Martin et al 2013 Phys. Rev. Lett. 110 063003; S. Martin et al 2015 Phys. Rev. A 92 053425, M. Ji et al 2017 J. Chem. Phys. 146 044301 [5] G. Ito et al 2014 Phys. Rev. Lett. 112 183001; N. Kono et al 2015 Phys. Chem. Chem. Phys. 17 24732 [6] V. Chandrasekaran et al 2014 J. Phys. Chem. Lett. 5 4078; V. Chandrasekaran et al 2017 J. Chem. Phys. 146 094302 [7] J. U. Andersen et al 1996 Phys. Rev. Lett. 77 3991 [8] Y. Ebara et al 2016 Phys. Rev. Lett. 117 133004 [9] Y. Nakano et al 2017 Rev. Sci. Instrum. 88 033110

† 1 E-mail: [email protected]

ISAMP TC-7, 6−8 January, 2018, Tirupati ID004 Azuma

39

Tunable magic wavelengths of cooling and trapping with focused LG beam Anal Bhowmik and Sonjoy Majumder

Department of Physics, IIT Kharagpur, Kharagpur – 721302, India

Topic: D

Mechanisms of cooling and trapping of at-oms or ions using laser beam have been widely employed in high precision spectroscopic measurements. To minimize the various sys-tematics in the measurements of any spectro-scopic properties, experimentalists need to trap or cool the atoms at particular wavelengths of the external laser field where the differential ac stark shift of an atomic transition effectively vanishes, known as magic wavelengths.

Determination of the magic wavelengths of al-kali-metal atoms for linearly polarized (i.e., spin angular momentum (SAM) equal to zero) laser sources have been well explored in litera-ture. Compared to the linearly polarized light, circularly polarized light (i.e., SAM=±1) has an extra part of the total polarizability, called the vector part, which arises due to the dipole mo-ment perpendicular to the field. For the circu-larly polarized light, this vector part has some advantages in the evaluation of the valence po-larizabiliy

Kuga et al. [1] was first realized Laguerre-Gaussian (LG) based dipole trap with orbital angular momentum (OAM) and was confined 10E+8 numbers of rubidium atoms to the core of a blue-detuned vortex beam (see FIG). Sev-eral other recent experiments of trapping atoms use LG light beams suggest the importance of the process even in blue-detuned region. Dur-ing the interaction of paraxial LG beam with atoms or ions, which is below its recoil limit, the lowest order transition is possible at quad-rupole level [2]. Therefore, we do not see the effect of OAM of light on dipole polarizability. However, due to coupling of SAM and OAM, the OAM of focused LG beam has significant contribution on dipole transitions [3] and sub-sequently to the dipole polarizability of atomic system and tuning of magic wavelengths [4].

Figure 1. The designs of confining ions to regions of maximal or minimal light intensity for red- or blue-detuned LG beam.

Figure 2. Tuning of two magic wavelengths for 5sà4d3/2,mjfor angle 50o, 60o and 70o. (both OM=1)

References [1] T. Kuga, Y. Torii, N. Shiokawa, and T. Hirano, (1997) Phys. Rev. Lett. 78, 4713 . [2] P Mondal, B Deb and S Majumder (2014) Phys. Rev. A, 89, 063418 [3] A. Bhowmik, P. K. Mondal, S. Majumder, and B. Deb (2016) Phys. Rev. A 93, 063852 [4] A Bhowmik, N N Dutta and S Majumder, Submitted Phys. Rev A, Arxiv:1712:000xx

100 102 104 106 108 110

2000

2100

2200

2300

2400

2500

2600

2700

2800

Mag

ic w

avel

engt

h (n

m)

Polarizability (a.u.)

4d3/2(+1/2)

112 114 116 118 120 12210381040104210441046104810501052105410561058

Mag

ic w

avel

engt

h (n

m)


4d3/2(+1/2)

96 98 100 102 104 106 108 110

3000

4000

5000

6000

7000

8000

9000

Mag

ic W

avel

engt

h (n

m)


4d3/2(-1/2)

112 114 116 118 120 122 1241042

1043

1044

1045

1046

1047

1048

Mag

ic W

avel

engt

h (n

m)


4d3/2(-1/2)

E-mail: [email protected], [email protected]

ISAMP TC-7, 6−8 January, 2018, Tirupati ID005 Majumder

40

Fast Ion Beams in a Cryogenic Storage Ring:Collisions and Internal Excitations

Andreas Wolf 1

for the CSR team

Max-Planck-Institut fur Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany

Topic E

Internal structures and excitations of atomic,molecular and cluster ions are sensitively probedby their collisions and reactions. Ion–neutralreactions, dissociative recombination with elec-trons, or electron emission from molecular andcluster anions leave neutral products difficult toaccess with stationary targets. However, fastion beams offer powerful single-particle detectionmethods for observing neutral daughter prod-ucts. Using these efficient detection methods forcollisions of stored and possibly state-controlledparticles motivated the development of storagerings for atomic, molecular and cluster ions. Inparticular, electrostatic storage rings [1, 2] weredeveloped for complex, heavy ionic species withenergies in the multi-keV range.

Cryogenic storage ring that recently startedoperation at three laboratories world-wide [3,4, 5] substantially improved the storage condi-tions and the control over internal ionic excita-tions. We here present the Cryogenic StorageRing (CSR) at the Max Planck Institute for Nu-clear Physics in Heidelberg, Germany [5]. It isbuilt to accept ion beams (cations and anions)of kinetic energy up to 300 keV per ionic chargeand stores these ions on a 35 m long closed orbit.The ion orbit comprises four 2 m long, field-freestraight sections for collision experiments. Theion energy is high enough to enable experimentswith a merged electron beam at matched electronand ion velocities, even for polyatomic molecules.The merged electron beam, produced by a pho-tocathode, also enables phase space cooling ofion beams stored in the CSR. Multi-particle co-incidence detectors operated downstream of themerged-beam zones offer the detection of neutralproducts for collision kinematics analysis.

The CSR was operated successfully at vac-uum chamber temperatures of 6 K and ion beamstorage time constants up to 45 min [5]. More-over, it was used for experiments on resonantphotodissociation of cations (CH+ [6]) and near-threshold photodetachment of anions (OH− [7]).

In both cases, the rotational levels radiativelycooled towards populations dominated by J = 0.Photodissociation and photodetachment cross-sections as well as radiative lifetimes were in-vestigated on the rotationally cold ions, storedin empty space without buffer gas over timesof up to 20 min. Recently, phase space coolingof ion bunches circulating in the CSR was real-ized with the merged, velocity matched electronbeam. The first experiments at the facility usinglaser and merged particle beam interactions andan outlook to planned studies will be covered.

Reaction microscope

(in development)

Ion beam diagnostics

Dipoleelectrodes

Quadrupoleelectrodes

Merged electron beam

Ion injection and merged neutral beam

300 kV accelerator platform

2 K cryocooler

Laser interaction

Figure 1. Overview of the Cryogenic Storage Ring

CSR (closed orbit circumference: 35 m)

References

[1] S. Pape Møller and U. V. Pedersen, Phys. Scr.T92, 105 (2001).

[2] H. T. Schmidt, Phys. Scr. T166, 914063 (2015).

[3] H. T. Schmidt et al., Rev. Sci. Instrum. 84,055115 (2013).

[4] Y. Nakano et al., Rev. Sci. Instrum. 88, 033110(2017).

[5] R. von Hahn et al., Rev. Sci. Instrum. 87, 063115(2016).

[6] A. O’Connor et al., Phys. Rev. Lett. 116, 113002(2016).

[7] C. Meyer et al., Phys. Rev. Lett. 119, 023202(2017).


ISAMP TC-7, 6−8 January, 2018, Tirupati IE001 Wolf

41

Elaborated Electron Beam Ion Sources for AMO Physics andLaboratory Astrophysics

Mike Schmidt∗ 1, Günter Zschornack∗† 2

∗ Dreebit GmbH, Großröhrsdorf, Germany† Dresden University of Technology, Department of Physics, Dresden, Germany

Topic: E. Development of major experimental facilities for AMO Physics and Laboratory Astrophysics

Electron Beam Ion Sources (EBIS) have beenproven as excellent sources of highly charged ionsfor applications in research and development.Compared to the classical approach of producinghighly charged ions, e.g. via stripping energeticlow charged ions in costly ion accelerator struc-tures, EBIS provide a significant less complexand simplier way to generate ions of a broad var-ity of elements with almost all charge states

Beams of highly charged ions extracted fromEBIS usually feature a low emittance and lowenergy spread and can be used for very efficientpost-acceleration, for surface analysis as well asfor surface modifications, just to name a few.However, EBISs are also excellent sources ofphotons (X-rays, ultraviolet, extreme ultravio-let, visible light) from highly charged ions.

The ion production in each EBIS is basedon electron impact ionization in a high-densityelectron beam which is compressed in a strongaxial magnetic field.

The standard technique for the generation ofthe required magnetic field for the electron beamformation and compression is the use of super-conducting magnets making the EBIS setup so-phisticated and complex. A more pracictal wayis the use of permanent magnets as it is realizedin the patend-pending Dresden EBIS model fam-ily of the Dreebit [1] providing table-top EBISmachines with small spatial requirements andlow initial and operation costs.

However, for high performance applications

Dreebit also provides a superconducting EBISsolution featuring electron beam currents of upto 500 mA at 6 Tesla magnetic field strength forvery short ionization times at high ion output.

Table 1 lists some of the important ion sourceparameters of the different Dreebit ion sourcemodels.

Table 1. Important parameters of the DresdenEBIS models (magnetic field B, trap length L, max-imum electron beam current Ie, maximum electronbeam energy Ee).

EBIT EBIS-A EBIS-SCB [Tesla] 0.25 0.6 6.0L [mm] 20 60 200Ie [mA] 50 200 500Ee [kV] 15 20 15

Complementing these unique ion sourcesDreebit provides complete Low Energy Facili-ties (LEF) equipped with all required compo-nents ranging from the ion optics (e.g. lensesand deflectors) to the diagnostics (Faraday cups,Pepperpot emittance meters, Wien filters) butalso including the vacuum system and commandand control elements.

We will present these EBIS related technol-ogy as a promising experimental facility for AMOPhysics and Laboratory Astrophysics.

References

[1] Author V.P.Ovsyannikov, G.Zschornack 1999 RSIVol 70 Page 2646-2651


ISAMP TC-7, 6−8 January, 2018, Tirupati IE002 Schmidt

42

Design of an experimental facility for Molecular Science research using UV-VUV

and soft X-ray photons

B.N. Rajasekhar* and Asim Kumar Das

Synchrotron Beamline Development Section

Atomic and Molecular Physics Division

Bhaha Atomic Research Centre, Trombay, Mumbai – 400 085

&

BARC beamlines section, B-1, Indus-1, RRCAT, Indore – 452013.

E. Development of major experimental facilities for AMO Physics and Laboratory Astrophysics

Molecular Science research is being carried out

using beamlines with different spectral

characteristics at Indus-1, synchrotron radiation

source (SRS), RRCAT, Indore [1]. An advanced

beamline capable of delivering photons with

high intensity photons at high resolution to study

photon induced processes involving valence,

intermediate and core electrons of atoms and

molecules is under development at Indus-2 SRS

[2]. This beamline uses a planar permanent

magnet (PPM) undulator installed in the LS-2

straight section of Indus-2 SRS [2] as the light

source. A varied line spacing plane grating

monochromator (VLSPGM) with a toroidal

focusing mirror and four interchangeable

gratings will be used to obtain monochromatic

light [3, 5]. To conduct advanced molecular

Physics experiments such as Photo-ionization,

photo-dissociation and photo-fragmentation of

molecules and clusters, an experimental station

design has been modeled. This experimental

setup is based on velocity map imaging l(VMI)

technique with provisions to conduct time

resolved and photon energy dependent imaging

spectroscopy of photo-electron and photo-ions

produced in a photon molecule interaction. Fig.1

shows a schematic of the details of the VMI

system. In this talk detailed design details of the

electron & ion optics simulations, and energy

resolution optimization of the experimental

facility will be discussed.

Fig.1. Schematic of the VMI apparatus (not to scale)

showing repeller, extractor, and ground electrodes

and relative distances

References:

1. S K Deb et.al. J. Phys.: Conf. Series 425

072009 2013, http://www.rrcat.gov.in.

2. http://www.rrcat.gov.in/technology/accel/in

dus2.html

3. Asim Kumar Das et.al. Ind. Jour. of Phys.,

88 1235 2014.

4. A. K. Das, B N Rajasekhar and N K Sahoo,

BARC External Report –

BARC/2014/E/008.

5. P. K. Sahani et.al., “Radiation shielding for

undulator beamline in Indus-2 synchrotron

radiation source”, e - proceedings,

RADSYNC – 2017, 19 -22, April 2017,

Ninth International Workshop on Radiation

Safety at Synchrotron Radiation Sources,

held at NSRRC, Taiwan, DOI:

http://radsynch17.nsrrc.org.tw/Documents/f

or-download/3-2-2.

*Email: [email protected]

ISAMP TC-7, 6−8 January, 2018, Tirupati IE003 Rajashekhar

43

Molecular Physics facilities at IUAC

C P Safvan∗ 1,

∗ Inter University Accelerator Centre, New Delhi – 110067, India

Topic: E

The Inter University Accelerator Centre atIUAC is a centre set up under the UniversityGrants Commission with a mandate to provideaccelerator based experimental facilities to Uni-versity students and faculty. In this talk we willpresent a basic introduction to the Inter Uni-versity Accelerator Centre, with a special focuson the facilities available at the Low Energy IonBeam Facility (LEIBF). In addition, IUAC pro-vides high energy, heavy ion beams from the tan-dem and linear accelerators.

The low energy ion beam facility at IUACprovides ion beams from an Electron CyclotronResonance source placed on a high voltage deck.This enables a wide range of energies and chargestates to be available for experiments. Severalion modification experiments are conducted reg-ularly for the materials science invetsigations.There are also two beamlines available for atomicand molecular physics experiments.

The invesigations at the low energy facilityat present are focussed on molecular dissociationdynamics: on how the removal of several elec-trons from a stable molecule effects the disso-ciation dynamics. A variety of molecules havebeen investigated, from simple diatomics like N2

to complex polyatomic aromatic hydrocarbons.A variety of characteristic processes have beeninvestigated: from production of excited targetmolecules to angular distribution of of the ionicfragments and intra-molecular bond formation.

We will also describe new and upcoming fa-cilities at the LEIBF, for example a decelera-tor for ions has been developed and applicationswith very slow ions are being considered. Veryslow irradiation of some biologically importantmolecules have been considered, and molecularreaction investigations with a modified reactionmicroscope is being designed. A new setup forthe investigation of X-rays emitted in slow ion-target (solids and gasses) is being actively pur-sued.

We will be modifying the existing time offlight spectrometer (recoil ion momentum spec-trometer) to enable the measurment of electronenergies and improve the resolution of the ions aswell as expand the possibilities of the post collis-sion charge state analyzer.

We will present a brief description of the ex-isting facilities, future plans, and invite all to usethese facilities.


ISAMP TC-7, 6−8 January, 2018, Tirupati IE004 Safvan

44

Plasma and beam diagnostics for electric propulsion research

Umesh R. Kadhane* 1

* Department of Physics, Indian Institute of space science and technology, Kerala, India

Topic: E.

Electric propulsion system (EPS) has become a very important method of propulsion in space applications ranging from station keeping of earth orbiting satellite to inter planetary space missions. With increasing demand for reducing power requirement and mass of spacecraft, and increasing the payload capability, EPS is at present a well established technology in space applications for in orbit propulsion. Among the electric propulsion devices Hall Effect Thruster (HET) is recognized as the most attractive technique. It uses a low-pressure discharge with magnetically confined electrons to ionize and accelerate a propellant gas.

On comparison with the chemical counterparts, even though the electric propulsion thrusters are not capable of providing high thrust, these thrusters can deliver high specific impulse and have longer life as well is a good candidate for long duration missions and manoeuvres that require large velocity increments. Inspite of these advantages, EPS is still a developing technology with several uncertainties and

complexities. These issues are aggravated by the fact that unlike the chemical thrusters which can be tested for full life cycle in minutes and hours, EPS life cycle tests need to be done over months. Since the theoretical modelling is not very advanced due to complex plasma physics involved, the prototyping becomes a challenging task. In view of these difficulties, the diagnostic systems become very essential for EPS research. The EPS plume consists of two components, plasma and ion beam. Both need to be studied using various plasma diagnostic and beam diagnostic tool.

At IIST several EPS diagnostic tools have been designed and developed. A few are well known and well established tools like the Langmuir probe, Retarding Potential Analyzer (RPA), ExB etc, and a few more complex probes like parallel plate mass and energy analyser, multispectral imaging, laser induced fluorescence (LIF) etc. Most of these tools are now an integral part of ISRO's EPS research program. Details of the design, development, testing and operational usage, and important findings will be reported.


ISAMP TC-7, 6−8 January, 2018, Tirupati IE005 Kadhane

45

Ultrafast ionization and fragmentation dynamics of molecules athigh x-ray intensity

Sang-Kil Son∗ 1,

∗ Center for Free-Electron Laser Science (CFEL), Deutsches Elektronen-Synchrotron (DESY), Hamburg,

Germany

Topic: F

X-ray free-electron lasers (XFELs) havebrought an impact on various scientific fields,including AMO physics, material science, astro-physics, and molecular biology. Understandinghow matter interacts with intense x-ray pulsesis essential for most XFEL applications. Ex-posed to an intense x-ray pulse, an atom withina molecule absorbs many photons sequentiallyand ejects many electrons, turning into a highlycharged ion within a femtosecond time scale.This multiphoton multiple ionization dynamicsdiffers from that at a third-generation x-raysynchrotron radiation source, where one-photonabsorption is dominant, and from multiphotonstrong-field ionization, where many photons aresimultaneously absorbed to ionize a single elec-tron. The created charges are redistributedwithin the molecule, and then it explodes dueto Coulomb repulsion. This fragmentation dy-namics occurs along with ionization dynamics.

In this talk, I will present a theoretical frame-work to treat x-ray-induced processes and tosimulate detailed ionization and fragmentationdynamics of atoms and molecules, introducingtwo dedicated x-ray physics toolkits, xatom [1-4] and xmolecule [5-7]. With a joint ex-perimental and theoretical study of small poly-atomic molecules irradiated by XFEL pulses, Iwill demonstrate how the theoretical model de-scribes the essential mechanisms underlying ex-plosion dynamics of molecules in intense x-raypulses. One of the key findings is that ioniza-tion of heavy-atom-containing molecules at highx-ray intensity is substantially enhanced in com-parison with that of isolated atoms. This is calledcharge-rearrangement-enhanced x-ray ionizationof molecules (CREXIM) [7] as illustrated in Fig-ure 1. The CREXIM effect plays an importantpart in the quantitative understanding of XFEL–molecule interactions and will need to be takeninto account for future XFEL applications.

Figure 1. Upper panel: Average total molecular

charge as a function of fluence calculated for CH3I

molecules and within the independent-atom model.

Lower panel: Illustration of the CREXIM mecha-

nism in the molecular case, in comparison with the

independent-atom case.

References

[1] Son S-K, Young L and Santra R 2011 Phys. Rev.A 83 033402

[2] Jurek Z, Son S-K, Ziaja B and Santra R 2016 J.Appl. Cryst. 49 1048

[3] Rudek B et al 2012 Nature Photon. 6 858

[4] Toyota K, Son S-K, and Santra R 2017 Phys. Rev.A 95 043412

[5] Hao Y, Inhester L, Hanasaki K, Son S-K andSantra R 2015 Struct. Dyn. 2 041707

[6] Inhester L, Hanasaki K, Hao Y, Son S-K andSantra R et al 2016 Phys. Rev. A 94 023422

[7] Rudenko A et al 2017 Nature 546 129


ISAMP TC-7, 6−8 January, 2018, Tirupati IF001 Son

46

Abstractsof

Contributed Talks

Dissociation dynamics of N2n+ cations (n=1-2) and kinetic energy release study in

the collision of 3.5keV electron with nitrogen molecule

Sunil Kumar, Suman Prajapati, Bhupendra Singh, B.K.Singh, R.Shanker1

Atomic Physics Laboratory, Department of Physics, Institute of Science, Banaras Hindu University, Varanasi, INDIA -221005

Synopsis (Topic:A) We have performed an energy selected electron-ion coincidence experiment with 3.5keV continuous electron beam with free nitrogen molecule and have investigated inner shell processes which lead the formation of nitrogen dications. The kinetic energy release in their dissociation has been studied and the ob-tained results have been compared with the previously reported values by the other workers.

The study of dynamics and structure of Nitrogen and its cations (N2

2+, N23+) is

important from both fundamental and applications point of view due to its importance in the area of atmospheric science, controlled fusion research, biophysics and several other branches of science. Inner shell processes play a major role in the formation and understanding of double and multiple ionization of target atoms or molecules. Selected core-hole states have been created by excitation (ionization) with energetic electrons having kinetic energy 3.5keV. The electronic decay of the core-hole through auto-ionization or an Auger process is monitored by the analysis of energy selected ejected electrons while the chemical transformations of the precursor ion are observed with a time of flight (TOF) mass spectrometer[1]. The present study has two-fold objectives: firstly, to throw light on two types of core hole creation, namely, complete ionization and alternately the creation of a neutral core hole excited state by promoting the N 1s electron into the first unoccupied molecular orbital, the 1Πg orbital and secondly, to provide detail information on the mechanism of formation and dynamics of dissociation of singly, doubly and possibly triply ionized molecular nitrogen ions under impact of 3.5keV electrons with nitrogen molecules by performing coincidences between emitted electrons having three specified energies, namely, Ee = 343±4eV, 355±4eV, 363±4eV and ions produced in an unimolecular collision reaction. From these measurements it has been possible to provide the details of involved excited energy states which are formed to associate with the corresponding dissociation products on the basis of kinetic energy released (KER) values for N2

2+→ N+ + N+ and N22+→

N2++N channels as well as on the shape and

intensity of the TOF mass peaks. A signature of Resonant Auger (RA) excitation channel yield-ing the singly charged parent ion has been ob-served [2]. The details of the experimental methods and ob-tained results will be presented and discussed.

.

Figure 1. Values of the kinetic energy released (KER) determined from our data are plotted as a function of the binding energy (B.E.) for two different fragmentation channels: N2

2+→ N+ + N+ and N22+→ N2+ + N of a nitro-

gen molecular dication formed in 3.5keV electron impact with N2 molecule. The lines connecting the data points are to guide eyes.

References [1] S Kumar et al. Indian J Phys (July 2017) 91(7):721–729 [2] S Kumar et al. J.Phys.B (Under Review)


ISAMP TC-7, 6−8 January, 2018, Tirupati CA001 KumarSunil

48

Ultraslow isomerization in photoexcited gas phase C−10

K. Saha∗ 1, V. Chandrasekaran∗†, O. Heber∗, M. Iron‡, M. L. Rappaport§, D. Zajfman∗

∗ Department of Particle Physics and Astrophysics, Weizmann Institute of Science, Rehovot 7610001, Israel.† Currently at Vellore Institute of Technology, Vellore 632014, India.

‡ Department of Chemical Research Support, Weizmann Institute of Science, Rehovot 7610001, Israel.§ Department of Physics Core Facilities, Weizmann Institute of Science, Rehovot 7610001, Israel.

Topic: ASynopsis : Isomerization and carbon chemistry in the gas phase are key processes in many scientific studies.We report here on the isomerization process from linear C−

10 to its cyclic isomer in gas phase. We observed that,when the system is excited above its isomerization barrier energy, the actual isomerization from linear to cyclicconformation can take place in a very long time scale lasting hundreds of microseconds. Such slow isomerizationrate is unusual in gas phase molecules and clusters.

Isomerization of polyatomic systems, suchas, molecules and clusters, is a very basic phe-nomenon in nature. Isomerization in gas phasemolecules is an important process in atmosphericchemistry and in interstellar medium. In the gasphase it is usually assumed that isomerizationrates are governed by molecular dynamics whenthere is enough internal energy to reach differ-ent isomeric paths. Typical rates have the sametime constant as rotation i.e., atomic motion rel-ative to the center of mass, which is of the or-der of picoseconds. Here, we present evidenceof extremely slow isomerization rates for transi-tion from gas phase linear chain C−10 cluster toits monocyclic ring conformation after photoex-citation above the isomerization barrier.

Experiments are performed by trapping vi-brationally and rotationally excited C−10 in a bentElectrostatic Ion Beam Trap (EIBT)[1]. Thetrapped ion beam is merged with an energy-tunable laser beam. The neutrals flying out ofthe trap, produced due to electron detachmentfrom C−10, are recorded as a function of trappingtime.

When a large polyatomic system such as C−10,is photoexcited, the excitation energy is quicklyconverted to vibrational energy due to internalconversion. The system may then deexcite viavarious processes such as recurrent fluorescence,infrared emissions, fragmentation, or by vibra-tional autodetachment in which neutrals are pro-duced due to delayed detachment of electrons.Depending on the internal energy of excited sys-tem, neutrals are usually formed after some de-lay with respect to photoexcitation. The neu-tralization rate is thus governed by the dynam-ics of the excited system and can reveal greatinsights about various dexcitation processes. Inthis study, we have measured the neutralization

rate of photoexcited linear C−10 at various pho-toexcitation energies (shown in Figure 1). Thecontribution of isomerization in the neutraliza-tion rate is determined by a statistical model thattakes into account all the deexcitation processes.

Figure 1. Neutral counts from C−10 as a function of

time after interaction with laser photons of various

energies. The open markers show the experimental

data. The lines are from model calculations. The

dashed lines denote contribution from one-photon

excitation while the dotted ones are due to exci-

tations by two photons. The solid lines represent

the contribution from both and match well with the

experimental data.

Our results reveal that ultraslow isomeriza-tion from linear C−10 to monocyclic C−10 is themain reason behind production of neutrals last-ing up to hundreds of microseconds after laserexcitation [2]. This finding may indicate a gen-eral phenomenon that can affect the interstellarmedium chemistry of large molecule productionalong with other gas phase processes.

References

[1] O. Aviv et al. 2008 Rev.Sci. Instrum. 79 083110

[2] K. Saha et al. 2017 Nature Physics (submitted)


ISAMP TC-7, 6−8 January, 2018, Tirupati CA003 Saha

49

Fragmentation dynamics of multiply charged OCS

Herendra Kumar∗ 1, Pragya Bhatt†, C.P. Safvan†, Jyoti Rajput∗ 2

∗ Department of Physics and Astrophysics, University of Delhi, Delhi-110007, India.† Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi-110067, India.

Topic: A

In collisions of highly charged ions with neu-tral molecules one or more electrons can be re-moved from the target molecule by either ion-ization or electron capture. The molecule afterremoval of electrons may dissociate into the con-stituent atomic/molecular ions. We performedan experiment in which a beam of multiplycharged ions 1.8 MeV Xe9+ are made to col-lide with neutral OCS molecules. At the colli-sion point electrons are released and the moleculegets multiply charged (i.e. OCSq+, q=1-8). Theexperiment was performed at the Low EnergyIon Beam Facility (LEIBF) of Inter UniversityAccelerator Centre (IUAC), New Delhi, India.The technique of multi-hit recoil ion momentumspectroscopy employing a position sensitive mi-crochannel plate (MCP) detector was used tomeasure the time and position information ofthe recoil ions generated upon fragmentation ofOCSq+. Electrons emitted during the interac-tion are used as timing reference for starting thedata acquisition. The three-dimensional momen-tum vectors are derived from the measured timeof flight and position information of the detectedfragment ions. The multi-hit capability of thesetup aids in gaining knowledge about the par-ent ion from which these fragments originate.For more details of experimental setup see ref-erence [1]. The aim of this study is to explorethe dissociation pathways of OCSq+ ion.

We have identified complete two and threebody dissociation channels of OCSq+ from thedouble and triple ion coincidence maps. Thedominant two body dissociation channels are S2+

+ CO+, CO+ + S+, CO2+ + S+, and CO2+ +S2+. Many three body dissociation channels areobserved as Cl+ + Om+ + Sn+, where l, m, & nrange from 1 to 3 and l+m+n=q.

In this presentation, the kinetic energy re-lease (KER) distribution, momentum correla-tion, and angular distribution will be discussed

for two and three body dissociation channels.The momentum correlation will be studied by us-ing Newton diagrams. Further, the dissociationmechanisms of OCSq+, (q=3-6) will be identifiedby using Dalitz plot. For example, Dalitz plot ofthe triple-coincidence events of OCS3+ is shownin fig 1. In this figure, we can see the signatureof concerted and stepwise processes. The eventslocated along the cross diagonal structure indi-cates break up pathway via two step processesinvolving metastable CO2+ and CS2+.

Figure 1. Dalitz plot of OCS3+ ion dissociating

into (C+ + O+ + S+) channel, where εi=p2iεk

, pi,

and εi are the momentum and kinetic energy of the

ith fragment; εk=∑p2i is the total kinetic energy.

Concerted process makes up the bulk of the im-

age while stepwise processes involving metastable

CO2+ and CS2+ are shown by X-shape structure.

References

[1] Kumar et al., 2014 J. Mass Spect. 374 44-48.


ISAMP TC-7, 6−8 January, 2018, Tirupati CA006 KumarHerendra

50

Isomerization of Acetylene doped in He nanodroplets by EUVsynchrotron radiation

Suddhasattwa Mandal∗ 1, Ram Gopal‡, Sivarama Krishnan†, Robert Richter¶, MarcelloCoreno‖, Hemkumar Srinivas††, Alessandro D’Elia∗∗, Vandana Sharma§ 2

∗ Indian Institute of Science Education and Research Pune, Pune - 411008, Maharashtra, India‡ TIFR Centre for Interdisciplinary Sciences, Hyderabad - 500107, Telangana, India† Indian Institute of Technology Madras, Chennai - 600036, Tami Nadu, India

¶ ElettraSincrotrone Trieste, Area Science Park, 34149 Trieste, Italy‖ Consiglio Nazionale delle RicercheIstituto Officina dei Materiali, Laboratorio TASC, 34149 Trieste, Italy

†† Max-Planck-Institut fur Kernphysik, 69117 Heidelberg, Germany∗∗ University of Trieste, Department of Physics, 34127 Trieste, Italy

§ Indian Institute of Technology Hyderabad, Sangareddy - 502285, Telangana, India

Topic: A

The effect of environment in the molecu-lar isomerization process, which is an importantchemical process happening in nature, remainsan intriguing object of investigation. Acetylenecation [HC = CH]+ is a well studied molec-ular ion in which isomerization occurs throughH atom migration from one C atom to other Catom upon absorption of EUV radiation[1].

We have studied the isomerization of acety-lene molecule embedded inside the Helium nan-odroplets under synchrotron radiation at the GasPhase beamline of Elettra synchrotron facility,Italy. The cold environment (∼0.35K) of Henanodroplet serves as an ideal host matrix forspectroscopic study of rovibroically cold embed-ded molecules. Ionisations of dopant moleculevia Penning process and charge transfer ioniza-tion are important processes upon photoexci-taion of the He nanodroplets at photon energies(20−25eV ) [2, 3]. The isomerization of gas phaseisolated acetylene occur at an energy of ∼ 17eV[1] which is well below the photoexcitation energyof He nanodroplets, therefore He nanodroplet en-vironment is expected to play an important rolein the isomerization process.

We have recorded the photoelectrons witha Velocity Map Imaging (VMI) spectrometer incoincidence with the photoions detected with aTime of Flight (TOF) mass spectrometer for pho-ton energies (20 − 25eV ). The signature of iso-merization in acetylene is the CH+

2 ion yield.The mass correlated photoelectron spectra and

photoion-photoion coincidence measurement en-abled us to gain insight into the isomerizationprocess followed by fragmentation.

We have not observe any substantial ion yieldof CH+

2 at ∼ 17eV photo energy, it seems theisomerization process is suppressed by the Hematrix. However we observed a small ionizationpeak of acetylene at 21.6eV photon energy whichseems to be through Penning ionisaion process.

We have also recorded the photoelectronspectra along with the angular distribution ofthe photoelectron with the polarization axis ofthe synchrotron radiation in coincidence with thephotoions for gas phase isolated acetylene at pho-ton energies (20− 25eV ). The photoelectron an-gular distributions are fitted with the equation

N(θ) = N0(1 + βP2(cosθ))

where θ is the angle of the emitted electrons withpolarization axis and β is the anisotropy param-eter which depends on the state of the moleculefrom which the molecule is ionized.

References

[1] Y. H. Jiang et al. 2010 Phys. Rev. Lett., 105,263002

[2] D. Buchta, S. R. Krishnan et al. 2013 J. Phys.Chem. A, 117, 4394

[3] D. Buchta, S. R. Krishnan et al. 2013 J. Chem.Phys., 139, 084301


ISAMP TC-7, 6−8 January, 2018, Tirupati CA035 Mandal

51

Vacuum ultraviolet photoabsorption spectroscopy of anisole

Aparna Shastri1, Asim Kumar Das and B.N. Raja Sekhar

2

Atomic and Molecular Physics Division, Bhabha Atomic Research Centre, Mumbai 400 085, India

Topic: A. Quantum collisions and spectroscopy of atoms, molecules, clusters and ions

The spectroscopy of benzene and its deriva-

tives have attracted much attention over the

years as they are the building blocks for the

more complex polycyclic hydrocarbons (PAHs)

which play an important role in atmospheric

and interstellar chemistry [1]. They also consti-

tute chromophores in larger biological mole-

cules like DNA bases [2]. Anisole or methoxy

benzene (C5H6OCH3) is one of the building

blocks of lignin, a major component of biomass

and plant cell walls [3]. The radicals formed in

the pyrolysis of anisole are important in under-

standing combustion processes and soot forma-

tion, relevant to environmental chemistry [3,4].

Recently, it has also been studied as a promis-

ing fluorescent tracer in gas phase imaging di-

agnostics [5].

A thorough knowledge of the ground and ex-

cited state electronic structure of a molecule is a

prerequisite to understanding its photochemistry

at a molecular level. From this perspective, vi-

brational spectroscopy of anisole and hydrogen

bonding have been studied quite extensively in

the ground state [6]. Studies on the excited elec-

tronic states however are essentially confined to

the first excited (S0–S1) system in the UV re-

gion [6]. The only report of its VUV absorption

spectrum [7] is limited to the region below

64,000 cm-1

(~7.9 eV) and does not give a com-

plete spectral analysis.

In the present work, we report a study of the

photoabsorption spectrum of anisole in the UV-

VUV region (40,000–95,000 cm-1) using syn-

chrotron radiation (cf. Figure 1). Experiments

are performed using the Photophysics beamline

at the 450 MeV storage ring Indus-1 [8]. The

first ionization potential (IP) of anisole has been

reported at 8.21 eV [9], suggesting the presence

of Rydberg series starting from ~ 4.8 eV. How-

ever, in spectra of benzene derivatives, Rydberg

states often appear as weak features superim-

posed on stronger valence/charge transfer bands

[10]. In the present experimental work, we ob-

serve several new, hitherto unreported features

in the region up the first IP as well as above the

first IP up to the third IP at ~ 11.06 eV.

Figure 1. UV–VUV Photoabsorption spectrum of

Anisole recorded using synchrotron radiation.

Interpretation of the observed transitions as

valence/Rydberg/charge transfer type, potential

energy curves of the first few excited states with

respect to specific bond stretching coordinates

and other related issues are addressed with the

help of DFT and TDDFT calculations on

ground and electronically excited states. Ex-

perimental details, computational methodologies,

results and analysis will be discussed.

References

[1] A.M. Scheer et al. 2010 J. Phys. Chem. A 114

9043

[2] D. J. Hadden et al. 2011 Phys. Chem. Chem.

Phys. 13 4494

[3] H. Xu et al. 2013 J. Phys. Chem A 117 12075

[4] B. Shu et al. 2017 Int. J. Chem Kinet 49 656

[5] S. Faust et al. 2013 Appl. Phys. B 112 203

[6] L. J. H. Hoffmann et al. 2006 Phys. Chem.

Chem. Phys. 8 2360 and references therein.

[7] K. Kimura et al. 1964 Mol. Phys. 9 117

[8] N.C. Das et al. 2003 J. Optics (India). 32 169

[9] T. Kobayashi et al. 1974 Bull Chem Soc Jap 47

2563

[10] K. Sunanda et al. 2016 J. Quant. Spectrosc.

Rad. Transf. 184 89

1



ISAMP TC-7, 6−8 January, 2018, Tirupati CA049 Shastri

52

Elemental analysis using Laser Induced Breakdown Spectroscopy

Swetapuspa Soumyashree1, Prashant Kumar, Rajesh K Kushawaha, S B Banerjee, K P Subramanian

Physical Research Laboratory Ahmedabad – 380009, Gujarat, India

Topic: A (or E)

The conventional LIBS algorithm is not ade-

quate to analyse dense LIBS spectra as in case

of steel sample. A novel technique based on fit-

ting the synthetic spectra onto the LIBS spectra

has been developed and is found to be success-

ful in estimating the accurate elemental compo-

sition in such samples.

The method automatically incorporates the ef-

fect of self-absorption in LIBS plasma while

generating synthetic spectrum. All other plasma

parameters are directly obtained from the rec-

orded emission spectra. Plasma neutrality con-

dition is used to normalize the individual num-

ber densities and estimate the absorption path

length. This procedure is found to be successful

for achieving convergence of retrieval algorithm

even for dense spectrum as well as for resolving

merged lines with accuracy. The experimental

LIBS spectra fitted with a synthetic spectrum is

shown in the following figure for steel sample.

We have also developed an automated search

algorithm to identify emission lines for un-

known samples using NIST database.

This algorithm was used in analysis of various

rock samples which confirms the presence of

elements like Ca, Al, Fe, Mn, Na, O, Pb, Si and

Ni in those samples. The detailed quantitative

study on these samples using the developed al-

gorithms will be presented.

References [1] Prashant Kumar, et al, to be published


ISAMP TC-7, 6−8 January, 2018, Tirupati CA051E Soumyashree

53

Multielectron effects in strong field ionization of few electron molecules

Vinay Pramod Majety*†1 and Armin Scrinzi*

* Department of Physics, Ludwig Maximilians University, 80333 Munich, Germany

† Max Planck Institute for the Structure and Dynamics of Matter, 22761 Hamburg, Germany

Topic: B

Strong field ionization is at the heart of

various ultrafast imaging techniques such as

high harmonic imaging, molecular orbital

tomography and laser induced electron

diffraction. Computational modeling of these

processes is a major challenge as it involves

solving the many body Schrodinger equation in

a non-perturbative way.

We report here the hybrid anti-symmetrized

coupled channels approach [1], a recent

development in this context. In conjunction

with the other established techniques such as

complex scaling and the time dependent surface

flux method; we will present a detailed study of

photoemission from CO2 molecule following

strong field ionization by few cycle near-IR

laser fields. The role of multi-electron

polarization, dynamic exchange, multiple

orbital ionization and interchannel coupling will

be discussed [2,3,4].

References

[1] VP Majety et al. 2015, New Journal of Physics

17, 063002

[2] VP Majety and A Scrinzi 2015, Physical Review

Letters 115, 103002

[3] VP Majety and A Scrinzi 2015, Journal of

Physics B: Atomic, Molecular and Optical Physics

48 (24), 245603

[4] VP Majety and A Scrinzi 2017, arXiv preprint

arXiv:1709.00721 (accepted in Phys Rev A)

†1 E-mail: [email protected]

ISAMP TC-7, 6−8 January, 2018, Tirupati CB003 Majety

54

Tunneling delays in strong field ionization of atomic hydrogen

U Satya Sainadh* 1, Han Xu* 1, X. Wang § 2, Atia-Tul-Noor* 1, William C. Wallace* 1, N. Douguet† 3,

Igor Ivanov ‡ 4, Klaus Bartschat† 3, Anatoli Kheifets¶ 5, R.T. Sang * 1, Igor Litvinyuk* 1.

* Australian Attosecond Science facility, Center for Quantum Dynamics, Griffith University, Brisbane QLD , Australia.

§School of Nuclear Science & Technology, Lanzhou University, Lanzhou, 730000, China.

† Department of Physics and Astronomy, Drake University, Des Moines, Iowa 50311, USA. ‡Center for Relativistic Laser Science, Institute for Basic Science, Gwangju 500-712, Republic of Korea.

¶Research School of Physics and Engineering, The Australian National University, Canberra ACT 0200, Australia.

Topic: B

Synopsis We present the results [1] of tunneling delays measured using attosecond angular streaking of atomic

Hydrogen using elliptically polarized, 6 fs pulses that are centered around 770 nm, within the intensity range of

1.65 to 4 X 1014 W/cm2 . We find a strong agreement in these results with the solutions of complete 3D-TDSE

simulations. Further, we compute the contribution of coulomb effects (between the ionized electron-parent ion)

to the measured angular offsets using Yukawa potential, subtracting which yields the real ‘tunneling delays’.

The ’attoclock’ technique [2] employs near-

circularly polarised few-cycle femtosecond pulses,

and is used in measuring tunnelling delays under

strong field ionisation. The peak of the circular field

ionises the electron and the ionised electrons get

streaked in the residual (post-peak) circular field of

light mapping the instant at which electrons appear

in the continuum to its final momentum. Thus the

time difference between the instant of peak electric

field and the instant at which electron appears in the

continuum, respectively is gives us the tunnelling

delays. The time-difference materialises as an an-

gular offset in the photo-electron momentum distri-

bution in the polarisation plane relative to the polar-

isation ellipse of the light.

Although previous attoclock experiments [2,3]

hinted at zero-tunnelling delays, exact theoretical

solutions were not available to study the ionisation

dynamics in detail. Atomic Hydrogen (H), being the

simplest atomic system for which a complete solu-

tion of 3D-TDSE is available analytically without

requiring approximations beyond the dipole approx-

imation in the non-relativistic regime can enable us

to benchmark the field. It can be later used to vali-

date various theoretical models that help us in un-

derstanding ionisation dynamics in complex atomic

systems.

We performed the attoclock experiment with H us-

ing COLTRIMS and 770nm, 6fs pulses at intensi-

ties from 0.165-0.39 PW/cm2. The H gas jet source

[4] is an RF-discharge tube that dissociates H2 with

a dissociation fraction of 60%. A comparison with

full 3D-TDSE codes is done and a strong agreement

is found between the experiment and the theory.

Further, using simulations with Yukawa potential

we present the contributions of coulomb potential to

the angular offsets. We finally present an upper

bound for ‘tunnelling delays’.

.

Figure 2: Experimental data of momentum distribution of

photoelectrons in the polarisation plane [1]. A corre-

sponds to the peak electric field and B & C are the ex-

pected and measured peaks of photoelectron-momentum

distribution in the polarisation plane

References

[1] U. Satya Sainadh et. al. 2017 arXiv:1707.05445;

U Satya Sainadh et al 2017 J. Phys.: Conf. Ser. 875

022039.

[2] P. Eckle et.al. 2008 Nat. Phys. 4, 565

[3] A.N. Pfeiffer et.al. 2013 Phys.414, 8491

[4]. J.P. Schwonek, 1990 PhD thesis, Massachusetts In-

stitute of Technology, Cambridge, A.


ISAMP TC-7, 6−8 January, 2018, Tirupati CB005 Sainadh

55

PC based Acousto Optic modulator Driver for Cold Atom Interferometer

Aishik Acharya * 1, R. Bharadwaj Reddy#, Manisha Bajaj*, Akash Kamoji*, Shruthi P. Michael*, Anu-

radha Anarthe * and D. Revathi*

* Electro Optical Instrument Research Academy, Hyderabad – 500069, Telangana, India #Department of Instrumentation & Control Engineering, Manipal Institute Of Technology, Manipal-576104, Karnataka,

India

Topic: C

Cold atom interferometry can be done by laser

cooling of neutral atoms. In our experimentation

cold atom cloud will be generated by cooling Ru-

bidium-87 atoms in a magneto optical trap. Six

counter propagating laser beams (in 0, 0, 1 con-

figuration) will be used for laser cooling from a

detailed optical setup (figure 1). To control the

laser frequency precisely for cooling trapping

and detection Acousto optic modulator (AOM) is

used. In this paper we have proposed a simple

control electronic driver circuit for AOMs to

control the laser frequency precisely.

Figure 1. Block diagram of optics setup

In acousto optic modulators (AOM) the

acousto optic effect is used to diffract and shift

the frequency of the light using sound waves. In

side of an AOM a piezo electric transducer is at-

tached to a quartz material. An RF signal is used

to drive the transducer to vibrate which in turn

produces acoustic wave inside the material. This

causes change in refractive index of the material.

Incoming light scatters off the resulting periodic

index modulation and interference occurs similar

to Bragg diffraction. The process acts like three

wave mixing resulting in sum and difference of

frequency generation between phonons and pho-

tons.

Thus it is clear that an RF field with control-

lable amplitude and frequency is required for de-

sired amount of light diffraction precisely. Con-

ventional function generators can be used to gen-

erate this. But for miniaturized and control appli-

cation such devices are not suitable to work with.

An universal driver circuit for driving the AOMs

has been developed for this purpose. The module

requires an external frequency reference of 10

MHz which is used as the clock frequency of Di-

rect Digital Synthesizer. A micro controller in-

terface has been developed to feed the control

word to the DDS and control a variable attenua-

tor digitally. A detailed block diagram is shown

in the figure 2. A computer interface based on

LabView platform has been developed which

communicates with the microcontroller over

USB to UART interface for controlling the RF

frequency and amplitude in closed loop opera-

tion. This helps to control the laser frequency and

intensity sequentially during cooling, trapping

and repumping cycles of Rb-87 atoms.

Figure 2. Basic block diagram for RF driver circuit

References

[1] “An electronic sequence controller for the Cs

fountain frequency standard developed at CSIR-NPL

India”, S. Yadav, A. Acharya, P. Arora and A Sen

Gupta, Measurement 75 (2015) 192–200.

[2] "A Guide to Acousto-Optic Modulators"

(http://massey.dur.ac.uk/resources/slcornish/1.

AOMGuide.pdf)


ISAMP TC-7, 6−8 January, 2018, Tirupati CC001 Acharya

56

Two Components Bose-Einstein Condensate in a Frustrated Optical Lattice

Nilanjan Kundu* 1, Utpal Roy* 2

* Department of Physics, Indian Institute of Technology Patna, Bihta, Patna-801103

Topic: C

Keyword: Bose-Einstein Condensation, Bichromatic Optical Lattice, Rogue waves

We contribute to the field of rogue waves by providing an exact analytical model of the coupled Bose-Einstein Condensation (BEC) in Bichromatic Optical Lattice (BOL). We start with the dimen-sionless 1D BEC of a weakly interacting ultra cold atomic gas with cubic nonlinearity, under the influ-ence of one-dimensional spatial BOL. Our main goal is to solve the two-component Gross Pitäevskii (GP) equation which is the modified form of Non Linear Schrӧdinger Equation (NLSE) for different types of potentials and nonlinearity. Although it is quite nontrivial to develop analytical techniques for these nonlinear systems, improvement of different methodologies in PDE makes it possible to map the equation to a known localized solution and observe their dynamics for various potentials. Rogue waves, topic of intense research, are extreme wave events mostly familiar for its large scale maritime disas-ters. This kind of waves is related with oceanic phenomenon. Apart from the fact that physicist have shown their existence in different systems: optics[1], plasmas, capillary waves and BEC, new studies related with the solution of the correspond-ing PDE having special properties of correlated so-lutions are of severe need. Manakov system is a special kind of system which gives the coupled Ro-gue wave solutions [5]. These type of solutions are basically the mathematical description of pedegrine soliton, which is localized in both the coordinates and is a rather mixture of dark-bright solitons. These types of multicomponent systems [2] were first experimentally realized in Rubidium atoms, where interatomic interaction brings out a number of interesting physical phenomena. Here we con-centrate on a coupled GP equation under external confinement i.e. frustrated optical lattice [3,4]. Af-ter deriving the consistency conditions related to the phase, amplitude and nonlinearity, the GP equation

is mapped to the Manakov equation which in turn gives an exact solution of bright-dark soliton mix-ture dependent on the periods of the potential.

Figure 1:A typical variation of the potential and den-sities of two components References

1. D. R. Solli, et al., 2007, Nature (London), 450, 1054

2. Manikandam, et al., 2016, Phys. Rev. E, 93, 032212

3. A. Nath, U. Roy, 2014, Laser Phys. Lett, 11, 115501

4. A. Nath and U. Roy, 2014, J. Phys. A: Math. Theor, 47, 415301.

5. A. Degasperis, et al.,2012, Phys. Rev. Letter, 109, 044102


ISAMP TC-7, 6−8 January, 2018, Tirupati CC004 Kundu

57

Nonautonomous matter-waves in a quasi-one-dimensional waveguide geometry

Parth Rajauria , Thokala Soloman Raju1

Department of Physics, IISER Tirupati, Tirupati – 517507, Andhra Pradesh, India

Topic: C:

In this paper, we use a variant of much discussednonlinear Schrodinger (NLS) equation or modifiedGross-Pitaevskii (GP) equation with an externalsource. This equation features prominently in thedescription of pulse propagation through asymmetrictwin-core fibers [1, 2], charge-density waves in con-dense matter physics and long-Josephson junctions.Although, pulse propagation in single-core waveg-uides is widespread, the study of self-similar wavesin dual-core waveguides is limited. In the quasi-one-dimensional or higher-dimensional NLS or GP equa-tions with space-time modulated parameters maygenerate rich nonlinear structures such as nonau-tonomous solitons, resonant solitons, and breathingor oscillatory solitons. Here, we analytically and nu-merically explore nonautonomous matter-waves thatdescribes the transport of Bose-Einstein condensedatoms from a reservoir to a waveguide, in the pres-ence of longitudinally modulated repulsive quinticnonlinearity, gain, and an inhomogeneous source.

Pertinently, we have considered a model that sim-ulates the coupling of a reservoir of Bose-Einsteincondensed atoms and the waveguide in a quasi-one-dimensional geometry. Here, the condensate at a par-ticular chemical potential is injected into the waveg-uide from a reservoir at some distance sayx0. Thereservoir emits plane matter waves in both direc-tions into the waveguide. Such a scenario can bewell captured by the following modified GP equa-tion with space-time modulated potential, inhomoge-neous source, quintic nonlinearity, gain or loss termgiven by [3]

ih∂ψ

∂t=

[− h2

2m

∂2

∂x2+ V (x, t) + g(t)|ψ|4 + iΓ(t)

]ψ +

S(t)exp[iϕ(x, t)]. (1)

In order to find the exact nonautonomous solutionsof Eq. (1), we use the following multivariate trans-formation:

ψ(x, t) = ρ(t)eiθ(x,t)Φ[η(x, t)]. (2)

Substitution of this ansatz into Eq. (1) results in the

following set of differential equations:

µΦ(η) = −∂2Φ(η)

∂η2+ σΦ5(η) + s0 ,(3)

ηxx = 0, ηt + θxηx = 0, (4)

2ρt + ρ(θxx − 2γ) = 0, 2s(t)− s0ρη2x = 0, (5)

2g(t)ρ4 − ση2x, 2v(x, t) + µη2x + θ2x + 2θt = 0. (6)

We have obtained a fractional-transform soliton solu-tion of Eq. (1) using the ansatz in Eq. (2). We havenumerically checked the stability of this solution fordifferent values of the strength of quintic nonlinear-ity and inhomogeneous source, using the split-stepFourier transform method. For t=20, we have ob-tained chaotic behavior of this exact solution. But,for t=10, we have obtained an oscillatory solution forthe parameter values specified in the figure caption.

Finally, we hope that these newly found matter-wave solutions may further raise the possibilityof some experiments and potential applications toBECs in the presence of externally driven source.

Figure 1. Numerically simulated oscillatory solution ofEq. (1) for g = 0.1 and the strength of the source iss0 = 0.05 with a dc-offset 0.05.

References

[1] G. Cohen 2000Phys. Rev. E61874

[2] T.S. Rajuet al.2005Phys. Rev. E71026608

[3] T. Paulet al.2005Phys. Rev. Lett.94020404


ISAMP TC-7, 6−8 January, 2018, Tirupati CC007 Rajauria

58

Abstractsof

ContributedPosters

Measurement of the angular distributions of thick target bremsstrahlung pro-

duced by 10-25keV electrons incident on thick Ti & Cu pure elements.

Bhupendra Singh*, Suman Prajapati

*, Sunil Kumar

*, Bhartendu Kumar Singh

*, Xavier Llovet

†, R

shanker*1

*Atomic Physics Laboratory, Department of Physics, Banaras Hindu University, Varanasi 22100, India

† Scientific and Technological Centers, University of Barcelona, Lluís Solé i Sabarís, 1-3, 08028 Barcelona, Spain

Topic:A

Recent experimental and theoretical studies

on angular distribution of bremsstrahlung (BS)

photons produced from 10-25keV electrons in-

cident on thick targets of Ti and Cu have been

made in our laboratory by using Si-PIN photo-

diode detector [1]. The angular measurements

was obtained by changing the incidence angle

(α) measured between the direction of incident

electron & normal to the target surface while

the photon detector was fixed perpendicular to

the electron beam direction in reflection geome-

try.

The Double differential bremsstrahlung

yield (DDBY) was obtained for both Cu and Ti

thick targets for the impact energy at 10, 15, 20

and 25keV and the incidence angle varies in

range between 150-75

0 with an angular uncer-

tainties of (±50).

Angular distribution of DDBY for Cu & Ti

targets; clearly shows the anisotropic distribu-

tion of bremsstrahlung photons. This anisotropy

is large for high photon energy and small for

low photon energy. As the low photon energy

emitted from deep inside the target, considera-

ble amount of absorption occurs which exhibit

the smallness of anisotropy while the high ener-

gy photons emerges from the surface of the tar-

get and gives large anisotropic distribution of

photons like thin targets [2]. The anisotropy for

Ti is 6% larger than Cu for low energy photons

and 11% smaller for high energy photons for

given impact energy. The nature of the angular

distribution of thick target BS also shows the

dependency on the atomic number of the ele-

ments.

Calculated DDBY of Cu and Ti thick tar-

gets have been compared with the predictions

from the general purpose PENELOPE MC cal-

culations [3].The agreement between experi-

ment & theoretical predictions is found to be

satisfactory within the uncertainties involved in

the measurements (~6%).

Figure 1. Comparison of the experimental data of

relative DDBY with the MC [3] calculations as a

function of incidence angle α: a) k=4keV and b)

7keV photons produced in 10keV electron impact

with a thick Ti target; c) k=3keV and d) 7keV pho-

tons produced in 15keV electron impact with a

thick Cu target respectively.

References:

[1] Bhupendra Singh et.al. (2017), communicated in

Rad. Phy. and Chem..

[2] L.Kissel et.al., (1983). At. Data Nucl. Data Tables

28, 381–460

[3] Xavier Llovet et.al., (2017), Microsc. Microanal.

23, 634-646.


ISAMP TC-7, 6−8 January, 2018, Tirupati CA002 Singh

60

Xenon Plasma Modeling with Relativistic Fine Structure Cross Sections

Priti 1, Lalita Sharma and Rajesh Srivastava

Department of Physics, IIT Roorkee, Roorkee – 247667, Uttarakhand, India

Topic: Quantum collisions and Spectroscopy of atoms, molecules, clusters, and ions.

The electron impact excitation cross section

data for xenon have great importance as they

are key component to Xe-plasma models devel-

oped for several applications viz. mercury-free

fluorescent lighting and flat-panel plasma dis-

plays, in particular for characterization of xenon

fed thruster plasmas [1]. In order to correctly

characterize the plasma to obtain reliable plas-

ma parameters viz. electron temperature elec-

tron density etc. we need to incorporate in colli-

sional radiative (CR) plasma model with com-

plete set of vast and consistent fine structure

electron excitation collision cross sections data

in the wide range of incident energy. We have

been putting continuous efforts through our se-

ries of calculations for electron-impact relativ-

istic excitation cross sections for several fine

structure transitions in rare-gas atoms viz. Ar,

Kr, Xe [2-5]. Using our calculated complete set

of cross section data we have successfully de-

veloped CR models for Ar and Kr.

In the continuation to our earlier work, now

we focus in the present work on developing a

suitable CR model for Xe-plasma and obtain a

complete set of electron impact excitation cross

section data for different fine structure transi-

tions in addition to the previously reported cal-

culations [3-5].

In this regard, a systematic calculation of the

electron impact excitation of Xe has been done

using fully relativistic distorted wave theory. A

complete set of consistent cross sections are

calculated for various transitions from its

ground (5p6) to other higher lying fine structure

states (in Paschen notations) 1si, 2si (i=2-5), 2pi

(i=1-10), 3pi (i=1-6), 3di (i=1-12), inter transi-

tion among all 1si fine structure states to 2pi ,

3pi and intra transition among 1si and 2pi in the

electron impact energy range from the excita-

tion threshold to 1keV. For this calculation, the

multi-configurational Dirac-Fock (MCDF)

bound state wave functions are calculated by

using GRASP2K [6]. Thereafter, static distor-

tion potential is obtained and the coupled Dirac

equations are solved numerically to calculate

the wave functions of both the initial and final

channels for the projectile electron. Analytic

fitting of the calculated cross sections are also

obtained so that these can be directly used in

any plasma model. Utilizing the obtained cross

sections we are developing a reliable CR model

for diagnostics of hall thruster Xe plasma. The

model incorporates various population transfer

mechanisms among fine structure levels such as

electron impact excitation, ionization, radiative

decay along with their reverse processes such as

electron impact de-excitation, three body re-

combination. The population density of differ-

ent fine structure states is being obtained by

solving the rate equations for all states simulta-

neously which interconnects the different popu-

lating and depopulating channels among the fi-

ne-structure levels. All the results for cross sec-

tions and plasma parameters will be presented

and discussed in the conference.

References

[1] RA Dressler et al., 2009 J. Phys. D: Appl. Phys. 42

185203

[2] LC Pitchford et al., 2017 Plasma Process Polym 14,

1.

[3] R Srivastava et al., 2006 Phys Rev. A 74, 012715.

[4] L Sharma et al., 2011 Eur. Phys. J. D 62, 399.

[5] L Shama et al., 2009 Journal of Physics: Conference

Series 185 012042.

[6] P. Jönsson, et. al.,2007 Comput. Phys. Commun.

177,597.


ISAMP TC-7, 6−8 January, 2018, Tirupati CA004 Priti

61

SOIAIC effect on Wigner-Eisenbud-Smith time delay: Xe 4d photoionization

A. Mandal∗1 and P. C. Deshmukh†,#2

∗ Department of Physics, Indian Institute of Technology Madras, Chennai, 600036, India† Department of Physics, Indian Institute of Technology Tirupati, Tirupati, 517506, India

# Department of Physics, Indian Institute of Science Education and Research Tirupati, Tirupati 517507, India

Topic: A, B

Photoionization is a many body process. An ap-propriate description of the mechanism needs to in-clude important electron-electron correlations [1].Interchannel coupling between different dipole andalso non-dipole channels are important in describingphotoionization observables [2].

7 0 7 5 8 0 8 5 9 0 9 5 1 0 00

2 0 0 04 0 0 06 0 0 08 0 0 0

7 5 8 0 8 5 9 0 9 5

1 0 0

2 0 0

3 0 0

τ 4d3/2

,1/2,p

,0(as) t d _ 4 d 3 / 2 _ 1 / 2 _ p _ 0 _ P I P T

t d _ 4 d 3 / 2 _ 1 / 2 _ p _ 0 _ I S S T

4 d 3 / 2

7 0 7 5 8 0 8 5 9 0 9 5 1 0 0- 2 0 0 0

02 0 0 04 0 0 06 0 0 08 0 0 0

7 5 8 0 8 5 9 0 9 50

1 0 0

2 0 0

3 0 0

τ4d

3/2,1/

2,p,60

(as)

t d _ 4 d 3 / 2 _ 1 / 2 _ p _ 6 0 _ P I P T t d _ 4 d 3 / 2 _ 1 / 2 _ p _ 6 0 _ I S S T

Figure 1. (Color online) WES time delay for 4d3/2,1/2

with final state spin polarization positive at differentphotoelectron ejection angle with respect to the polar-ization of the photon (0o and 60o respectively from top).Red line is PIPT calculation and black line is ISST cal-culation. Inset are the zoomed portions of the graphwhere the hump like structure is present.

Development in ultrafast laser technology has madeit possible to resolve the photoionization dynamicsin atomic time scale [3] and opens the door to inves-tigate the effect of electron correlations in real time[4].

A particular illustration of interchannel couplingeffect is with reference to dipole channels originat-ing in spin orbit split initial states [5, 6]. Theeffect of SOIAIC (Spin Orbit Interaction ActivatedInterchannel Coupling) on WES (Wigner EisenbudSmith) time delay [7] is investigated for a moderateZ atom [Z=54, Xe], and furthermore, the angle de-pendence of SOIAIC effects on WES time delay isinvestigated here.

Some illustrative results are shown in Fig. 1, thePIPT (Pseudo Independent Particle Truncation) curveshows a sharp peak (positive time delay) around thephoton energy of 76eV, whereas the ISST (Intra Sub-Shell truncation) curve shows a sharp dip (negativetime delay, i.e. time advancement) around 77eV ofphoton energy at θ = 60o. The cumulative effects ofall the dipole transitions provide the detailed spec-trum of the WES time delay from T4d3/2,1/2,+. At 60o

angle, both the real and the imaginary parts of theamplitude T4d3/2,1/2,+ go through a zero at both levelof truncation with different rates with respect to en-ergy. As a result of this the time delay is positive inthe PIPT calculation and it is negative in the ISSTcalculation.

This study is particularly important to understandthe photoionization time delay in near threshold re-gion.

References

[1] W. R. Johnson et al. 1979 Phys. Rev. A 20 964.

[2] W. R. Johnson et al. 1982 Phys. Rev. A 25 337.

[3] R. Pazourek et al. 2015 Rev. Mod. Phys. 87 765.

[4] M. Ossiander et al. 2016 Nature Physicsdoi:10.1038/nphys3941.

[5] A. Kivimaki et al. 2000 Phys. Rev. A 63 012716.

[6] D. A. Keating et al. 2017 J. Phys. B 50 17.

[7] E. P. Wigner 1955 Phys. Rev. 98 145.


ISAMP TC-7, 6−8 January, 2018, Tirupati CA005B Mandal

62

Study of the excited even configuration of Cs VII

Abid Husain*, S. Jabeen, Abdul Wajid

* Department of Physics, Aligarh Muslim University, Aligarh, UP-202002, India

Topic: A. Quantum collisions and Spectroscopy of atoms, molecules, clusters an ions

The ground most level 2P1/2 and first excita-

tion of Cesium VII was reported by V. Kauf-

man and J. Sugar [1] for the first time in 1987.

They reported all the nine levels belonging to

the ground configuration 5s25p and the first four

excited even configurations 5s5p2, 5s25d and

5s26s. They reported twenty-eight out of the

thirty-five levels belonging to the doubly excit-

ed odd configurations 5s2nf (n=4,5)

5s26p,5s5p5d,5s6s5p and 5p3 and one of the fur-

ther excited even configuration 5s5p4f have

been reported by R. Gayasov and Y.N. Joshi[2]

in 1999.

In the present work we have confirmed pre-

viously reported energy levels belonging to

5s25p, 5s5p2 ,5s25d, 5s26s, 5s2nf (n=4,5) 5s26p,

5s5p5d, 5s6s5p, 5p3, 5s5p4f configurations sat-

isfactorily. The work has been further extended

to the incorporate the thirty four levels belong-

ing to the even parity configuration 5s2nd (n=6,

7), 5s2ns (n=7, 8) and 5p25d levels as the

transitions were lying below1000Å. The ab

initio calculation was performed using cowan’s

code [3].

References [1] V. Kaufman and J. Sugar, 1987, J. Spt. Spc. Am. B 4,

1924-1926.

[2] R. Gayasov and Y.N. Joshi, 1999, Phys. Scripta, 60,

312-320.

[3] R.D. Cowan “Theory of atomic structure and spec-

tra” University of California Press, Berkeley 1981

*E-mail [email protected]

ISAMP TC-7, 6−8 January, 2018, Tirupati CA007A Husain

63

Electron-impact excitation of Xe+ ion and polarization of subsequent emissions

S.Gupta1, Lalita Sharma

and Rajesh Srivastava

Indian Institute of Technology Roorkee, Roorkee-247667, Uttrakhand, India

Topic: A- Quantum collisions and spectroscopy of atoms, molecules, clusters and ions.

Study of electron impact excitation of inert

gas atoms has been a topic of fundamental in-

terest for a long time. These atoms exhibit

strong relativistic and spin-orbit interaction ef-

fects indicated by their fine-structure splitting of

the different states, making it a highly challeng-

ing case for testing different theoretical models.

In addition to their basic fundamental interest,

electron collision cross sections are important

for analysis of photon emissions from plasmas

as well as for applications to different gaseous

discharges [1−3]. Furthermore, cross sections

are essential for identifying electron-impact ex-

cited lines in spectra of various astrophysical

objects including stars and interstellar gas

clouds. During the past few years, a number of

theoretical and experimental studies of xenon

have been carried out to obtain electron excita-

tion cross sections for various lower and excited

states [4]. However, very limited efforts have

been make to study the electron excitation of

inert gas ions [3-5]. Recently, Dipti and Sri-

vastava [5] have reported their extensive relativ-

istic distorted wave (RDW) calculations for

electron excitation Ar+ ion from its ground state

to several excited fine structure excited states

and the polarization studies of their decay by

photon emissions.

The study of neutral and ionic state of Xenon

have important fundamental interest and appli-

cations viz. in ion thrusters for space propulsion

in which the propellant is accelerated by an

electric-Hall effect and use the electron to ion-

ize the propellant which efficiently accelerate

the ions to produce thrust. These thrusters are

alternative to chemical propulsion system of

spacecraft. There are number of reports on the

theoretical and experimental electron impact

excitation cross sections of neutral Xe atoms [1-

3, 6-7] and these data have been utilized to

characterize various Xe imbedded plasma [3].

However, Dressler et.al.[1] have reported elec-

tron impact emission cross sections which are

derived from the luminescence spectra. Their

emission spectra show in addition to important

Xe atomic lines, few lines from the Xe+ ion. In

their spectra they observed 12 visible 8 near in-

fra-red lines for electron energies ranging from

10-70 eV. In order to explain Xe+ ionic lines a

collisional–radiative plasma model incorporat-

ing electron impact excitation cross sections for

various atomic states of the Xe+ ions are re-

quired.

In the present work, Electron impact excita-

tion in Xe+ ions has been studied using fully

relativistic distorted wave theory. Calculations

are performed to obtain the excitation cross-

sections and rate-coefficients for the transitions

from the lower ground state 3p5 (J=3/2) to fine-

structure levels of excited states 5p46s, 5p

46p,

3p47s, 3p

47p, 3p

45d and 3p

46d. Polarization of

the radiation following the excitation has been

calculated using the obtained magnetic sub-

level cross-sections. We have derived the ex-

pressions for polarization of different transitions

which are obtained in terms of magnetic sub

level cross sections which we calculated. All the

details of calculations along with the results will

be presented in the conference.

References

[1] Dressler et al. 2006 J.Appl. Phys. 99 113304

[2] Dressler et al. 2006 J.Appl. Phys. 99 113305

[3] Dressler et al. 2009 J.Phys. D: Appl. Phys 42

185203

[4] Lin C C et al. 1998 Phys. Rev. A 58 4603

[5] R. Srivastava et al. 2016 J Quant Spectrosc Radiat

Transf 176 12-23

[6] R. Srivastava et al. 2011 Eur. Phys. J. D 62 399-

403

[7] R. Srivastava et al. 2009 J. Phys.: Conf. Ser. 185 012042


ISAMP TC-7, 6−8 January, 2018, Tirupati CA008 Gupta

64

Wigner-Eisenbud-Smith time delay in photoionization of n f subshell: angleand spin resolved study

A. Mandal∗1 and P. C. Deshmukh†,#2


# Department of Physics, Indian Institute of Science Education and Research Tirupati, Tirupati 517507, India

Topic: A, B

Time domain studies of light-matter interac-tions covers a variety of research with differentfocii, extending from astrophysical to biologicalrelevance to foundational aspects of quantum the-ory [1, 2]. It has been realized that photoioniza-tion time delay is angle dependent in general [4].

1 0 0 1 5 0 2 0 0 2 5 0 3 0 0 3 5 0

0

5 0 0

1 0 0 0

1 5 0 0

2 0 0 0

1 0 0 1 5 0 2 0 0 2 5 0 3 0 0 3 5 0- 2 0

- 1 0

0

1 0

2 0

τ WES (a

s)

p h o t o n e n e r g y ( e V )

0 o

3 0 o

6 0 o

9 0 o

4 f 5 / 2

H g

1 0 0 1 5 0 2 0 0 2 5 0 3 0 0 3 5 0- 4 0- 2 0

02 04 06 08 0

1 0 01 2 0

τ WES (a

s)

p h o t o n e n e r g y ( e V )

0 o

3 0 o

6 0 o

9 0 o

4 f 7 / 2

H g

Figure 1. (Color online) WES time delay for 4 f5/2 and4 f7/2.

How exactly the photoionization time delay de-

pends on the angle of emission with respect to thephoton polarization is very much specific to thechannels and energies under inspection. Wigner-Eisenbud-Smith (WES) [3] time delay in single pho-ton, dipole photoionization from np and nd subshellshave been studied earlier [4, 5]. In the present workwe study WES time delay in photoionization fromthe spin-orbit split 4 f states. Following the formal-ism of [4, 5, 6] we compute the WES time delay forall possible channels from 4 f orbital of atomic Hg.The initial state angular momentum projection andfinal state spin averaged results are shown in Fig. 1.

The interference between different channels pro-duces an angle dependence of the WES time delaywhich become particularly interesting in the neigh-borhood of 160eV. The angle-dependence is maxi-mum at about the same energy ( 160 eV) because the4 f photoionization cross section undergoes a localminimum due to the competition between the oscil-lator strengths in the 4 f → εg and 4 f → εd channels.

Considering the fact that the local cross-sectionminimum is not a Cooper minimum, this study wouldbe of significant importance in the investigations onphotoionization dynamics.

References

[1] R. Pazourek et al. 2015 Rev. Mod. Phys. 87 765

[2] M. Schultze et al. 2010 Science 328 1658

[3] E. P. Wigner 1955 Phys. Rev. 98 145

[4] A. Kheifets et al. 2016 Phys. Rev. A 94 013423

[5] A. Mandal et al. 2017 Phys. Rev. A, in press

[6] W. R. Johnson et al. 1979 Phys. Rev. A 20 964


ISAMP TC-7, 6−8 January, 2018, Tirupati CA009B Mandal

65

Potential energy curves of the higher lying resonances inelectron-CO scattering

Amar Dora∗ 1 and Jonathan Tennyson† 2

∗ Department of Chemistry, North Orissa University, Baripada - 751 003, Odisha, India† Department of Physics and Astronomy, University College London, London WC1E 6BT, UK

Topic: A

Electron collision with molecules and the sub-sequent processes are of practical use in manyareas of technology. Detailed study of theseprocesses at the molecular level are therefore ofprime importance in their modelling and opti-mization. In the case of electron collision withcarbon monoxide, which is the second most com-mon molecule in the Universe after hydrogen,there have been several such studies by both ex-perimentalists and theoreticians. Most of thepast studies have concentrated only on the low-est lying 2Π shape resonance which is at about1.6 eV. In the recent years, however, there hasbeen some experimental studies [1-5] by differentgroups at higher collision energies, while almostnone exist on the theoretical side. These studieswhich measure the ion yield cross sections clearlyshow the presence of several resonances in the 9to 12 eV region. However, the characterizationof these high lying resonances based on the veloc-ity time sliced imaging, the technique which allthese groups used, has proved controversial withclaims and counter-claims, and calling for highlevel theoretical calculations [5].

We have been pursuing to study the dissocia-tion dynamics of the e+CO system theoretically.Recently, in our first attempt [6] to study thehigh lying resonances using the R-matrix methodwith a smaller basis set of cc-pVTZ we have hadpartial success where we found only one 2Σ+ Fes-hbach resonance at 12.9 eV having very narrowwidth in addition to the lowest 2Π shape reso-nance. In our newer fixed-nuclei R-matrix cal-culations at the equilibrium bond length of COusing a very large basis set cc-pV6Z we foundthree 2Σ+ resonances at 10.1, 10.38 and 11.1eV and a 2∆ resonance at 13.3 eV along withthe lowest 2Π resonance at 1.9 eV. We have nowcomputed the positions and widths of these reso-nances as a function of the inter-nuclear distance

using R-matrix theory and also have calculatedthe bound parts of the anion potential energycurves using MRCI level of theory. At the con-ference we will present these results (see Figure1) and discuss about the parentage of these res-onances. These results will be significant in viewof the controversy surrounding characterizationsby experimentalists.

0

5

10

15

20

25

1.7 1.8 1.9 2 2.1 2.2 2.3

Ene

rgy

(eV

)

R (bohr)

1Σ+

1Σ-

1∆1Π

3Σ+

3Σ-

3∆3Π

1 2Σ+

2 2Σ+

3 2Σ+

1 2∆1 2Π

Figure 1. Resonance positions and target CASSCF

energies as a function of inter-nuclear distance us-

ing cc-pV6Z basis set.

References

[1] P. Nag and D. Nandi, 2015, Phys. Chem. Chem.Phys. 17 7130

[2] S. X. Tian at al., 2013, Phys. Rev. A 88 012708

[3] P. Nag and D. Nandi, 2015, Phys. Rev. A 91056701

[4] S. X. Tian and Y. Luo, 2015, Phys. Rev. A 91056702

[5] K. Gope, V. Tadsare, V. S. Prabhudesai, N. J.Mason, and E. Krishnakumar, 2016, Eur. Phys.J. D 70 134

[6] A. Dora, J. Tennyson and K. Chakrabarti, 2016,Eur. Phys. J. D 70 197


ISAMP TC-7, 6−8 January, 2018, Tirupati CA010 Dora

66

Orientation effects in ionisation of CO by proton and ion impact

Bhas Bapat∗, Deepak Sharma∗ 1, Ajit Kumar†, Pragya Bhatt‡ and C P Safvan‡

∗ Indian Institute of Science Education and Research, Pune 411008† Dept. of Physics, Jamia Milia Islamia, New Delhi 110025‡Inter University Accelerator Centre, New Delhi 110067

Topic: A

Multiple ionization of the molecules dependson the orientation of the molecules with the beamdirection. Usually target molecules are ran-domly oriented in space, so experimental mea-surement of this dependence is not straightfor-ward. For the special case of fragmentation (dis-sociative double or higher ionisation) of a di-atomic molecule, it is possible to establish thisangle from the coincidence measurement of theangular distribution of the two separated ions.Several workers have looked into this aspect andmany trends have been observed for homonuclearas well as heteronuclear molecules, mostly N2

and CO [1, 2, 3, 4]. Specifically, no studies havemade a distinction between the effects of align-ment – which merely indicates a propensity to anaxis, and orientation – which indicates a specificpointing towards one or the other direction of anaxis. We have investigated the fragmentation ofCO molecule subject to collisions with protonsand highly charged ions. Angular distributionsof the fragments are derived from the coincidencemomentum spectra of Cn1+ and On2+ ions re-sulting from the dissociation of COn+ ions withn1 + n2 = n. The orientation dependence of theionisation cross-section is parametrised by the fitto the observed angular distribution of fragmentions

N(θ) = N0 [1 + β1P1(cos θ) + β2P2(cos θ)] sin θ

In this function β1 represents the asymmetry ofthe cross-section in the forward and backwardhemispheres w.r.t. the projectile, and is a mea-sure of the orientation effect in heteronuclearmolecules, while β2 is a measure of anisotropy,applicable to both heteronuclear and homonu-clear molecules. For proton impact in the en-ergy range 25–200 keV we find strong orientationdependence of the ionisation cross-sections, espe-cially at lower incident energies and higher degreeof target ionisation. In Figure 1, experimentalresult for multiple ionization of CO in collisionwith proton at 50 keV energy is shown. Asym-

metry effect is observed together with anisotropyand both the effects increases with degree of ion-ization. Model calculation shows that for a fixeddegree of ionization orientation effect should de-crease with increase in projectile energy as theo-retically calculated by Kaliman et al [5].

0

0.2

0.4

0.6

0.8

1

1.2

1.4

0 30 60 90 120 150 180

Inte

nsity

[arb

.uni

t]

Angle[deg]

CO2+CO3+CO4+sin(θ)

Figure 1. Multiple ionization of CO in collision

with proton at 50 keV energy

Orientation effects also dependes on the in-teraction strength of the projectile, defined bySommerfeld parameter k = q/v. For the highinteraction strength, more electron may be re-moved for a given trajectory but at the same timethe contributions from large impact parametersbecome significant. However, as the impact pa-rameter becomes significantly large than the sizeof the molecule, the orientation effect becomesweaker. Collisions with Ar7+ and Xe9+ impactshow only a weak dependence at even higher de-gree of ionisation.

References

[1] Wohrer, K. and Watson, R. L. 1993 Phys. Rev. A48 4784

[2] C Caraby et al 1997 Phys. Rev. A 55 2450

[3] U Werner et al 1997 Phys. Rev. Lett. 79 1662

[4] B Siegmann et al 2001 Phys. Rev. A 65 010704

[5] Z Kaliman et al 2001 Phys. Rev. A 65 012708


ISAMP TC-7, 6−8 January, 2018, Tirupati CA011 Sharma

67

The IAEA database for stopping power, trends in the energy loss experimental research

C. C. Montanari* 1, P. Dimitriou† 2

* Instituto de Astronomía y Física del Espacio, CONICET and Universidad de Buenos Aires, Argentina. *Facultad de Ciencias Exactas y Naturales, Univerisdad de Buenos Aires, Buenos Aires, Argentina.

†Division of Physical and Chemical Sciences, International Atomic Energy Agency, Vienna, Austria.

A: An overview of the state of art of the energy loss of ions in matter is presented based on our work for the stopping power database of the International Atomic Energy Agency. Our goal is to identify areas of interest, trends, and emerging data needs. We address the interest in new materials such as polymers, oxides or silicon compounds of technological interest, and the necessity of theoretical developments to describe the energy loss of ions in these targets.

The aim of this work is to present a re-view of the stopping power of ions in matter, focused on the experimental data published since 2000. We based on the stopping power database of the International Atomic Energy Agency (IAEA) [1]. This exhaustive collection of experimental data, graphs, programs and comparisons, is the legacy of Helmut Paul ([1,2] and references therein) who made it ac-cessible to the global scientific community, and has been extensively employed in theoretical and experimental research during the last 25 years. This collection comprises compilations of experimental measurements made in different laboratories worldwide and covers the period since the early measurements in the 30s and 40s up to the present. The values of more than 850 references are included.

0

20

40

60

80

100

2001

-20

04

201

3-20

16

2009

-20

12

200

5-2

008

Stopping Power measurements

4 year period

Num

ber

of

ion-

atom

sys

tem

s m

easu

red

Compounds Atoms

Period: 2001-2016 Last period:103 exp in compounds55 exp in atomic targets

Figure 1. Number of ion-target systems measured since 2001 as function of time. Compounds duplicate the atomic targets. Data from IAEA database [1].

The field of stopping powers in matter is evolving with new trends in materials of inter-est, including oxides, polymers, and biological targets [3-5].

The stopping powers are relevant to a wide range of applications such as ion beam analysis, deposition ranges (perhaps the most demanding data is on water and biological targets due to the application to hadron therapy), ion implantation (i.e. for doping metal oxide semiconductors to the industry of electronic devices and hard glasses), and radiation damage (the relation with the electronic stopping power is empiri-cally clear, with different evaluations such as the losses of functional groups in complex molecules [6].

BarilocheValparaiso

Linz

IThemba, SA

Argelia

Upsala Jyvaskyla

Helsinki

Catania

Porto Alegre

San Pablo

Oak Ridge

Kurukshitra

New Delhi

Varsovia

Zagreb

2010-2016

Kyoto

Figure 2. Laboratories around the world with meas-urements of electronic energy loss since 2010.

References

[1] https://www-nds.iaea.org/stopping/ [2] Paul (2013), AIP Conf. Proc. 1525, 295. [3] Montanari et al (2017), Nucl. Instr. Meth. Phys. Res. B 408, 50. [4] Nandi et al (2013), Phys. Rev. Lett. 110, 163203. [5] Roth et al (2017), Phys. Rev. Lett. 118, 103401. [5] Miksova et al (2016), Nucl. Instr. Meth. Phys. Res. B 371, 81. [6] Kusumoto et al (2016)., Rad. Measurements 87, 35.


ISAMP TC-7, 6−8 January, 2018, Tirupati CA012 Montanari

68

Energy loss of low energy protons and antiprotons in metals

C. C. Montanari 1, J. E. Miraglia 2

Instituto de Astronomía y Física del Espacio, CONICET and Universidad de Buenos Aires, Argentina Facultad de Ciencias Exactas y Naturales, Univerisdad de Buenos Aires, Buenos Aires, Argentina

Topic A: We propose a non-perturbative approximation to the electronic stopping power based on the central screened potential of a projectile moving in a free electron gas, by Nagy and Apagyi. We calculate the energy loss of protons and antiprotons in ten solid targets: Cr, C, Ni, Be, Ti, Si, Al, Ge, Pb, Li and Rb. Our formalism is valid for low impact velocities, where plasmon excitations are not important. We extend the energy loss calculations to intermediate and high energies by using the Lindhard dielectric formalism (including plasmons) and the SLPA model to include the inner-shell contri-bution.

In the last decade, the stopping power has had a revival due to the requirement of more accurate experimental data, and to the possibili-ties and precision of the up to date techniques [1]. Perhaps, the most challenging ones are the low-energy antiproton experiments at CERN and the future prospects of the Facility for Anti-proton and Ion Research at Darmstadt [2].

The low energy behavior of the stopping power has attracted many of the experimental efforts in the last years [3,4]. The accuracy of the new experimental techniques and the neces-sity of full theoretical data, lead us to wonder on the highest theoretical precision to describe the low-energy new experimental values.

Figure 1. The friction for low energy antiprotons in solids. Curves, the present model. Symbols, experi-mental data in [5].

We present here a non-perturbative binary collisional model to describe the electronic stopping power, dS/dx, of heavy charged pro-jectiles in a free electron gas. The friction Q=(dS/dx)/v is a sensitive parameter at low im-pact velocities, which is approximately constant in an homogeneous free electron gas.

In Fig. 1 we display friction for antiprotons in three different solids, Al, Si and C. In figure

2, we display similar results but for proton im-pact. As the targets Si, Al and Ge have very similar rs, the value of Q is expected to be very similar for the three targets. This is verified ex-perimentally and in our theoretical description.

Figure 2. The friction for low energy protons in solids. Curves, the present model. Symbols, experimental data in [5].

The combination of this model for low im-pact energies and perturbative ones (but includ-ing plasmons) for higher energies proved to de-scribe the stopping power in a large energy range [5]

References

[1] Montanari et al (2017), Nucl. Instr. Meth. Phys. Res. B 408, 50. [2] FAIR, Facility for Antiproton and Ion Research, http://www.fair-center.eu/. [3] Celedon et al (2015), Nucl. Instr. Meth. Phys. Res. B 360, 103. [4] Roth et al (2017), Phys Rev Lett 118, 103401. [5] Montanari et al (2017), Phys Rev A 96, 012707.



69

Electron interaction scattering cross sections of Astromolecules

Rakesh Bhavsar 1, Yogesh Thakar 2, Chetan Limbachiya 3

1, 2 M. N. College, Visnagar – 384315, Gujarat, India

3The M.S.University of Baroda, Vadodara-390001, Gujarat, India

Synopsis: Total Cross sections calculations for electron interaction with astromolecule is presented here.

Topic:A

The discovery and study of astromolecules

have gained importance due to the

fundamental interest in basic science as well

as for the investigation of possible extra-

terrestrial life and such studies have been

made possible and facilitated by the advent

of modern space activities. The molecules

found in the inter-stellar clouds, various

cometary and planetary environments as well

as those which are detected over moons of

the planets are being explored [1, 2]

We report a theoretical total scattering

cross sections of electron interaction with

Astro- molecules in the energy range from

threshold to 5 keV. Here ‘Spherical Complex

Optical Potential’ (SCOP) [3] formalism

employed to evaluate Qel, Qinel, and Qtotal

and used our semi-empirical, ‘Complex

Spherical Potential – ionization contribution’

(CSP-ic) method to derive Qion and ΣQexc

[4]. Results are compared with experimental

and theoretical data wherever availabl

References

[1] Gautier, Nathalie Carrasco , Arnaud Buch , Cyril Szopa , Ella Sciamma-O’Brien, Guy Cernogora, ,

ICARUS Nitrile gas chemistry in Titan’s atmosphere 213, 625–635 (2011)

[2] N Carrasco et al., Volatile products controlling Titan’s tholins production.

ICARUS, 219, 230-240 (2012)

[3] Mohit Swadia, Rakesh Bhavsar, Yogesh Thakar, Minaxi Vinodkumar & Chetan Limbachiya

Molecular Physics, 115, 2521-2527 (2017)

[4] M. Swadia, Y. Thakar, M. Vinodkumar, and C. Limbachiya, Eur. Phys. J. D.

71, 85(2017).

1 E-mail: [email protected] 2 E-mail: [email protected] 3 E-mail: [email protected]

ISAMP TC-7, 6−8 January, 2018, Tirupati CA014 Bhavsar

70

Electron interaction scattering cross sections of Biologically relevant molecule

Yogesh Thakar 1, Rakesh Bhavsar 2,Chetan Limbachiya 3

1, 2 M. N. College, Visnagar – 384315, Gujarat, India

3The M.S.University of Baroda, Vadodara-390001, Gujarat, India

Synopsis: Total Cross sections calculations for electron interaction with Biologically relevant molecule is presented

here.

Topic: A

The high energy ionizing radiation like X-

rays, γ-rays and ±β-particles is widely used

in medical diagnostic and cancer therapy.

Simplifying, during interaction of such high

energy particles with living cells two

complex processes are very important. In the

first stage the high energy primary radiation

can induce direct damage to the cell. During

that process variety of secondary species,

including low energy electrons (LEE) are

produced. In the second process secondary

species can react with their environment,

what can lead to the further damage of the

cell. The number of these low energy (0−20

eV) secondary electrons is

significant,4×104electrons per 1 MeV of

radiation [1]

Such LEE can react with molecular

environment in different way and some of the

allowed pathways can lead to chemical reactions

for example via dissociative electron attachment

or ionization. It has been proved experimentally

[2,3] that such low energy electrons can induce

significant amount of single and double stand

breaks in the DNA. Since that discovery, many

experimental and theoretical works concerning

low- and intermediate-energy electron

interaction with DNA and its building blocks, as

well as simple molecular analogs of its

constituents have been done [4-6]

We report Various Theoretical total

scattering cross sections for interaction of

electron with Biological relevant molecule.

Here we deploy SCOP [7] for calculations of

Elastic, Inelastic, and total Cross Sections

Using CSP-iC formalism [8] ionization cross

sections are calculated. Excitation cross

sections are byproduct of above calculations.

Results are compared with experimental and

theoretical data wherever available

References: [1]. V. Cobut, Y. Fongillo, J.P. Patau, T. Goulet, M.J. Frases, J.P.Jay-Gerin Radiat. Phys.Chem. 51,229(1998)

[2. B. Boudaiffa, P. Cloutier, D. Hunting, M.A. Huels, L.Sanche, Science 287, 1658 (2000)

[3] B. Boudaiffa, D.J. Hunting, P. Cloutier, M.A. Huels, L.Sanche, Int. J. Radiat. Biol.76, 1209 (2000)

[4] L. Sanche, Mass Spectrom. Rev.21, 349 (2002)

[5] L. Sanche, Eur. Phys. J. D 35, 367 (2005)

[6] C. Winstead, V. McKoy, Radiat. Phys. Chem.77, 1258(2008) Eur. Phys. J. D(2012) 66: 54

[7] Mohit Swadia, Rakesh Bhavsar, Yogesh Thakar, Minaxi Vinodkumar &Chetan Limbachiya, Molecular

Physics, 115, 2521-2527 (2017) [8] M. Swadia, Y. Thakar, M. Vinodkumar, and C. Limbachiya, Eur. Phys. J. D.71,85(2017)



ISAMP TC-7, 6−8 January, 2018, Tirupati CA015 Thakar

71

Electron Induced chemistry of Chlorobenzene

Dineshkumar Prajapati∗,† 1, Hitesh Yadav† 2, Minaxi Vinodkumar‡ 3, P C Vinodkumar† 4

∗ Shree M R Arts & Science College, Rajpipla - 393145, India† Department of Physics, Sardar Patel University, Vallabh Vidyanagar - 388120, India

‡ V. P. & R. P. T. P. Science College, Vallabh Vidyanagar - 388120, India

Topic: A

Electron impact studies with organic targetsgained prominence after the study, that sec-ondary electrons produced by energetic radia-tions are responsible for single and double strandbreaks in DNA. Moreover systematic and de-tailed knowledge of cross sections resulting fromelectron collisions with simple organic systemscan help us to understand the behaviour of morecomplex biomolecules.

A detailed theoretical study is carried outfor electron interactions with chlorobenzene(C6H5Cl) with impact energies ranging from0.01 to 5000 eV. Owing to the wide energy rangewe have been able to investigate variety of pro-cesses and report data on dissociative electronattachment (DEA) through resonances, verticalelectronic excitation energies, differential, mo-mentum transfer, ionization and total cross sec-tions (TCS) as well as scattering rate coefficients.In order to compute TCS we have employed abinitio R-matrix method (0.01 to 20 eV) [1, 2] andthe spherical complex optical potential (SCOP)method (20 to 5000 eV) [3, 4]. The R-matrixcalculations were performed using close couplingapproximation employing a static exchange pluspolarization (SEP) model. The target proper-ties reported using quantum chemistry codes arein good agreement with earlier reported data asshown in Table 1.

Table 1. Target Properties of Chlorobenzene

Target property (unit) Present Other[5]

Ground State (Hartree) -688.64 -689.99

Ionization Potential (eV) 9.200 9.080

Dipole Moment (Debye) 1.689 1.690

As a sample result we report here DCS dataof e-C6H5Cl scattering at 20 eV in Figure 1. Thepresent data finds overall good agreement withthe dataset of Barbosa et al.[6].

0 20 40 60 80 100 120 140 160 1800.1

1

10

100

1000

DC

S (1

0-16 c

m2 /s

r)

Present Barbosa exp. Barbosa_IAM-SCAR Barbosa_SMCPP

20eV

(degree)

Figure 1. Differential Cross Section of chloroben-

zene at 20eV

Minaxi Vinodkumar acknowledge DST-SERB, New Delhi for the Major research project[EMR/2016/000470] for financial support underwhich part of this work is carried out.

References

[1] M.Vinodkumar et al. 2015 RSC Adv. 5 24564

[2] M. Vinodkumar et al. 2016 Phys. Rev. A 93012702

[3] H. Yadav et al. 2017 Molecular Physics 115-8952-961

[4] M.Vinodkumar et al. 2015 RSC Adv. 5 69466

[5] http://cccbdb.nist.gov

[6] Barbosa et al. 2016 J. Chem. Phys. 145 084311

1E-mail: [email protected]: [email protected]: [email protected]: [email protected]

ISAMP TC-7, 6−8 January, 2018, Tirupati CA016 Prajapati

72

Optical breath gas sensing using UV-VUV absorption spectroscopy

Sunanda Krishna Kumar

1, B.N. Rajasekhar

2 and Asim Kumar Das


Topic A. Quantum collisions and spectroscopy of atoms molecules, clusters and ions.

Volatile organic compounds (VOCs) release and

analysis linked to medical condition is a new fron-

tier in medical diagnostics [1]. This technique

finds application in Breathe analysis, an inexpen-

sive, rapid and non-invasive diagnostic method,

useful in a variety of clinical applications. In the

present work we are proposing to use UV-VUV

spectroscopy to study the VOC composition from

exhaled gas involved in a respiration process as an

analytical tool for two gas detection. Few sensor

development projects do exist for measuring hu-

midity in breathing condition [2] and breath sen-

sor to detect NH3 [3]. However an optical sensor

for detecting two VOC emissions (Carbon disul-

fide (CS2) and pentane (C5H12)) contained in

breath sample of a subject suffering from Schi-

zophrenia [2] does not exist till date. In this paper

we present the spectroscopic method required to

identify a spectral region free from spectral interfe-

rence among these molecules to develop optical

sensing method for two molecule gas detection.

For this purpose vertical excited state ener-

gies have been computed and plotted for atmos-

pheric molecules, CS2 and C5H12 as shown in fig.1.

It is clear from the excited state data that atmos-

pheric gases absorb in different characteristic wa-

velength regions and carbon disulfide & pentane

also have specific absorptions. From the excited

state information it appears that there is no absorp-

tion of N2 and CO above 170nm; O2, H2O and CO

and CO2 have little absorption in the energy region

of 185 -220 nm and almost zero absorption beyond

220nm up to 250 nm (CO2 and CO have very little

absorption; in comparison with molecules under

consideration.

Figure 1. Excited state energy comparison of atmos-

pheric molecules, CS2 and C5H12

Details of computed excited state energies,

excited state ordering, simulated & experimental

spectra required for unambiguous selection of

spectral region for two optical molecular gas sens-

ing will be presented in this paper.

References:

1. Julian W. Gardner, Sensors 2016, 16, 947.

2. S.Morisawa et.al. Proc. IEEE Sensors, 2004, pp.1277.

3. R. Lewicki et.al. Optical Society of America, 2009,

pg. CMS6.

4. M Phillips et.al. 1993, J Clin Pathol 46 861.



ISAMP TC-7, 6−8 January, 2018, Tirupati CA017 KrishnaKumar

73

Fully relativistic structure calculations of heavy targetsfor inelastic collisions

Mendez, A. M. P. 1, Mitnik, D. M., Montanari, C. C.

Instituto de Astronomıa y Fısica del Espacio, CONICET–UBA, Buenos Aires, Argentina

Topic: A. Fully relativistic structure calculations for Ta (Z=73), Pt (Z=78), Th (Z=90) and U (Z=92) arepresented here. The description of these atoms requires the solution of the relativistic Dirac equation. Weused the hullac suite of codes to compute their atomic structure. The results obtained for the energies of thebound orbitals are compared with experimental ones, obtaining a good overall agreement. The method uses theparametric potential model that allows to obtain a unique potential. This enable us to represent both bound andcontinuum states in the same footing, which is of great interest in several inelastic collisional calculations, suchas stopping, straggling and multiple ionization.

The description of heavy atoms requires thesolution of the relativistic Dirac equation. Tothis end, we used the hullac code package [1],which allows one to obtain accurate relativis-tic one-electron orbitals and multiconfigurationbound states and energies. The calculations arebased on first-order perturbation theory with acentral field, including the contribution from theBreit interaction and quantum electrodynamicscorrections. The detailed energy levels are com-puted using the relac code [2], which uses theparametric potential model. This model consistsin minimizing the first–order relativistic energyof a given set of configurations for a paramet-ric analytical function for the screening chargedistribution. Although this code was written forcalculations of heavy ionized atoms, it can besuccessfully employed in other atomic systems,such as the ones presented here.

First, we calculated the atomic structure withnonrelativistic and semirelativistic approachesusing the autostructure code [3]. We com-pared the computed binding energies of thebound orbitals with the experimental values insolid compiled by Williams [4]. The nonrelativis-tic calculations showed large discrepancies withthe experimental results, which probed the neces-sity of a relativistic approach. Then, the semirel-ativistic method was tested, allowing to obtainbetter agreement with the experimental bindingenergies. However, the large errors found for themost tightly bound inner orbitals evidenced theneed of fully relativistic calculations.

The binding energies obtained for Ta, Pt, Thand U using the fully relativistic method areshown with up–filled triangles in Fig. 1. Thefigure also includes the experimental bound en-ergies (hollow circles) [4]. The values computedfor the inner orbitals agree with the experimentalones in about 2%. The discrepancies found with

the more external shells are accounted for thestructure differences between the atoms (com-puted) and the solids (experiments). Previousstructure calculations for other atomic systemsshowed accurate description of relativistic targetsin various inelastic collisions processes, particu-larly energy–loss and straggling [5]. Further col-lisional calculations for these atoms are presentedin the conference by one of the authors.

1s

2s

2p-

2p+ 3s

3p-

3p+

3d-

3d+ 4s

4p-

4p+

4d-

4d+

4f-

4f+ 5

s5p-

5p+

5d-

5d+ 6s

6p-

6p+

6d-

6d+ 7s

10-1

100

101

102

103

104

1s

2s

2p-

2p+ 3s

3p-

3p+

3d-

3d+ 4s

4p-

4p+

4d-

4d+

4f-

4f+ 5

s5p-

5p+

5d-

5d+ 6s

6p-

6p+

5f-

5f+ 6d-

6d+ 7s

10-1

100

101

102

103

104

Th

U

Ta

Pt

Bin

din

g e

ner

gie

s (r

yd)

Figure 1. Theoretical and experimental binding

energies for Pt, U, Ta, and Th.

References

[1] A. Bar-Shalom, M. Klapisch, and J. Oreg, J.Quant. Spectrosc. Radiat. Transf. 71, 169 (2001).

[2] M. Klapisch, J. L. Schwob, B. S. Frankel, andJ. Oreg, J. Opt. Soc. Am. 67, 148 (1977); M.Klapisch, Comput. Phys. Commun. 2, 239 (1971).

[3] N. R. Badnell, J. Phys. B 30, 1 (1997); M. S.Pindzola and N. R. Badnell, Phys. Rev. A 42,6526 (1990).

[4] http://xdb.lbl.gov/Section1/Sec 1-1.html

[5] C. C. Montanari, C. D. Archubi, D. M. Mitnik andJ. E. Miraglia, Phys. Rev. A 79, 032903 (2009);Phys. Rev. A 80, 012901 (2009).



74

Kinetic energy release distribution in electron dissociative ionization of CO2

Manoj Kumar!, R. Singh and S. Pal

Department of Physics, M.M.H. College, Ghaziabad-201001 (UP)

Topic: (A) Quantum collision and Spectroscopy of atoms, molecules, clusters, and ions.

There has been increasing interest in dissocia-

tive/ multiple ionization of atoms and molecules by

charged particles. Because of coulomb repulsion

between two positive charged ions are unstable and

dissociate into ionic fragments with a concomitant

kinetic energy release. Therefore, it is necessary to

understand the mechanism of the kinetic energy

release before the excitation and dissociation dy-

namics of doubly charged molecular cations can be

explained. Experimental studies may provide in-

formation such as the shape of the potential surface

of the precursor-ion states, and the energy partition-

ing among the internal degrees of freedom of the

ionic fragments and their kinetic energies in the

framework of direct double photo-ionization of mo-

lecules and subsequent dissociation [1].

In the present work, we have evaluated kinet-

ic energy released distribution of ionic fragments

(C+ and O

+) produced upon dissociative double io-

nization of CO2 by electron impact with energies

varying from ionization threshold to 100 eV. A

semi-empirical formulation [2], based on the photo

ionization cross section/ the oscillator strength data

as input has been employed to evaluate the ioniza-

tion cross sections corresponding to the formation

of doubly charged ions. The calculated electron io-

nization cross section profile then used to compute

the kinetic energy release distribution.

On the other hand the angular distribution

cross sections for the ion formation is obtained as

𝑑𝜎

𝑑𝛺=

𝜎

4𝜋 1 +

𝛽

4 1 + 3𝑝𝑐𝑜𝑠2𝜃

where σ, β, θ and p are ionization cross section,

asymmetric parameter, angular distribution and de-

gree of polarization, respectively. The trend of the

present results reveal qualitative agreement as for

the photo-ionization profiles.

References

[1] T. Masuoka et al. 2000, J. Chem.Phys. 113

6634.

[2] R.Kumar, 2013 Rapid Commun. Mass Spec-

trom. 27 223 and references therein.

! E-mail: [email protected]

ISAMP TC-7, 6−8 January, 2018, Tirupati CA019 KumarManoj

75

VUV Spectroscopy of Diethyl Carbonate

Asim Kumar Das1, Sunanda Krishnakumar and B. N. Rajasekhar

2

Atomic & Molecular Physics Division, Bhabha Atomic Research Centre, Trombay, Mumbai - 400085.

Topic: A. Quantum collisions and spectroscopy of atoms, molecules, clusters and ions

Diethyl carbonate (OC(OCH2CH3)2) is one

of the green solvents widely used as electrolyte

in lithium batteries and molecular modeling is a

powerful tool for a microscopic understanding

of interactions, processes and phenomena in-

volving them [1]. Diethyl carbonate, a carbon-

ate ester, is a clear liquid at room temperature

with a low flash point. It is used in the produc-

tion of polycarbonates and proposed as a fuel

additive [2]. It is used as a solvent in medicinal

applications e.g. erythromycin intramuscular

injections [3]. In spite of its usefulness as a sol-

vent in many important application areas, processes and phenomena involving diethyl

carbonate is far from complete as the spectro-

scopic data available on this molecule is sparse.

Therefore, experiments have been carried out to

obtain electronic excited state information on

this molecule in gas phase. VUV photoabsorp-

tion spectrum of diethyl carbonate (DEC) in gas

phase is recorded using monochromatic syn-

chrotron radiation from Photophysics beamline

[4] at Indus-1 synchrotron radiation source at

RRCAT, Indore in the energy region 7 eV to

11.3 eV as shown in Fig. 1. In addition, gas

phase infrared spectroscopy has been carried

out using FTIR in the energy region 4000-500

cm-1

. The results from these studies shall add

valuable information of the energetic of excited

states, energy ordering, assignment and nature

of excited states etc.

In addition, geometry optimization and vi-

brational frequency calculations of neutral and

ionized DEC have been carried out using den-

sity functional theory (DFT) method for a vari-

ety of basis sets and correlation functional. The

ground state equilibrium structure of DEC be-

longs to C2V point group. The vertical and adia-

batic ionization energy obtained from these

simulations is 11.52 eV and 11.25 eV respec-

tively. Time dependent DFT (TDDFT) calcula-

tions have been performed for the analysis of

electronic excited singlet and triplet states.

Lambda diagnostic analysis suggests that low

lying excited states are predominantly Rydberg

in nature. Spectrum shown in Fig.1 contains

two broad features with overlying vibronic fea-

tures. The first excited state of finite oscillator

strength at 8 eV corresponds to transition from

HOMO (orbital 32 of symmetry b1) to LUMO

(orbital 33 of symmetry a1). The computational

studies predict strong interaction between the

valence and Rydberg states below 9 eV.

Figure 1. VUV absorption spectra of DEC recorded

using synchrotron radiation at Photophysics beamline

The experimental results and analysis of the

VUV absorption spectrum will be presented

along with computational results performed us-

ing GAMESS (USA) [5].

References

[1]Sudip Das et al. 2017, Curr. Opin. Green Sustain.

Chem. 5, 37

[2]K Shukla et al. 2016, RSC Adv. 6, 32624

[3]William H. Brown, Organic Chemistry 6th

Ed.

[4] N C Das et al. 2003, J. Opt. (India) 32, 169

[5]M W Schmidt et al.1993, J. Comput. Chem. 14,

1347



ISAMP TC-7, 6−8 January, 2018, Tirupati CA020 Das

76

Ab initio calculations of spectroscopic parameters of HfH+ andPtH+

Renu Bala 1, H. S. Nataraj 2, Minori Abe 3

1,2 Department of Physics, Indian Institute of Technology Roorkee, Roorkee - 247667, India3 Department of Chemistry, Tokyo Metropolitan University, 1-1 Minami-Osawa, Hachioji, Tokyo 192-0397,

Japan

Topic: A

The polar diatomic molecules are of interestto experimentalists looking for a non-zero elec-tric dipole moment of an electron (eEDM). Thecurrent best limit on eEDM also comes from theultracold molecular experiment on ThO. On theother hand, calculating spectroscopic parame-ters and properties of such molecules containingheavy atoms is a challenge to theorists because oftheir complex electronic structure. As the eEDMhitherto has evaded detection, new systems arebeing proposed and explored constantly. Twosuch molecular candidates: PtH+, and HfH+

have been proposed by Meyer et al. [1] andthey have obtained the potential energy curves(PECs) for ground- and lower- excited statesusing perturbation theory non-relativistically.PtH+ is also studied by Skripnikov et al. [2] forsome spectroscopic constants of a few low ly-ing excited states. Quite recently, low lying Ωelectronic states of PtH and PtH+ have beencomputed by Shen et al. [3] using MRCISD+Qmethod.In this work, we have performed relativistic en-ergy calculations for 1Σ ground state of PtH+

and also HfH+ molecular ions at SCF and CCSDlevel of correlation using DIRAC15 program [4].The cc-pVQZ basis set for H atom and Dyall va-lence basis set, dyall.v4z for Pt and Hf are usedin conjunction with Gaussian charge distributionand C2v point group symmetry. From the calcu-lated PECs, we have obtained the spectroscopicconstants and vibrational states using VIBROTprogram in MOLCAS [5]. The diatomic con-stants together with the number of vibrationalstates for the two cations calculated at SCF levelare tabulated in Table 1. The PECs and rel-ative energy spacing, (Ev+1 − Ev) between theadjacent vibrational states is shown against thevibrational quantum number in Figure 1. Thedetailed results will be presented in the confer-ence.

Table 1. The spectroscopic parameters (Re in au

and De in eV and the rest in cm−1) and number

of vibrational states (v) for HfH+ and PtH+ calcu-

lated at SCF level.

Molecule Re De ωe ωexe Be αe v

HfH+ 3.47 6.49 1799 19.8 4.97 0.09 60

PtH+ 2.87 7.26 2307 21.9 6.94 0.10 43

-15090.4

-15090.2

-15090

-15089.8

HfH+

0

500

1000

1500HfH

+

5 10 15 20Nuclear distance (au)

-18437.1

-18436.8

-18436.5

PtH+

0 10 20 30 40Vibrational quantum number

500

1000

1500

2000

PtH+E

ner

gy

(au

)

Ev

+1-E

v (

cm-1

)

(a) (b)

(c) (d)

Figure 1. PECs of, (a) HfH+, (c) PtH + and rel-

ative vibrational energy spacing (b) HfH+ and (d)

PtH+.

References

[1] E. R. Meyer et al. 2006 Phys. Rev. A 73 062108

[2] L. V. Skripnikov et al. 2009 Phys. Rev. A 80060501(R)

[3] K. Shen et al. 2017 J. Phys. Chem. A 121 3699

[4] DIRAC, a relativistic ab initio electronic struc-ture program, Release DIRAC15 (2015),writtenby T. Saue, L. Visscher, H. J. Aa. Jensen et al.(see http://www.diracprogram.org)

[5] G. Karlstrom, et al. MOLCAS: a program pack-age for computational chemistry, Comput. Mat.Sci. 28, 222 (2003).

1E-mail: [email protected]: [email protected]: [email protected]

ISAMP TC-7, 6−8 January, 2018, Tirupati CA021 Bala

77

Ultrafast spectroscopy of perovskite interfaces Manas R. Parida * 1 and Omar F. Mohammed † 2

* Department of Physics, Central University of Rajasthan – 305801, Rajasthan, India † Solar and Photovoltaics Engineering Research Center, Division of Physical Sciences and Engineering, King Abdullah

University of Science and Technology, Thuwal 23955-6900, Kingdom of Saudi Arabia

Topic: A

Ultrafast charge transfer (CT), separation (CS) and recombination (CR) at the donor-acceptor interface, has been proven to be key in solar cell performance.1 How to control these ultrafast processes remains a topic for debate. Here, we report in situ doping of heterovalent Bi3+ ions in colloidal CsPbBr3 perovskite NCs for the first time by hot injection to precisely tune their band structure and excited state dy-namics.2 Upon excitation with a 370 nm laser pulse, the bleaching maxima, also referred to as ground state bleach (GSB) was observed at 506 nm and positive absorption bands attributed to the excited-state absorption (ESA) of the excit-ed charge carriers centered at 465 nm was ob-served in both doped and undoped NCs. Fur-ther, the transient absorption (TA) spectra re-vealed a blue shift in the GSB position to 499 nm for 0.8% Bi-doped CsPbBr3 NCs as com-pared to the undoped one, which is consistent with the ground-state absorption. The spectral changes in the TA of Bi- doped CsPbBr3 NCs could be attributed to strong perturbation to the electronic structure that occurs when Bi dopant atoms are introduced in the CsPbBr3 NCs struc-ture. The emission quenching accompanied by decrease in PL decay lifetime in Bi- doped CsPbBr3 NCs further substantiated the presence of trap states within the band gap of the host CsPbBr3 NCs upon doping with Bi. Such traps provide alternative ways for electronic relaxa-tion and consequently reduce the radiative re-combination.

Then, we took an important step forward by mapping the tremendous impact of metal dop-ing on charge transfer from the NCs to different molecular acceptors. We investigated the steady state absorption and emission properties of the undoped and doped NCs in the presence of tet-racyanoethylene (TCNE) and fullerene

(PCBM). When TCNE/PCBM was added suc-cessively to the CsPbBr3 NCs-both doped and undoped, resulted a gradual decrease in emis-sion intensity. It is worth mentioning that such exciton quenching could also be a consequence of energy transfer, however, we refute such possibility as there is no spectral overlap be-tween absorption of TCNE and emission of NCs. Our time-resolved data demonstrate clear-ly that the charge transfer at the interface of the NCs can be tuned and assisted by metal doping. More specifically, we found that the doping in-creasing the free energy driving force (-∆G) which is the energy difference between the mo-lecular acceptor and donor moieties and subse-quently facilitates the interfacial charge transfer process shown in scheme 1. The novel insights highlighted in this work shed light on the key variable components not only the energy differ-ence between the molecular acceptor and donor moieties and subsequently facilitates the inter-facial charge transfer process.

Figure 1. A schematic diagram of electron transport at the perovskite NC-fullerene interface.

References [1] QA Alsulami et al. 2016, Adv. Energy Ma-

ter. 6, 1502356 [2] Manas et al. 2017, JACS, 139,731-737


ISAMP TC-7, 6−8 January, 2018, Tirupati CA022 Parida

78

Absolute dissociative electron attachment cross sectionmeasurement studies for difluoromethane

Dipayan Chakraborty 1, Pamir Nag and Dhananjay Nandi 2

Indian Institute of Science Education and Research Kolkata, Mohanpur 741246, India

Topic: A

Dissociative electron attachment (DEA) pro-cess is important both in fundamental studiesand application point of view. DEA is a twostep process resulting into an anionic and neutralfragments from parent neutral molecule. DEA tofluromethanes have great applications in plasmachemistry, material science and semiconductorindustries [1]. So far only one theory [2] and oneexperimental [3] studies on DEA to CH2F2 areavailable in the literature. No absolute cross sec-tion data are available.In the present case DEA to CH2F2 has been stud-ied for 0 to 20 eV incident electron energy rangeand three different fragment ions are observed.The process can be explained as

CH2F2 + e− → (CH2F2)−∗ →

F− + CH2FCHF− + HFF−2 + CH2

From the geometry it is clear that F− channel isa simple bond cleavage whereas, CHF− and F−

2

channels are associated with the rearrangementsin the temporary negative ion (TNI). Absolutecross section of the fragment ions are studiedwithin the above mentioned energy range exceptfor F−

2 ions due to low count rate. The absolutecross section has been shown in figure. 1 for bothF− and CHF− ions and the peak values are tab-ulated in Table. 1. In the excitation function weobserved two negative ion resonance (NIR) statesaround 2 eV and 11 eV incident electron energy.Previous experimental study reported the forma-tion of F− and CHF− fragment ions only [3].The excitation function for F− and CHF− chan-nels above 6 eV incident electron energy is wellagreed with the present report. Recently onetime of flight (TOF) based mass spectrometerwith higher mass resolution is developed in ourgroup and the experiment is performed. Pres-ence of lower energy NIR state which is likely forfluoromethane group, is observed first time forCH2F2. Though in the present context we are

unable to comment about the symmetry of thelower energy NIR state.

Table 1. Absolute DEA cross sections.

Ion Peak position (eV) Cross section( ×10−21 cm2)

F− 1.9 3.14111.4 9.745

CHF− 1.9 1.48511.2 2.7

Higher energy NIR states are previously reportedtheoretically by Modelli et. al [2] where the au-thors predict the presence of two broad σ∗ res-onances with symmetry b2 and a1 around 10eV incident electron energy. In the present casedue to poor electron energy resolution the peaksare not separated though their presence are con-firmed. Detail study of the dissociation dynamicswill be presented in the conference.

Figure 1. Absolute cross section of (a) F− and (b)

CHF− ions obtained from electron collisions with

CH2F2 molecule.

References

[1] L. G. Christophorou et al. 1996 J. Phys. Chem.Ref. Data 25 1341

[2] A. Modelli et al. 1992 J. Chem. Phys. 96 2061

[3] H.-U. Scheunemann et al. 1982 Ber. Bunsenges.Phys. Chem. 86 321


ISAMP TC-7, 6−8 January, 2018, Tirupati CA023 Chakraborty

79

The spectrum of quadruply ionized mercury: Hg V

Aadil Rashid† 1

, A. Tauheed† 2

† Department of Physics, Aligarh Muslim University, Aligarh-202002, Uttar Pradesh, India

Topic: A.

The spectrum of mercury was recorded in the

300-2000Å wavelength region on a 3-m normal

incidence vacuum spectrograph, using a triggered

spark source. This spectrograph is equipped with a

holographic grating with 2400 lines/mm (with a

plate factor of 1.385 Å/mm) in the first order. The

ground state electronic configuration of the ion is

5d8. The analysis of the (5d

8 + 5d

76s)-5d

76p transi-

tion arrays [1] has been studied earlier. In the pre-

sent work, theoretical calculations have been car-

ried out for 5d8, 5d

7(6s + 7s + 8s + 6d + 7d + 8d) in

the even parity system and 5d7(6p + 7p), 5d

7(5f +

6f) and 5d66s6p in the odd parity system using

Cowan’s code [2] with superposition of configura-

tions and relativistic corrections. We are mainly

interested in the analysis of 5d76p-5d

77s and 5d

76p-

5d76d transition arrays. The optimization of energy

parameters with the help of known level values

have been used to predict the new energy levels.

The analysis is in progress and the latest findings

will be presented in the conference.

References

[1] J.-F. Wyart, A. J. J. Raassen, G. J. van het Hof,

and Y. N. Joshi, Phys. Scr. 47, 784–791 (1993).

[2]https://www.tcd.ie/Physics/people/Cormac.McGu

inness/Cowan/Code/aphysics.lanl.gov/pub/cowan/

† 1 [email protected]

2 [email protected]

ISAMP TC-7, 6−8 January, 2018, Tirupati CA024 Rashid

80

Xe 5s Photoionization near the Second Cooper Minimum using RMCTD

Aarthi Ganesan* 1, Gagan B Pradhan

†, Pranawa C Deshmukh

$&2

* Department of Physics, CPGS, Jain University, Bangalore- 560011

†Department of Physics, National Institute of Technology, Jamshedpur- 831014, Jharkhand

$ Department of Physics, IIT Tirupati, Tirupati – 517506, Andhra Pradesh

&Department of Physics, IISER Tirupati, Tirupati – 517507, Andhra Pradesh

Topic: A

Synopsis: The angular distribution asymmetry parameter is calculated using the Relativistic Multi-Configuration

Tamm-Dancoff Approximation (RMCTD) for the Xe 5s photoelectrons in the region of the second Cooper min-

imum (SCM). The results are compared with those from the RRPA and the RRPA-with-relaxation, and with the

experimental data.

Xenon subshell photoionization has been exten-

sively studied [1-5]. The photoionization of Xe

5s subshell undergoes a second Cooper mini-

mum (SCM) at ~95 eV above the 5s threshold

energy. Whitfield et al., [6] have measured the

angular distribution of the Xe 5s photoelectrons

in the SCM region. The measurement has been

done using two different beam lines, the plane

grating monochromator, PGM, (open circles in

Figure 1) and the new varied line-spacing plane

grating monochromator, VLS-PGM, (closed

circles in Figure 1) both with an undulator pho-

ton source.

The deviation of the photoelectron angular

distribution asymmetry parameter β from 2.0

due to the relativistic effects is further accentu-

ated in the Cooper minimum [7] region due to

fact that the matrix elements of the relativistic

subshells go to zero at different energies. The

experimental dip of the β parameter reaches a

value of 1.66 as shown in the figure.

Various theoretical calculations are done in

this SCM energy region. The RRPA [4] method

that includes most of the important electron cor-

relations measures a larger dip in the β value,

~1.34, compared to the experimental plot. The

RRPA-with-relaxation [2] shows a further dip

compared to the unrelaxed RRPA calculation

(Figure 1).

In the present work, we have employed also

the Relativistic Multi Configuration Tamm-

Dancoff Approximation (RMCTD) [8] to study

the photoionization of Xenon 5s. Non-RPA cor-

relations are included in the RMCTD by (a)

mixing the important exited state configurations

(b) and by including dipole channels also from

the excited state configurations to the continu-

um, along with the bound-to-bound dipole

channels to account for additional correlations.

The RMCTD (GM) result, which is the geo-

metric mean of the length and the velocity

forms, is in very good agreement with the ex-

perimental data (see Figure 1).

75 100 125 150 175 200 225

1.2

1.3

1.4

1.5

1.6

1.7

1.8

1.9

2.0

RMCTD (GM)

RMCTD (V)

RRPA-R

5s

Photoelectron energy (eV)

RRPA

RMCTD (R)

Figure 1. The angular distribution asymmetry pa-

rameter of Xe5s photoelectrons using the RRPA [20

ch], the RRPA-R [20 ch] and the RMCTD methods.

RMCTD (R) is the length form, RMCTD (V) is the

velocity form and the RMCTD (GM) is the geomet-

ric mean of both the forms. Expt plot [6].

References

[1] Kutzner M, Radojevic V and Kelly H P 1989

Phys. Rev. A 40 5052

[2] Johnson W R and Cheng K T 1978 Phys. Rev.

Lett 40 1167

[3] Johnson W R and Lin C D 1979 Phys. Rev. A

20 964

[4] Deshmukh P C and Manson S T 1985 Phys.

Rev. A 32 3109

[5] Fahlman A et al., 1983 Phys. Rev. Lett 50 1114

[6] Whitfield et al., 2007 J. Phys. B 40 3647

[7] Cooper J W 1962 Phys. Rev. A 47 1841

[8] Radojevic V and Johnson W R 1985 Phys. Rev.

A 31 2991



ISAMP TC-7, 6−8 January, 2018, Tirupati CA025 Ganesan

81

Positron collision dynamics for C2-C3 hydrocarbons

Suvam Singh∗ 1, Pankaj Verma, Vishwanath Singh, Bobby Antony∗ 2,

∗ Atomic and Molecular Physics Lab, Department of Applied Physics Indian Institute of Technology (ISM),

Dhanbad, Jharkhand 826004, India

Topic: A

Positrons are not easily obtainable as com-pared to their electronic counterpart. However,in recent times the progress in trapping methodsand their storage has now permitted the accumu-lation of a adequate number of low-temperaturepositrons to form plasma. Positrons annihilateelectrons and because of having opposite chargeand same mass number they can combine withelectrons to form neutral plasmas having dynam-ical symmetry between the charged species. Re-cent years have seen a huge interest in laboratoryexperiments on electron-positron plasmas such asPAX/APEX experiment[1].

The present work is devoted to study var-ious cross sections for C2-C3 hydrocarbons viapositron scattering. The present work is under-taken because the present set of targets has nu-merous applications in various fields. Hydrocar-bons are one of the abundant sources in plasmamaterials which are formed by chemical erosionof the surface occurring due to plasma-wall in-teractions, hence they become one of the majorcontamination sources in the hydrogenic plasma.The composition of the hydrocarbon fluxes flow-ing inside the plasma covers a wide spectrumof molecules from methane to propane [2]. Thedischarge of more complex C2-C3 hydrocarbonsbecomes increasingly vital as the impact energyof plasma ions striking the surface decreases [2].These hydrocarbons play a very significant rolein plasma diagnostics in the Tokamak fusiondivertor, in edge plasmas of magnetically con-fined high temperature hydrogen plasma and alsoin low temperature plasma processing. Apartfrom their application in plasma science they arewidely studied in the field of astrophysics wherethey are observed as an important constituent inthe planetary and cometary atmosphere [3]. Tounderstand the behaviour of these molecules inplasma and space physics, reliable cross sectionsare needed. Cross sections form an integral partin studying collision dynamics of any target.

The modified form of spherical complex op-

tical potential (SCOP) formalism [4, 5] is usedin this work to calculate positron scattering to-tal cross sections over a wide energy range frompositronium formation threshold to 5000 eV forsmall hydrocarbons. To estimate direct ioniza-tion cross section the modified form of CSP-ic[6] method is used. Total ionization and positro-nium formation cross section by positron impactare also evaluated.

Figure 1 shows the total cross section forpositron scattering from methane. There is anexcellent agreement of the present and previousexperimental data.

Figure 1. Positron scattering from ethene

References

[1] T. S. Pedersen et al. 2012 New J. Phys. 14 035010

[2] H. Deutsch et al. 2000 J. Phys. B: At. Mol Opt.Phys. 33 L865

[3] H. Nishimura and H. Tawara 1994 J. Phys. B: At.Mol Opt. Phys. 27 2063

[4] S. Singh et al. 2016 J. Chem Phys. A 120 5685

[5] S. Singh et al. 2017 J. Phys. B: At. Mol Opt. Phys.50 135202

[6] S. Singh and B. Antony 2017 J. Appl. Phys. 121244903



82

Dissociative electron attachment study of di & tri atomic molecule

Minaxi Vinodkumar ∗ 1, Hitesh Yadav† 2, P. C. Vinodkumar † 3

∗ Electronics Department, V. P. & R. P. T. P. Science College, Vallabh Vidyanagar - 388120, Gujarat, India† Department of Physics, Sardar Patel University, Vallabh Vidyanagar - 388120, Gujarat, India

Topic: A

Low energy collision study below 10 eV is sig-nificant due to the formation of short-lived ani-ons (resonances) which are responsible for dis-sociative electron attachment (DEA) that leadsto fragmentation of target to produce neutraland anionic fragments through vibronic excita-tions. Such processes are very important inunder-standing the local chemistry induced byelectron target interaction. This phenomenon issimply represented as

AB + e− → A + B− or A− + B (1)

Dissociative electron attachment (DEA) pro-cess, despite being an important phenomenonin the field of plasma physics [1], environmen-tal science [2] and radiation damage [3], findssparse attention by theoretical groups. On thecontrary, substantial progress has been made inexperimental studies of this process, largely be-cause of new experimental techniques involvingelectron beams with high energy resolution.

We have used R-matrix [4] method for low en-ergy computation of eigenphases through whichresonance width and resonant energy are com-puted which are important inputs for com-putingthe DEA cross sections via. Quantemol-N soft-ware [5, 6].

Fig. 1 shows the result of DEA process of H-anion formation from HCl. The present theoreti-cal data is in good agreement with the experi-mental data of Orient and Srivastava [7] above10 eV. Below 10 eV present result are lower com-pare to experimental data of Orient and Srivas-tava [7]. The detailed results will be presented in

the conference.

0 2 4 6 8 10 12 14 16 18 20

1E-4

1E-3

0.01 Srivastava Present

DEA

Cro

ss s

ectio

n (Å2 )

Ei eV

Figure 1. H− anion from HCl, where the solid line

represents the present result and solid sphere repre-

sents the measured results of Orient and Srivastava

[7]

Acknowledgment

Dr. Minaxi Vinodkumar acknowledges DST-SERB, New Delhi for Major research project[EMR/2016/000470] for financial support underwhich part of this work is carried out.

References

[1] Chutjian et al., 1996 Phys. Rep. 264, 393.

[2] Q-B. Lu and L. Sanche, 2001 Phys. Rev. Lett. 87,078501

[3] L. Sanche, 2005 Eur. Phys. J. D. 35, 367.

[4] M. Vinodkumar et al. 2016 Phys. Rev. A 93,012702.

[5] J. J. Munro et al. 2012 J. Phys. Conf. Ser. 388,012013.

[6] H. Yadav et. al, 2017 Molecular Physics, 115,952..

[7] O. J. Orient and S K Srivastava, 1985 Phys. Rev.A 32, 2678.


ISAMP TC-7, 6−8 January, 2018, Tirupati CA027 Vinodkumar

83

Electron impact scattering studies of Halomethane (CH3X,X = F,Cl, Br, I)

Hitesh Yadav ∗ 1, Minaxi Vinodkumar † 2, Chetan Limbachiya ‡ 3, P. C. Vinodkumar ∗ 4

∗ Department of Physics, Sardar Patel University, Vallabh Vidyanagar - 388120, Gujarat, India† Electronics Department, V. P. & R. P. T. P. Science College, Vallabh Vidyanagar - 388120, Gujarat, India

‡ Department of Applied Physics, The M. S. University of Baroda, Vadodara - 390001, Gujarat, India

Topic: A

Electron molecule scattering phenomenon areof great importance and have various applica-tions in the allied fields. Scattering cross sectionshelps in determining the rates at which gas phaseprocesses and chemical reactions happen whetherin industrial sector or in planetary atmospheres[1]

In this paper, we mainly discuss about theelectron impact molecular scattering cross sec-tions of Halomethane molecules (CH3X,X =F,Cl,Br, I). Halomethanes are tetrahedralmolecules and are derivatives of methane (CH4)with one of the hydrogen atom being replaced byone of the halogen atoms i.e. F, Cl, Br, or I. ThisHalomethane are available naturally as well ashuman made compounds as they attracted wideattention due to their chemical activities. Theybecome active when exposed to ultraviolet lightat high altitudes and destroy the earth’s protec-tive ozone layer.

The physical properties of Halomethanes de-pends on the number and identity of the halogenatoms in the molecule. In general halomethanesare volatile but less so than of methane because ofthe polarizability of the halides and the polarityof the molecules makes them useful as solvents.

We have used the well established theoreti-cal method Spherical Complex Optical Poten-tial (SCOP) [2] for the computation of Elastic,Inelastic and total cross sections. And Com-plex Spherical Potential - ionization contribution(CSP-ic) [2] for the computation of ionizationand electronic excitation cross sections. In fig-ure 1, we present the total cross section of theCH3Br molecule, which is in very good agree-ment with measured data of Benitez et. al [3]

and Krzysztofowicz & Szmytkowski [4].

10 100 10000

10

20

30

40

50

60

TCS

(Å2 )

Ei (eV)

Present TCS Benitez et. al. Krzysztofowicz

e-CH3Br

Figure 1. Total Cross section of CH3Br molecule,

where the solid line represents the present com-

puted result, while the solid sphere represents the

Benitez et. al [3] and dot star represents the

Krzysztofowicz & Szmytkowski [4] measured re-

sults.

Acknowledgment

Dr. Minaxi Vinodkumar acknowledges DST-SERB, New Delhi for Major research project[EMR/2016/000470] for financial support underwhich part of this work is carried out.

References

[1] G. W. F. Drake, 2006 Handbook of Atomic, Molec-ular and Optical Physics, Springer, pp-890.

[2] H. Yadav et. al, 2017Molecular Physics, 115, 952.

[3] A. Benitez et. al, 1988 J. Chem. Phys. 88, 6691.

[4] A. M. Krzysztofowicz & C. Szmytkowski, 1994Chem. Phys. Lett. 219, 86.


ISAMP TC-7, 6−8 January, 2018, Tirupati CA028 Yadav

84

Electron scattering from endohedrally confined Ca atoms

S. Bharti1, P. Malkar

1, L. Sharma

* 1, B. K. Sahoo

2,3 and R. Srivastava

1

1Department of Physics, IIT Roorkee, Roorkee – 247667, Uttarakhand, India

2Atomic and Molecular Physics Division, Physical Research Laboratory, Navrangpura, Ahmedabad 380009, India

3State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics,

Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, China

Topic: A, D

The spatial entrapment of atoms or molecules is

possible in nature as well as artificially e.g.,

impurity atoms in mesoscopic scale semiconductor

artificial structures, molecular zeolite sieves,

fullerenes and quantum devices [1]. The

confinement of atoms leads to distinct and

interesting changes in their physical and chemical

properties.

In the present work we focus on endohedral

entrapment of atom inside fullerene cage which can

be synthesized in laboratory owing to rapid

development in experimental technology. Although

all fullerenes can confine endoheral atoms, C60, in

particular, is more interesting among all the

fullerenes as it can be approximated by a spherical

ball with a single endohedral atom kept at the center

of this approximate ball. Thus the altered energy

levels of the encapsulated atom can be considered

as the result of a potential that is slightly perturbed

from having spherical symmetry.

Recently, Hasoğlu et al have investigated

correlation effects of endohedral confinement on

the energy of Be, Mg, and Ca atoms using non-

relativistic Hartree-Fock method [2]. They

mentioned the possibility of confinement of Ca

atom at the center of the C60 shell, giving rise to a

stable equilibrium. Kumar et al investigated non

dipole effects in photoionization of outer 4s shell of

Ca entrapped in a spherical attractive well potential

[3]. It is therefore interesting to understand the

effect of such an environment on the structure of a

captured Ca atom.

We have investigated elastic electron scattering

from Ca atom trapped inside the endohedral

fullerene C60 molecule using optical model

potential. The confining potential is taken as an

attractive spherically symmetric potential well.

Relativistic coupled cluster (RCC) and Dirac-Fock

methods (DF) are employed to obtain the wave

functions of the confined Ca atom at various depths

of the potential well. Effect of correlations as well

as encapsulation on the first excitation energy,

ionization potential and dipole polarizability are

studied in detail. Results are obtained for

differential and integrated cross sections for free as

well as confined Ca. We compare our results for

free Ca with the experimental data [4] and other

theoretical calculations using DF method [5]. An

example of such comparison is shown in figure 1

for differential cross section (DCS) at 20 eV. The

behaviour of the cross sections with increasing well

depth and with the importance of correlation effects

will be discussed in detail at the conference.

Figure 1. DCS for e-Ca elastic scattering at 20 eV.

References

[1] W. Jaskólski, 1996, Phys. Rep. 27 1.

[2] Hasoğlu et al. 2016, Phys. Rev. A 93 022512.

[3] Kumar et al. 2014 J. Phys. B 47 185003.

[4] S. Milisavljevic et. al. 2005 J. Phys. B: At. Mol.

Opt. Phys. 38 2371

[5] M. Hasan et. Al. 2014 Can. J. Phys. 92 206-215

* E-mail: [email protected]

[email protected]/[email protected]

ISAMP TC-7, 6−8 January, 2018, Tirupati CA029D Sharma

85

Molecular effects in L shell ionization of Au and Bi by slow Ag ions

Kajol Chakraborty†* 1, Ruchika Gupta†*, Ch. Vikar Ahmad†*, Tulika Sharma#, Anjali Rani*, Akhil Jhingan+ , Deepak Swami+ , Samit K. Mandal* and Punita Verma† 2

† Department of Physics, Kalindi College, University of Delhi, East Patel Nagar, Delhi – 110008, India

* Department of Physics and Astrophysics, University of Delhi, Delhi – 110007, India # Amity Institute of Applied Sciences, Amity University, Noida – 201313, India

+ Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi – 110067, India Topic: A

Heavy ion induced inner shell ionization produces multiple vacancies in the outer shell simultaneous to the vacancies in the inner shell thus creating a complicated electronic configu-ration [1,2]. Relatively slow, heavy ion atom collisions which are slow compared to the orbital velocity of the innermost electrons K or L (vion<ve) lead to formation of quasi-molecules. The inner shell electrons in such systems adjust continuously and adiabatically to the combined, time varying, two center poten-tial of both the partners. For very heavy partners with Z1+Z2 >100 (Z1 and Z2 are the atomic numbers of the projectile and target respective-ly), one can look into the atomic world of su-perheavy systems.

Ag9+,12+ ions accelerated upto 120 and 200 MeV respectively using the 15 UD Pelletron at Inter Uni-versity Accelerator Centre (IUAC) were bombarded on 150 µg/cm2 Au and 50 µg/cm2 Bi on a carbon backing of 10 µg/cm2 in General Purpose Scattering Chamber (GPSC) facility. X ray measurements have been done using Canberra LEGe detector of resolution 160 eV at 5.9 keV. Two Canberra surface barrier detectors were also used for charged particle detection.

Intensity ratios and production cross sections (PCS) have been measured for Ag K and Au, Bi L X-rays. Au and Bi L X-rays have been observed with higher intensities as compared to Ag K X-rays (Figure 1). Energy shift with respect to dia-gram lines have been observed both for target as well as projectile X-rays indicating the presence of spectator vacancies in outer shells. PCS for Au L X-rays and Ag K x-rays are in agreement with val-ues reported by Mokler for 57 MeV Iq+ on Au [3].

Figure 1. Spectrum of 120 MeV Ag9+ on 150µg/cm2

Au.

For an insight into the inner shell couplings and hence vacancy transfer mechanism diabatic correlation diagrams for Ag on Au and Ag on Bi have been drawn. The diagrams indicate clearly the finite probability of direct ioniza-tion of 3d levels of united atom. Diagrams show a finite probability of vacancy transfer from Ag 4d levels to Au 2p levels through levels of united atom (Z=126). This forms a plausible explanation of high intensity ratios of target L X-Rays with respect to Ag K X-rays. Future investigations are aimed towards under-standing inner shell vacancy channels in sys-tems with ZUA> 137, the region in which normal Dirac equation for a point charge cannot be solved.

References [1] Punita Verma et al. 2000 Physica Scripta 61 335-338. [2] Uchai et al. 1985 J. Phys. B, At. Mol. Phys. 18 L389-L393. [3] Mokler et al. 1972 Physical Review Letters 29 13.


ISAMP TC-7, 6−8 January, 2018, Tirupati CA030 Chakraborty

86

VUV Spectroscopy of Dodecane Molecule using synchrotron radiation

Kiran Kumar Gorai*1

, Param Jeet Singh, Aparna Shastri, S. N. Jha

*Atomic & Molecular Physics Division, Bhabha Atomic Research Centre, Trombay, Mumbai - 400085.

Topic: A. Quantum collisions and Spectroscopy of atoms, molecules, clusters, and ions

Dodecane (C12H26), an acyclic alkane is a

colorless liquid of the paraffin family and is

widely used as a diluent for tributyl phosphate

in nuclear waste reprocessing [1]. In recent

years dodecane has gathered considerable

attention as a possible surrogate for kerosene-

based fuels such as Jet-A, S-8 etc. [2]. Liquid

alkanes are also ideal candidates for immersion

lithography due to their high refractive index

and near transparency in the 193 nm region [3].

Combustion and pyrolysis processes of alkanes,

relevant to their use as fuels, typically involve

dissociation through excited vibrational or elec-

tronic states [4]. In order to understand the

chemical reactions involved in all these

processes at a microscopic level, it is essential

to have detailed information about the ground

and excited state structure of the molecule. So

far there have been very few reports in literature

regarding the spectroscopy of the dodecane

molecule [3, 5], and no reports on its

electronically excited states. With this motiva-

tion to obtain excited state information on

dodecane, photoabsorption experiments in the

wavelength region 1200–2000 Å have been

carried out using High Resolution Ultra Violet

(HRVUV) beamline [6] at the Indus-1

synchrotron radiation source, RRCAT, Indore

(cf. Figure 1). Samples with stated purity of >

99% are further purified with several freeze-

pump-thaw cycle in order to remove volatile

impurities. Absorption spectra of dodecane,

recorded at several pressures, are shown in

Figure-1. The observed spectra consist of a very

intense broad band at ~1200-1700 Å and a weak

band at ~1900 Å. An overall red shift for the

broad transition ~1200-1700 Å with increasing

pressure is seen in the observed spectrum.

To aid the analysis, geometry optimization and

vibrational frequency calculations of neutral

and ionized dodecane have been carried out

using density functional theory (DFT) for a

variety of basis sets and correlation functionals.

The optimized geometry and calculated

vibrational frequencies for the lowest energy

conformer, which is predicted to be of Cs sym-

metry, are in good agreement with earlier

literature [3]. Time dependent DFT (TDDFT)

calculations have been performed for the

analysis of electronic excited states. The

simulated stick spectrum agrees fairly well with

the experimental spectrum. Details of the

experiment, theoretical calculations and spectral

analysis will be discussed.

Figure 1 VUV absorption spectra of dodecane record-

ed at various pressures using the HRVUV beamline at

the Indus-1 synchrotron radiation source.

References

[1] Sung Ho Ha et al. 2010, Korean J. Chem. En

27(5), 1360

[2] Tim Edwards et al. 2001, Journal of Propulsion

and Power 17, 2

[3] J Sebek et al. 2011 Phys. Chem. Chem. Phys. 13,

12724

[4] S.M. Wu et al. 2000, J. Phys. Chem A 104, 7189

[5] D.R. Worton et al. 2015, Environ. Sci. Technol

49, 131130

[6] P.J. Singh et al. 2011, Nucl. Intrum. Meth A, 634,

113


ISAMP TC-7, 6−8 January, 2018, Tirupati CA031 Gorai

87

Detecting the elemental constitution of environmental samples of Delhi and sur-rounding regions using XRF spectroscopy

Ruchika Gupta*† 1, Ch. Vikar Ahmad*†, Kajol Chakraborty*†, Preeti Rao#, Raj Mittal#, Chirashree Ghosh$ and Punita Verma* 2

* Department of Physics, Kalindi College, University of Delhi, East Patel Nagar, Delhi – 110008, India † Department of Physics and Astrophysics, University of Delhi, Delhi – 110007, India

# Department of Physics, Punjabi University, Patiala – 147002, India $Department of Environmental Studies, University of Delhi, Delhi – 110007

Topic: A.

Metal toxicity has proven to be a major threat for human life as there are several health risks asso-ciated with it. Metal bio-magnification within living systems is a persisting problem. Investigations on determining the contamination level of environmen-tal samples has been going on for a substantial amount of time in India as well as all over the world. Electro-chemical, chemical or spectroscopic techniques have been popular for the above- men-tioned detection purpose. These methods although being easier and compatible, lack sensitivity for multi element detection and accuracy. Thus there is a need for a better technique which can detect con-taminants in trace and ultra-trace amounts and also has multi element detection capacity apart from ad-justing negligible to nil interference problems. Pre-sent work is an effort to identify contamination in differentl soil and plant samples of diverse land use sites in Delhi using XRF spectroscopy.

X-ray Fluorescence (XRF) spectroscopy specifi-cally a versatile method for composition analysis, is non-destructive, has high sensitivity with multi-element detection capability. This method has high sensitivity in detecting elements with atomic num-ber in the range of 18<Z<92 in trace and ultra-trace amounts in both thick as well as in thin samples [1,2].

To establish metal contamination in envi-ronmental samples, soil and plant samples were collected from diverse land use sites of Delhi. To investigate the samples for their elemental constituents using XRF technique, thick pellets of dia 2.5 cm were prepared from powdered sample materials. For preliminary measure-ments, some targets were irradiated, in turn, with X-ray photons from a 50 kV X-ray tube equipped with Rh anode at XRF Lab, Punjabi University, Patiala, India. The tube voltage was kept at 10 kV and filament current 0.1 mA, the emitted x-rays were detected using a Amptek X-123 spectrometer with Si-PIN detector hav-

ing a resolution of 145 eV at 5.9 keV [3]. Each pellet was irradiated for 1000 seconds for statis-tical precision. Figure 1 shows the recorded XRF spectrum of a soil sample.

Figure 1. XRF spectrum of soil sample.

Details of these preliminary measurements performed to quantify the efficiency of the set-up will be presented. Investigation will be con-tinued in future to assess metal contamination level in environmental samples on a large scale basis to identify and mark randomly highly metal accumulated vegetation species and soil types. After knowing accurate value of spatio-temporal contamination level of samples, vari-ous suitable control methodologies can be de-vised to stop further toxicity followed by im-plementation of better scientific ways to reduce the level of pollution. This will ultimately lead to sustainable management of environment.

References [1] Bandhu et al. 2000 NIM B 160 126. [2] McCumber et al. 2017 Chemosphere 167 62. [3] Gupta et al. 2010 Appl. Radiat. Isot. 68 1922.


ISAMP TC-7, 6−8 January, 2018, Tirupati CA032 Gupta

88

Characterization of thin aluminized polypropylene backed atomic targets using

2 MeV He+ Ions.

Sarvesh Kumar1,2, Sunil Kumar2, Deepak Kumar Swami3, D.P. Goyal1, and T. Nandi3§ *

1Indira Gandhi University Meerpur, Rewari (Haryana) India.

2Department of Applied Sciences, Chitkara University, Himachal Pradesh 174103, India. 3Inter-University Accelerator Centre, New Delhi 110067, India.

Topic: A: Quantum Collisions and Spectroscopy of atoms, molecules, clusters and ions.

Thin atomic targets have been the key re-

quirement in ion-atom collisions since decades.

To meet the single collision conditions in inner

shell ionization studies such targets have their

own importance.

RBS (Rutherford backscattering Spec-

trometry) has been a proven tool for elemental

analysis, chemical composition, depth profiling

and uniformity of thin targets. In this article, we

report characterization of ultra-thin (3-5μg/cm2)

targets of high Z, (Z=64-83) deposited on thin

aluminized polypropylene.

The target thickness was kept thin to

meet single collision condition in ion atom col-

lisions and for inner-shell ionization studies.

Cross examination of thickness was done using

alpha particle energy loss measurement. And a

reasonable agreement was found between the

two different types of measurements.

RBS measurements were performed us-

ing NEC’s 5SDH-2 Tandem Pelletron Accelera-

tor at IUAC, New Delhi using 2 MeV He+

Beam. The backscattered He were detected us-

ing SSB Detector at 1660. [1]

In this characterization thin atomic tar-

gets (Bi and Pt) were bombarded by 2.000 MeV

4He+ and charge of 4.00 uCoul @ 2.44 nA. En-

ergy of backscattered particles was collected at

1660 using SSBD (Silicon Surface Barrier De-

tector with FWHM of 25 KeV).

These targets were made using the vac-

uum deposition technique [2]. The target uni-

formity was verified to be reasonable.

The thickness and the uniformity of

these targets were measured by the energy loss

method using alpha particles from a radioactive

decay of 241Am and compared by RBS meas-

urement. Targets of 78Pt and 83Bi (thickness ~

5 µg/cm2) elements deposited on 3µm alumi-

nized Mylar.

The above described targets were used for L

x ray measurements some part of which is al-

ready published [3]. Bi thickness was found

28.9 angstroms with micro-density of 9.81 g/cc

yields. While the Aluminized Polypropylene

thickness was found to be Al surface with mi-

cro-density of 2.70 g/cc yields 2.2318e+017 At-

oms/cm2 (370.5 angstroms).

Figure 1. RBS spectra of Bi and Pt bombarded by 2

MeV He+ ions

References

[1] http://www.ijsrd.com/articles/NCILP018.pdf

[2] S. Kalkal et.al., “Fabrication of 90,94Zr targets

on carbon backing,” Nucl. Instr. Meth. A, vol. 613,

no. 2, pp. 190–194, 2010.

[3] S. Kumar et al., “L shell x-ray production in

high-Z elements using 4-6 MeV/u fluorine ions,”

Nucl. Instruments Methods Phys. Res. Sect. B Beam

Interact. with Mater. Atoms, vol. 395, pp. 39–51,

2017.



ISAMP TC-7, 6−8 January, 2018, Tirupati CA033 KumarSarvesh

89

L shell x-ray production in ultra-thin 76Os using 4-6 MeV/u fluorine ions.

Sunil Kumar1*, Sarvesh Kumar1,2, Deepak Kr Swami3 M. Oswal4, N. Singh4, D. Mehta4 D.P. Goyal2

and T. Nandi3§

1Department of Applied Sciences, Chitkara University, Himachal Pradesh 174103, India. 2Indira Gandhi University Meerpur, Rewari (Haryana) India

3Inter-University Accelerator Centre, New Delhi110067, India. 4Department of Physics, Panjab University, Chandigarh160014, India.

Topic: A: Quantum Collisions and Spectroscopy of atoms, molecules, clusters and ions.

The measurement of emitted x-rays from

targets has resulted in major advances in radia-

tion [1], plasma [2], atomic and nuclear physics

[3], and in particle induced x-ray emission

(PIXE) technique [4]. Since the beginning of

PIXE, light ions such as protons or alphas are

normally used, nevertheless there is an increas-

ing interest towards heavy ions due to higher

cross sections and thereby better sensitivity.

However, multiple ionization effect is more se-

vere in heavy ion induced data and the effect is

rarely addressed for the x-ray emission ele-

mental analysis even though heavy ions is used.

The L x-ray production cross-sections have

been measured in ultra-thin targets ionized by

the 76–114 MeV 19F ions.

Figure 1 L X-rays of Osmium ionized by 4 MeV/u 9F19.

A typical spectrum is shown in Fig.1. Here,

ZP/ZT = 0.11842105 and the projectile velocity

to the orbital velocity ratio in the range of

0.35357≤ vP/vT ≤ 0.433033 indicates that the

present data are in the asymmetric and slow col-

lision regime. Experimental details are pub-

lished in [5].

Figure 2. Osmium L X-ray intensity ratios with re-

spect to Lα transition.

Figure 2 shows the L x-ray intensity ratios of

Osmium with respect to Lα transition.

References

[1] Satoh T et.al. 2015 Int. J. PIXE 25 147–52. [2] Sharma P et.al. 2016 Phys. Plasmas 23 83102.

[3] Dyson N A et.al. 1990 (Cambridge University

Press).

[4] Antoszewska-Moneta M et.al. 2015 Eur. Phys.

J. D 69 77.

[5] Kumar S et.al. 2017 Nuclear Instr.& Methods B

395,39-51.



ISAMP TC-7, 6−8 January, 2018, Tirupati CA034 KumarSunil

90

Ionization cross section of water clusters ((H2O)n,n=1-4) byelectron impact

Paresh Modak 1, Vraj Patel 2, Himani Tomer 3, Bobby Antony 4

Department of Applied Physics, Indian Institute of Technology (Indian School of Mines) Dhanbad

Topic: A

Electron impact processes in aqueous envi-ronment have great importance in physiochem-ical study of a system. Radicals and ions pro-duced during these processes interact with thesurroundings and give crucial information of theinteraction dynamics. Water clusters play sig-nificant role in such environment and help tounderstand the quantum chemical processes ofvarious applied fields of science such as wasteremediation, environmental cleanup, chemistryof ionosphere, radiation processing, nuclear re-action, medical diagnosis etc. [1]. Also waterclusters have crucial role in a atomic plant forcooling [2]. Hence, precise knowledge of electron-water cluster interaction is necessary for the un-derstanding of physiochemical processes occur-ring in these environments. The ionization crosssection is used as input parameter for modelingit along with its reaction rates.

The present study reports the results of the-oretical investigation of ionization cross sectionfor (H2O)n (n=1-4) by electron impact from ion-ization threshold to 5 keV. For this we employedCSP-ic [3] formalism for each monomer. Thenthe distance of monomers from its nearest neigh-bor is used for further calculations. This methodis well established for the computation of ioniza-tion cross section from the inelastic channels fortargets in its gaseous ground state. The vibra-tional and rotational contributions are neglectedin the present energy range. Then ionizationcross section for the cluster is calculated usingthe following modified additive rule for cluster

σion(Xn)=naσion(X)where n is number of monomer present in thecluster and σion(X) is ionization cross section of a

single monomer and a correspond to hard spherepacking fraction.

The ionization cross section for water dimeris reported in Fig.1. Present calculation showsgood agreement in cross section throughout theenergy range of present interest. The differencein cross section value is almost 2% throughoutthe present energy range. This is due to differ-ent method used to consider the ionization con-tribution form a single monomer. Joshipura etal. used an geometric approach to include thescreening effect where as we have used an empir-ically determined value of a=0.84 in Eq.1.

Figure 1. Ionization cross section of water dimer

with reported data

References

[1] Garrett Bruce C.et al. Chem Rev 2005 355

[2] Tachikawa et al. J Phy Chem A 2004 7853

[3] Joshipuraet al. Phys Rev A 2004 022705-2


ISAMP TC-7, 6−8 January, 2018, Tirupati CA036 Modak

91

Disentangling charge exchange processes in bulk from surface

Prashant Sharma*1 and T. Nandi*2

*Inter-University Accelerator Centre, JNU Campus, New Delhi110067, India.

Topic: A

Charge exchange processes of projectile

ions traversing a solid is highly intricate because of

coexistence of many physical phenomena including

ionization, excitation, radiative decay, Auger decay,

electron decay, non-radiative and radiative electron

capture, multiple vacancy creations, electron loss to

continuum, electron capture to continuum multiple

electron capture, radiative electron capture in the

continuum, three-electron-Auger process, radiative

double electron capture, etc. These charge chang-

ing and charge exchange processes originate from

either bulk or exit surface of the foil for the fast ion-

atom collisions. REC process can come from both

the bulk as well as surface and have no lifetime

structure. Whereas the wake riding electron [1]

driven processes at the exit surface gives rise to ex-

cited states including the circular Rydberg states

[2]. Further, influence of wake and dynamic screen-

ing effect [1] can also not be ignored. Hence, disen-

tangling the processes cropping up at the bulk and

surface in extremely difficult. On the other hand, x-

ray spectroscopy technique [3] can measure the

charge state distributions (CSD) through the charac-

teristic Kα X-ray line that occurs due to the atomic

processes responsible in the bulk only [4], whereas

REC photo peak is used to obtain the CSDs for an

intermediate stage responsible for the processes

occurring in the bulk and REC [5] itself. The inte-

gral picture is of course obtained from electromag-

netic measurements or a suitable semi empirical

formula. In the present case, we have used Sciwietz

formalism [6]. Fig.1 demonstrates an example of

disentanglement of charge exchange processes in

different regimes viz. bulk, bulk plus REC process,

and integral effect of the foil.

Fig.1. Disentanglement of charge exchange pro-

cesses occurring in the bulk, the bulk as well as

REC process, and the total foil (bulk and exit sur-

face).

References

[1] J. Burgdörfer 1992 Nucl. Instru. Meth. B67 1

[2] T. Nandi 2008 The Astrophys. J. 673 L103

[3] J. P. Santos et al. 2010 Phys. Rev. A 82 062516

[4] P. Sharma et al. 2016 Phys. Lett. A 380 182

[5] P. Sharma 2017 et al. submitted to Euro. Phys. Lett.

[6] G. Schiwietz et al. 2004 Nucl. Instru. Meth. B 226

683.

1E-mail: [email protected] 2E-mail: [email protected]

ISAMP TC-7, 6−8 January, 2018, Tirupati CA037 Sharma

92

Determination of energy and angle dependent electron ionization cross sections

for methylamines

R. Singh, Manoj Kumar, N. Kumar and S. Pal*

Department of Physics, M.M.H. College, Ghaziabad-201001 (UP)

Topic: (A) Quantum collision and Spectroscopy of atoms, molecules, clusters, and ions.

The absolute photon and electron spectra of

methylamines are of interest and importance in

many areas of science and technology including

those of astrophysics, laser physics, photochemi-

stry, or in other applications where the interaction

of high energy radiation or particles with these mo-

lecules is to be understood [1].

In the present work, differential cross sections

as a function of energy of the secondary/ ejected

electron in ionization of mono-methylamine

(CH3)NH2, di-methylamine (CH3)2NH and tri-

methylamine (CH3)3N by electron impact are calcu-

lated at the fixed incident electron energies viz. 100

and 200 eV. The isotropic angular behaviours of

cross sections at the same energies are also eva-

luated. The modified JK semi empirical formulation

[2-3], which requires the oscillator strength data as

input has been employed. In absence of any theoret-

ical and or experimental data, we have derived

integral total ionization cross sections in the im-

pinging electron energy range varying from ioniza-

tion threshold to 1000 eV and compared those with

the available experimental and theoretical data for

mono-methylamine [4-5]. The present results reveal

god agreement with the available results.

References

[1] G.R.Burton et al. 1994,. Can. J. Chem. 72

529.

[2] R.Singh et al. 2013, J. Elect. Spectr. Relt.

Phen. 185 635.

[3] R.Kumar, 2013 Rapid Commun. Mass Spec-

trom. 27 223.

[4] M.Vinodkumar et al. (2008) J. Phys. (Conf.

Ser.) 115 012013.

[5] F.M. Silva et al. (2014) Eur. Phys. D 68:12.

* E-mail: [email protected]

ISAMP TC-7, 6−8 January, 2018, Tirupati CA038 Pal

93

Kα X-RAYS FROM VARIUOSLY IONIZED IODINE

Anuradha Naratajan * 1

and L.Natarajan + 2

*Department of Physics, SIWS College, Wadala, Mumbai-400031

+Department of Physics, University of Mumbai, Mumbai-400098

Topic: A

A study on the X-ray satellites resulting from the

rearrangement of initial vacancies is essential in

understanding the ultrafast dynamics of the

ionization process. In addition, in recent years,

the advantage of tunable monochromatic X-ray

sources over broad band radiation sources in

practical applications and high intensity X-ray

Free Electron laser needed to produce a high

energy density plasmas have been explored [1,2]

. As K X-ray data on multiply ionized high Z

atoms are largely unknown, in this work, we

investigate the structure of K shell resonances of

iodine from 1s-2p transitions with various L

shell ionic states in an otherwise closed shell

configuration. The calculations have been

carried out using multi-configuration Dirac-Fock

wavefunctions with the inclusion of magnetic

interaction, retardation and quantum

electrodynamics effects [3]. The intrinsic

variations in the transition parameters with

degree of ionization have been analyzed. To the

best of our knowledge, no theoretical or

experimental data exist except for the Kα fine

structure lines.

References

[1] M. Montenegro et al. 2009 J. Phys. Chem. A 113, 12364

[2] L. Young et al.2010 Nature 466, 56

[3] P. Jonsson et al. 2013 Comput. Phys. Commun.184, 2197

_____________________________________________________________________________________

[email protected]

Email:2 [email protected]

ISAMP TC-7, 6−8 January, 2018, Tirupati CA039 Natarajan

94

The Spectrum of Doubly Ionized Silver: Ag III

S. Ankita*

1 and A. Tauheed

2

Department of Physics, Aligarh Muslim University, Aligarh-202002, India

Topic:A

Ag III, a member of Rh I isoelectronic series,

has 4p64d

9 as its ground configuration. The

regular outer electronic excitation leads to the

configurations of the type 4d8np (n≥5), 4d

8nf

(n≥4) and 4d8nd (n≥5), 4d

8ns (n≥5) in the odd

and even parity system respectively. The core

excitation of the above said configurations also

leads to the 4p54d

10, 4d

75p

2, 4d

75s

2 and 4d

75s5p

configurations.

The analysis of this spectrum was reported

by Gibbs and White [1], Gilbert [2] and

Benschop et al [3]. At present, only two excited

configurations namely 4d85p and 4d

85s have

been studied along with the ground doublet. The

two major configurations arising out of the

ground state excitation namely 4d84f and 4d

86p

remain untouched. In the present work we have

undertaken the study of these configurations

through the transition array 4d9- 4d

8(4f+6p) and

with the aid of Relativistic Hartree-Fock and

least squares fitted parametric calculations

using Cowan’s code [4].

The silver spectra were recorded on a 3-m

normal incidence vacuum spectrograph at St. F.

X. University, Canada using a triggered spark

source in the wavelength region 345-2071 Å.

We re-investigated the earlier results pub-

lished by Gilbert [2] and Benschop et al [3] and

found a number of ambiguities in ref [3]. There-

fore, a few level values of the configuration

4d85p have been revised. The work is in the

progress and the latest findings on 4d8(4f+6p)

configurations will be presented at the confer-

ence.

References

[1] Gibbs et al 1928, Proc. Natl. Acad. Sci. Amer.

14, 559-564.

[2] W. P. Gilbert, 1935, Phys. Rev. 48, 338-342.

[3] Benschop et al, 1975, Can. J. Phys. 53, 498-503.

[4] R. D. Cowan, 1981, The Theory of Atomic Structure

and Spectra, (Berkeley, CA: University of California

Press) and Cowan code package for Windows by A K

Kramida



ISAMP TC-7, 6−8 January, 2018, Tirupati CA040 Ankita

95

Study Molecular Dissociation Dynamics using Velocity Map Imaging

Arnab Sen, Anbu Selvem Venkatachalam, Shilpa Rani Sahu, Ram Gopal, Vandana Sharma

Department of Physics, IISER Pune, Pune -411008, Maharashtra, India


We indigenously designed and fabricated a

simple ion imaging spectrometer based on a

single ion extraction field, lensing field and a

field-free drift region [1] coupled with a posi-

tion sensitive delay line anode detector which

offers 3D ion momentum imaging capabilities.

The ion imaging spectrometer also known as Ve-

locity Map Imaging (VMI) spectrometer (Fig. 1)

employs a field configuration to collect ions from

the reaction volume and focusses ions with the

same initial velocities them onto the same radial

coordinate on the detector.

When the detector records the triplet (xion, yion and,

tion) of each ion hit, where (xion, yion) are the position

coordinates of the ion splat and tion the flight time of

the ion relative to its generation. Depending on the

geometry of the spectrometer and the applied poten-

tials, the initial 3D momentum (px, py and pz) can be

reconstructed.

I will report the performance of this spectrometer

using the example of a dissociation of multi-

electron molecules, O+2 and CH3I+ following its

ionization in a strong laser field (3x1013 W/cm2, 800

nm, 30 fs) during the conference.

Figure 1. Schematic diagram of electrostatic lens

used for velocity map imaging of photodissociation.

References

[1] André T. J. B. Eppink and David H. Parker, Rev. Sci. Inst, 68, 3477 (1997)


ISAMP TC-7, 6−8 January, 2018, Tirupati CA041 Sen

96

Synchrotron based VUV spectroscopy of dimethylacetamide

Param Jeet Singh1, Asim Kumar Das, Kiran Kumar Gorai, Aparna Shastri, B N Raja Sekhar, Sunan-

da K, S N Jha, N K Sahoo.

Atomic & Molecular Physics Division, BARC, Mumbai – 400085, India.


Abstract Vacuum ultraviolet (VUV) photoabsorption spectroscopic study of dimethyl acetamide (DMAc) has been

performed using synchrotron radiation. Band system appearing ~1700Å has been resolved into three components.

Analysis of the observed spectrum is supported with DFT and TDDFT based quantum chemical calculations.

In recent years, diamide-based extractants

have attracted attention of nuclear industry as

alternate solvents for nuclear fuel reprocessing

[1]. Several investigations have been reported to

optimize the amide structure for their best ex-

tracting properties [1-4]. Dimethylacetamide

(DMAc) is also commonly used as an reaction

intermediate in adhesive industry, pharmaceuti-

cals, synthesis of pesticides and plasticizers [5]

and is a potency reproductive toxicant [6]. In

the atmosphere, DMAc undergoes photolysis

and reacts with OH, Cl, O3 and NO3 radicals

[7]. A few photochemical reaction dynamics

take place through excited electronic states.

There is very little literature[8] on the interac-

tion of UV and VUV radiation with this mole-

cule and the gas-phase photochemistry of

DMAc is not well understood.

VUV spectroscopic study of DMAc has

been performed using synchrotron radiation

from Indus-1 source, RRCAT, Indore. Photoab-

sorption experiments in the wavelength range of

1050–2300Å are carried out using a 0.5m stain-

less steel gas cell coupled to photophysics

beamline [9]. Samples of DMAc with stated

purity of >99% were further purified using

freeze-pump-thaw method to remove the vola-

tile impurities. Xenon atomic lines are used for

wavelength calibration. Spectra are recorded at

several pressures for resolving weak features;

Figure 1 shows representative spectra at 0.02

mbar. Analysis of the experimental spectrum is

aided by density functional theory (DFT) and

time dependent DFT (TDDFT) based quantum

chemical calculations. In the present study,

mainly four broad absorption bands are ob-

served peaking at 1095Å, ~1700Å, 1915 Å and

2150 Å. A band reported ~1700Å by Kaya et. al

[8] has been resolved into three features in the

present study. All the observed bands are due to

electronic excitations. The observed bands have

been assigned based on the calculations. Elec-

tronic states and corresponding vibrational en-

ergy levels involved in these observed transi-

tions will be presented and discussed in this pa-

per.

Figure 1 VUV photoabsorption spectrum of dimethyla-

cetamide at 0.02 mbar recorded using synchrotron radia-

tion

References

[1] A. Rao, B.S. Tomar, 2016, Separation and

Purification Technology 161, 159

[2] P.K.M. S.A. Ansari, D.R. Raut, V.C. Adya, S.K.

Thulasidas, V.K. Manchanda, 2008, Separation and

Purification Technology 63, 4.

[3] S.A. Ansari, N. Kumari, D.R. Raut, P. Kandwal,

P.K. Mohapatra, 2016, Separation and Purification

Technology 159, 161

[4] V.K. Manchanda, P.N. Pathak, 2004, Separation and

Purification Technology 35, 85.

[5] H. Cheung, R.S. Tanke, G.P. Torrence, 2000,

Ullmann's Encyclopedia of Industrial Chemistry,

Wiley-VCH Verlag GmbH & Co. KGaA.

[6] European Chemicals Agency, 2014, Opinion on

N,N-Dimethylacetamide (DMAC).

[7] G. Solignac, A. Mellouki, G. Le Bras, I. Barnes, T.

Benter, 2005, Journal of Photochemistry and

Photobiology A: Chemistry 176, 136.

[8] K. Kaya, S. Nagakura, 1967, Theoret. Chim. Acta 7,

7.

[9] N.C. Das, B.N. Raja Sekhar, S. Padmanabhan, A.

Shastri, S.N. Jha, S.S. Bhattacharya, S. Bhat, A.K.

Sinha, V.C. Sahani, 2003, Journal of Optics 32, 169.



97

Positron Scattering Cross Sections for Methyl Halides

Nidhi Sinha∗ 1, Durgesini Patel∗ 2 and Bobby Antony∗ 3

∗Department of Applied Physics, IIT (Indian School of Mines) Dhanbad, Jharkhand-826004, India

Topic: A

Positron scattering from various atomic andmolecular targets have driven significant atten-tion from the scientific community in the re-cent decades. This rests on the vast range ofapplications of such interaction, viz. plasma,medical sciences and astrophysics. Furthermoresuch studies are crucial for the analysis of anti-hydrogen formation; testing of QED and CPTtheorem. A thorough discussion on this can befound in the book written by Charlton and Hum-berston [1]. However, investigation on positronscattering fails to keep pace as compared to thecase of its anti-particle electron. As such we havechosen the less attended methyl halides (CH3X,X=F, Cl, Br and I) as targets in the presentcalculations. These molecules yield majority ofthe inorganic free halogen radicals to the strato-sphere resulting in ozone depletion [2]. Further-more, these targets have vital biochemical andindustrial uses.

In the present calculations, we aim to pro-vide a comprehensive set of cross sections forthe methyl halide molecules. Spherical complexoptical potential (SCOP) formalism is utilizedto compute elastic, inelastic and total scatter-ing cross sections. This formalism was origi-nally developed for electron scattering investi-gation which our group have modified for thepositron case [3]. The energy range chosen isfrom 1 eV to 5000 eV for the elastic and totalcross sections; however the inelastic cross sec-tions are calculated from the respective inelasticthreshold. Figure 1 shows the total cross section(Qtot) for positron-CH3I collision. We have alsodepicted the inelastic cross section in the same

plot to get an idea of the contribution from theinelastic channel in the scattering process at dif-ferent energies. There is significant disagreementbetween the present results and that of Kimuraet al.[4] in the low energies. However, the agree-ment is excellent with that of Varella et al.[5] forthe entire comparative energy range.

Figure 1. Total cross section for positron scatter-

ing from methyl iodide

References

[1] Charlton and Humberston 2001 Positron PhysicsCambridge University Press

[2] Eden et al. 2007 Chemical Physics 331 232-244

[3] Singh et al. 2016 Journal of Physical ChemistryA120 5685

[4] Kimura et al. 2001 Journal of Physical Chemistry115 16

[5] Varella et al. 2013 J. Phys. B: At. Mol. Opt. Phys.46 175202


ISAMP TC-7, 6−8 January, 2018, Tirupati CA043 Sinha

98

Energy levels and classified lines in the third spectrum of gold: Au III

Aashna Zainab1 and Ahmad Tauheed2

Department of Physics, Aligarh Muslim University, Aligarh-202002

Topic: A (Spectrum of Au III)

Abstract:

The spectrum of doubly ionized gold

(Au III) has been investigated in the wavelength

region 450- 2100 Å, recorded on a 3 m and 10.7

m normal incidence vacuum spectrographs at

Antigonish laboratory (Canada) and at NIST

(U.S.A.) respectively using triggered spark light

source. The ground configuration of Au III is

5p65d9 and the regular excited configurations are

of the type 5d8nℓ. However, the core excited

configurations are more complicated which

includes 5p65d76s2, 5p65d76p2 in the even parity

system and 5p65d76s6p, 5p55d10 and 5p55d96s in

the odd parity system.

This spectrum has been reported earlier

by Wyart et al. [1]. They have studied the 5d86p,

5d76s6p odd parity configurations and 5d9,

5d8(6s+7s+6d) and 5d76s2 even parity

configurations. The analysis of the 5d86p and

5d86s configuration is almost complete while

70% of the levels in 5d76s6p configuration is

still unknown. We therefore, are investigating

primarily this configuration and have

established about 25 new energy levels based on

the identification of more than 100 spectral

lines. Hartree-Fock calculations involving the

superposition of configurations were used to

predict the energy levels, wavelengths and

transition probabilities. Final interpretation of

the results were made on the basis of least

squares fitted parametric calculations. Fairly

good agreement has been found.

References

[1] Wyart et al. 1996, Physica Scripta, 53, 174

__________________________________________________________________



ISAMP TC-7, 6−8 January, 2018, Tirupati CA044 Zainab

99

Phase Space Structures and Isotope Separation of Bromine Molecules

Suranjana Ghosh,1 Barun Halder,

2 and Utpal Roy

2

1Amity University, Rupaspur, Patna-801503

2 Indian Institute of Technology of Patna, Bihta, Patna-801103

Topic: A

Localized quantum wave packet is the coherent

sum of quantum states created by short, phase-

controlled optical pulses [1]. A suitably prepared

wave packet, more appropriately, a coherent state,

is an ideal candidate to investigate the dynamics of

the system through the time evolution, governed by

a nonlinear energy function. Many applications in

the literature emphasize on the autocorrelation

function, which is an overlap of the initial wave

packet with that after certain time. However,

autocorrelation function does not satisfactorily

reveal information regarding quantum interferences.

Mesoscopic nonlocal superposition has become a

prime tool towards quantum metrology in recent

times [2]. Quantum interferences structures like

sub-Planck-scale structures play very important role

in this field of research. Here, we have used phase-

space analogy to distinguish two isotopes of

Bromine molecule, 79

Br2 and 81

Br2, by utilizing a

coherent state involving vibrational levels.

Due to the nonlinear energy spectrum of the Morse

potential, the wave packet shows interesting

phenomena like revivals and fractional revivals

during its course of evolution. Smallest interference

structures produced in phase space are known to be

the most sensitive to detect an infinitesimal external

fluctuation or decoherence. We proposed a new

method of separating two isotopes of Bromine

molecule at the shortest possible time, in the

literature, to the author’s knowledge [3, 4]. This

method is much more efficient than separating the

isotopes by utilizing autocorrelation function. The

time of separation is considerably reduced, which is

clearly demonstrated through Wigner phase-space

picture.

Figure 1. Autocorrelation functions for , 79

Br2 (red,

deeper) and , 81

Br2 (green, light) vibrational wave

packets. The isotopes are shown to be separated after

20ps.

References [1] I. Sh. Avermukh 1996 Phys. Rev.Lett. 77 17.

[2] J. R. Bhatt, P. K. Panigrahi, and M. Vyas 2008

Phys. Rev. A 78 034101.

[3] S. Ghosh, A. Chiruvelli, J. Banerji, and P. K.

Panigrahi Phys. Rev. A 73 013411.

[4] S. Ghosh, R. Sharma, U.Roy, P. K. Panigrahi, Phys.

Rev. A 92 053819.

[email protected], [email protected], [email protected]

ISAMP TC-7, 6−8 January, 2018, Tirupati CA045 Halder

100

Isoelectronic Energy Levels of Xe-like Ions: La IV- Ce V

Abdul Wajid 1, S. Jabeen , Abid Husain

Department of Physics, AMU, Aligarh – 202002, Uttar Pradesh, India

Topic: A. Quantum collisions and Spectroscopy of atoms, molecules, clusters and ions

Three times ionized lanthanum (La IV)

and four times ionized cerium (Ce V) have

Xenon-like structure and 5s25p6 is the ground

configuration of Xenon like ions. Excited

configurations 5s25p5 (nd+ns+nf+np+ng+nh+ni)

n>4 have been studied for the first three

members of the Xenon isoelectronic sequence.

In the present work our aim is to predict energy

levels for 5s25p5 (5f+7d+8s+7p) configurations

of La IV and 5s25p5 (5f+7d+7s+7p)

configurations of Ce V using the trend of

isoelectronic sequence.

We have also calculated energy levels of

5s25p6,5s25p5 (4f + 5f + 6p + 5d + 6d + 7d + 7s

+ 8s) configurations theoretically by Hartree-

Fock method with relativistic correction using

Cowan code, with inclusion of large number of

interacting configurations. Energy levels values

of above mentioned configurations will be

presented.

References

[1] Cowan, R. D., The Theory of Atomic Structure

and Spectra, (Univ. of Calif. Press 1981) and

computer codes.

[2] Kramida, A., Ralchenko, Yu., Reader, J., and

NIST ASD Team (2015). NIST Atomic Spectra

Database (ver. 5.3), [Online].


ISAMP TC-7, 6−8 January, 2018, Tirupati CA046 Wajid

101

Laser-induced fluorescence spectroscopy of jet-cooled LaNH: Observation of

(0,0) C 2 𝑋

2

+ transition

Sheo Mukund 1, Soumen Bhattacharyya

2 and S.G. Nakhate

3


Homi Bhabha National Institute, Bhabha Atomic Research Centre, Mumbai 400 085, India

The Lanthanum imide (LaNH) molecules are produced in a pulsed supersonic molecular beam setup by the

reaction of laser ablated Lanthanum metal plasma with 2% ammonia (NH3) seeded in helium. A (0,0) band of

the C 2r 𝑋 2

+

system is observed by employing laser-induced fluorescence (LIF) spectroscopy. The

rotationally resolved subbands, C 23/2 𝑋 2

+ and C 2

1/2 𝑋 2

+ are analyzed and molecular constants of the

C state are determined by the unperturbed rotational lines.

The laboratory spectra of LaNH molecule has

been studied previously. In brief, the optical

Stark effect was measured for the 301 and 20

1

bands of the B X transition [1]. Later, the first

spectroscopic study of the Ã X and B X

systems was reported in the Ph.D. thesis of

Scott J. Rixon [2]. The molecular constants for

the X 2

+ ground state were determined by

employing high-resolution spectroscopy. The

bending and LaN stretching vibrational

frequencies for the ground state were

determined from dispersed fluorescence studies. We report the LIF investigation of the (0,0)

band of the C (case a) X (case bS) transition of

LaNH.

LaNH molecules are produced by the reaction

of gas phase lanthanum atom with ammonia in

laser vaporization pulsed free-jet apparatus [3].

Molecules in the beam were probed at right

angle to the supersonic expansion axis by a

tunable pulsed dye laser at resolution 0.06 cm-1

by using the angle tuned intra-cavity etalon

facility available with the laser. The resulting

LIF was dispersed by a monochromator and

detected by a photo-multiplier tube. The

resulting signal was integrated by a gated

integrator and stored on a computer.

Two intense bands centred at 23,366 and

23,093 cm-1

are identified as (0,0) band of

C 23/2 𝑋 2

+ and C 2

1/2 𝑋 2

+ transitions.

These bands are rotationally analyzed by fixing

the rotational constants for the ground state to

the values reported in Ref [2]. The molecular

constants for the C state are determined by least

square fitting of wavenumber of the

unperturbed rotational lines using PGOPHER

program [4] and are given in Table 1. The

experimental spectrum of C 21/2 𝑋 2

+

(0,0)

band along with simulated spectrum is shown in

Figure 1.

Local rotational perturbations are observed

only in the f-parity levels of both substates of

the C 2r state. However, the perturber state

could not be identified. It is speculated that the

two perturber states may be of 2Σ

+/ symmetry.

Table 1. Molecular constants (in cm-1

) for the (000)

vibrational level of the C 2r state of LaNH molecule

Constants 𝐶 21/2 𝐶 2

3/2

T 23093.259(4)a 23365.510(5)

B 0.273674(63) 0.27922(19)

D 105 – -5.06(15)

D 107 – -1.742(33)

p -0.0672(10) – a Numbers in parentheses denote one standard

deviation.

Figure 1. Rotationally resolved spectrum of the

C 21/2 𝑿 2

+ transition in LaNH

References

[1] Steimle et al. 2003 J. Chem. Phys. 118 1266

[2] S.J. Rixon. High resolution electronic spectra of

some new transition metal-bearing molecules. PhD

Thesis, Department of Physics & Astronomy,

University of British Columbia 2004.

[3] Nakhate et al. 2010 JQSRT 111 394

[4] http://pgopher.chm.bris.ac.uk

1 [email protected]

2 [email protected]

3 [email protected]

Topic: A ISAMP TC-7, 6−8 January, 2018, Tirupati CA047 Mukund

102

Theoretical method to study electron-impact rotational excitationof molecular ions

Jasmeet Singh∗† 1, Marjan Khamesian†

Viatcheslav Kokoouline†

∗ Department of Physics, Keshav Mahavidyalaya, University of Delhi, Delhi-110034, India.† Department of Physics, University of Central Florida, Orlando, FL-32816, USA.

Topic: A

In this study, cross sections and thermally-averaged rate coefficients for electron-impact ro-tational transitions in HeH+ are computed [1]for four lowest rotational levels of HeH+ usingthe UK R-matrix method combined [2, 3] to themultichannel quantum defect theory (MQDT)[4]. Here, we have applied channel elimina-tion procedure to evaluate more accurate resultsat low energy (< 0.01 eV). Scattering matricesfor the process are generated using the UK R-matrix method (Quantemol-N package) [5] andthen used to compute rotational excitation crosssections for low energy region for different com-binations of initial and final rotational states ofthe target molecule. The approach is applied toobtain cross sections for rotational excitation ofHCO+. The thermally-averaged rate coefficientsfor this molecular processess are studied over a

wide electron temperature range.

References

[1] Marjan Khamesian Theoretical study of negativemolecular ions relevant to the interstellar and lab-oratory plasma, 2016, Ph. D. thesis, University ofCentral Florida.

[2] J. Tennyson, 2010 Phys. Rep. 491 29.

[3] P. G. Burke 2011 R-Matrix Theory of Atomic Col-lisions: Application to Atomic, Molecular and Op-tical Processes (Springer Series on Atomic, Op-tical, and Plasma Physics) (Berlin, Heidelberg:Springer-Verlag).

[4] M. Aymar, C. H. Greene and E. Luc-Koening1996 Rev. Mod. Phys. 68 1015.

[5] J. Tennyson, D. B. Brown, J. J. Munro, I. Rozum,H. N. Varambhia, and N. Vinci. 2007 J. Phys.Conf. Series 86 012001.


ISAMP TC-7, 6−8 January, 2018, Tirupati CA048 SinghJasmeet

103

Imaging electron-nuclear dynamics in strong field rescattering.

N Bhargava Ram*1,2

, S G Walt2, M Atala

3, N I Shvestov-Shilovski

4, A von Conta

2, D Baykusheva

2, M

Lein4 and H J Worner

2

1Department of Physics, IISER Bhopal, Bhopal, India

2Lab. For Physical Chemistry, ETH Zurich, Switzerland

3Max Planck Institute for the Structure and Dynamics of Matter, Hamburg, Germany

4Leibniz Universitat, Hannover, Germany

Topic: A, B.

Strong-field photoelectron holography and laser-

induced electron diffraction are two powerful

emerging methods for probing the ultrafast dynam-

ics of molecules. However, both of them have so far

remained restricted to static systems and to nuclear

dynamics induced by strong-field ionization. Here,

we extend these promising methods to image purely

electronic valence-shell dynamics in molecules us-

ing photoelectron holography [1]. Using impulsive

stimulated Raman scattering by an intense non-

resonant laser pulse, we simultaneously create a

valence-shell electron wave packet consisting of the

21/2 and 23/2 electronic states of NO and a ro-

tational wave packet that causes periodic alignment

of the molecule. A second, time delayed laser pulse

induces strong-field ionization, followed by veloc-

ity-map imaging of the photoelectrons.

Figure1. Holographic imaging of a molecular va-

lence-shell-electron wave packet

Fig 1 shows the characteristic signatures of strong-

field photoelectron holography. Our analysis shows

that the time-dependent photoelectron holography is

particularly sensitive to the temporal evolution of

the momentum-space wave function in the direction

perpendicular to electron tunneling.

A similar analysis of the photoelectron images

recorded around the first rotational revival,

where electronic and rotational dynamics take

place on similar time scales reveals the signa-

ture of coupled electronic and nuclear dynamics

(not shown). This observation suggests that

time-resolved photoelectron holography may

offer a particularly sensitive probe of coupled

electronic-nuclear dynamics in molecules, such

as those occurring at conical intersections.

References

[1] S G Walt et al. , 2017 Nat. Commun. 8, 15651

ISAMP TC-7, 6−8 January, 2018, Tirupati CA050B Ram

104

Electron scattering total ionization cross section of H2CCCC: A cumulene car-bene detected in interstellar medium

Nafees Uddin* 1, Pankaj Verma* 2 and Bobby Antony* 3

* Department of Applied Physics, IIT(ISM) Dhanbad, Dhanbad – 826004, Jharkhand, India

Topic: A

Cumulene carbenes, the H2Cn species com-prising of double bonded long chain carbon backbone with terminal unbonded carbenes, are of immense astrophysical importance due to their presence in interstellar medium. The first three members of these interstellar molecules, H2CC, H2CCC and H2CCCC are highly polar isomers of acetylene, cyclopropenylidene and diacetylene respectively, which are non-polar molecules. Electron scattering studies of cu-mulene carbenes are of prime importance in pursuit of the knowledge of unknown astro-physical phenomenon.

In the present paper we report the total ioni-zation cross section of Butatrienylidene (H2CCCC), the third in the series of cumulene carbines. The first detection of this molecule in the laboratory was reported by Killian et al [1] and subsequently detected astronomically in the circumstellar shell of IRC +10216 by Cer-nichera et al [2] with IRAM 20m radiotele-scope. Kawaguchi et al [3] detected the pres-ence of Butatrienylidene in the dark TMC-1 molecular cloud.

The structure of H2CCCC as determined by Travers et al [4] is shown in Figure 1.

Figure 1. Structure of H2CCCC [4]

In the present work, the total ionization cross sections (Qion) of H2CCCC on electron impact is calculated for incident energies (Ei) ranging from ionization threshold (I) of the target to

5000 eV . Total inelastic cross section is evalu-ated using the well established Spherical Complex Optical Potential (SCOP) formalism [5]. Total ionization cross section is estimated from the total inelastic cross section using the Complex Scattering-Potential ionization contribution (CSP-ic) method [6].

References

[1]Killian T, Vrtilek J, Gottlieb C, Thaddeus P, Labora-tory detection of a second carbon chain carbene: Butatrienylidene, H2CCCC. 1990 The Astrophysical Journal.;365:L89-L92. [2] Cernicharo J, Gottlieb C, Guelin M, Killian T, Thaddeus P, Vrtilek J. Astronomical detection of H2CCCC. 1991 The Astrophysical Jour-nal.;368:L43-L45. [3] Kawaguchi K, Kaifu N, Ohishi M, Ishikawa S, Hirahara Y, Yamamoto S. Observations of cumulene carbenes, H2CCCC and H2CCC, in TMC-1. 1991 Astronomical Society of Japan, Publications (ISSN 0004-6264).;43(4):607-619. [4] Travers M, Chen W, Novick S, Vrtilek J, Gottlieb C, Thaddeus P. Structure of the Cumulene Carbene Butatrienylidene: H2CCCC. 1996 Journal of Molecular Spectroscopy.;180(1):75-80. [5] R. Naghma, B.N. Mahato, M. Vinodkumar, and B.K. Antony, 2011 J. Phys. B 44 , 105204. [6] Antony B K, Joshipura K N and Mason N J 2004 Int. J. Mass Spectrom. 233 207

1E-mail: [email protected] 2 E-mail: [email protected] 3E-mail: [email protected]

ISAMP TC-7, 6−8 January, 2018, Tirupati CA052 Uddin

105

Structural stability of polycyclic aromatic hydrocarbons andpolycyclic nitrogen heterocycles under charged particle collisions

P. K. Najeeb∗ 1, M. V. Vinitha∗, A. Kala∗, P. Bhatt†, C. P. Safvan†, S. Vig‡ and U.Kadhane∗ 2

∗ Department of Physics, Indian Institute of Space Science and Technology, Thiruvananthapuram, India†Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi, India

‡ Department of Earth and Space Sciences, Indian Institute of Space Science and Technology,

Thiruvananthapuram, India

Topic: A

Polycyclic aromatic hydrocarbons (PAHs)are a group of organic compounds consistingof two or more fused aromatic rings. Poly-cyclic aromatic nitrogen heterocycles (PANHs)are species with one or more CH groups sub-stituted by a nitrogen atom in PAHs [1]. It isthe proposed widespread existence of PAHs andPANHs in the interstellar medium (ISM) thathas largely driven recent investigations of theirspectroscopic and photo physical attributes [2].Naphthalene(C10H8) is one of the smallest PAH,but it exhibits many general spectroscopic andstructural properties of larger PAHs [3] andhence is a good test candidate for PAHs. SmallPANHs like quinoline(C9H7N) and its isomerisoquinoline(C9H7N) readily dissociate under ex-posure to interstellar radiation and thus an in-terest in their photochemistry, as they producereactive photo products that may contribute tothe composition of the ISM [4]. Particularly ofsignificance is the HCN loss mechanism in thesesystems. The main focus of the present workis to compare fragmentation process under ener-getic charged particle interaction on naphthalenewith its nitrogen derivatives.

Generally for PAHs and PANHs, the loss ofH and C2H2/HCN are the most dominant sta-tistical dissociation channels. Astro-biologicallyimportant statistical dissociation channels of thenaphthalene and its nitrogen containing deriva-tives are probed using time of flight mass spec-trometry technique (ToF). On the basis of pro-jectile beam energy dependence of the yield, theeffect of plasmon excitation in quinoline and iso-quinoline is shown for the first time. A strongdependence of the statistical dissociation yieldon the location of nitrogen atom in the twomolecules is observed and the decay time evo-lution was found to be exactly same for the samechannels. A detailed analysis of HCN loss showedidentical time scales in quinoline and isoquino-

line but nearly twice the yield in favor of iso-quinoline. The presence as well as the posi-tion of nitrogen in PANHs have very little effecton the crosssection for capture as well as elec-tron emission. The ratio of ionization to cap-ture cross-section, as well as the ratio of dou-ble ionization to capture ionization, are indepen-dent of the presence and position of Nitrogen inPAHs [Figure 1]. An attempt is made to correlatethese observations with the various structure pa-rameter obtained using structure calculations.

10

100

40 60 80 100 120 140 1601

10

100

(a)Quinoline (C9H7N)Naphthalene (C10H8)Isoquinoline (C9H7N)

ic

eeci

Proton beam energy (keV)

(b)

Figure 1. The ratio of partial crosection

for (a) ionisation (σi) to capture (σc) (b) dou-

ble ionisation (σee) to capture ionisation (σci) for

naphthalene (C10H8) quinoline (C9H7N) isoquino-

line (C9H7N) with different proton beam energies

References

[1] S. B. Charnley et al. 2005 Advances in Space Re-search 36 137

[2] A. G. Tielens. 2008 Annu. Rev. Astron. Astro-phys. 46 289

[3] E. Ruehl et al. 1989 The Journal of PhysicalChemistry 93 17

[4] Mishra P M, Rajput J, Safvan C P, Vig S andKadhane U 2013 Physical Review A 88 052707


ISAMP TC-7, 6−8 January, 2018, Tirupati CA053 Kadhane

106

Collisional isomerisation between naphthalene and azulene due to energetic

proton

Vinitha M V 1, †,Najeeb P K1,Anudit K1, P. Bhat2, C P Safvan2, S Vig3, U kadhane1,*

1Department of Physics, Indian Institute of Space Science and Technology, Thiruvanthapuram, India,

2Inter-University Accelerator Centre, Aruna Asif Ali Marg, New Delhi, India

3Department of Earth and Space science, Indian Institute of Space Science and Technology, Thiruvananthapuram, India

Topic:A

Polycyclic aromatic hydrocarbons (PAHs)

are popular for their collective excitation.

Astronomical and terrestrial relevance of

PAHs have resulted intense study of their

structure and dynamics in the last couple of

decades. PAHs, irrespective of their complex

structure show unusual resilience in harsh

radiations. Structural stability, dynamics and

rearrangement of this class of molecules can

be explored using charged particle as the

projectile and separating the statistical and

non-statistical decay channels. It is instructive

the study of proton impact collisions for small

PAHs at intermediate velocities which will

help in understanding how low energy cosmic

rays can interact with PAHs in interstellar

medium. These studies help in understanding

energetics of ion-PAH collision as well as post

collisional relaxation mechanisms. The onset

of H, 2H/H2 and C2H2 loss studies for proton-

naphthalene collision is investigated by this

group in past [1].

The experiment was carried out at the Low

Energy Ion Beam Facility, IUAC, Delhi. A ToF

Mass Spectrometer with a position sensitive

MCP detector is used to detect the recoil ions

after interaction with the proton beam. We used

proton beam at different energies (Energy

ranges from 50keV-200keV). The target vapour

was send to interaction chamber via a fine

needle. The recoil ion gets extracted to the

negative potential on top while the electron gets

extracted to positive potential below. During

the interaction it may happen that the projectile

proton may capture an electron from the

molecule. This neutral can be detected by

another channeltron downstream. Since this is a

continuous beam, we take electron or neutral

projectile as trigger to start data acquisition and

the data is recording in list mode to preserve the

multi coincidence information.

Single and double ionisation and subsequent

neutral loss processes in electron emission and

electron capture modes have been studied in

detail for naphthalene and its isomer azulene at

intermediate proton velocities. Relative yields

of C2H2 loss as a function of proton energy, in

direct and capture ionisation processes for both

PAHs is shown in figure1.Quantitative

exercises have been carried out to explain the

energy loss processes causing ionisation and

neutral evaporation for both the isomers in the

proton energy regime discussed here. Azulene

being isomer of naphthalene, the isomerisation

dynamics have become the key interest of the

study.

Figure 1. Normalised C2H2 loss from C10H8+ for electron

emission and electron capture modes in naphthalene and

azulene.

Reference

[1] P M Misra,J Rajput,C P Safvan,S Vig and

U Khadhane,2013,J.Phy.Rev.A,88,052707.

†[email protected]

*[email protected]

ISAMP TC-7, 6−8 January, 2018, Tirupati CA054 Kadhane

107

Two- and three-body dissociation dynamics of H2O2

M. Nrisimhamurty 1, L. C. Tribedi, D. Misra 2

Department of Nuclear and Atomic PhysicsTata Institute of Fundamental Research, Dr. Homi Bhabha Road, Colaba, Mumbai-400005, INDIA

Topic: A. To investigate the ion-induced dissociation dynamics of H2O2 in collisions with 1 MeV Ar8+ ions.

Interaction of atoms and molecules by ener-getic highly-charged ions is of utmost importanceto explore the structure of matter. However,these studies remained as a challenging task fora brief period due to the many-body nature ofatoms/ molecules and complexity involved dur-ing ion-induced breakup. But this field of re-search (particularly, ion-induced fragmentationdynamics) gained momentum from last couple ofdecades after the invention of the state-of-the-artrecoil-ion momentum spectroscopy (RIMS) [1].This technique is highly robust in obtainingkinematically-complete information about thevarious reaction pathways involved, in terms ofkinetic energy release, momentum distributionsand angular correlations. Not only that, RIMSalso set a benchmark which lead to the devel-opment of next generation theoretical method-ologies to unravel the ion-induced dissociationdynamics. Though today, ion-impact breakupdynamics of a large no. of di- and tri-atomicmolecules have been rigorously studied but in-formation about polyatomic molecules is yet tobe explored. Thus, this motivated us to work andreport about the ion-induced dissociation studiesof one such polyatomic molecule, H2O2.

Hydrogen peroxide (H2O2), a non-planarmolecule, is of basic interest here due to its rel-evance in understanding the chemistry of ozone.It along with HCHO and OHn, has been identi-fied to be playing a decisive role in the behav-ior of oxidation power and self-cleaning capacityof the atmosphere [2, 3]. In addition, recently ithas been discovered in the interstellar medium [4]and proved to be a prominent molecule to bestudied to understand the radiation damage ofbiological matter [2]. Although the above factorshighly-demands kinematically-complete informa-tion about H2O2, it being unstable in ambientconditions resulted in the availability of very fewdetails about its structure and dynamics. Hence,present observations on dissociation dynamics ofH2O2 are of paramount importance.

In the present work, 1 MeV Ar8+ ions are ob-

tained from the electron cyclotron resonance ionaccelerator (ECRIA) at TIFR, Mumbai. Elec-trons that are created during the fragmentationdo serve as a start signal. Recoil ions producedare projected onto a position- and time-sensitivedetector [5]. From the coincidence observations,we found two dissociation channels for two-bodydecay of H2O2 whereas H2O2 fragments into H+,H+ and O+

2 in a three-body dissociation process.Interestingly, a signature of angular anisotropyis observed as shown in the Fig. 1, which maybe an outcome of post-collisional effects.

Figure 1. Angle between the individual momen-

tum vectors and beam direction for the disso-

ciation channel H2O2+2 −→ H++O2H+. Solid

and dashed line corresponds to H+ and O2H+

fragments, respectively. The dotted curve corre-

sponds to isotropic distribution (sinθ). Inset shows

“dN/d(cosθ)” behaviour against various angles.

References

[1] J. Ullrich et al. 1997 J. Phys. B 30 2917

[2] D. Nandi et al. 2003 Chem. Phys. Lett. 373 454

[3] T. Klippel et al. 2011 Atmos. Chem. Phys. 114391

[4] F. Du et al. 2012 Astron. Astrophys. 538 A91

[5] A. Khan et al. 2015 Rev. Sci. Instrum. 86 043105


ISAMP TC-7, 6−8 January, 2018, Tirupati CA055 Madugula

108

Effects of interchannel coupling on angular distribution ofphotoelectrons and on time delay in the autoionization regions of

Neon 2s → np resonance series

S. Banerjee∗ 1, H. R. Varma‡ 2, & P. C. Deshmukh†,# 3

∗ Department of Physics, Indian Institute of Technology Madras, Chennai, 600036, India‡ School of Basic Sciences, Indian Institute of Technology Mandi, Kamand, H.P. 175005, India† Department of Physics, Indian Institute of Technology Tirupati, Tirupati, 517506, India

# Department of Physics, Indian Institute of Science Education and Research, Tirupati, 517507, India


Autoionization in atomic physics is a veryinteresting topic in the area of research forall the time. Autoionization resonance occursdue to the interference of bound to bound andbound to continuum transitions at certain energyranges. The electron correlations play a vital roleparticularly in these regions. Among the vari-ous observables that depend on phase, angularasymmetry parameter (β) is important one tostudy [1]. It also shows dependence on electroniccorrelation. Time, on the other hand, is not anobservable in quantum mechanics, but time de-lay [2, 3] in photoionization can be measured [4].Our study aims to look at the variation of β andthe time delay (τ) in Neon 2s → np resonanceseries. We employ relativistic random phase ap-proximation (RRPA) [5] and relativistic multi-channel quantum defect theory (RMQDT) [6] forpresent calculations. We have used two differentlevels of interchannel coupling to find out the de-pendence of the aforementioned observables onelectronic correlations. The figure shows that, βremains qualitatively the same, while time delaygoes from only positive to a combination of pos-itive and negative values when we coupled morechannels for calculation. There are discussionson the behaviour of time delay near resonanceregion using a generalized expression [7] for timedelay in terms of Fano parameters [8].

Figure 1. Angular asymmetry and WES time de-

lay in vicinity of 2s→ 4p resonance

References

[1] T. Banerjee et al. 2007 Phys. Rev. A 75(4),042701

[2] E. P. Wigner 1955 Phys. Rev. 98(1), 145

[3] L. Eisenbud 1948 Ph. D.(Doctoral dissertation,thesis Princeton University)

[4] S. Saha et al. 2014 Phys. Rev. A 90(5), 053406

[5] W. R. Johnson and C. D. Lin 1979 Phys. Rev. A20(3), 964

[6] C. M. Lee and W. R. Johnson 1980 Phys. Rev. A22(3), 979

[7] P. C. Deshmukh et al. 2017 (private communica-tion)

[8] U. Fano 1961 Phys. Rev. 124(6), 1866


ISAMP TC-7, 6−8 January, 2018, Tirupati CB001 Banerjee

109

Attosecond-Streaking Spectroscopy on a Liquid-Water Microjet

A. Jain1, R. Heider2, M. Wagner2, A. Duensing2, T. Gaumnitz1, I. Jordan1, J. Ma1,

J. Riemensberger2, M. Mittermair2, W. Helml2, R. Kienberger2, H. J. Wörner1

1. Laboratorium für Physikalische Chemie, ETH Zürich, Vladimir-Prelog-Weg 2, CH-8093 Zürich, Switzerland

2. Physik-Department, Technische Universität München, James-Franck-Str. 1, D-85748, Garching, Deutschland

Topic: B, E

Abstract: Attosecond-streaking experiments on gas- and liquid-phase water employing the liquid microjet are pre-

sented. The streaking traces are used to extract delays between the inner- and outer-valence states, giving access to the

attosecond dynamics of photoionization, transport and scattering processes in water.

I. Introduction

Attosecond-streaking spectroscopy1, has given

real-time access to photoionization delays of atoms

in the gas phase2, and the additional effects of elec-

tron transport processes through atomic layers and

interfaces of solid-state systems3,4. Here, we report

on the first attosecond-streaking experiments on

liquid samples. We have realized as-streaking pho-

toelectron spectroscopy on water in the gas and liq-

uid phases using a liquid microjet5.

II. Experimental Method

A carrier-envelope-phase-stabilized (~200 mrad

rms), sub-5 fs, Ti:Sapphire laser system (4 kHz, 1.2

mJ, 790 nm) is used to generate isolated attosecond

pulses by intensity gating, centered at 90 eV (~5 eV

FWHM, 455 as Fourier transform-limited). The

residual NIR and the generated as-XUV pulses are

focused by a two-component mirror assembly onto

the liquid microjet (25 µm diameter). Scanning the

delay between the XUV pump and the NIR streak-

ing pulse with a linear piezo stage allows us to

measure time-dependent photoelectron spectra by

means of a field-free time-of-flight (TOF) spec-

trometer. Successive measurements on gas-phase

water evaporating from the liquid microjet and from

liquid water inside the microjet are performed by

translating the jet in and out of the laser focus.

Figure 1. (a) Measured and (b) Reconstructed streaking

trace in liquid-phase water with isolated attosecond puls-

es at 90 eV giving a delay of ~16 as between inner- and

outer-valence shell.

III. Results

The measurements on gas-phase water molecules

provide effective photoionization delays between

the outer- (1b1, 3a1, 1b2) and inner-valence (2a1)

shells. These delays contain information on pho-

toionization dynamics of the molecule and, possi-

bly, electron-correlation phenomena that are known

to play a role in inner-valence ionization. For case

of liquid-water, using the spectrogram fitting tech-

nique2,3, we obtain a delay of ~16 as between pho-

toelectrons emitted from the inner- and outer-

valence shell. Measurements on liquid water addi-

tionally provide insight into transport of electrons

through liquid water on the attosecond time scale,

including elastic and inelastic scattering of electrons

with liquid-phase water molecules.

Figure 2. Photoelectron spectra from liquid-phase water:

measured using synchrotron radiation7, (blue), convolut-

ed with 5 eV Gaussian corresponding to inner-mirror

reflectivity (red) and measured spectra with isolated atto-

second pulses at 90 eV (yellow).

References

[1] F. Krausz, M. Ivanov, Rev. Mod. Phys., 81,163 (2009).

[2] M. Schultze et al., Science, 328, 1658 (2010).

[3] S. Neppl et al., Nature, 517, 342(2015).

[4] R. Locher et al, Optica, 2, 405 (2015).

[5] B. Winter, M. Faubel, Chem. Rev., 106, 1176 (2006).

[6] I. Jordan et al., Rev. Sci. Instrum., 86, 123905 (2015).

[7] B. Winter et al., J. Phys. Chem. A, 108, 2625 (2004).


ISAMP TC-7, 6−8 January, 2018, Tirupati CB002E Jain

110

Photoionization dynamics of Ar@C540

Sourav Banerjee∗ 1, Afsal Thuppilakkadan‡ 2, H. R. Varma‡ 3, & P. C. Deshmukh†,# 4

∗ Department of Physics, Indian Institute of Technology Madras, Chennai, 600036, India‡ School of Basic Sciences, Indian Institute of Technology Mandi, Kamand, H.P. 175005, India† Department of Physics, Indian Institute of Technology Tirupati, Tirupati, 517506, India



Fullerenes, which are nanostructure forma-tions of carbon atoms, have attracted intense re-search activities. A variety of fullerenes exist innature with varying number of carbon atoms. Anatom can be trapped inside the hollow space ofthese systems and this external cage can bringsignificant modifications in the properties of theatom. An outstanding feature of the photoion-ization spectrum of such confined atoms [1] isthe presence of confinement oscillations due tothe interference between the directly ionized elec-tron wave and its reflected component from thecage. A number of studies have been reportedon atoms trapped in fullerenes (A@Cn), where ndenotes the number of carbon atoms present [1].In this work, we report photoionization studiesof argon atom encaged in a C540 giant fullerene(Ar@C540). The presence of C540 is modeled bya spherical attractive well with the atom at itscenter. The cage has been modelled by a spher-ical potential of depth (U0)= 0.441 a.u., thick-ness (∆)= 1.9 a.u. with inner radius (r0)= 18.85a.u. [1]. It is to be noted that, the assumptionthat the atom at the center is not fully realisticbecause of the big size of C540. The exact levelof displacement from the center is not preciselyknown. The present studies can be considered asthe zeroth approximation of the cage and it canprovide useful information to understand pho-toionization dynamics of other complex types ofendohedral systems such as A@C60@C240@C540

where it is reasonable to assume the atom at itscenter.Here, we employ relativistic random phase ap-proximation (RRPA) methodology which in-cludes many electron correlation and relativisticeffects. In Figure 1, we show the 1s cross sec-tion of Ar@C540. It is found that amplitude ofthe confinement oscillations are much smaller inRRPA compared to an earlier reported Hartree-Fock results [2]. In order to understand the dif-

ference, the RRPA calculations are further car-ried out in its non-relativistic limit(NRL-RRPA)so that it can mimic the non-relativistic results.The results from NRL-RRPA also show oscilla-tions with smaller amplitude as in the case ofRRPA. The work can be extended to study pho-toionization dynamics for different cage parame-ters.

Figure 1. Photoionization cross section for

Ar@C540 in different schemes

Recently photoionization studies in the timedomain have emerged as intense research areasin atomic physics [3]. The present work alsoaims at studying the role of non-dipole interac-tions in the dynamics of 1s photoionization. Theconfinement oscillations are also expected in thequadrupole channels and it is of great intereststudy the modification on time delay engenderedby the confinement oscillations in Ar@C540.

References

[1] V. K. Dolmatov et al. 2004 Rad. Phys. and Chem.70(1), 417-433

[2] V. K. Dolmatov et al. 2008 Phys. Rev. A 78(1),013415

[3] P. C. Deshmukh et al. 2014 Phys. Rev. A 89(5),053424


ISAMP TC-7, 6−8 January, 2018, Tirupati CB004 Banerjee

111

Shape resonance induced Wigner time delay in atomic photoeffects

S.Saha* 1

, J.Jose† 2

and P.C. Deshmukh$, # 3


† Department of Physics, IIT Patna, Bihta – 801103, Bihar, India

$ Department of Physics, IIT Tirupati, Tirupati – 517506, Andhra Pradesh, India

# Department of Physics, IISER Tirupati, Tirupati – 517507, Andhra Pradesh, India

Topic: B

Wigner time delay [1] studies in the case of

negative ion phodetachment were reported

for relativistically split dipole channels

originating from the 3p subshells of Cl- [2]

and the 4d subshells of Tm- [2, 3] earlier.

The outgoing photoelectron in the

photodetachment process [4] escapes in the

field of the neutral residual atom and thus

doesn’t contain the large Coulomb

component in its phase. That helps in

studying the Wigner time delay, emerged

solely due to the centrifugal barrier shape

resonance [5]. In the shape resonance

region, one expects the phase to change

rapidly and thereby cause significant time

delay, according to Wigner-Eisenbud

formalism [1, 6]. However, in the case of

photoionization studies, this

phenomenology is obliterated [2] by the

large Coulomb phase. In the present work

we investigate the amplitude, phase and

time delay for all the relativistically split

nd→εf channels in the photodetachment of

Br- and in the photoionization of atomic Kr

(isoelectronic to Br-) and for all the three

relativistically split nd→εf channels and

nf→εg channels in the photodetachment of

Au-

and in the photoionization of atomic

Hg (isoelectronic to Au-) using the

relativistic random phase approximation

(RRPA) [7]. This comparative study will

help us to demonstrate the suppression of

the centrifugal barrier shape resonance

effects in photoionization process. In Fig.

1, photodetachment phases for all the three

relativistically split nd→εf channels of Br-

(left y-axis) and the total 3d cross section

(right y-axis) are shown. The time delay

has been displayed in Fig. 2 for all the

three relativistically split nd→εf channels.

The cross section goes through the delayed

maximum indicating the presence of shape

resonance. The sharp change in the phase in all

three channels causes significant time delay

near the threshold region in all three channels.

The present study enables the determination of

the resonance energy where the phase change

is most rapid in the broad resonance region.

100 150 200 250 300 350

-0.2

-0.1

0.0

0.1

0.2

0.3

0.4

0.5

0.6

3d3/2

->f5/2

3d5/2

->f5/2

3d5/2

->f7/2

Phas

e (

Photon energy (eV)

Br-

3p1/2

3p3/2

3d3/2

3d5/2

100 150 200 250 300 350

0

1

2

3

4

5

6

Cross sec3d5/2+3d3/2

Cro

ss s

ecti

on (

Mb)

Figure 1. Photodetachment phases for all three

relativistically split nd→εf channels and total 3d

cross section of Br-

76 77 78 79 80

-200

0

200

400

3d3/2

->f5/2

3d5/2

->f5/2

3d5/2

->f7/2

Tim

e d

elay

(as

)

Br-

3d3/2 3d

5/2

Photon energy (eV)

Figure 2. Photodetachment time delays for all three

relativistically split nd→εf channels of Br-

References:


[2] S. Saha et al 2016 BAPS 61(8) 53

[3] S. Saha et al 2017 BAPS 62(8) 137

[4] V. K. Ivanov 1999 J. Phys. B 32 R67

[5] A. R. P. Rau and U. Fano 1968 Phys. Rev. 167

7

[6] L. E. Eisenbud 1948 Ph. D. thesis, Princeton

Univ. [7] W. R. Johnson and C.D. Lin 1979 Phys. Rev. A

20 964 1 E-mail: [email protected]



ISAMP TC-7, 6−8 January, 2018, Tirupati CB006 Saha

112

Influence of SOIAIC in photodetachment and photoionization time delays

near the centrifugal barrier shape resonance

S.Saha* 1

, J.Jose† 2

and P.C. Deshmukh$, # 3


† Department of Physics, IIT Patna, Bihta – 801103, Bihar, India

$ Department of Physics, IIT Tirupati, Tirupati – 517506, Andhra Pradesh, India

# Department of Physics, IISER Tirupati, Tirupati – 517507, Andhra Pradesh, India

Topic: B

Effects of spin orbit interaction activated

inter-channel coupling (SOIAIC) [1, 2] on

photoionization parameters were studied in

an earlier work [3] in our group. SOIAIC

effects were seen in the dipole cross

sections of Xe 4d and Rn 5d subshells.

Here, we report how SOIAIC affects the

Wigner time delay [4] in photoeffect. Time

delay has been calculated for all the

relativistically split ndεf channels in the

photodetachment of I- and also in the

photoionization of atomic Xe using the

relativistic random phase approximation

(RRPA) [5]. This comparative study will

also help us in understanding the time

delay associated with the two processes. In

the case of photodetachment, the time

delay occurs solely due to the centrifugal

barrier shape resonance [6]. Whereas in the

case of photoionization, the large Coulomb

phase governs the time delay near the

threshold. Calculations have been

performed at select levels of truncation in

the RRPA: (Level L1) Pseudo-Independent

Particle Truncation (PIPT): At this level of

truncation, we exclude SOIAIC by

including channels only from j= l+1/2

subshell (Case L1a) or from j= l-1/2 (Case

L1b) subshell; (Level L2) Intra-Subshell

Truncation (ISST): here, we include

SOIAIC by coupling the channels arising

from both the subshells j=l±1/2 of the spin-

orbit doublet. In Figure 1 and Figure 2 the

photodetachment time delay for ndεf

transition in I- and photoionization time

delay for ndεf transition in Xe are plotted

respectively at the above mentioned levels

of truncation. The influence of SOIAIC

affects the time delay near the threshold

region in both the cases.

40 60 80 100 120 140

-150

-100

-50

0

50

100

150

200

Tim

e d

elay

(as

)

L1a: 4d5/2->f7/2

L1a: 4d5/2->f5/2

L1b: 4d3/2->f5/2

L2: 4d5/2->f7/2

L2: 4d5/2->f5/2

L2: 4d3/2->f5/2

Photon energy (eV)

4d3/2

4d5/2 I-

Figure 1. Time delays are shown for all the three

relativistically split ndεf channels in

photodetachment of I- using dashed (L1) and solid

(L2) lines. Different colours correspond to different

transitions.

60 80 100 120 140

-100

0

100

200

300

400

500

L1a: 4d5/2

->f7/2

L1a: 4d5/2

->f5/2

L1b: 4d3/2

->f5/2

L2: 4d5/2

->f7/2

L2: 4d5/2

->f5/2

L2: 4d3/2

->f5/2

Photon energy (eV)

Xe

Tim

e d

elay

(as

)

4d5/2

4d3/2

Figure 2. photoionization time delays are shown

for all the three relativistically split ndεf channels

in photoionization of Xe using dashed (L1) and

solid (L2) lines. Different colours correspond to

different transitions.

References:

[1] A. Kivimäki et al 2000 Phys. Rev. A 63 012716

[2] M. Ya. Amusia et al 2002 Phys. Rev. Lett. 88

093002

[3] S. Sunil Kumar et al 2009 Phys. Rev. A 79

043401


[5] W. R. Johnson and C.D. Lin 1979 Phys. Rev. A

20 964

[6] A. R. P. Rau and U. Fano 1968 Phys. Rev. 167

7




ISAMP TC-7, 6−8 January, 2018, Tirupati CB007 Saha

113

Effect of model potentials (smooth Vs hard) on the Wigner timedelay of H@C60 Photoionization

Afsal Thuppilakkadan∗ 1, Subhasish Saha† Jobin Jose† Hari R. Varma∗

∗ School of Basic Sciences, IIT Mandi, Mandi – 175005, Himachal Pradesh, India† Department of Physics, IIT Patna, Bihta– 801103, Bihar, India

Topic: B

Understanding photoionization dynamics inthe time domain has been a subject of, bothexperimental and theoretical, immense researchactivities in recent years [1]. Studies of Wigner-Eisenbud-Smith time delay(tWES) associatedwith the photoionizaton [2] channels leads todeeper understanding of the role of correlationand relativistic interactions present in the sys-tem. A number of studies on atoms focussing theregion of Cooper minimum are already reported[3, 4].Time delay studies of endohedral atoms are ofgreat interest because of the presence of con-finement oscillations in their ionization channels.Such studies of tWES in the resonance regionprovide a better understanding of the dynamicsof photoionization of confined atomic systems[5, 6]. These previous studies used an annularsquare well potential (VASW ) to simulate theconfining environment which is described below:

VASW (r) =

−U, if rc − 42 ≤ r ≤ rc + 4

20, otherwise,

where rc is the center of confinement cage and 4is its width. This model has unrealistic disconti-nuities (hard) at the shell boundaries. However,earlier it was shown that photoionization crosssection calculated by employing a smooth poten-tial do not differ much compared to the crosssection obtained by VASW [7]. Here, we use amodel jellium potential termed Gaussian annu-lar square well (VGASW ) model, described below,to investigate cross-section, phase shift and timedelay in the photoionization of the confined Hatom (H@C60).

VGASW (r) =A√2πσ

e−( r−rc√

2σ)2

+ VASW .

This model simulate both the qualitative andquantitative nature of the potential employedby Puska and Nieminen [8]. A comparisonis made between the results obtained by em-ploying ASW and GASW model potentials.

Figure 1. Phase shift and time delay in photoion-

ization of H@C60 employing ASW and GASW po-

tential

Figure 1 shows a comparison of time delay andphase shift associated with the 1s → εp pho-toionization obtianed by employing ASW andGASW potentials with depth of the well as 1.03au. Phase shift in photoionization is determinedby referring to the asymptotic behavior of ra-dial part of the wave-function obtained numer-ically. Both time delay and phase shift showconfinement oscillations. However, amplitude ofconfinement oscillations is significantly reducedwhen GASW potential is used in the calcula-tion near the threshold. A detailed analysis willbe presented by studying this system for differ-ent depths of confining potentials. We will alsopresent alternate analytical calculation to sub-stantiate the numerical results obtained.

References

[1] Pazourek et al. 2015 Rev.mod.phy. 87 765

[2] M. Schultze et al. 2010 Science 328 1658

[3] A. S. Kheifets 2013 Phys. Rev. A 87 063404

[4] Saha S et al. 2014 Phys. Rev. A 90 053406

[5] P. C. Deshmukh et al. 2014 Phys. Rev. A 89053424

[6] A Kumar et al. 2016 Phys. Rev. A 94 043401

[7] V. K. Dolmatov et al. 2012 J. Phys. B 45 105102

[8] M. J. Puska et al. 1993 Phys. Rev. A 47 1181

1E-mail: afsal [email protected]

ISAMP TC-7, 6−8 January, 2018, Tirupati CB008 Thuppilakkadan

114

A Two Dimensional Magneto Optical Trap with High and Tunable Optical

Depth for Slow Light Applications

Sumit Bhushan and Raghavan K Easwaran

Department of Physics, IIT Patna, Bihta, Patna- 801103, Bihar, India

Topic: C

The storage of light pulses inside a medium

is vital for applications such as quantum infor-

mation, quantum communication, and quantum

computing [1]. This storage is facilitated by

media which are capable of slowing down the

group velocity vg of light to extremely small

values. The most commonly used method to

realize such storage is Electromagnetically In-

duced Transparency (EIT) which makes a me-

dium transparent to a resonant light and simul-

taneously reduces the group velocity of light by

7 or more orders of magnitude, thereby making

the storage of these light pulses possible [2].

Out of the many media in which such storage

has been demonstrated, cold atomic medium in

a two dimensional magneto optical trap (2D-

MOT) has the most distinct advantages like

high Optical Depth (OD), high efficiency of

storage, and high Delay Bandwidth Product

(DBP).

Here, we are presenting design of a 2D-

MOT with very high and tunable OD resulting

in very small group velocity. Our design can be

divided into three main parts, (a) vacuum

chamber design, (b) magnetic coil design, and

(c) the laser system. The vacuum assembly con-

sists of a source chamber and a science cham-

ber. As shown in Fig. 1, the source chamber has

a glass opening through which the probe and

pump beams constituting the EIT set up are in-

jected into the medium. 87

Rb atoms are sent into

the source chamber through an inlet on the top

of it and are trapped by cooling and trapping

lasers in the science chamber along a line of

length L2D = 8cm where the magnetic field is

zero because of the anti-Helmholtz rectangular

coils as shown in Fig. 2. The cooling lasers

(CL) shown in Fig. 2 are rectangular sheet

beams with dimensions 80mm x 10mm and are

slightly red detuned from the D2 transition of 87

Rb atoms.

Figure 1. Side view of our proposed design

Figure 2. Current carrying rectangular coils in anti-

Helmhotz configuration. CL denotes cooling lasers.

The number density NA of trapped atoms in

our design is 2.3 x 1011

atoms/cm3. OD obtained

in our design is 1374 resulting in a group veloc-

ity of 1.4 m/s. The DBP is 163 and hence the

number of pulses that can be stored with our

design is 29 which is very high when compared

to other slow light systems.

References

[1] Afzelius M et al. 2015 Phys. Today 68 42

[2] Hau L V et al. 1999 Nature 397 594

[3] Bhushan S and Easwaran R K 2017 Appl. Opt.

56 3817



ISAMP TC-7, 6−8 January, 2018, Tirupati CC002 Bhushan

115

Quantum State Transfer through Coherent Atom-Molecule Conversion in Bose-

Einstein Condensate

Subhrajit Modak*, Priyam Das†, 1 and Prasanta K. Panigrahi*

* Indian Institute of Science Education and Research Kolkata, Mohanpur, West Bengal - 741246, India

† Department of Physics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi - 110016, India

Topic: C - Laser cooling, Bose-Einstein Condensates, Atomic clocks, and Quantum computing.

Abstract: We demonstrate complete quantum

state transfer of an atomic BoseEinstein con-

densate to molecular condensate, mediated by

solitonic excitations in a cigar shaped mean-

field geometry. Starting with a localized soli-

tonic atomic condensate, we show compatible

gray solitonic configuration in the molecular

condensate, which results in complete atom-

molecule conversion. The effect of inter and

intra-species interactions on the formation of

molecular condensate is explicated in the pres-

ence of Raman Photoassociation. It is found that

Photoassociation plays a crucial role in the co-

herent atom-molecule conversion as well as in

the soliton dynamics. The gray soliton disper-

sion reveals bi-stable behavior, showing a re-

entrant phase in a physically accessible para-

metric domain.

Figure 1. Schematic diagram of the atomic-

molecular configuration, where atomic density is de-

scribed by the bright soliton and molecular profile

possesses gray soliton. The strength of the inter at-

om-molecular transfer is responsible for a complete

state transfer from atomic to molecular BECs.

Figure 2. Depiction of the density profiles of atomic

and molecular wave packets. (a) shows the propaga-

tion of bright soliton in the atomic condensate to that

of gray soliton in the molecular condensate in (b).

Figure 3. (a) Shows dispersion relation of molecular

condensate for different values of α, revealing a degener-

acy in molecular energy for higher values of α. (b) de-

picts the variation of molecular energy as a function of

the inter-conversion and Mach angle. The periodic nature

of energy clearly shows the coherent nature of atom-

molecule inter-conversion. Here parameter values are

same as that in Fig. (2).

References

[1] S. Modak, Priyam Das and P. K. Panigrahi

2017 arXiv: 1708.04286.

[2] D. J. Heinzen et. al., 2000 Phys. Rev. Lett.

84, 5029.

[3] F. Richter et. al. 2015 New J. Phys. 17,

055005.


ISAMP TC-7, 6−8 January, 2018, Tirupati CC003 Das

116

Breathing Dynamics of Ultracold Atoms in a Vibrated Optical Lattice

Jayanta Bera1,a

, A. Q. Batin1, Suranjana Ghosh

2, Utpal Roy

1,b

1 Indian Institute of Technology of Patna, Bihta, Patna, Bihar- 801103

2 Amity University Patna, Rupaspur, Patna, Bihar-801503

Topic: C

Ultracold quantum gas is known to be very robust,

highly tunable and versatile system, which has

recently found numerous interesting applications

towards quantum optics, quantum information, weak

measurement, higher harmonic generation etc. Bose-

Einstein Condensate (BEC) in a harmonic trap is a

well known situation and the advent of highly

controllable laser techniques helped physicists to

bring out new phenomena in BEC in presence of

tunable optical lattices (OL) [1-3]. A large number of

experimental works have been carried out in the

literature. Analytical and numerical investigations on

BEC have also got huge emphasize to have a clear

understanding of the dynamics under various trap-

geometry and non-linear parameter modulation in

1D, 2D and 3D [4]. The nonlinear Gross-Pitäevskii

equation (GPE) is most appropriate to study the

dynamics of BEC in weak nonlinear interaction. The

solution of the GPE is a difficult task even in lower

dimensions. There are few analytical methods for

some well known potential profiles. Analytical

variational approach is also one of the useful methods

to study the dynamics of GPE [6,7].

In this work, we analytically study the 1D dynamics

of BEC in the presence of harmonic plus optical

lattices (HOL) potential using variariational

approach. We mainly concentrate on the variation of

the width of the condensate density with time, where

the depth of the OL has a sinusoidal temporal

modulation. As a result, the change in the width of

the condensate due to the harmonic trap is modulated

by an overall oscillation coming from the amplitude

breathing of the OL. It is apparent in fig (1) that the

basic frequency or fundamental frequency (FF) of

oscillation in presence of only harmonic trap is

present with highest amplitude. Additionally, some

higher and lower frequencies are also visible at

regular intervals from FF. This is depicted in fig (2).

Subsequently, these side band frequencies (SBF) are

also correlated to the FF. a)

[email protected], b)

[email protected]

In addition to the number of numerical studies in the

literature, this analytical approach will provide a clear

correlation of the available frequencies in the

dynamics with the trap parameters, which will bring

out potential applications towards precise

experimentations to detect fluctuations of various

physical quantities like, thermal fluctuations, field

variation etc.

Fig. (1) : Oscillation of the width with time in

presence of HOL trap and with modulation

oscillation frequency(ω)=0.8π. All the parameters are

dimensionless.

Fig. (2) : Frequency plane of the time-evolution

depicted in fig. (1). The amplitudes of the SBFs

depend on the amplitude of the modulation parameter

of OL.

References: 1. I Bloch, 2005, Nature physics , 1, 23.

2. A Nath and U Roy, 2014, Laser Phys. Lett., 11, 115501.

3. I Bloch, 2004, Phys. World, 17, 25.

4. A Nath and U Roy, 2014, J. Phys. A: Math. Theor, 47,

415301.

5. I Vidonović et al., 2011, Physical Review A, 84, 01361.

6. V M Pe´rez-Garcı´a et al., 1997, Physcial Review A,

56(2), 1050.

7. A M Kamchatnov et al.,2004, Physical Review A, 70,

02360

ISAMP TC-7, 6−8 January, 2018, Tirupati CC005 Batin

117

A pedagogical simulation of the Aharonov-Bohm effect

Voma Uday Kumar and P C Deshmukh

Indian Institute of Technology Tirupati, Tirupati – 517506

Topic: Ion traps, Laser cooling (D, C)

In the Aharonov-Bohm experiment, it was seen

that the quantum phase of an electron could be

altered to detectable extent by a magnetic field

even in a region where the field intensity is zero

[1,2]. Dramatic effects of the AB effect for

trapped ions were reported decades ago [3]. In a

recent paper, Nogochi et al. reported [4] that

charged particles in quantum tunneling system

are coupled to the magnetic vector potential even

during quantum tunneling, in accordance with the

Aharonov–Bohm effect.

The results of Noguchi et al. paper [4] on the

tunneling of a quantum rotor in a Paul trap has

created much interest in the study of the ABE and

Berry Phase [5] among scientists working in the

area of ion-trap studies, laser cooling, BEC etc.

This topic is of great interest even in the

understanding of the gravitational field as it is

possible that particles are affected by the

gravitational potential even in the absence of a

force. Ultracold atoms have been employed to

demonstrate this remarkable phenomenon [6]. In

the present work, we report a computer

simulation of the AB effect toward a pedagogical

discussion on the exciting quantum

phenomenology.

The MATLAB GUI Software has been employed

to elucidate the AB effect from a fundamental

point of view. In the figure shown below we show

the results of the simulation in which the

interference pattern in a Young’s double slit

experiment with electrons is phase shifted by the

magnetic vector potential created by a long

solenoid despite the fact that the elecrtons do not

at any point enter the region of the solenoid’s

magnetic field.

Fig.1: The dashed line shows the envelope of the

interference pattern with no current in the solenoid,

and the continuous line enclosing the shaded portions

shows the same when the current is switched on.

We trust that the simulation developed will be of

interest to both theorists and experimentalists

working in the field of ion traps.

References:

[1]Aharonov,Y.,& Bohm,D et al.(1959).Significance

of Electromagnetic Potentials in the Quantum theory.

Physical Review, 115(3), 485–491.

[2]M. V. Berry, F.R.S. et al.(1984). Quantal phase

factors accompanying adiabatic changes. Proc. R. Soc.

Lond. A 392, 45-57.

[3]Robert R.Lewis et al.(1983).Aharonov-Bohm

effect for trapped ions. Physical Review A volume 28

[4]Atsushi Noguchi et al.(2014). Aharonov–Bohm

effect in the tunneling of a quantum rotor in a linear

Paul trap.

NatureCommunications,DOI: 10.1038/ncomms4868.

[5]Michael A. Hohensee et al.(2012).Force-Free

Gravitational Redshift: Proposed Gravitational

Aharonov-Bohm Experiment. Phys. Rev. Lett. 108,

230404.

[6]Matt Jaffe1 et al (2017).Testing sub-gravitational

forces on atoms from a miniature in-vacuum source

mass. DOI: 10.1038/NPH

ISAMP TC-7, 6−8 January, 2018, Tirupati CC006D Udaykumar

118

Cooling of trapped ions with a tiny cloud of ultracold atoms: the role of resonant

charge exchange

Sourav Dutta1 and S. A. Rangwala

Raman Research Institute, C. V. Raman Avenue, Sadashivanagar, Bangalore – 560080, India.

Topic: D - Trapping and manipulation of quantum systems.

Trapping and cooling of ions have been in-

strumental in advancing numerous fields includ-

ing precision measurements, quantum compu-

ting, quantum simulations and cold chemistry.

Demonstration of new ion cooling methods is

therefore of paramount importance in the ad-

vancement and expansion of these research are-

as. Optically dark ions such as Na+, Rb

+, Cs

+

cannot be laser cooled, leaving cooling by colli-

sions with cold atoms as the next most viable

option. Indeed, experiments have time and

again verified that an ion trapped in a Paul trap

can be cooled by elastic collisions with cold at-

oms when the ion is heavier than the atom.

However, there is a long-standing debate on

whether the reverse, cooling of low-mass ions

by higher-mass atoms, is possible.

In the first part of my presentation, I shall

discuss our experiments which demonstrate, for

the first time, cooling of low-mass ions by ul-

tracold heavier atoms [1]. Specifically, we show

that 39

K+ ions trapped in a Paul trap are cooled

by ultracold 85

Rb atoms trapped in a magneto-

optical trap (MOT), provided the MOT is cen-

tered with the Paul trap. A similar cooling of 85

Rb+ ions by ultracold

133Cs atoms is also

demonstrated. The ions are cooled because the

ultracold atoms are localized and placed pre-

cisely at the centre of the ion trap, where the

ion’s secular speed is the maximum. Therefore,

elastic collisions with ultracold atoms always

reduce the speed, and hence the temperature, of

the ion. The result raises hope that cooling of

H2+, H3

+ and HD

+ with ultracold

6Li atoms may

now be possible.

In the second part of the presentation, I shall

discuss our experiments which demonstrate, for

the first time, a novel ion cooling mechanism

based on inelastic, resonant charge exchange

collisions between the trapped ion and the par-

ent neutral atom [2]. Specifically, we experi-

mentally demonstrate cooling of trapped 133

Cs+

ions by collisions with co-trapped, ultracold 133

Cs atoms and, separately, by collisions with

co-trapped, ultracold 85

Rb atoms. We observe

that the cooling of 133

Cs+ ions by

133Cs atoms is

more efficient than cooling of 133

Cs+ ions by

85Rb atoms. This indicates the presence of a

cooling mechanism beyond elastic ion-atom

collisions for the Cs-Cs+ case, which is cooling

by resonant charge exchange. The efficiency,

per-collision, of cooling by resonant charge ex-

change is established to be higher than cooling

by elastic collisions. The results provide an ex-

perimental basis for future studies on charge

transport by electron hopping in ultracold atom-

ion systems [3].

References

[1] Dutta S, Sawant R, Rangwala S A. 2017 Physical

Review Letters 118 113401

[2] Dutta S, Rangwala S A. 2017 arXiv:1705.07572

[3] Côté R. 2000 Physical Review Letters 85 5316


ISAMP TC-7, 6−8 January, 2018, Tirupati CD001 Dutta

119

Quantum dynamics and frequency shift of a Driven multi-photon anharmonic

oscillator

Dolan Krishna Bayen * 1 and Swapan Mandal

* 2

* Department of Physics, Visva-Bharati, Santiniketan-731235, INDIA

Topic: D

The Hamiltonian and hence the relevant

equations of motion involving the dynamics of

a driven classical anharmonic oscillator with

2m − th anaharmonicity are framed. By

neglecting the nonsychronous energy terms, we

derive the model of a driven multi-photon

(2m − th) quantum anharmonic oscillator. The

dynamical nature of the field operators are

expressed in terms of the coupling constant,

excitation number and the driven parameter.

The solutions presented here are fully analytical

and are exact in nature. The basic physics is

easily understood in terms of models. Of

course, the model of a harmonic oscillator (HO)

is perhaps the most useful one among them. The

model of a simple harmonic oscillator is

realized when a particle moves under the action

of restoring force. In spite of the wide

applications of the SHO model, it is inadequate

when we come across with the real physical

situations. For a real physical system, the

inclusion of damping and/or anharmonicities

are inevitable. In addition to these, the oscillator

may also be put under the action of an external

force and hence the model of a forced (driven)

oscillator. It is true that the presence of damping

in the model of a SHO is not a serious problem

as long we are interested in the classical regime.

On the otherhand, the presence of damping in

the model of a SHO makes the problem a

nontrivial one. Therefore, the damped quantum

harmonic oscillator requires a special attention.

In this communication, we will ignore the

presence of damping if any. Because of the

wide range of applications and of the

fundamental nature of the problem, the

problems of anharmonic oscillator have

attracted people from various branches of

physics [1-9].The solution of driven anharmonic

oscillator is explored under the RWA and is

certainly based on the complete analytical

approach. The present solution will find

applications in the investigation of quantum

statistical properties of the radiation fields and

in the dynamics of the trapped particles in a

MOT. These quantum statistical properties

include squeezing, higher ordered squeezing,

photon antibunching and photon statistics.

References

[1] A H Nayfeh, Introduction to perturbation

techniques (Wiley, New york, 1981).

[2] A H Nayfeh and D T Mook, Non-linear

oscillations (John Wiley, New york, 1979).

[3] R Bellman, Methods of nonlinear analysis Vol.1

(Academic press, New york, 1970) p.198.

[4] S L Ross, Differential equation 3rd eds. (John Wiley,

New york, 1984).

[5] S Mandal, Physics Letters A, 299, 531, (2002).

[6] S Mandal, J.Phys.A 31, L501 (1998).

[7] C C Gerry, Physics Letters A, 124, 237, (1989).

[8] V Buzek, Physics Letters A, 136, 188, (1989).

[9] R Tanas, Physics Letters A, 141, 217, (1989).



ISAMP TC-7, 6−8 January, 2018, Tirupati CD002 Bayen

120

High-intensity laser ion experiments in Penning Trap

Sugam Kumar ∗ 1, S.Ringleb †, N.Stallkamp †,‡, M.Vogel ‡, W.Quint ¶, Th. Stohlker †,‡,§,G.G.Paulus †,§, C.P Safvan ∗

∗ Inter University Accelerator Centre, New Delhi – 110067, Delhi, India† Institute of Optics and Quantum Electronics, Friedrich-Schiller-Universitat – 07743, Jena, Germany

‡ GSI Helmholtzzentrum for Schwerionenforschung GmbH – 64291, Darmstadt, Germany§ Helmholtz-Institut Jena – 07743, Jena, Germany

¶ Physikalisches Institut, Ruprecht Karls-Universitat Heidelberg – 69120, Heidelberg, Germany

Topic: D

We have designed and constructed a mechan-ically compensated Penning trap to study thebehaviour of atomic and molecular systems inextreme electromagnetic fields. This is realizedby the preparation and confinement of atomicand molecular ion targets in a Penning trap, andthe non-destructive analysis of reaction prod-ucts upon interaction with high-intensity laserlight. For a determination of absolute reactioncross sections, it is crucial to identify and countboth the educts and products. Therefore, wehave designed and built the HILITE (High Inten-sity Laser Ion-Trap Experiment), which employsseveral Penning-trap techniques for ion capture,confinement, selection and ion-target formation.To cover a broad range of laser parameters it isnecessary to have access to different laser sources.The setup is hence built in a compact fashionwhich allows it to be moved easily from one lo-cation to the other. The main focus concerningmeasurement performance lies on versatility andreliability.

The trap electronics is located in the bore ofa 6T superconducting magnet. The trap itselflocated in the centre of the magnetic field, wherethe homogeneity magnetic flux density is betterthan 10ppm. The trap is a cylindrical open-endcap design with access from both sides forin-coupling of the laser beam and ion injectionfrom an external source. In order to achieve longion storage times the design residual gas pres-sure is better than 10−12 mbar. To compromisethis open design with a sufficient vacuum in theinteraction region, a set of baffles at cryogenictemperatures is applied on each side of the trap-electrodes. Furthermore we use one set of bafflesas a single-pass charge counter to characterizethe ion bunches entering and leaving the trap.Another set of baffles is used as a pulsed drift

tube to decelerate ions for dynamic capture ofexternally produced ions, for example from anEBIT or a beamline.

For non-destructive ion detection we use res-onant amplification of mirror currents induced inthe trap electrodes by the ion oscillations. Twohigh quality factor resonators with resonant fre-quencies of 229kHz and 702kHz are employed tomeasure the axial frequencies whereas a helicalresonator which amplifies multiples of fundamen-tal frequencies is the used to measure cyclotronfre-quencies. By tuning the trap potential, thisallows to measure charge-to-mass ratio spectra ofthe confined ions over a broad range. To be alsosensitive to a small ion numbers, we apply a de-structive measurement technique. Using a MCPdetector-system with a timing anode we are ableto measure even single ions, when ejecting thereaction products out of the trap.

Figure 1. Schematic of Trap electrodes and Baffles

The plan includes the use of the PHELIXlaser with wavelength 1053 nm at GSI andPOLARIS (1030 nm) and JETI (800 nm) atJena, Germany with intensities up to order1021W/cm2. We present the current status ofthe experiment and the results of the character-ization experiments of our ion trap.

References

[1] Gabrielse et al. 1989 IJMSIP 88 319

[2] M. Richter et al. 2009 PRL 102 163002


ISAMP TC-7, 6−8 January, 2018, Tirupati CD003 KumarSugham

121

Non-linear Axial Oscillations of an Electron plasma in a PenningTrap

Prakash∗ 1, Durgesh Datar∗ 2, Dyavappa B M∗ 3, Sharath Ananthamurthy† 4

∗ Department of Physics, Bangalore University, Bengaluru – 560056, Karnataka, India† School of Physics, University of Hyderabad, Hyderabad – 500046, Telangana, India

Topic: D

We have obtained experimentally the mo-tional resonance spectrum of an electron plasmaconfined in a Penning trap. This is obtainedthrough weak dipole excitation of the centre ofmass eigen frequencies of particle collective mo-tion as well as the frequencies due to coupling ofthe degrees of freedom. Even under low excita-tion strengths of the radio frequency source theaxial oscillation resonance exhibits, apart fromindividual and collective particle oscillations ofthe electron plasma, higher order resonances aswell. Both particle oscillation components havedifferent shape and width. The behavior of thecenter-of-mass resonance suggests that it is aparametric instability of a Mathieu type equa-tion of motion[1].

In this experiment, the axial electron plasmaoscillations are excited by sweeping the frequencyof an applied rf-field by using an external an-tenna. A number of resonances are visible whichappear not only at the fundamental frequenciesω+, ω− and ωz but also at linear combinationsof these frequencies. Here ωc, ω+, ω− and ωz arerespectively the free electrons cyclotron, the per-turbed cyclotron, the magnetron and axial fre-quencies of oscillation.

In previous work[1, 2] the axial oscillation at2ωz is examined under higher resolution. Thisreveals the structure of a broad asymmetric min-imum in the electron number, accompanied by asharp resonance on the high frequency side. Theasymmetry in the low-frequency component is as-cribed to non-linearity in the trapping potential.

In our measurements we have observed theaxial resonances of order higher than 3ωz. Thesehigher order axial resonances have not been ob-served so far, for any traps geometries. The be-havior is modeled by including a cubic nonlinear-ity term in the equation for the oscillating elec-tron plasma in the trap. Possible period dou-

bling behavior as the excitation field strength isincreased, is being examined currently.

0 200 400 600 800

1.4

1.5

1.6

1.7

1.8

1.9

2.0

Sign

al H

eigh

t(a.

u.)

Frequency (MHz)

B= 309 G, Power= -20dBm, Pressure= 2*10-8

Ifil

= 1.4 A, Vbias

= -0.8 V, Voltage= 10 V

ωz

2ωz

ω

ωc

3ω−

4ωz

A)

B)

0 200 400 600 800

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

Sign

al H

eigh

t (a

.u.)

Frequency (MHz)

B= 309 G, Power= -10dBm, Pressure= 2*10-8

Ifil

= 1.5 A, Voltage= 10 V

ω−ωz

ωz

3ωz

4ωz

ωz

ω ω

c

Figure 1. Motional resonance spectrum of an elec-

tron cloud obtained for magnetic field 309 Gauss

and RF power is (A)-20dBm, (B) -10dBm for stor-

age voltage 10 Volts.

References

[1] Paasche. P et al. 2002 The European Physi-cal Journal D-Atomic, Molecular, Optical andPlasma Physics 18 295-300

[2] Tommaseo. G et al. 2004 The European Phys-ical Journal D-Atomic, Molecular, Optical andPlasma Physics. 28 39–48


ISAMP TC-7, 6−8 January, 2018, Tirupati CD004 Prakash

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A Novel Cooling Process Using Autoresonance in an Electrostatic Ion Beam Trap

R. K. Gangwar,1,* K. Saha,1 O. Heber,1,# M. L. Rappaport,2 and D. Zajfman1

1Department of particle Physics and Astrophysics, Weizmann Institute of Science, Rehovot, Israel 7610001 2Physics Core Facilities, Weizmann Institute of Science, Rehovot 7610001 Israel *Email: [email protected],[email protected]

Topic: D Trapping and manipulation of quantum systems

Control of kinematic as well as internal degrees of freedom of ions is a basic requisite in many branches of physics, such as spectroscopy, funda-mental quantum physics, quantum electrodynamics and quantum computation. It enables detailed ex-periments such as studies with merged beams where precise control of kinetic energies of the two beams permits fine-tuning of their relative velocities. Therefore many techniques to control the external and internal degrees of freedom of molecular ions have been proposed and implemented in various traps.

Recently, we demonstrate a simpler approach that can easily be implemented in any electrostatic storage device, i.e., a technique applicable to all trapped ions irrespective of their charge and mass. We have successfully reduced a relatively wide ini-tial longitudinal momentum distribution (Δp/p) of a bunch of ions oscillating inside an electrostatic ion beam trap (EIBT) by at least an order of magnitude to temperatures well below 1 K. This reduction was achieved by applying adiabatic autoresonance (AR) acceleration, which removes from the bunch the ions that are at the edges of the momentum distribu-tion, Δp, so that the distribution in the bunch nar-rows, albeit with fewer particles. At the same time, ion-ion interaction near the turning points in the mirrors enhances thermalization within the bunch. This scheme is similar to evaporative cooling that removes particles at the high end of the momentum distribution.

We have extended these techniques to explore whether ion-ion interactions can lead to control the ro-vibrational degrees of freedom of molecular ions. Our preliminary results are encouraging and further experiments are currently being conducted. Detailed results and explanation of the technique shall be presented.

References

[1] R. K. Gangwar, et al, Autoresonance cooling of ions inside an electrostatic ion beam trap, Phys. Rev. Lett., 119, 103202 (2017). *Email: [email protected] # E-mail: [email protected]

ISAMP TC-7, 6−8 January, 2018, Tirupati CD005 Gangwar

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Development of a 22-pole radio-frequency ion-trap experimentalset-up to study ion-atom and ion-photon collisions of astrophysical

interests

Roby Chacko∗ 1, P. C. Deshmukh†,# 2, & G. Aravind∗ 3



Topic: E. Development of major experimental facilities for AMO Physics and Laboratory Astrophysics

We are developing a major experimental facil-ity to trap ions using a 22-pole radio-frequencyion-trap [1, 2] at IIT Madras, with an aim todo laboratory astrophysics experiments. We aremainly interested in studying ion-atom collisionreactions and ion-photon collision reactions ininter-stellar medium(ISM) conditions, by simu-lating the ISM conditions in the laboratory. Thesetup can also be employed to address a vari-ety of problems in fundamental physics and in-terdisciplinary areas ranging from ion-atom colli-sions at low temperatures to the photoabsorptionby biomolecules such as the retinal chromophore,which is responsible for our colour vision.

Figure 1. Schematic of the experimental set-up

As depicted in the schematic diagram, thecomplete setup consists of a pulsed supersonicexpansion anion source, Quadrupole Mass spec-

trometer (QMS) for parent ions, 22-pole ion-trap,QMS for daughter ions and a detector. Thetrapped ions could also be cooled via buffer gascooling for effective trapping and for studyingcollisions at low temperatures.

The ion-trap is made out of OFHC copperwith Molybdenum rods as electrodes, with ut-most precision. We had developed our own radio-frequency power source, a synchronized control-ling and data acquisition cum analysis systemfor the QMS-detector combined system, a liq-uid nitrogen based coldhead which can cool thetrapped ions as low as 80K and quadrupole ion-benders for bending the ions by 900. We will bepresenting our initial results of trapping the ionsin the conference. Ion-atom collisions will be per-formed within the trap. We aim to study the for-mation of large ISM dusts beginning from smallpoly aromatic hydrocarbon (PAH) anions. Theformation of complex large PAHs and the stabil-ity of PAHs against collisions with photons andmatter under low temperature conditions is im-portant to understand the ISM dynamics [3, 4].The set-up will be employed to do temperaturedependent reaction rate studies, which would re-veal the reaction dynamics at various regions ofISM with temperature gradients.

References

[1] Gerlich D., 1995 Phys. Scr. T59, 256-263

[2] Wester R., 2009 J. Phys. B: At. Mol. Opt. Phys.42, 154001

[3] Gerlich D., Smith M., 2006 Phys. Scr. 73, C25

[4] Smith I. W. M., Rowe B. R., 2000 Acc. Chem. res33(5), 261-268


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Towards a search for Dark Matter candidates using atomic Dysprosium Arijit Sharma* 1, Mahapan Leyser*, Anna V. Viatkina*, Lykourgos Bougas*, Dmitry Budker*† 2

* Helmholtz-Institut Mainz (HIM), Johannes Gutenberg Universität, Mainz 55128, Germany † Institut für Physik, Johannes Gutenberg Universität, Mainz 55128, Germany

Topic: E.

Studies of rotation curves of galaxies, initiated by Oort & Zwicky (1930`s) and later by Rubin (1970`s) led to the Dark Matter (DM) hypothesis and the subsequent evidence for the existence of Dark Matter and Dark Energy. Search for the elu-sive dark matter candidates has been going on since the early 1970`s. Oddly the Standard Model (SM) with all its tremendous successes (most notably, in the recent past, being the discovery of the Higgs boson at the LHC, CERN) has so far failed to pro-vide an insight into the candidates that may directly or indirectly relate to Dark Matter or Dark Energy. Experimental efforts have also been initiated for searches of axions and WIMPs (Weakly Interacting Massive Particles), who are potential Dark Matter candidates, with the recent results on WIMPS pub-lished from the XENON1T [1] and PANDAX-II [2]. However, these experimental searches includ-ing the ones at the LHC, CERN have still not pro-duced any definitive outcome related to the origin and still yet elusive, Dark Matter particles. In our group, we are trying to search for possible Dark Matter (DM) candidates through precision atomic spectroscopy on dysprosium (Dy) atoms. Dysprosium (Dy) is an atomic system that has in the past been used for searching for possible varia-tions of fundamental constants [3] with the aim of constraining possible dark matter candidates and also exploited for the search of parity-violating effects mediated by cosmic fields that may be part of dark matter. This experiment was also used to-wards a search for ultralight dilatonic dark matter [4] (that was also used to improve constraints on possible quadratic interactions of scalar dark matter

by 15 orders of magnitude), and most recently, a search for possible exotic interactions sourced by massive bodies and mediated by light scalar bosons [5]. We are proposing to use the same system for per-forming precision ISS (Isotope Shifts Spectroscopy) measurements with sub-Hz precision, with the aim of searching for New Physics (NP) beyond the Standard Model (BSM) through possible non-linearities that may arise on a King Plot (KP). The idea is based on isotope shifts spectroscopy (ISS) and establishing a King Plot (KP) through frequen-cy measurements across multiple isotopes of dysprosium (Dy) in the RF (Radio Frequency) and the optical domain. In an ideal scenario, the King Plot (KP) is linear with mass and frequency ratio scaling measured for two different transitions across multiple isotopes. Non-linearities in the King Plot may arise from possible dark matter candidates that couple to the atomic nucleus and electrons through short range forces. I shall present our ex-perimental efforts that have been initiated towards this end with an emphasis on the current status and possible experimental outcomes.

References [1] E Aprile et al. 2017 Phys. Rev. Lett., 119, 181301 [2] Xiangyi Cui et al. 2017 Phys. Rev. Lett., 119, 181302 [3] N. Leefer et al. 2013 Phys. Rev. Lett. 111, 060801 [4] K. van Tilburg et al. 2015 Phys. Rev. Lett. 115, 011802 [5] N. Leefer et al. 2016 Phys. Rev. Lett. 117, 271601


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Development of nanoscale magnetometry using nitrogen-vacancy center in diamond

M. Ummal Momeen*1, and Jianping Hu†2

* Department of Physics, School of Advanced Sciences, VIT University, Vellore-632014, Tamil Nadu, India †Department of Chemistry, School of Advanced Sciences, VIT University, Vellore-632014, Tamil Nadu, India

Topic: F

Measurement of weak magnetic fields with high precision and spatial resolution is an in-teresting challenge for scientists. Among the solid state devices, the most sensitive magnetic sensors are based on Superconducting Quan-tum-Interference Devices (SQUID) [1]. How-ever, these devices are in need of cryogenic cooling and do not have the intrinsic absolute calibration of the field. Atomic vapor cell magnetometers [2] can be used for high sensi-tivity measurements at room temperature. An atomic magnetometer can have excellent sen-sitivity but it has only the millimeter range spa-tial resolution. A magnetic resonance force mi-croscopy (MRFM) [3] can perform with both high sensitivity and high spatial resolution for imaging any magnetic samples, but it needs cryogenic environment and in many cases the magnetic field of the magnetic tip (the detector of the MRFM) alters the magnetic characteris-tics of the sample to be measured. The finest magnetic field sensor should combine high sensitivity, nanoscale spatial resolution and wide operating temperature range (from am-bient room temperature to harsh cryogenic conditions). The study of nitrogen-vacancy (NV) center in diamond has gained lot of attention in recent years [4] because it has applications in nanoscale single spin magnetometry, nanoscale thermometry in a living cell and quantum in-formation processing. The NV center is a solid state defect in diamond, where a substitutional nitrogen impurity atom lies adjacent to a va-cancy in the diamond lattice. It has been dem-onstrated that the NV center in diamond is a suitable candidate for probing weak magnetic fields with high sensitivity and nanoscale spa-tial resolution even under ambient conditions. NV center is unique among the solid state sys-

tems because it can be spin polarized by opti-cal excitation even at room temperature, and the spin state of a single NV can be read out optically. In addition to the high sensitivity and nanoscale spatial resolution, the large dynamic range is also a challenging requirement for an excellent magnetic field measurement/imaging techniques. In this work we focus on the de-sign and construction of experimental setup for nitrogen-vacancy center in diamond research, which will be a platform for pursuing the re-search in the direction of nanoscale spatial resolution magnetometry for magnetic samples and also for the study of quantum information science. The schematic of our proposed expe-rimental arrangement is depicted in Figure 1.

Figure 1. Schematic diagram of NV center magnetometry setup.

References

[1] J. P. Cleuziou et al. 2006 Nat. Nano 1 53 [2] H. B. Dang et al. 2010 Appl. Phys. Lett 97 151110 [3] H. J. Mamin et al. 2007 Nat.Nano 2 301 [4] M. S. Grinolds et al. 2013 Nat.Phys 9 215

1 E-mail: [email protected]; 2 E-mail: [email protected]

ISAMP TC-7, 6−8 January, 2018, Tirupati CF001 Momeen

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Novel tunable near field broadband microwave antenna designs for nitrogen-vacancy center in diamond

Jianping Hu†1, and M Ummal Momeen*2

† Department of Chemistry, School of Advanced Sciences, VIT University, Vellore – 632014, Tamil Nadu, India * Department of Physics, School of Advanced Sciences, VIT University, Vellore – 632014, Tamil Nadu, India

Topic: F

Nitrogen-vacancy center (NV center) is an atomic defect in diamond. As a precision quan-tum sensor, it has broad applications in quantum information and quantum computation networks [1]. The electronic spin in a NV center can be manipulated by microwave and addressed using optical transitions [2]. To deliver microwave to the NV centers, thin copper wire, loop coil, double split-ring resonator and planar ring resonator were devel-oped [3-6]. However detailed considerations to all the aspects including microwave power effi-ciency, spatial homogeneity of microwave magnetic field, wide bandwidth, access to opti-cal path, simultaneous control mechanisms were not present together in these existing designs.

We demonstrate a novel microwave near field antenna specifically designed for manipu-lation of NV centers in diamond. It is tunable and the precise fabrication requirement is ab-ated. The working frequency is centered around 2.87 GHz with broad bandwidth. It ensures the detection of high dynamic range external mag-netic fields and waivers the need of tuning and matching of the antenna. It also imparts spatial homogeneity of microwave magnetic field with-in the diamond with the range of millimeter, easing wide spatial range magnetic-field imag-ing. It is power efficient and the power rating requirement of microwave power amplifier is ambient. These advantages facilitate the expe-riments on high dynamic range magnetic field sensing and imaging via NV centers.

Figure 1(a) shows the structure of this near field microwave antenna etched from PCB. The setup to deliver microwave to the diamond plate with NV centers is shown in Figure 1(b). Figure 1(c) illustrates the cross sectional structure of

this PCB based antenna. The copper trace con-tacting the diamond plate is masked with solder resist to avoid fluorescence from copper. The input impedance of this antenna is 50 Ω.

Figure 1. Novel tunable near field broadband mi-crowave antenna for NV center diamond.

References [1] L. Childress et al. 2013 MRS Bull 38 134 [2] F. Jelezko et al. 2006 Phys. Stat. Sol. (a) 203 3207 [3] L. Childress et al. 2006 Science 314 5797 [4] M. Chipaux et al. 2015 Eur. Phys. J. D 69 166 [5] K. Bayat et al. 2014 Nano Lett. 14 1208 [6] K. Sasaki et al. 2016 Rev. Sci. Instrum. 87 053904

1 E-mail: [email protected]; 2 E-mail: [email protected]

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Tirupati and the Host Institutes


b

About Tirupati

Tirupati, located within the hills of Eastern Ghats, is a heritage city of tremendous religious

importance. The place is considered one of the holiest Hindu pilgrimage sites because of Tirumala Sri

Venkateswara Temple, which is located on the

seventh peak of Tirumala Hill. It is one

amongst the eight most holy and worshipped

places of Lord Mahavishnu. Sri

Govindarajaswami Temple is also very

important shrine in Tirupati. Another famous

destination sought by pilgrims is Srikalahasti,

situated on the banks of Swarnamukhi River.

Apart from being scattered with ancient

temples and shrines, the nearby areas are famous for their beauty and serenity. Adjacent to the Sri

Venkateswara Temple are the massive 460 acre TTD Gardens having an impressive range of flowers.

Flowers from this garden are supplied to the religious places in and around Tirumala. Surrounded by

the Seshachalam Hills of the Eastern Ghats, the area is rich in flora and fauna. The hills also host the

highest waterfall ‘Talakona waterfall’ in the state, which is situated at about 50 km from Tirupati and

is regarded as the main entrance to the Tirumala Hills.

There are several natural creations like the Silathoranam

(rock garland), a natural arch, very close to Sri Venkateswra

temple in Tirumala hills. The arch measures 8 m in width

and 3 m in height. For wildlife lovers, Sri Venkateswara

national Park is definitely the place to visit. Sri

Venkateswara zoological park, museum, regional science

center are other major tourist attraction in Tirupati.

Tirupati is also one among hundred Indian cities to be

developed as a smart city under Smart Cities Mission by

Government of India. Tirupati is also home to many

educational institutions and universities. Apart from IISER,

the place hosts IIT, Sri Venkateswara University and many

engineering colleges as well.

Along with the religious and scenic reasons, shopping

experience in Tirupati is also something that you would

want to indulge in. The place is famous for unique

handicrafts such as woodcarvings and traditional Tanjore

style Gold Leaf paintings, famous for their mythological motifs and themes. The place also offers a

flattering number of choices for food with Tamil, Andhra and Hyderabadi cuisines.

Telugu is the official and widely spoken language. Tamil, Kannada and Hindi are the other languages

spoken due to the large number of visiting pilgrims. Tirupati deals with extreme summers, however

during monsoon season and winters, pleasant weather makes the ambiance pristine.

Sri Venkateswara Temple

Natural Arch

Talakona Waterfall


c

To reach Tirupati, frequent flights are accessible from major cities. Tirupati airport is nestled in the

region of Renigunta and the adjacent International airport is Chennai from which the place has a good

connectivity with different corners of the country and abroad. The main railhead of the place is Tirupati

Railway Station that is linked with major cities.

About IISER Tirupati

The strategic plan to set up Indian Institutes of Science Education and Research was the outcome of a

recommendation of the Scientific Advisory Committee to the Prime Minister of India. It suggested the

establishment of Institutes for teaching basic sciences with state of the art research facilities, which

would motivate faculties to attract meritorious students to have their careers in basic sciences. Five

IISERs were established under the umbrella of MHRD during the period 2006-08 at Kolkata, Pune,

Mohali, Bhopal and Thiruvananthapuram. Today, the IISERs have established themselves as leadership

institutions for basic sciences and declared by the Act of Parliament as the institutions of national

importance, nurturing advanced education and frontier research.

IISER Tirupati is the sixth Institute under the chain of IISERs, established by the Govt. of India under

the ministry of HRD as an Institute of National Importance. The foundation stone for the Institute was

laid by the then HRD Minister, Smt. Smriti Zubin Irani, on March 28, 2015 at the 250 acre land in

Yerpedu village on Tirupati -Venkatagiri highway, earmarked for the establishment of the permanent

campus. The campus currently operates from a transit site at Sree Rama Engineering College. IISER

Pune was designated as the mentor institute and its Director, Prof. K N Ganesh was appointed as the

mentor Director for IISER Tirupati (who is currently the Founder Director of the institute). The

academic program of the institute started in August, 2015 with the admission of 50 students as the

first batch of its BS-MS program. The PhD program at IISER Tirupati was initiated in August 2017.

Currently the institute has over 250 BS-MS and PhD students. In addition to imparting rigorous

undergraduate education, the faculty at the institute pursue state-of-the-art research in several

contemporary areas including Neuroscience, Plant biology, Ecology and evolution, Cancer biology &

Immunology, Infectious disease, Organic & Biochemistry, Inorganic & Materials Chemistry, Theoretical,

Analytical & Physical Chemistry, Earth and Climate Sciences, Microfluidics, Astronomy & Astrophysics,

Condensed Matter Theory, Particle Physics, Atomic and Molecular Physics, String Theory, Topology,

Harmonic Analysis, Number Theory, Differential Geometry, and Non-Linear Dynamics among other

interdisciplinary areas.

IISER Tirupati transit campus


d

About IIT Tirupati

The Indian Institutes of Technology (IITs) are highly prestigious autonomous public institutions for

higher education and research in technology and basic sciences in India. They are governed by the

Institutes of Technology Act, 1961, Government of India, which declares them as the Institutes of

National Importance. IIT Tirupati was started in March, 2015 along with five other 3rd generation IITs

at Palakkad, Jammu, Bhilai, Goa, and Dharwad increasing the count of IITs to 23 spread across the

country. Presently, it is operating from a temporary campus on the Tirupati–Renigunta road, and plans

are well under way to set up its own campus in the next 3 or 4 years at a site (about 530 acres in extent)

at Merlapaka Village, Yerpedu Mandal, Chittoor District, Andhra Pradesh (14 km from the Tirupati

airport). The transit campus is fast coming up at the permanent campus site and would be operational

by the next academic year (2018). The Institute started functioning with the support of its mentoring

Institute, IIT Madras, from the academic year 2015–16 and growing very rapidly under the leadership

of Prof K. N. Satyanarayana, the founder director. The academic programme was launched in August

2015 with 120 students to the B. Tech programme in four disciplines of Engineering. The MS (Research)

and PhD programs for January 2018 semester were initiated. At present, the institute has

approximately 400 students in various undergraduates and post graduates disciplines and more than

40 regular faculty members. IIT Tirupati is expected to be a 12,000-student campus in the coming

decades. It is expected that within a few years the Institute would be able to put in place excellent

infrastructures required to house a strong student community and corresponding world class faculty,

state-of-the-art laboratories etc. Apart from the teaching activities, IIT Tirupati has been

enthusiastically involved in frontline research in both basic science and technology. Some of the thrust

research areas of the institute are smart infra-structure, education technology, energy and

environment, materials and nano science.

IIT Tirupati transit campus


e

Map of Tirupati with important contacts


f

Map of Tirupati II