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8th Topical conference (TC-2020)
on Atomic and Molecular
Collisions for Plasma Applications
ABSTRACT BOOK
Organized By
Department of Physics,
Indian Institute of Technology Roorkee,
Roorkee-247667, Uttarakhand, INDIA
SPONSORS
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
Advisory Committee A. K. Chaturvedi (IIT Roorkee)
A. K. Das (DST New Delhi)
Bhas Bapat (IISER Pune)
B. N. Jagatap (IIT Bombay)
B. N. Rajasekhar (AMPD BARC)
C. P. Safvan (IUAC New Delhi)
G. Ravindra Kumar (TIFR Mumbai)
Hema Ramachandran (RRI Bangalore)
K. L. Yadav (IIT Roorkee)
Lokesh Tribedi (TIFR Mumbai)
Manmohan (University of Delhi)
N. Sathyamurthy (IISER Mohali)
P. C. Deshmukh (IIT Tirupati)
R. Shankar (BHU Varanasi)
Shashank Chaturvedi (IPR Gandhinagar)
Tauheed Ahmad (AMU Aligarh)
Conveners Lalita Sharma, Assistant Professor
Rajesh Srivastava, Professor
Department of Physics, IIT Roorkee
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
About the Conference The 8th Topical Conference of the Indian Society of Atomic and Molecular
Physics(ISAMP) is the latest in the series of the 3-day biennial national
conferences. The present meeting will be held at the Indian Institute of
Technology (IIT) Roorkee, Roorkee from 3rd to 5th March, 2020. The theme of
the conference is ‘Atomic and Molecular Collisions for Plasma Applications'.
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PLENARY TALKS
1. Plasma chemistry for modelling plasmas under extreme conditions
Shashank Chaturvedi
PL-01
2. Physics of plasmas confined by a dipole magnet
Sudeep Bhattacharjee
PL-02
3. Some of the applications of laser induced plasma of solid and solid liquid
interface
Alika Khare
PL-03
INVITED TALKS
4. First results from the IISER Pune EBIS
Bhas Bapat, Sumit Srivastav and Deepak Sharma
IT-01
5. Analytical response relativistic atomic many-body method
B. K. Sahoo
IT-02
6. Modelling of atomic polarizability for dispersion interactions
Bindiya Arora
IT-03
7. Fock-space relativistic coupled-cluster calculation of two-valence atoms
and ions
Brajesh Kumar Mani and Dilip Angom
IT-04
8. Electronically excited states of molecules: experimental and theoretical
perspectives
Aparna Shastri
IT-05
9. Dissociative electron attachment to isolated molecules and clusters
Dhananjay Nandi
IT-06
10. Diagnosis of Tokamak plasma using passive spectroscopy
Joydeep Ghosh
IT-07
11. Photoionization studies of argon inside charged fullerene
Afsal Thuppilakkadan, Jobin Jose and Hari R. Varma
IT-08
12. Shannon’s entropy in endohedrally confined atoms: Indicator of avoided
crossing and correlation energy
Jobin Jose
IT-09
13. Laser cooling and trapping of Rb at narrow blue transition
Dangka Shylla, Elijah Ogaro Nyakang'o, Rajnandan Choudhury Das and
Kanhaiya Pandey
IT-10
14. Precision quantum measurements using optical clock
Subhadeep De
IT-11
15. Spectroscopic constants and thermochemistry of some ozone depleting
systems
T. K. Ghosh
IT-12
16. Electron impact low energy studies for Di-triatomic targets
M. Vinodkumar
IT-13
17. Application of plasma produced nanostructures in surface wettability and
sensing
M. Ranjan, V. Pachichigar, Sooraj KP and S. Augustine
IT-14
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
18. Study of nonlinear waves in multicomponent space plasmas
N. S. Saini
IT-15
19. Strong field ionization with ultrashort orbital angular momentum beams
R. Gopal, A. Sen, A. Sinha and V. Sharma
IT-16
20. Diagnostic of Non-Thermal Atmospheric Pressure Plasma Jet Through
Emission and Absorption Spectroscopy
R. K. Gangwar, P S Srikar and S M Bakshi
IT-17
21. Multidiagnostic characterization of ultrashort and short pulse laser
produced plasmas
Pranitha Sankar and Reji Philip
IT-18
22. Neutrino-plasma interactions in gravitating degenerate astrophysical
plasmas
R. P. Prajapati
IT-19
23. Gas-phase formation of ammonia in the diffuse interstellar medium
calculation of the rate coefficients of the key steps
Sunil Kumar S, Salvi M and Raghunath O. Ramabhadran
IT-20
24. Atom-optic kicked rotor: From quantum chaos to atom interferometry
Umakant Rapol
IT-21
25. Photodissociation and dissociative electron attachment: similarities and
differences
V. S. Prabhudesai
IT-22
26. Foam structure of dopants in helium nanodroplets? Some evidences in
photoionization of acetylene doped helium droplets
Suddhasattwa Mandal, Ram Gopal, M. Shcherbinin, Robert Richter, H.
Srinivas, Marcello Coreno, Alessandra Ciavardini, A D’Elia, B Bapat, M
Mudrich, S. R. Krishnan and V. Sharma
IT-23
27. Accurate calculation of weak intermolecular interaction energy
Narendra Nath Dutta
IT-24
28. Electron induced ionization cross sections of atoms, ions and molecules
relevant to plasma applications
Ghanshyam Purohit and Daiji Kato
IT-25
POSTERS
29. Gravitational instability of partially-ionized plasma with hall current FLR
corrections flowing through porous medium
Sachin Kaothekar and R. K. Chhajlani
PP-01
30. Ionization cross sections of water molecules impacted by dressed ions
D. Jana, A. Mondal and M. Purkait
PP-02
31. Atomic-size Fraunhofer-type diffraction for electron capture in ion-atom
collision
S. Samaddar, K. Purkait and M. Purkait
PP-03
32. VUV spectroscopy of ethyl methyl carbonate
A. K. Das, S. Krishnakumar and B. N. Rajasekhar
PP-04
33. Electron impact excitation of singly charged In and Sn ions
Swati Bharti, Lalita Sharma and Rajesh Srivastava
PP-05
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
34. Structural, vibrational and electronic spectroscopic study of 7-(4-
trifluoromethyl) coumarin acrylamide using experimental and theoretical
methods
D. Vijay, Asim Kumar Das, B.N.Rajasekhar and A.Veeraiah
PP-06
35. Behavior of impurities in radiative improved mode plasmas of ADITYA-U
Tokamak
M. B. Chowdhuri, J. Ghosh, R. Manchanda, R. L. Tanna, K. A. Jadeja, N.
Yadava, N. Ramaiya, S. Patel, G. Shukla , K. Shah, K. M. Patel, Tanmay
Makwan , U. C. Nagora, S. K. Pathak, J. V. Raval, M. K. Gupta, M. V.
Gopalakrishna, K. Tahiliani, Rohit Kumar, Suman Aich, B. V. Nair, C. N.
Gupta and ADITYA-U Team
PP-07
36. Radial profile of visible continuum emission from ADITYA-U tokamak
plasmas
R. Manchanda, M. B. Chowdhuri, J, Ghosh, N. Yadava, N. Ramaiya, S. Patel,
U. C. Nagora, S. K. Pathak, J. V. Raval, M. K. Gupta, K. A. Jadeja, R. L. Tanna,
C. N. Gupta and ADITYA-U Team
PP-08
37. Calculations of total electron impact ionisation cross sections for
Fluoroketone and Fluoronitrile
Nirav Thakkar, Mohit Swadia, Minaxi Vinodukmar and Chetan Limbachiya
PP-09
38. Ab initio study of structure, spectroscopic constants and thermal properties
of an ozone depleting reaction
Gargi Nandi and T. K Ghosh
PP-10
39. Dissociation dynamics of multiply charged CO2 under impact of slow and
highly charged ions
S. Srivastav, D. Sharma and B. Bapat
PP-11
40. Electron Beam Ion Trap/Source for ion–molecule collisions in the non-
perturbative regime
B. Bapat, D. Sharma and S. Srivastav
PP-12
41. Orientation effect in multiple ionisation of OCS under proton and C2+
impact at 50 keV
D. Sharma, B. Bapat, P. Bhatt and C. P. Safvan
PP-13
42. Electron interaction with Para-Benzoquinone(C6H4O2) and
Naphthoquinone(C10H6O2)
Dhaval Chauhan and Chetan Limbachiya
PP-14
43. Electron impact elastic scattering cross section from acetylene
Dibyendu Mahato, Lalita Sharma and Rajesh Srivastava
PP-15
44. Electron impact excitation cross section of magnesium for plasma
application
S S Baghel, S Gupta, R K Gangwar and R Srivastava
PP-16
45. Study of the nature of impurity transport coefficients using separate atomic
databases in the ADITYA tokamak
A. Bhattacharya, J. Ghosh, M. B. Chowdhuri, P. Munshi and the ADITYA team
PP-17
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
46. C-R model for Ar-CO2 mixture plasma using reliable fine structure cross
sections
Neelam Shukla, Reetesh Gangwar and Rajesh Srivastava
PP-18
47. Modeling the tunneling reaction NH2+ + H2 → NH3
+ + H at interstellar
temperature by variational transition state theory
M. Salvi, Raghunath O. Ramabhadran and S. Sunil Kumar
PP-19
48. Electron Scattering from HCNO
Paresh Modak, Nafees Uddin and Bobby Antony
PP-20
49. Pulse width effect on the ionization and dissociation of Methyl Iodide in the
intense femtosecond laser field
Arnab Sen, Bhas Bapat, Ram Gopal and Vandana Sharma
PP-21
50. Double slit projectile wave interference at slow and intermediate electron
transfer collisions
Md A. K. Azad Siddiki, Nrisimhamurty Madugula, M.A. Rehman, M.R. Chowdhury,
L.C. Tribedi and Deepankar Misra
PP-22
51. Mercury hydroxide as a promising triatomic molecule to probe P, T-odd
interactions
R. Mitra, V. S. Prasannaa and B. K. Sahoo, X. Tong, M. Abe and B. P. Das
PP-23
52. Electron interaction with Fluorocompounds for application in plasma
sciences
Smruti Parikh and Chetan Limbachiya
PP-24
53. A comparative analysis of non-relativistic and relativistic calculations of
electric dipole moments and polarizabilities of heteronuclear alkali dimers
R. Mitra, V. S. Prasannaa and B. K. Sahoo
PP-25
54. Characterizing Laguerre-Gaussian pulses using angle-resolved attosecond
streaking
Irfana N. Ansari, Deependra S. Jadoun and Gopal Dixit
PP-26
55. Theoretical investigation of various inelastic processes of e-CO2 scattering
S. Vadhel, M. Vinodkumar and P. C. Vinodkumar
PP-27
56. Relativistic coupled-cluster calculations of electric dipole polarizability of
Al and In
Ravi Kumar and B. K. Mani
PP-28
57. Ion-pair dissociation dynamics in electron collision with carbon dioxide
probed by velocity slice imaging
Narayan Kundu, Anirban Paul and Dhananjay Nandi
PP-29
58. Differential cross section for positron-biomolecules interaction
Nidhi Sinha and Bobby Antony
PP-30
59. Quantum coherence in dissociative electron attachment: isotope effect
S. Swain, E. Krishnakumar and V. S. Prabhudesai
PP-31
60. Angular distribution of H - from dissociative electron attachment to H 2 at
10eV
S. Swain, E. Krishnakumar and V. S. Prabhudesai
PP-32
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
61. Electron ionization cross sections of C2H4 molecule
Pawan Kumar Sharma and Rajeev Kumar
PP-33
62. Laser cooling and trapping of neutral 87Rb atoms
Raj Kumar, Neeraj Singh, Anju Pal, Navpreet Kaur and Ajay Wasan
PP-34
63. Angle dependence of WES photoionization time delay from atoms trapped
in a negatively charged cage
S. Banerjee and P. C. Deshmukh
PP-35
64. Theoretical investigation on electron impact with halogen diatomic
molecule X2 (X = F, Cl, Br, I)
Hitesh Yadav, Minaxi Vinodkumar, Chetan Limbachiya and P. C. Vinodkumar
PP-36
65. Dissociative electron attachment dynamics to nitrogen dioxide
Anirban Paul, Dipayan Biswas and Dhananjay Nandi
PP-37
66. Initial results from the 22-pole ion trap experimental set-up
Roby Chacko, N. R. Behera, S. Dutta and G. Aravind
PP-38
67. Study of reaction kinetics of O + XO → X + O2
S. Naskar and T. K. Ghosh
PP-39
68. Spectroscopic properties of divalent lead halides
S. Ghosh and T. K. Ghosh
PP-40
69. Camphor doped helium nano-droplets in soft X-Ray radiation
S. Sen, S. Mandal, R. Gopal, R. Richter, M. Mudrich, V. Sharma and S.
Krishnan
PP-41
70. Significance of dynamic quadrupole polarizabilities on the determination
of magic wavelengths of the clock transitions in the alkaline-earth metal
ions
Mandeep Kaur, Sumeet, B K Sahoo and Bindiya Arora
PP-42
71. Electron impact ionization cross section of atoms and molecules using
binary-encounter-Bethe model
Piyush Sinha and Shivani Gupta
PP-43
72. Photoelectron velocity map imaging spectroscopy facility for probing
astrophysical anions
Saroj Barik and G. Aravind
PP-44
73. Probing molecular chirality by laser-driven electronic fluxes
Sucharita Giri and Alexandra Maxi Dudzinski
PP-45
74. Penning spectroscopy of ionic molecular cluster in he nanodroplets
Suddhasattwa Mandal, Ram Gopal, Robert Richter, Marcello Coreno,
Alessandra Ciavardini, Alessandro D’Elia, Bhas Bapat, Marcel Mudrich,
Vandana Sharma and Sivarama Krishnan
PP-46
75. Electron interactions with plasma processing gases
Rakesh Bhavsar, Yogesh Thakar and Chetan Limbachiya
PP-47
76. Design of Penning trap setup for lifetime studies of metastable states in
atomic ions.
Deepak Chhimwal, S. Kumar, L. Nair, W. Quint, C.P. Safvan and M. Vogel
PP-48
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
77. Electron and positron impact ionization cross sections of nitrogen
molecules
Kamlesh Kumar Jat and Ghanshyam Purohit
PP-49
78. Electron induced processes on plasma relevant materials, Be and W atoms
Kailash Chandra Dhakar and Ghanshyam Purohit
PP-50
79. Exploring quasi molecular phenomenon using heavy ion heavy atom
collisions
R. Gupta, C. V. Ahmad, K. Chakraborty, D. Swami, G. Sharma and P. Verma
PP-51
80. Detailed collisional radiative model for laser produced Zn plasma
Shivam Gupta, Reetesh Kumar Gangear and Rajesh Srivastava
PP-52
81. Saturated absorption spectroscopy of molecular iodine for frequency
stabilization of 739 nm laser
Lakhi Sharma, A. Roy, S. Panja and S. De
PP-53
82. Strong field ionization from atoms and nano-tips in structured beams
Abhisek Sinha, Debobrata Rajak, Sanket Sen, Ram Gopal and Vandana Sharma
PP-54
83. Iron impurity behavior in the ADITYA tokamak
S. Patel, A.K. Srivastava, M. B. Chowdhuri, R. Manchanda, A. Bhattacharya,
J. V. Raval, U. Nagora, P. K. Atrey, R. L. Tanna, J. Ghosh and ADITYA Team
PP-55
84. Partial wave analysis of electron scattering from argon atoms
David Joseph and Naveen Chahal
PP-56
85. High harmonic generation in bichromatic inhomogeneous pulses
Ankur Mandal and Pranawa C. Deshmukh
PP-57
86. Electron-impact cross sections of isovalent AlCl & AlF molecules from
0.1~eV to 5~keV
S. Kaur, A. Bharadvaja and K. L. Baluja
PP-58
87. Positron impact ionization cross sections from pentane isomers
Vardaan Sahgal, A. Bharadvaja, S. Kaur and K. L. Baluja
PP-59
88. New ultrafast laser and instrumentation facility at PRL Ahmedabad for
femtosecond and attosecond science
R. K. Kushawaha, Madhusudhan P, Rituparna Das, Pranav Bhardwaj,
Swetapuspa Soumyashree, Pooja Chandravanshi and Nimma Vinitha
PP-60
89. Edge temperature and density measurements in ADITYA-U Tokamak with
helium spectral line intensity ratio
Tanmay Macwan, Sharvil Patel, Nandini Yadava, Ritu Dey, Kaushlender Singh,
Suman Dolui, Rohit Kumar, Suman Aich, Malay B Choudhary, Ranjana
Manchanda, R. L. Tanna, K. A. Jadeja and K. M. Patel and J. Ghosh
PP-61
90. Neutral and impurity influx measurement from limiter and wall of Aditya-
U Tokamak
Nandini Yadava, J. Ghosh, M. B. Chowdhuri, R. Manchanda, Sripathi
Punchithaya K, Ismyil, N. Ramaiya, Ritu Dey, Tanmay Macwan, S. Patel, R. L.
Tanna and Aditya-U team
PP-62
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
91. Diffraction of proton beams by an optical crystal: Kapitza-Dirac effect for
plasma ions with spin
Sushanta Barman and Sudeep Bhattacharjee
PP-63
92. Electron impact excitation of highly charged iso-electronic series of Ge like
Ba, Te, Sn, Cd ions
P. Malker and L. Sharma
PP-64
93. Dynamics of dissociative electron attachment to ethanol
S. Das, S. Swain and V. S. Prabhudesai
PP-65
94. Effect of background static gas on momentum images in velocity slice
imaging of dissociative electron attachment
S. Das, S. Swain and V. S. Prabhudesai
PP-66
95. Theoretical investigation of the electronic structure of HgH+
R. Bala, H. S. Nataraj, M. Kajita and M. Abe
PP-67
96. Analysis of the visible transitions in tungsten (WIX and WX) observed with
electron beam ion trap
Priti, Daiji Kato, Izumi Murakami, Hiroyuki A. Sakaue and Nobuyuki
Nakamura
PP-68
97. Plasma screening effect on excitation energies and transition data of P-like
Zn
Arun Goyal, Sunny Aggarwal, Narendra Singh and Man Mohan
PP-69
98. Strongly coupled plasma effect on excitation energies and transition data of
Ca VI
Sunny Aggarwal, Arun Goyal and Man Mohan
PP-70
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PL-01
Plasma chemistry for modelling plasmas under extreme conditions
Shashank Chaturvedi
Institute for Plasma Research, Gandhinagar
Plasmas cover an enormous range in terms of density and temperature. The elemental
composition can also vary depending upon the material from which plasma is produced. As a
result, there can be large variation in the population distribution of different atomic, molecular
and ionic species, not to mention excited states. This implies a correspondingly large variation
in physical & chemical properties, which is why plasmas find a variety of uses ranging from
Nuclear Fusion at one extreme to applications in industrial tools, medical/health sector, textile
sector, waste disposal, aerospace and so on. The computational modelling of each of these
systems must take into account not just the physics but also the chemistry involving all possible
species. In this talk, we will use two examples to highlight the computational complexities
involved in modelling plasmas. The first is industrial plasma systems, and the second is warm
or hot dense plasmas produced under shock-loading conditions.
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PL-02
Physics of plasmas confined by a dipole magnet
Sudeep Bhattacharjee*
Department of Physics, Indian Institute of Technology Kanpur - 208016
Brief overview: The talk will cover the properties of a plasma confined by a dipole magnetic
field. Unlike other confinement schemes, here the plasma is confined by a unique balance
between the plasma pressure and the magnetic pressure, and resembles that of the
magnetospheric plasma surrounding our earth. We have developed such an experiment in our
laboratory. The talk will discuss about processes such as diffusion, recombination and
ionization in the plasma and their scaling with the magnetic field, including resulting density
and temperature profiles. Additionally, the talk will try to cover the setting up of the steady
state density profiles as a result of diffusion induced transport. Please find references of two
recent articles on this topic below.
References [1] Anuj Ram Baitha, Ashwani Kumar, and Sudeep Bhattacharjee, Review of Scientific Instruments 89, 023503
(2018)
[2] Anuj Ram Baitha, Ayesha Nanda, Sargam Hunjan and Sudeep Bhattacharjee Plasma Res. Express 1, 045005
(2019)
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PL-03
Some of the applications of laser induced plasma of
solid and solid liquid interface
Alika Khare
Department of Physics, Indian Institute of Technology Guwahati, Guwahati 781039, India
E-mail: [email protected]
Laser induced plasma (LIP) is finding its application in a very broad perspective. It is being
used extensively in material processing with a high degree of precision. It has qualified as a
source of coherent X –Rays and higher harmonics generation as well as a source of highly
energetic electrons/ions and neutral beams. Whenever a high power laser is focused on a
medium, it results into the formation of its high density high temperature transient plasma.
When the laser is focused on the solid target, the material from the targets with in the focal
region is ablated out along with the formation of the plasma. The plasma emits its
characteristics emission which forms the basis of Laser induced breakdown spectroscopy
(LIBS), an upcoming powerful tool to identify the chemical composition of any system in any
format. LIP of solid comes out with solid density and expands in the surrounding medium. In
case surrounding medium is vacuum or a low pressure gas, then expansion is very huge and if
a substrate is placed in front of this, the constitute ions and atoms can be deposited on it
rendering the formation of thin film. This technique of deposition is termed as pulsed laser
deposition (PLD). Pulsed Laser Deposition (PLD) technique has been observed to be very
successful for the synthesis of variety of thin films with very high precision in a simple and
single step manner which could be complicated via other techniques. In the recent years, pulsed
laser ablation in liquid (PLAL) has paved a new way of synthesizing the nano particles (NP)
of any material. This technique is also single step, simple, devoid of any hazardous chemicals,
free from contamination and very versatile. The characteristics of NP can be easily tuned by
controlling the laser parameters and the surrounding liquid. The confinement of laser produced
plasma by the surrounding liquid causes highly transient extreme pressure and temperature
which prefers the growth of metastable phases which are normally not possible via other
routine chemical roots. In the present talk, some of the above applications of Laser induced
plasma shall be highlighted.
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
IT-01
First results from the IISER Pune EBIS
Bhas Bapat *, Sumit Srivastav and Deepak Sharma
Indian Institute of Science Education and Research, Homi Bhabha Road, Pune 411008
Collisions between ions and molecules is a process that has been studied for long. Typically,
small projectile charge q and high velocities v are considered to fall in the domain of
perturbative collisions (i.e. when q/v < 1), while for high projectile charge and low velocities
the collisions are considered to fall in non-perturbative domain. In the latter case one may
approach a regime where the projectile velocity matches the average speeds of electrons in
different shells and interesting ionization patterns may emerge. In particular, charge exchange
may dominate over direct ionization, and specific ionization states may be enhanced.
In order to perform experiments in the latter category, it is necessary to generate ions in
different highly charge states with an ability to tune their energies. An electron beam ion
source/trap employing a combination of static magnetic and electric fields is a suitable source
for such studies. It is able to generate slow and highly charged ions with very narrow spread
of energies and offers high selectivity of charge state by minor tuning of parameters. Such an
ion source has recently been installed at IISER Pune. It is manufactured by DREEBIT GmbH,
Germany, and is capable of providing charge states of Argon in the range 1–16+ and virtually
any other element in a comparable range of charge states, so long as the element is available
as gaseous or liquid compound. The energy of the ions can be varied over 5–30 keV/q.
The ion source is fully operational, and coupled to an ion momentum spectrometer for
performing molecular fragmentation studies. A post-collision projectile analyser is being
added. The ion source facility will be made open to external users by the end of the year.
Preliminary results on multiple ionization of CO2 will be presented in the talk.
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
IT-02
Analytical response relativistic atomic many-body method
B. K. Sahoo
Atomic, Molecular and Optical Physics Division, Physical Research Laboratory, Navrangpura,
Ahmedabad 380009, India
Email: [email protected]
To yield accurate results for atomic properties, it is imperative to employ potential atomic
many-body methods that account for both electron correlation and relativistic effects
rigorously. The coupled-cluster (CC) theory is considered as the gold standard for treating
electron-correlation effects [1], so relativistic version CC (RCC) method can serve for the
above purpose. However, the currently used RCC methods for atomic calculations have many
drawbacks as they can generate uncontrolled theoretical uncertainties. For example, the
commonly used expectation-value-evaluation (EVE) approach in the RCC theory involves
non-terminating series and does not satisfies the Hellmann-Feynman theorem, whereas the
finite-field (FF) approach in the RCC theory depends on the choice of a perturbation parameter.
To overcome these problems, we have implemented recently an analytic-response approach
within the RCC (AR-RCC) theory framework. In my talk, I shall discuss about the general
features of the AR-RCC theory and demonstrate its first applications to the precise
determination of local Lorentz invariance violating parameters [2] and isotope shift constants
[3].
Reference [1] I. Shavitt, R. J. Bartlett, Many-body Methods in Chemistry and Physics, Cambridge University Press,
Cambridge, UK (2009).
[3] B. K. Sahoo, Phys. Rev. A (Rapid Communication) 99, 050501 (2019).
[2] B. K. Sahoo et al, New J. Phys. (Fast Track Communication) 22, 012001 (2020).
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
IT-03
Modelling of atomic polarizability for dispersion interactions
Bindiya Arora
Department of Physics, Guru Nanak Dev University, Amritsar, Punjab
E-mail: [email protected]
The dispersion interactions are fundamental for studying the structure, stability and various
properties of atomic and molecular systems. Assessing these interactions accurately can result
in new pathways towards engineering, technology and research. In this presentation I will talk
about the role of atomic polarizability for accurate evaluation of dispersion interaction. The
dispersion C6 coefficients for interatomic interactions and C3 coefficients for the interaction
of various atomic systems with different wall surfaces such as a perfect conductor, metal,
semiconductor, dielectric surfaces and carbon nano structures will be discussed. The
significance of the interactions between atoms and atomically thin films of the multi-layered
transition metal molybdenum disulfide (MoS2) dichalcogenides for their applications in
optoelectronics, sensors and storage devices will be highlighted.
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
IT-04
Fock-space relativistic coupled-cluster calculation of
two-valence atoms and ions
Brajesh Kumar Mani1,* and Dilip Angom2
1Department of Physics, Indian Institute of Technology, Hauz Khas, New Delhi 110016,
India 2Physical Research Laboratory, Ahmedabad - 380009, Gujarat, India
Relativistic coupled-cluster is one of the most reliable many-body methods to accurately
calculate the many-electron wave functions and properties of atoms and ions [1, 2, 3]. Despite
its great potential to predict atomic properties within the accuracy commensurate with atomic
experiments or even better, its application is mostly limited to the closed-shell and one-valence
atomic systems. One of the reasons for this could be attributed to the complications associated
with its implementation for multireference systems. We have developed an all particle Fock-
space relativistic coupled-cluster (FSRCC) based method for the properties calculation of two-
valence atoms and ions [4, 5]. Using this method, we have calculated the atomic properties
which are relevant to optical atomic clock in the case of Al+ ion [5]. In this talk, I shall discuss
about the FSRCC method we have developed and also share some results in the context of Al+
atomic clock.
References [1] H. S. Nataraj, B. K. Sahoo, B. P. Das, and D. Mukherjee, Phys. Rev. Lett. 101, 033002 (2008).
[2] R. Pal, M. S. Safronova, W. R. Johnson, A. Derevianko, and S. G. Porsev, Phys. Rev. A 75, 042515
(2007).
[3] B. K. Mani, Siddhartha Chattopadhyay, D. Angom, Comp. Phys. Commu. 213, 136 (2017).
[4] B. K. Mani and D. Angom, Phys. Rev. A 83, 012501 (2011).
[5] Ravi Kumar, S. Chattopadhyay, B. K. Mani and D. Angom, (To be published)
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
IT-05
Electronically excited states of molecules: experimental and theoretical
perspectives
Aparna Shastri*
Atomic & Molecular Physics Division, Bhabha Atomic Research Centre, Mumbai-400085
Electronically excited states of molecules play an important role in chemical reactions
occurring in the earth’s atmosphere, laboratory plasmas, astrophysical objects, etc. A thorough
understanding of the electronic structure and spectrum of a molecule is a prerequisite to
unravelling its behaviour in complex reactions induced by highly energetic photons/other
particles. A direct method to obtain information about electronically excited states of a
molecule is through its photoabsorption spectrum and since excited states typically lie in the
ultraviolet-vacuum ultraviolet (UV-VUV) region, synchrotron radiation (SR) is an ideal source
for such studies.
Our group has an ongoing program for VUV spectroscopy of molecules using SR at the 450
MeV storage ring Indus-1, RRCAT, Indore. Over the past few years, using the two indigenously
developed beamlines (Photophysics and HRVUV) at Indus-1[1-3], high quality VUV spectral
data has been generated for several molecules, which have been included in reputed
international molecular databases [4,5].
On the theoretical side, analysis and interpretation of molecular electronic spectra is quite
challenging because of the number of degrees of freedom involved and various interactions
between them. Generally, satisfactory explanation of the observed spectral features require
extensive quantum chemical calculations which are used to predict properties like excited state
energies, their valence/Rydberg/intermediate nature, geometry changes and vibrational modes
in excited states, behaviour of excited state potential energy curves, etc. In this talk, I shall
present an overview of both experimental and theoretical aspects of the VUV spectroscopic
studies being pursued in our group. A few recent studies [6-8] will be highlighted.
References [1] A. Kalinin, D. A. Banerji, P. R. Hannurkar, M. G. Karmarkar, S. Kotaiah, S. P. Mhaskar, P. K. Nema, S. S.
Prabhu, M. P. Kumar, S. Ramamurthi, Curr Sci 82, 283 (2002).
[2] N. C. Das, B. N. Rajasekhar, S. Padmanabhan, A. Shastri, S. N. Jha, S. S. Bhattacharya, S. Bhat, A. K. Sinha,
V. C. Saini, J Opt 32, 169 (2003).
[3] Param Jeet Singh, A. Shastri, R. Sampath Kumar, S.N. Jha, S.V.N.B. Rao, R. D’Souza and B.N. Jagatap,
Nucl. Instrum Methods Phys Res A 634, 113 (2011).
[4] UV/Vis+ Photochemistry database (https://science-softcon.de/spectra)
[5]The MPI-Mainz UV/VIS Spectral Atlas of Gaseous Molecules of Atmospheric Interest
(http://satellite.mpic.de/spectral_atlas/index.html)
[6] A. Shastri, Param Jeet Singh, K. Sunanda, Asim Kumar Das and B.N. Raja Sekhar, Phys Chem Chem Phys
19, 6454 (2017).
[7] A. Shastri, Asim Kumar Das, K. Sunanda, Param Jeet Singh and B.N. Raja Sekhar, J Chem Phys 147, 224305
(2017).
[8] A. Shastri, A.K. Das and B.N. Raja Sekhar, J Quant Spectrosc Radiat Transfer 242, 106782 (2019).
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
IT-06
Dissociative electron attachment to isolated molecules and clusters
Dhananjay Nandi*
Indian Institute of Science Education and Research Kolkata, Mohanpur 741246, West Bengal, India
Low energy electron-molecule collision dynamics is of great interest from fundamental as well
as practical applications. We probe dissociative electron attachment (DEA) to isolated
molecules and clusters of fundamental interest using well established techniques. Our recent
development toward the production of cold molecular target using pulsed supersonic jet
enables us to study DEA to cold molecules and clusters. The results show many exciting
observations.
In this conference, we will discuss kinematically complete measurements of DEA to
sulfur dioxide (SO2) and ammonia (NH3) using velocity slice imaging technique. Finally, we
will present our observations on DEA to small cluster of oxygen.
References [1] I. Jana and D. Nandi, Phys. Rev. A 97, 042706 (2018).
[2] I. Jana and D. Nandi, J. Phys. B: At. Mol. Opt. Phys. 52, 185202 (2019).
[3] D. Chakraborty, A. Giri and D. Nandi, Phys. Chem. Chem. Phys. 21, 21908 (2019).
[4] I. Jana V. Ramaprasad and D. Nandi, arXiv:submit/2576569 [physics.atm-clus] 14th February, 2019.
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
IT-07
Diagnosis of Tokamak plasma using passive spectroscopy
Joydeep Ghosh*
Institute for Plasma Research, Bhat, Gandhinagar-382428, India
E-mail: [email protected]
Radiation emanated from a magnetically confined tokamak plasma contains enormous
information about the plasma properties. Hence, spectroscopic diagnostics remains an
important tool to diagnose the tokamak plasma. Radiation from a tokamak plasma, especially
from X-ray to NIR region are recorded either in totality or in spectrally resolved regions to
obtain various plasma parameters along with their temporal evolutions. These include size and
shape of the plasma, electron temperature, Te, ion temperature, Ti, radiation power loss, Prad,
plasma rotation velocity, recycling from the walls, impurity behavior, electric and magnetic
fields inside the plasma etc. Broadly, the tokamak plasma is divided into two areas for the
spectroscopic studies. In the edge plasma, i.e., near the boundary of the plasma column, most
of the emission is in visible region, whereas the center of plasma column mainly radiates in
VUV and X-ray wavelength regions as the plasma temperature increases manifold towards the
center of the plasma column. Adequate modelling is required to obtain plasma parameters from
the measurements. In this presentation, an overview of studies on impurity temperature and
dynamics, plasma column rotation, neutral penetration inside the plasma column, Hα emission
during gas-puffs, carried out in ADITYA/ADITYA-U tokamak using spectroscopic
measurements and modelling will be presented.
*Contributions from: M. B. Chowdhuri, Ranjana Manchanda, Ritu Dey, A. Bhattacharya, Nandini
Yadava, G. Shukla, Kajal Shah, Sharvil Patel, Nilam Nimavat, Ketan Patel, S. Banerjee, Vinay Kumar,
P. Vasu, and ADITYA/ADITYA-U team.
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
IT-08
Photoionization studies of argon inside charged fullerene
Afsal Thuppilakkadan1, 2 Jobin Jose and Hari R. Varma1*
1 School of Basic Sciences, IIT Mandi, Kamand 175075, Himachal Pradesh 2 Department of Physics, IIT Patna, Bihta-801103, Bihar, India
Photoionization studies of confined atomic systems such as atom inside fullerene (A@C60)
continue to attract attention across scientific community owing to its importance in various
research fields. An outstanding feature of the ionization spectrum of confined atomic systems
is the presence of confinement resonances emerging from the interference between the
outgoing photoelectron wave and the reflected wave from the confinement well. A number of
studies have been reported discussing various features of such resonances and its consequences
on various photoionization parameters [1, 2]. Earlier theoretical studies on Ne@C60q, q being
the charge on fullerene, have shown the appearance of a different type of confinement
resonances, known as Coulomb confinement resonances, appearing on the 1s ionization
spectrum due to the presence of charged fullerene [3, 4]. In the present work, we extend the
studies for the case of Ar@C60q to study such resonances and its impact on the photoionization
spectrum.
References[1] V. K. Dolmatov, adv. quantum chem. 58, 13(2009) and references therein
[2] Subhasish Saha, Afsal Thuppilakkadan, Hari R Varma, Jobin Jose, J. Phys. B 52, 145001 (2019) and
reference therein.
[3] V. K. Dolmatov, S. T. Manson, Phys. Rev. A 73, 013201 (2006).
[4] A. Kumar, H. R.Varma, P. C. Deshmukh, S. T. Manson, V. K. Dolmatov, A. S. Kheifets, Phys. Rev. A 94,
043401 (2016).
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
IT-09
Shannon’s entropy in endohedrally confined atoms: Indicator of avoided
crossing and correlation energy
Jobin Jose1*
1 Department of Physics, Indian Institute of Technology Patna, Bihta, Patna 801103
Shannon’s entropy is an indicator of localization of electronic density [1]. The electronic
density of confined atom has been investigated using Shannon’s entropy as a probe parameter
[2, 3]. Sensitivity of Shannon’s entropy with variation of confinement strength unveiled its
profile near the avoided crossings in endohedral atoms [4]. Objective of the present work are
two fold: (1) To understand the sensitivity of Shannon’s entropy to different confinement
potentials in the avoided crossing region and (2) To address the variation in Shannon’s entropy
with many-electron correlation energy.
To accomplish the first objective, Shannon’s information entropy of the ground state and some
of the excited states of confined H atom as a predictor of avoided crossing is studied. This is
achieved by varying the strength of the confinement and examining structure properties like
ionization energy and Shannon’s information entropy. Along with the energy level repulsion
at the avoided crossing, Shannon’s information entropy is also exchanged between the
involved states. The reciprocity relation of entropy in the radial and momentum space
consequent to the Heisenberg’s uncertainty relation is scrutinized in parallel.
Towards understanding the entropy difference due to the many-electron correlations in
confined atoms, correlation energy of Be@C60 and Mg@C60 have been investigated using
modified Dirac-Fock (DF) and multi-configuration Dirac-Fock (MCDF) methods. These
calculations are done using the grasp92 suit of codes [5]. A term-Correlation entropy is
defined, sensitivity of which is studied with varying confinement strengths.
Endohedral systems in the present work is approximated using two spherically symmetric
potentials: hard Annular Square Well (ASW) and smooth Gaussian Annular Square Well
(GASW) [6]. Sensitivity of Shannon’s entropy to the choice of potentials is employed to look
for a realistic confinement potential.
References [1] C.E. Shannon, Bell Syst. Tech. J. 27, 379 (1948).
[2] W. S. Nascimento , F. V. Prudente, Chem. Phys. Lett. 691, 401 (2018).
[3] L. G. Jiao, L. R. Zan, Y. Z. Zhang, Y. K. Ho, Int. J. Quantum Chem. 117, 25375 (2017).
[4] D. M. Mitnik, J. Randazzo, G. Gasaneo, Phys. Rev. A 78, 062501 (2008).
[5] F. A. Parpia, C. Froese Fischer, I. P. Grant, Comp. Phys. Comm. 94, 249 (1996).
[6] Subhasish Saha et al., J. Phys. B: At. Mol. Opt. Phys. 52, 145001 (2019).
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
IT-10
Laser cooling and trapping of Rb at narrow blue transition
Dangka Shylla1, Elijah Ogaro Nyakang'o1, Rajnandan Choudhury Das1 and Kanhaiya
Pandey1*
Indian Institute of Technology, Guwahati
The temperature of magneto-optical trap (MOT) is limited by the linewidth of the transition.
Rb is commonly cooled and trapped using 5S1/2 → 5P3/2 at 780nm (IR) transition. The linewidth
of this transition is 2π⋇6 MHz which limits the temperature of the MOT to be 150 μK. The
linewidth of the other transition, 5S1/2 → 6P3/2 at 420 nm (blue) is 2π⋇1.2 MHz which is 5 times
narrower than the 5S1/2 → 5P3/2 and hence expected to provide lower temperature by 5 times.
In this talk, we present details of our experiment including spectroscopy and loading the Rb
atoms in blue MOT.
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
IT-11
Precision quantum measurements using optical clock
Subhadeep De
Inter-University Centre for Astronomy and Astrophysics (IUCAA), Post Bag 4, Ganeshkhind, Pune
411007, India.
At IUCAA, we have recently started to set up the Precision Quantum Measurement-lab (PQM-
lab) that aims to develop quantum enhanced technologies to support national missions as well
as to pursue precision atomic spectroscopy for probing fundamental sciences. The PQM-
facility shall comprise of a trapped ytterbium-ion (Yb+) optical clock for absolute optical
referencing, ultra-stable Fabry-Perot (FP) cavity that acts as a steady flywheel oscillator,
stabilized optical frequency comb to generate the photons at the desired wavelengths and phase
stabilized link-fiber via bi-directional communication through it. Such a system will facilitate
long distance precise intercomparison of the optical photons and can be utilized to stabilize
various other sources with respect to a standard optical reference. We plan to develop the
optical atomic clock based on the ultra-narrow 4f146s 2S1/2 - 4f136s2 2F7/2 electric octupole (E3)
transition at 467 nm wavelength of Yb+. Upon commissioning, this facility will produce phase
& frequency stabilized narrow-linewidth and ultra-stable optical reference source, which is
requisite for state-of-the-art instruments and high-end technologies, namely, Laser
Interferometer Gravitational-Wave Observatory (LIGO) and quantum communication,
respectively. Other than these applications, the PQM-facility will be used for variety of
precision measurements such as, geodesy, probing temporal constancy of the dimensionless
fundamental constants, quantum metrology and so on. An overview of this planned activity
together with possible applications of it will be presented in the meeting.
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
IT-12
Spectroscopic constants and thermochemistry of some
ozone depleting systems
T. K. Ghosh
Department of Physics
Diamond Harbour Women’s University, Sarisha, WB, India
Email: [email protected]
In the atmosphere, particularly in the lower stratosphere region, ozone plays a vital role in
protecting harmful ultra-violet (UV) radiation in reaching to our earth and thereby decreases
several hazardous effects on human life and civilization like sunburn, skin cancer, global
warming, effects on earth’s environment, impact on vegetation, etc. Several natural occurring
processes, preservation processes and factory outlets contain Chlorofluorocarbons (CFCs) and
other compounds containing halogens (Cl, Br or I), generally grouped as Ozone Depleting
Substances (ODS). These ODS chemically react with the ozone available in the stratosphere
and thereby deplete the ozone layer.
It has been found that halogen oxides play an important role in such ozone depletion, viz.
IO + XO → I + X + O2 (X = Cl, Br)
I + O3→ IO + O2
X + O3→ XO + O2
Net: 2 O3→ 3 O2
These reactions may proceed through different channels, like
IO + XO → X + OIO (X = Cl, Br)
→ I + XOO → I+X+O2
→ IX + O2
→ I + OXO
However, experimental investigations on these systems are available, theoretical investigations
are limited. The geometry and spectroscopic properties of particularly XOO and XOO
molecules are still speculative.
The present report is focused on the spectroscopy of some molecules important in ozone
depletion. Ab initio calculations have been done to investigate geometry, spectroscopic
constants and thermochemical data of the reactants, products, various minimum energy
geometries and transition state geometries formed in course of the reactions. IRC calculations
are also to be reported for the reaction pathways of the different channels. The data may be
helpful in understanding their effectiveness in ozone depletion as well as may serve as future
references.
References [1] S. Solomon, R.R. Garcia and A.R. Ravishankara, J. Geophys. Res. 99, 20491 (1994).
[2] World Meteorological Organization/United Nations Environment Programme (WMO/UNEP): Scientific
assessment of ozone depletion, Geneva, WMO Rep. 25, 1992.
[3] Gilles, M.K.; Turnipseed, A.A.; Burkholder, J.B.; Ravishankara, A.R; Solomon, S.J. J. Phys. Chem. A101,
5326 (1997).
[4] Guha, S., Francisco, J.S., J. Phys. Chem. A114, 4254 (2010).
------------------------------------------
Acknowledgement: This work is funded by DSTB, Govt. of WB under the Project No.
357(Sanc.)/ST/P/S&T/16G-26/2018.
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
IT-13
Electron impact low energy studies for Di-triatomic targets
M. Vinodkumar
1 V. P. & R. P. T. P. Science College, Vallabh Vidyanagar, Gujarat, India
Electron impact studies at low energy is very important since it involves elastic and distinct
inelastic processes such as discrete electronic excitations, dissociative electron attachment,
ionization etc. Each of the inelastic processes is very important especially at low energy since
it involves complex physics and helps us to understand many phenomenon such as resonance,
fragmentation, dissociation, recombination etc. In particular, the Dissociative electron
attachment processes occur in many applied fields such as gas discharges, plasmas, biological
systems, astrophysical environment as well as in atmosphere [1].
In the present work, I will discuss mainly dissociative electron attachment (DEA) cross
sections for Di-tri atomic targets along with other inelastic processes. DEA is a low energy
phenomenon generally below ionization threshold of the target where incoming electron
temporarily gets attached to the target molecule to form transient negative ion (TNI). The TNI
is a short lived state of the order of picoseconds or femtoseconds. The TNI either auto- detaches
or it decays leading to anionic fragments. Since the anionic fragment is a charged particle it
can be detected by conventional mass spectrometry, hence it is subject of great importance
experimentally. Moreover, theoretically the DEA process can be well understood by studying
the potential energy surface of neutral as well as anionic as fragment [2]. We employ R-matrix
formalism [3, 4] for computing discrete electronic excitations, and resonance width and
position by fitting them to Briet Wigner profile using RESON program. It has been observed
that DEA cross sections for halogen molecules are strongest [2, 5] and will be presented during
the conference.
Acknowledgement: Dr. Minaxi Vinodkumar acknowledges DST-SERB, New Delhi for major
research project [EMR/2016/000470] for financial support under which part of this work is carried out.
References [1] I. Fabrikant, S. Eden, N. Mason, J. Fedor, Adv. At., Mol., Opt. Phys. 66, 545-657 (2017)
[2] N. Mason, B. Nair, S. Jheeta & E. Szymańska, RSC Adv 168, 235-247 (2014).
[3] J. Tennyson, Phys. Rep. 491, 29 (2010)
[4] M. Vinodkumar, H. Desai, P. Vinodkumar. RSC Adv 5(31), 24564 (2015)
[5] H. Yadav, M. Vinodkumar, C. Limbachiya, P. C. Vinodkumar, J. Phys. B: At. Mol. Opt. Phys. 51, 045201
(2018).
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
IT-14
Application of plasma produced nanostructures in surface wettability and
sensing
M. Ranjan1,2, V. Pachichigar 1,2, Sooraj KP1 and S. Augustine1,2
1Institute for Plasma Research, Gandhinagar-382428, India 2Homi Bhabha National Institute, Mumbai-400094, India
Email: [email protected]
Low energy Ar ion irradiation leads to regular nanoripples and nanodots like structures on the
surfaces. Properties of such nanostructures can be tailored by ion energy, incidence angle and
ion dose [1, 2]. In the recent past such nanostructures found applications in plasmonics and
magnetism [1, 2]. In the current work, I shall be showing how PTFE surface become
superhydrophobic in just few seconds ion irradiation in the ion energy range 300 eV to 800 eV
[3]. The surface morphology revealed the formation of hierarchical micro and nanostructures
on its surface. Detailed wetting behaviour of irradiated PTFE was studied using contact angle,
surface free energy and rolling speed measurement. A systematic increase in the contact angle
was observed with increase in ion energy, irradiation time and surface roughness. After a
threshold irradiation time, the water droplet started rolling from the horizontal surface in each
ion energy range. The self-cleaning property of this superhydrophobic PTFE was effectively
achieved by conducting dust removal test with carbon powder.
In the later part, I will discuss how plasma produced nanoripple patterns can be used as a
template for growing highly ordered nanoparticles [1, 2]. These nanoparticle arrays can show
strong surface plasmon resonance whose spectral position depends on the polarization of
incident light. We have shown that the plasmon resonance of silver nanoparticle arrays grown
on ripple patterned templates can be tuned by changing the ripple periodicity/aspect ratio and
Surface Enhanced Raman Scattering (SERS) intensity can be optimised with these parameters
[4,5]. SERS based detection of glucose deposited on ion beam produced ripple patterned
substrate with silver nanoparticle arrays will be reported for concentrations 5x10-2 g/ml,
5x10-3 g/ml, 5x10-4 g/ml and 5x10-5 g/ml without using binder molecule. These concentrations
are relevant to blood glucose level [4,5]. A comparative study of detection of Glucose
deposited on plane Si substrate, Plane Si substrate with silver nanoparticles and patterned Si
substrate with Silver nanoparticles will be reported. Due to larger enhancement of nanoparticle
chain, we could detect Glucose without the binder molecule for much lower concentrations.
Some preliminary study conducted on breast cancer cell detection and blood plasma will also
be presented using above mental nanoparticles.
Reference [1] M. Bhatnagar, M. Ranjan, R. Smith, S. Mukherjee, Applied Physics Letters 108, 223101 (2016).
[2] M. Ranjan, M. Bhatnagar, S. Mukherjee, Journal of Applied Physics 117, 103106 (2015).
[3] V. Pachchigar, M. Ranjan, S. Mukherjee, Scientific Reports 9, 8675 (2019).
[4] M. Arya, M. Bhatnagar, M. Ranjan, S. Mukherjee et al., Journal of Physics-D 50, 455603 (2017).
[5] Sooraj K P, M.Ranjan, R.Rao, S. Mukherjee, Applied Surface Science 31. 576 (2018).
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
IT-15
Study of nonlinear waves in multicomponent space plasmas
N. S. Saini
Guru Nanak Dev University, Amritsar-143005, India
Over the past many years, the dense quantum plasmas have been the focus of many researchers
because of its wide ranging applications in different fields such as semiconductor devices [1],
metallic nano-structures [2], and astrophysical objects [3]. The particles with quantum nature
have a great influence on the macroscopic properties of such type of plasmas. The de-Broglie
wavelength of the charge particle is comparable to the inter-particle distance and Fermi
temperature exceeds the system temperature in quantum plasma. In such situations, the
quantum mechanical effects play very important role in the dynamics of charged particles and
the plasma particles behave like Fermi gas [4]. The quantum tunneling effects are also taken
into account by considering the Bohm potential term in the corresponding momentum
equations of degenerate electrons. The ion- acoustic waves (IAWs) are among the most well
studied electrostatic modes in both linear and nonlinear regimes in dense astrophysical
plasmas. In the present talk, the influence of various plasma parameters on the nonlinear
dynamics of ion acoustic excitations (solitons, periodic waves and other kinds of nonlinears
structures) have been investigated in a dense magnetized plasma by employing the spin-
evolution quantum hydrodynamic model. The plasma model composed of degenerate
electrons having both spin-up and spin-down states as well as non-degenerate cold ions. The
Korteweg-de Vries (KdV) equation is derived using the reductive perturbation technique and
solved numerically to investigate the characteristic features of nonlinear structures. The family
of the KdV equation is used to describe a non-modulated wave, which is usually called the
KdV solitons, while the nonlinear Schrödinger equation (NLSE) describes the dynamics of the
nonlinear modulated waves. In this talk, the nonlinear Schrödinger equation is described to
study the characteristics of different order rogue waves [5]. The parametric role of the spin
density polarization ratio on the amplitude and width of nonlinear structures and rogue waves
is also investigated. The numerical results obtained in the present investigation may be
applicable to high density astrophysical regions such as white dwarfs and can also be helpful
in understanding the properties of compact astrophysical objects where degenerate electrons,
light nuclei and heavy nuclei are available.
Reference
[1] M. C. Yalabik, G. Neofotistos, K. Diff, H. Guo, and J. D. Gunton, IEEE Trans. Electron
Devices 36, 1009 (1989).
[2] J. Y. Bigot, J. Y. Merle, O. Cregut, and A. Daunois, Phys. Rev. Lett. 75, 4702 (1995).
[3] S. L. Shapiro and S. A. Teukolsky, Black Holes, White Dwarfs, and Neutron Stars—The
Physics of Compact Objects (Wiley-VCH, Weinheim, 2004).
[4] G. Manfredi, Fields Inst. Commun. 46, 263 (2005).
[5] N. Kaur and N. S. Saini, Astrophys. Space Sci. 336, 331 (2016)
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
IT-16
Strong field ionization with ultrashort orbital angular momentum
beams
R. Gopal1*, A. Sen2, A. Sinha3 and V. Sharma1
1 Tata Institute of Fundamental Research, Hyderabad 2 Indian Institute of Science Education and Research, Pune
3Indian Institute of Technology, Hyderabad
Finite light beams with an azimuthal dependence of the phase over the beam are said to possess
an orbital angular momentum (OAM), which can be generated through holograms, spiral plates
or ring resonators etc. Light-matter interaction with these beams raises a fundamental question
on the nature of transfer of this property of light to matter [1]. In experiments so far, only with
macroscopic systems, has the OAM of the light beam manifested. In this talk, I will describe
our experiments on the photoionization with linearly polarized, ultrashort (25 fs) intense (1013-
1014 W/cm2) laser pulses endowed with a definite OAM (l =1). Photoionization with these laser
pulses is through non-resonant multi-photon processes or tunnel ionization through the
suppression of the Coulomb barrier of the atom. Three-dimensional angular distributions of
the singly ionized electron is captured through a newly commissioned ‘Reaction Microscope’
[2]. Through careful experimentation it appears that no transfer of the angular momentum of
the beam to the ionized electron occurs, at least, in these strong-field single atom-laser
interaction conditions.
References [1] A. Picon et al., New Journal of Physics 12, 083053 (2010).
[2] J. Ullrich et al., Rep. Prog. Phys. 66, 1463-1545 (2003).
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
IT-17
Diagnostic of non-thermal atmospheric pressure plasma jet through
emission and absorption spectroscopy
R. K. Gangwar1,*, P S Srikar1 and S M Bakshi2
1Department of Physics, Indian Institute of Technology Tirupati, Tirupati 517506, AP, INDIA 2Civil & Environmental Engineering, Indian Institute of Technology Tirupati, Tirupati 517506, AP,
INDIA
Non-thermal plasma jets at atmospheric pressure are receiving significant attention from the
scientific community [1]. A major part of motivation comes from the fact that the plasma jet
can produce a significant amount of reactive species (oxygen or nitrogen-based) at room
temperature. This makes them very suitable candidates for a wide range of applications such
as cancer therapy, wound healing, sterilization, material processing, mass-spectrometry and
many more. However, in order to establish these plasma sources as a viable solution, the
detailed diagnostic is a prime requirement. The non-thermal atmospheric pressure plasma jet
(NTAPJ) is normally very small in dimension and exhibits a very high gradient of plasma
species. This restricts the application of traditional plasma diagnostic approaches such as a
Langmuir probe. Further, the laser scattering based approaches could be useful but they are
very expansive and also not very portable. Besides, the implementation is not very straight
forward. The optical emission spectroscopy-based approaches can provide a very suitable
solution for diagnostic studies. However, due to the non-equilibrium nature of the plasma, the
extraction of plasma parameters from these measurements requires the development of the
population-kinetic models. The development of the population-kinetic model is also very
challenging as plasma operates in ambient air. This requires the inclusion of a large number of
reactions of plasma species with the molecules present in the air. In order to resolve these
issues, we recently implemented a hybrid approach by combining the absorption and emission
spectroscopy measurements. Under this scheme, a simpler collisional radiative model can
extract reliable information from the measurement. During my talk, I shall present the details
of the approach along with the diagnostic that was carried on an Ar atmospheric pressure
plasma jet.
Reference [1] S. Reuter et al., The kINPen—a review on physics and chemistry of the atmospheric pressure plasma jet and
its applications, Journal of Physics D: Applied Physics 51, 233001 (2018).
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
IT-18
Multidiagnostic characterization of ultrashort and short pulse laser
produced plasmas
Pranitha Sankar and Reji Philip
Raman Research Institute Sadashivanagar, Bangalore 560080
The field of laser produced plasmas (LPP) has greatly attracted the research community
because of its wide range of applications such as pulsed laser deposition, generation of light
sources and ion beams, plasma-based acceleration etc. In this talk we discuss space and time-
resolved studies of plasmas produced by ultrashort (100 fs) and short (7 ns) laser pulse ablation
of Aluminium (Al) and Tungsten (W) targets, kept at different ambient pressures ranging from
10-5 to 760 Torr. Optical time of flight spectroscopy (OTOF), optical emission spectroscopy
(OES), time-resolved ICCD imaging, and ion dynamics studies have been carried out in these
plasmas. Electron temperature and number density have been calculated from the optical
emission spectra.
Figure 1: Different processes in laser ablation in their respective timescales, spanning the range
of femtoseconds to milliseconds.
The intensities of the plasma plumes as well as the relative abundance of the ions are found to
be different between ultrashort laser ablation (ULA) and short laser ablation (SLA), because
of differences between laser-target and laser-plasma interactions. OTOF measurements, time-
resolved ICCD imaging and ion emission measurements reveal the presence of both fast
moving as well as slow-moving species in SLA, while this distinction is not equally obvious
in ULA. Linear, shock wave and drag models are used to model plume and ion dynamics in
the low, intermediate and high-pressure regions respectively. In addition, the expansion
dynamics of the ULA aluminum plasma is investigated as a function of the laser beam size on
the target, using a combination of the above-mentioned diagnostic tools. Optical emission
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
spectroscopic analysis shows that higher emission intensities and ion populations can be
obtained for smaller beam sizes. Time-resolved ICCD imaging of the expanding plasma shows
a spherical morphology for plumes produced by smaller beam sizes, and a cylindrical
morphology for those produced by larger beam sizes. A comprehensive comparison of X-ray
emission from ULA and SLA plasmas also has been carried out. These results will be discussed
in this talk.
Figure 2: Experimental setup for the multidiagnostic characterization of laser produced
plasmas.
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
IT-19
Neutrino-plasma interactions in gravitating degenerate astrophysical
plasmas
R. P. Prajapati
Dept. of Pure and Applied Physics, Guru Ghasidas Vishwavidyalaya, Bilaspur 495009 (C.G.)
The neutrinos are weakly interacting particles with plasma constituents and play a crucial role
in the energy transfer between the neutrino beam and the plasma in the supernova core-
collapse. The physics of collective neutrino-plasma interactions and excitation of plasma
turbulence by a large neutrino flux has been discussed in many problems [1, 2]. In this work,
the interactions of arbitrarily propagating energetic neutrino beam with dense magnetized
degenerate quantum plasma has been studied. The neutrino magnetohydrodynamic (NMHD)
model is formulated considering the effects of quantum in the ideal quantum
magnetohydrodynamic (MHD) plasma. The theoretical model establishes the interplay
between weak interacting neutrinos and magnetized quantum plasma. The general dispersion
relation is derived and neutrino beam driven instability is analyzed in the supernova core-
collapse. It is observed that quantum corrections significantly modifies the growth rate of
neutrino beam instability. The neutrino beam density and quantum corrections decrease the
critical Jeans wavenumber of perturbations, below which the system becomes gravitationally
unstable. The time scale of the neutrino beam is too short as compared to the Jeans time scale
which causes a faster mixing of the neutrino beam in the gravitational collapse of supernova.
The neutrino beam energy destabilizes the growth rate of the Jeans instability in the core-
collapse [3].
This work is also applicable to understand the neutrino-beam-plasma interactions in the
crust of neutron stars and magnetars considering magnetic field well below the Schwinger limit
so that the nonlinear effects and electron-positron pair creation can be safely ignored in
quantum electrodynamics (QED) [3].
References [1] F. Haas, K. A. Pascoal, and J. T. Mendonca, Phys. Plasmas 23, 012104 (2016).
[2] F. Haas, K. A. Pascoal, and J. T. Mendonca, Phys. Rev. E 95, 013207 (2017).
[3] R. P. Prajapati, Phys. Plasmas 24, 122902 (2017).
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
IT-20
Gas-phase formation of ammonia in the diffuse interstellar medium
calculation of the rate coefficients of the key steps
Sunil Kumar S1,∗, Salvi M1 and Raghunath O. Ramabhadran2
1Department of Physics, IISER Tirupati, Tirupati - 517507, Andhra Pradesh, India 2Department of Chemistry, IISER Tirupati, Tirupati - 517507, Andhra Pradesh, India
Ammonia, one of the most important molecules relevant to the ecosystem on earth, was the
first nitrogen-bearing molecule detected in the interstellar medium (ISM) [1, 2]. However, the
formation mechanisms of ammonia in the diffuse ISM is still not completely understood.
Currently, the pathway proposed [2] to occur in gas-phase in the diffuse ISM in producing
NH3 is as follows:
𝑁+ + 𝐻2 → 𝑁𝐻+ + 𝐻 (1)
𝑁𝐻+ + 𝐻2 → 𝑁𝐻2+ + 𝐻 (2)
𝑁𝐻2+ + 𝐻2 → 𝑁𝐻3
+ + 𝐻 (3)
𝑁𝐻3+ + 𝐻2 → 𝑁𝐻4
+ + 𝐻 (4)
𝑁𝐻4+ + 𝑒− → 𝑁𝐻3 + 𝐻 (5)
In this work, the third and fourth of the above reactions were analyzed theoretically using variational transition state theory (CVT); the latter was addressed recently by Alvarez et al. [3]. The rate coefficients of the third reaction as a function of temperature ranging from 10 to 300 K was determined using variational transition state theory and the results (Fig. 1) were found to be in reasonable agreement with recent experimental results [4]. These two reactions are found to be exothermic and feature a small activation barrier which essentially is a consequence of the zero-point energy corrections. The results demonstrate that quantum mechanical tunneling plays a key role in the formation of ammonia in the ISM (T < 100 K).
Figure 1: The rate coefficients of the reaction between NH2
+ and H2 as a function of temperature. The calculations were made at two levels of theory, MP2 and CCSD with basis set aug-cc-PVTZ. The thin lines are results from CVT calculations without tunneling. The results marked with legends “Wigner” and “Eckart” represent the rate co-efficients that include Wigner and Eckart tunneling corrections respectively.
References [1] Herbst, E., DeFrees, D. J. & McLean, A. D., Astrophys. J. 321, 898 (1987).
[2] Le Gal, R. et al., Astron. Astrophys. Suppl. Ser. 562, A83 (2014).
[3] A lvarez-Barcia, S., Russ, M.-S., Meisner, J. & Kastner, J., Faraday Discuss. 195, 69 (2017).
[4] Rednyk, S. et al., Astron. Astrophys. Suppl. Ser. 625, A74 (2019).
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
IT-21
Atom-optic kicked rotor: From quantum chaos to atom interferometry
Umakant Rapol*
Department of Physics, Indian Institute of Science Education and Research Pune-411008
In this talk I will present our recent work using an Atom-Optic Kicked Rotor (AOKR) with
ultracold atoms and Bose-Einstein Condensate.
AOKR is a rich experimental test bed for simulating the physics of classically chaotic
quantum systems. Using AOKR we show that one can engineer the 'Thermal Bath" to which
quantum systems couple and decohere. Decoherence can be prolonged by appropriately
engineering the bath. In particular, we show that one can make the system decohere in such a
manner that it deviates from an exponential to power law a function of time. In addition, we
also show that the system shows an optimal diffusion under specific conditions of the bath. In
the second part of the talk, a variation of the AOKR on a BEC can be used to study and use the
Talbot effect for building an Atom Interferometer.
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
IT-22
Photodissociation and dissociative electron attachment: similarities and
differences
V. S. Prabhudesai1*
1 Tata Institute of Fundamental Research, Mumbai 400005 India
Dissociative electron attachment (DEA) is one of the most important processes that occurs
when low energy electron (< 20 eV) interacts with molecule. The process involves capture of
low energy electron resulting in the formation excited anion state also called a negative ion
resonance (NIR) and its subsequent dissociation. This process competes with the electron
ejection also known as autodetachment. These NIR states are always described in terms of the
corresponding neutral ground or excited state also called the parent state for the NIR. On
similar lines, in photodissociation, the photon is absorbed by the molecule resulting in its
excitation which is followed by dissociation.
Although both the processes involve molecular excited states, the presence of additional
electron makes dynamics of the NIR state in DEA much richer than that of neutral excited state
in photodissociation. In this talk, I will describe two such cases where we have encountered
the similarities as well as differences in these processes that highlight the interesting aspects
of DEA.
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
IT-23
Foam structure of dopants in helium nanodroplets? Some evidences in
photoionization of acetylene doped helium droplets
Suddhasattwa Mandal1, Ram Gopal2, M. Shcherbinin3, Robert Richter4, H. Srinivas4,
Marcello Coreno4, Alessandra Ciavardini4, A D’Elia5, B Bapat1, M Mudrich3, S. R.
Krishnan6 and V. Sharma7*
1 Indian Institute of Science Education and Research Pune, Pune – 411008, Maharashtra, India 2 Tata Institute of Fundamental Research Hyderabad, Hyderabad – 500107, Telangana, India
3 Aarhus University, 8000 Aarhus C, Denmark 4 Elettra-Sincrotrone Trieste, Strada Statale 14-km 163.5, 34149 Basovizza, Trieste, Italy
5 University of Trieste, Department of Physics, 34127 Trieste, Italy 6 Indian Institute of Technology Madras, Chennai – 600036, Tamil Nadu, India
7 Indian Institute of Technology Hyderabad, Sangareddy – 502285, Telangana, India *[email protected]
The impact of environment in the fragmentation dynamics of small molecules remains an
intriguing object of investigation wherein the dynamics of these systems embedded in Helium
nanodroplets generally gets modified. We have performed an experiment at Elettra Synchrotron
Facility at Trieste wherein we doped Helium nanodroplets with acetylene molecule. Acetylene
molecule being heliophilic embed inside the nanodroplet. Here, we studied the ionization of
acetylene through the relaxation of photoexcited Helium nanodroplet. This is a well-known
Penning process. In the current work, we demonstrated that the ionization of acetylene molecule
through Penning process is not limited only to the n=2 droplet excitation but is also extended to
higher excitation bands of droplet such as n=4. Employing the spectroscopic techniques, we also
revealed the oligomer formation of acetylene inside Helium nanodroplets. The acetylene molecules
coalesce in the form of loosely bound van der Waals aggregates, called as foam-like [1] structure.
This structure collapses into a composite oligomer ion following Penning ionization [2]. A detailed
experimental investigation will be presented during the talk.
References [1] S Göde, R Irsig, J Tiggesbäumker, K-H Meiwes-Broer, New. J. Phys, 15, 015026 (2013)
[2] S. Mandal et al [under preparation]
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
IT-24
Accurate calculation of weak intermolecular interaction energy
Narendra Nath Dutta
Department of Chemical Sciences, Indian Institute of Science Education and Research Mohali,
Punjab-140306, India
An accurate potential energy surface due to weak interaction or noncovalent interaction
between two molecules to form a supermolecule is very much important in the study of binding
and folding of a biological complex [1], in the analysis of a molecular scattering experiment
[2] and also in the molecular spectroscopy [3]. Though several variants of electron density
based methods [4] are relatively much popular tools to compute such surfaces, their reliability
can be questioned in many situations. An alternative way to compute such a potential energy
surface can be to use a suitable wavefunction based method [1]. Here we show two of such
methods: an explicitly-correlated coupled-cluster method [5] with added bond functions [6]
for closed-shell systems and a multireference version of symmetry-adapted perturbation theory
(MRSAPT) [7, 8] for open-shell systems. The former can calculate the interaction energy by
subtracting the sum of the individual energies of the two molecules from the total energy of
the supermolecule: ∆E = EAB - (EA + EB) with A and B indicating the two molecules. Very
recently, we recommend a variant of explicitly-correlated coupled-cluster methods with added
bond functions (CCSD(Tbb)-F12b/aug-cc-pVDZ+(3s3p2d2f)) which has a potentiality to
calculate the interaction energy at the geometrical equilibrium with mean unsigned error within
0.05 kcal/mol of basis set limit [9]. Here the mean is calculated by computing the interaction
energies of 46 supermolecular species of di_erent sizes ((HF)2 dimer to adenine-thymine
complex). The extension of this work for the entire potential energy surface is a future plan to
be carried out. The latter method, MRSAPT, which is currently under development [8],
considers the weak interaction as a perturbation to a supermolecule consisting of two non-
interacting molecules. The advantage of MRSAPT or in fact any version of SAPT [7] is that it
not only computes the interaction energy accurately, but also can decompose this energy in
terms of its physical components: electrostatic, induction, and dispersion along with their
exchange counterparts. Therefore, the SAPT or MRSAPT depicts the picture of relative
strengths among these components at various regions of a potential energy surface.
Acknowledgement: A thankful gratitude to Dr. Konrad Patkowski, Auburn University, USA
to work as an advisor and a coordinator to carry out these works.
References [1] E. G. Hohenstein, and C. D. Sherrill, WIREs Comput. Mol. Sci. 2, 304 (2012)
[2] V. Aquilanti, and D. Ascenzi, J. Chem. Phys. 109, 3898 (1998)
[3] I. I. Mizus et al., Phil. Trans. R. Soc. A 376: 20170149 (2018)
[4] W. Koch, and M. C. Holthausen, A Chemist's Guide to Density Functional Theory, (Wiley-VCH, 2000)
[5] G. Knizia, T. B. Adler, and H.-J. Werner, J. Chem. Phys. 130, 054104 (2009)
[6] F. -M. Tao, J. Chem. Phys. 100, 3645 (1994); Int. Rev. Phys. Chem. 20, 617 (2001)
[7] K. Szalewicz, WIREs Comput. Mol Sci. 2, 254 (2012)
[8] N. N. Dutta, D. G. A. Smith, and K. Patkowski, Towards Multireference Symmetry-Adapted Perturbation
Theory, Presented in SETCA-2017 at University of Mississippi, USA
[9] N. N. Dutta, and K. Patkowski, J. Chem. Theory Comput. 14, 3053 (2018)
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
IT-25
Electron induced ionization cross sections of atoms, ions and molecules
relevant to plasma applications
Ghanshyam Purohit1* and Daiji Kato2,3,4
1Department of Physics, University College of Science, Mohanlal Sukhadia University, Udaipur-
313001, India 2National Institute for Fusion Science, National Institutes of Natural Sciences 322-6 Oroshi-cho, Toki
Gifu, 509-5292, Japan 3Department of Fusion Science, SOKENDAI, 322-6 Oroshi-cho, Toki Gifu, 509-5292, Japan
4Department of Advanced Energy Engineering Science, Kyushu University,Kasuga Fukuoka, 816-
8580, Japan
*[email protected], [email protected]
Ionization of targets such as atoms, ions, and molecules by charged projectiles such as
electrons/positrons has been studied from a long time and has various applications; few may
be listed as diagnostics of fusion plasmas, modeling of physics and chemistry related to
atmosphere, understanding the effect of ionizing radiation on biological tissues etc. The
ionization cross sections are essential in the modeling of plasma in fusion research. Beryllium
(Be) is one of the materials which is directly exposed to the plasma components in the
International Thermonuclear Experimental Reactor (ITER) [1]. Formation of gas-phase Be in
various charge states and of hydrides of Be, takes place when the erosion of Be walls occurs
in contact with the hot plasma containing hydrogen and its isotopes. Electron collision
processes on the beryllium and its charged states play an important role in the fusion edge and
diverter plasmas. The tungsten (W) and tungsten based materials have also been recommended
as one of the materials to be used as plasma facing components for the International
Thermonuclear Experimental Reactor (ITER) [1], and it is also been used in the number of
current tokamaks such as JET, ASDEX-Upgrade and DIII-D. Electron induced processes are
prevalent in such magnetic fusion devices in a wide range of energies.
We report the results of our recent work on calculation of electron impact ionization cross
sections for Be, W atoms, charged states of Be and W [2-4] and BeH. The status of charged
particle ionization processes from targets with introductory idea about the theoretical
formalism involved will be reviewed and results for the electron impact ionization of
atomic/ionic/molecular targets will be discussed.
References:
[1] G. Federici, Phys. Scr. T 124, 1 (2006).
[2] G. Purohit and D. Kato, J. Chem. Phys. 148, 084307 (2018).
[3] G. Purohit, D. Kato and I. Murakami, Plasma and Fusion Research 13, 3401026 (2018).
[4] G. Purohit and D. Kato, J. Phys. B: At. Mol. Opt. Phys. 51, 135201 (2018).
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PP-01
Gravitational instability of rotating plasma with radiative heat-loss
function and FLR corrections
Sachin Kaothekar1* and R. K. Chhajlani2
1 Department of Physics Mahakal Institute of Technology and Management, Ujjain-456664, (M.P.),
India 2 Retired Professor School of Studies in Physics Vikram University, Ujjain-456010, (M. P.
*email address of the corresponding author:[email protected]
The effect of finite ion Larmor radius (FLR) corrections and rotation on the gravitational
instability and radiative instability of infinite homogeneous plasma has been explored
integrating the consequences of radiative heat-loss function and thermal conductivity. The
general dispersion relation is obtained by means of the normal mode analysis scheme with the
help of appropriate linearized perturbation equations of the problem. These dispersion relations
are further discussed for rotation axis parallel and perpendicular to the magnetic field. Stability
of the medium is argued by applying Routh Hurwitz’s criterion and it is found that Jeans
criterion establishes the stability of the medium. We locate that the presence of radiative heat-
loss function and thermal conductivity amend the fundamental Jeans criterion of gravitational
instability into radiative instability criterion. Numerical computations have been executed to
show the effect of various parameters on the growth rate of the Jeans-gravitational instability.
We find that rotation, and FLR corrections steady the growth rate of the organization in both
the transverse mode and longitudinal mode or propagation. Our result demonstrates that the
rotation, and FLR corrections affect the dens molecular clouds configuration and star
formation.
References [1] S., Kaothekar, G. D., Soni, R. P., Prajapati and R. K., Chhajlani, Astrophys. Space Sci. 361, 204, (2016).
[2] J. S., Dhiman and R., Dadwal, Astrophys. Space Sci. 332, 373-378, (2011).
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PP-02
Ionization cross sections of water molecules impacted by dressed ions
D. Jana1, A. Mondal2 and M. Purkait1*
1Department of Physics, Ramakrishna Mission Residential college, Narendrapur,
Kolkata-700103, India 2Department of Physics, Ramsaday College, Amta, Howrah-711401, India
*mpurkait [email protected]
The investigation of electronic reactions involved in collision between ions and molecules are
of relevance in many areas like plasma physics, astrophysics, medical physics and radio-
biology. In particular, in radiation biology, single electron ionization processes are the main
mechanisms leading to energy loss for swift ions penetrating the living matter at medium and
high impact energies. In the present work, we focus our research on single electron ionization
of water molecule by dressed ions impact using the three coulomb wave (3CW) model [1]. The
3CW model is used to study the variation of double-differential cross sections (DDCS) with
(i) electron emission angle at fixed emission energy and (ii) electron ejection energy at fixed
emission angle. Both the studies consider one electron of the target as active and treat others
to be frozen. Molecular orbital is expressed by linear combination of slater-type atomic orbitals
(STO) [1]. The transition amplitude in prior form is given as
𝑇𝑖𝑓 = ⟨𝜓𝑓|𝑉𝑖|𝜓𝑖⟩; (1)
The perturbation in the initial channel is given by
𝑉𝑖 = 𝑉𝑇𝑃(�� ) + 𝑉𝑃𝑒(𝑠 ); (2)
𝑉𝑃𝑒(𝑠 ) =𝑞
𝑠−
𝑒−𝜆𝑠
𝑠[(𝑍 − 𝑞) + 𝑏𝑠];
(3)
where, b and 𝜆 are variational parameters fixed by the diagonalizing the model Hamiltonian
of the active electronprojectile interaction with respect to Slater basis [2].
Figure 1: DDCS for single ionization as a function of electron emission angle for fixed value
of electron emission energy.
The authors gratefully acknowledge the financial support from the SERB, New Delhi, (No.
CRG/2018/001344).
References [1] A. Mondal, C. R. Mandal, M. Purkait, J. Phys. B: At. Mol. Opt. Phys. 49, 075201 (2016).
[2] M. Das, M. Purkait, C. R. Mandal, Phys. Rev. A 57, 3573 (1998).
[3] C. C. Dal et al., Nucl. Instrum. Methods Phys. Res. B 267, 781 (2009).
[4] C. A. Tachino et al, J. Phys B: At. Mol. Opt. Phys. 47, 035203 (2014).
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PP-03
Atomic-size Fraunhofer-type diffraction for electron capture in
ion-atom collision
S. Samaddar, K. Purkait and M. Purkait*
Department of Physics, Ramakrishna Mission Residential College, Narendrapur,
Kolkata-700103, India *mpurkait [email protected]
The study of electron capture in ion-atom collisions have received a great deal of interest in
both fundamental and applied fields. On the applied side, these collisions are needed in
different fields; such as plasma physics, astrophysics, biophysics and fusion research.
Moreover, charge transfer in ion-atom collision provides much more information about the
fundamental studies of wave property of light which is nothing but diffraction. However, in
atomic collision studies, the interaction region of the target and the incoming projectile is
supposed to be a circular aperture. Thus the Fraunhofer-type diffraction is observed in the
projectile angular-differential cross sections. So the differential cross sections (DCS) for
electron capture is very much important to study the dynamics of ion-atom collision physics.
Recently, for the development of reaction microscope [1], that provides much more capture-
dynamics in different few-body ion-atom collision system by measuring the DCS with very
high precision. Motivated by this experiment, different theoretical models [2,3] have been
developed for understanding the capturedynamics. Therefore, in the center of mass frame, the
DCS for electron capture is given by
𝜎(𝜃𝑃, 𝐸) = (𝑑𝜎
𝑑Ω) =
𝜇𝑖𝜇𝑓𝑘𝑓
4𝜋2𝑘𝑖|𝑇𝑖𝑓
(±)|2,
(1)
and the TCS is given by
𝜎(𝐸) =𝜇𝑖𝜇𝑓𝑘𝑓
4𝜋2𝑘𝑖∫ |𝑇𝑖𝑓
(±)|2𝑑(cos 𝜃𝑃)
+1
−1
, (1)
Where 𝑇𝑖𝑓(±)
is the prior (-) or post (+) form of the transition amplitude and 𝜃𝑃is the projectile
cattering angle. The prior and post form of the transition amplitude may be written as
|𝑇𝑖𝑓(±)
| = ⟨𝜓𝑓−|𝑉𝑖,𝑓|𝜓𝑖
+⟩, (1)
where 𝜓𝑖+i is the initial state which is distorted by the incoming screened projectile.
Figure 1: DCS weighted by sinθ with the projectile scattering angle.
References [1] D. L. Guo et al, Phys. Rev. A 95, 012707 (2017).
[2] S. Halder, A. Mondal, S. Samaddar, C. R. Mandal, M. Purkait, Phys. Rev. A 96, 032717 (2017).
[3] J. W. Gao et al, Phys. Rev. A 97, 052709 (2018).
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PP-04
VUV spectroscopy of ethyl methyl carbonate
A. K. Das1*, S. Krishnakumar1 and B. N. Rajasekhar1
1 Atomic & Molecular Physics Division, Bhabha Atomic Research Centre, Mumbai-400085
Green chemistry [1] promotes use of renewable raw material and energy resources for
production and synthesis of environment friendly biodegradable products and
prevention of waste. Ethyl methyl carbonate (EMC) comes under the category of
carbonate green solvents because of its clean production technology, non-toxicity and
biodegradability. EMC because of its low freezing point (-550C) finds application as
co-solvent in electrolytes used to enhance the low temperature performance of
rechargeable lithium ion batteries down to -400C. It is an asymmetric aliphatic
carbonate; the symmetric ones being dimethyl carbonate [2] and diethyl carbonate [3]
which too used as green solvents along with ethylene carbonate.
Considering the sparse spectroscopic data required for understanding the chemistry of
EMC with lithium ions, experiments have been carried out to obtain electronic excited
state information in gas phase. For this purpose, VUV photoabsorption spectrum of
EMC is recorded using monochromatic synchrotron radiation from Photophysics
beamline [4] at the Indus-1 synchrotron radiation source at RRCAT, Indore [5] in the
wavelength region 1050 Å-1800 Å. In addition, vibrational spectroscopy studies of
EMC are carried out in the 4000-500 cm-1 region to understand energetic of excited
states, energy ordering, assignment and nature of excited states etc. Geometry
optimization and vibrational frequency calculations of neutral and ionized EMC have
been carried out using density functional theory (DFT) method for a variety of basis
sets and correlation functional. The ground state equilibrium structure of EMC belongs
to CS point group. However, the lowest conformer of EMC is trans in nature whereas
for the two symmetric alkyl carbonates, cis-conformer was found to be stable. The
vertical and adiabatic ionization energies of EMC obtained from these simulations are
10.5 eV and 9.92 eV respectively. The highest occupied molecular orbital (HOMO) is
a non-bonding orbital on the oxygen atom of the carbonyl group whereas the lowest
unoccupied molecular orbital (LUMO) is of 3s Rydberg type. Time dependent DFT
(TDDFT) calculations have been performed for the analysis of electronic excited singlet
and triplet states. The valence excitation at 8.3 eV from HOMO-1 to an antibonding
orbital is of highest oscillator strength.
The experimental results and analysis of the VUV absorption spectrum will be presented
along with computational results performed using GAMESS (USA) [6].
References [1] P. T. Anastas, J. C. Warner. Green chemistry: theory and practice; Oxford University Press, New
York, London 1998. [2] A. K. Das, S. Krishnakumar, B. N. Rajasekhar, J Quant Spectrosc Radiat Transfer 217, 116 (2018).
[3] A. K. Das, B. N. Rajasekhar, S. Krishnakumar, J Quant Spectrosc Radiat Transfer 217, 53 (2018).
[4] N. C. Das, B. N. Rajasekhar, S. Padmanabhan, A. Shastri, S. N. Jha, S. S. Bhattacharya, S. Bhat, A. K.
Sinha, V. C. Saini, J Opt 32, 169 (2003).
[5] A. Kalinin, D. A. Banerji, P. R. Hannurkar, M. G. Karmarkar, S. Kotaiah, S. P. Mhaskar, P. K. Nema, S. S.
Prabhu, M. P. Kumar, S. Ramamurthi, Curr Sci 82, 283 (20022).
[6] M. W. Schmidt, K. K. Baldridge, J. A. Boatz, S. T. Elbert, M. S. Gordon, J. H. Jensen, S. Koseki, N.
Matsunaga, K. A. Nguyen, S. Su, T. L. Windus, M. Dupuis, J. A. Montgomery, J Comput Chem 14, 1347
(1993).
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PP-05
Electron impact excitation of singly charged In and Sn ions
Swati Bharti*, Lalita Sharma and Rajesh Srivastava
Indian Institute of Technology Roorkee, Roorkee Uttarakhand, India 247667
Studies on electron impact excitation of singly and multiply charged metal ions are important
for better understanding of atomic structure and have many practical applications in several
research areas including astrophysics, fusion research and material processing techniques. The
observations from Goddard High Resolution Spectrograph (GHRS) aboard the Hubble Space
Telescope (HST) indicate the existence of elements heavier than zinc in the interstellar medium
[1] including In II and Sn II. In II has been the subject of various experimental and theoretical
studies due to its significant presence in interstellar medium and application in solid state
lasers. It is also a good candidate for optical frequency precision. A detailed investigation of
absorption spectra of heavy elements relevant for astrophysical reasons and other plasma
applications shows that SnII has an abundance in interstellar medium [2].
A systematic study of the excitation process requires the knowledge of
accurate dipole transition probabilities or oscillator strength for spontaneous
emission between the various configurations of the ions. Therefore, it is very significant to
improve earlier calculations. A well optimized set of configuration state functions (CSFs) have
been considered for the atomic structure studies of these ions. Theoretical investigation using
the multiconfiguration Dirac-Fock (MCDF) method have been carried out for the 15 lines for
singly charged In ion and 10 fine structure transitions of Sn II, After ascertaining the quality
of the wave function, we carried out the electron impact excitation cross section calculations
using relativistic distorted wave theory. The excitation cross section for InII ion from ground
state configuration 5s2 1S0 to excited state configurations 5s5p and 5s6p and from excited state
configuration 5s5p to 5s6s and 5s5d, from 5s6s to 5s6p, from 5s5d to 5s6p excited state
configuration have been calculated within 20 to 200eV energy range of the incident electron
for 37 transitions. While for Sn II ion transitions from ground state 5s25p to excited state 5s25d,
5s5p2 and 5s26s have been investigated within same range of incident electron energy from 20
to 200eV. The fitted cross section parameters for desired purpose of plasma applications are
also listed for both of the ions considering further implementation.
References [1] J. A. Cardelli, Science 265 209 (1994)
[2] U. L. Sofia, D. M. Mayer and J. A. Cardelli, Astrophys. J, 522, L000 (1999)
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PP-06
Structural, vibrational and electronic spectroscopic study of
7-(4-trifluoromethyl) coumarin acrylamide using experimental and
theoretical methods 1D. Vijay, 2Asim Kumar Das, 2B. N. Rajasekhar and 1†A. Veeraiah
1Molecular Spectroscopy Laboratory, Department of Physics, D.N.R. College (A), Bhimavaram,
India-534202 2Atomic& Molecular Physics Division, BARC, Mumbai, India
†Corresponding author:[email protected]
Understanding photochemical behavior of structural isomers of 7-(4-trifluoromethyl)
coumarin acrylamide” (TFCA) having different properties of consequence in biological
activities demand spectroscopic information of this class of compounds. Barring 67-(4-
trifluoromethyl) coumarin acrylamide” (TFCA) other isomers of HC’s are well studied
spectroscopically. To understand and compare the photochemical activity of TFCA with other
isomers a detailed study of this molecule has been taken up. For this purpose, electronic,
vibrational and structural properties of TFCA have been studied using ultraviolet absorption
and Infrared spectroscopy techniques. Quantum chemical calculations have been performed at
DFT/B3LYP level of theory to get the optimized geometry and vibrational frequencies of
normal modes to support and analyze experimental data. The detailed vibrational assignments
were made on the basis of potential energy distributions. Chemical activity, molecular orbital
energies, band gap and hyper-polarizability information has been computed from quantum
chemical simulations. NBO analysis carried out helped in understanding the stability of the
molecule arising from hyper-conjugative interaction and charge delocalization. UV-Visible
spectrum of the compound recorded in the region 300-600nm helped in obtaining band gap
data of the compound. MolecularElectrostatic Potentials (MESP) plotted and the respective
centers of electrophilic -and nucleophililc attacks were predicted with the help of Fukui
functions calculations. Further, it was observed that the negative electrostatic potential regions
are mainly localized over the oxygen atoms and the positive regions are localized over the
benzene ring. Details of the results and analysis of experimental and theoretical spectroscopy
studies are presented in this paper.
Keywords: 7-(4-trifluoromethyl) coumarin acrylamide” (TFCA) , DFT, FT-IR, FT- Raman,
UV-Vis spectra and MESP,.
Keywords: 7-(4-trifluoromethyl) coumarin acrylamide (TFCA), DFT, FT-IR, UV-Vis Spectra
References:
[1] Marisa Spiniello, Anton Blencowe , Greg G. Qiao, J PolymSci Part A: PolymChem 46: 2422–2432, (2008)
[2] M K Subramanian, P M Anbarasan and S Manimegalai, journal of physics, Vol. 74, No. 5 pp. 845-860,
(2010)
[3] D. Vijay, Y. SushmaPriya, M. Satyavani, Asim Kumar Das, B.N. Rajasekhar, A. Veeraiah,
SpectrochimicaActa Part A: Molecular and Biomolecular Spectroscopy, S1386-1425(19)31321-6, (2019)
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PP-07
Behavior of impurities in radiative improved mode plasmas
of ADITYA-U Tokamak
M. B. Chowdhuri1*, J. Ghosh1, R. Manchanda1, R. L. Tanna1, K. A. Jadeja1, N. Yadava2 , N.
Ramaiya1, S. Patel3, G. Shukla3 , K. Shah3, K. M. Patel1, Tanmay Makwan1 , U. C. Nagora1,
S. K. Pathak1, J. V. Raval1, M. K. Gupta1, M. V. Gopalakrishna1, K. Tahiliani1, Rohit
Kumar1, Suman Aich1, B. V. Nair1, C. N. Gupta1 and ADITYA-U Team1 1Institute for Plasma Research, Bhat, Gandhinagar 382 428, India
2The National Institute of Engineering, Mysuru 570 008, Karnataka, India 3Pandit Deendayal Petroleum University, Raisan, Gandhinagar, 382 007, Gujarat, India
Impurity seeding in the tokamak plasma is done to obtain the improved confinement of the
plasma, which is known as radiative improved (RI) mode and considered as an alternative way
of operation for achieving fusion grade plasma. In this type of plasma operation, large fraction
(50 %) of input power goes to the radiation losses originating due to mid Z impurity seeding.
Not only that, impurity seeding into the tokamak plasma is used for the disruption mitigation
and also to reduce the heat load on the plasma facing components of the tokamak. In ADITYA-
U tokamak, experiments were carried out to obtain RI mode like plasma using neon and argon
gases puffing. It was found that line average electron density, ne and central electron
temperature, Te(0), were increased after the gas puffing. Substantial change in plasma edge
properties was observed with the increase of radiation loss and the reduction of hydrogen
recycling, which led to better plasma confinement. Here, the plasma effective charge, Zeff and
radiative loss play crucial role in to attaining the improved mode in impurity seeded plasma.
Then, the Zeff and radiative loss are studied with respect to various plasma parameters.
Impurities concentration of both intrinsic and those seeded into the plasmas are estimated and
their contributions into the radiation loss and Zeff are investigated. In this presentation, details
on the experiment and obtained results on impurity behavior will be discussed.
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PP-08
Radial profile of visible continuum emission from ADITYA-U tokamak
plasmas
R. Manchanda1*, M. B. Chowdhuri1, J, Ghosh1, N. Yadava2 , N. Ramaiya1, S. Patel3, U. C.
Nagora1, S. K. Pathak1, J. V. Raval1, M. K. Gupta1, K. A. Jadeja, R. L. Tanna, C. N. Gupta
and ADITYA-U Team1 1Institute for Plasma Research, Bhat, Gandhinagar 382 428, India
2The National Institute of Engineering, Mysuru 570 008, Karnataka, India 3Pandit Deendayal Petroleum University, Raisan, Gandhinagar, 382 007, Gujarat, India
The plasma effective charge, Zeff, is needed to be estimated to get an idea of the amount of the
impurity present in the tokamak plasma as the Zeff is one for pure hydrogen plasma and
increases with the presence of impurity. It is usually estimated through the measurement of
bremsstrahlung continuum emission around 536 nm in the visible wavelength range. For this
purpose, some spectroscopic diagnostics has been developed to measure the spatial profile of
visible continuum emission from ADITYA-U tokamak having plasma minor radius of 25 cm.
Here, the collimating beam probe having lens of focal length of 14 mm and diameter of 9 mm
is used to collect a, optical fiber with 1 mm diameter, 0.22 numerical aperture for transporting
and photo multiplier tube detecting the light from tokamak. A multi-channel wavelength
selection system based on multiple lenses, optical fiber and an interference filter having
diameter of 5 cm has been developed to select the required continuum emissions around 536
nm, which is spectral line free region, from many lines of sight passing through the plasma.
The spatial profile of emission has been collected through an indigenously developed double
O-rings based UHV compatible rectangular viewport covering the outer half of the plasma.
This diagnostic enables to measure the emission with a spatial resolution of 2.5 cm and total
eight chords have been employed to get the spatial profile. An Abel like matrix inversion
technique has been used to get centrally peaked radial profile of visible continuum emissions.
In this presentation, details on the diagnostics and initial result will be discussed.
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PP-9
Calculations of total electron impact ionization cross sections for
Fluoroketone and Fluoronitrile
Nirav Thakkar1,*, Mohit Swadia2, Minaxi Vinodukmar3 and Chetan Limbachiya4
1 Sheth M. N. Science College, Patan-384 265 2 HVHP Institute of PG Studies and Research, Kadi-382 421
3V.P. & R.P.T.P. Science College, Vallabh Vidyanagar- 388 120 4Dept. of Applied Physics, The M S University of Baroda, Vadodara- 390 001
We report theoretical results of electron driven processes for fluoroketone (C6F12O and
C5F10O) and fluoronitrile (C4F7N and C3F5N) molecules over a wide energy range from
ionization potential (IP) to 5000 eV. These gases are potential substitutes for SF6 molecules.
The electron impact ionization cross section (Qion) is the key parameter in the simulation of
gas discharges. Moreover, the Qion can be used in the preliminary screening of large scale
alternatives of SF6[1,2]. Recently, these molecules have also gained much attention because of
their low global warming potential (GWP). In industrial applications, while the gases
composed of C5F10O are used to generate gas discharge and low temperature plasmas, in all
such plasmas, ionization caused by the collision between electrons and fluoroketone and
fluoronitrile molecules is one of the fundamental processes. The electron-impact ionization
cross sections (Qion) are required to model the plasma processes and evaluate the insulating,
radiating, or cleaning performance of fluoroketone gases [2]. In order to describe the ionization
processes in various plasmas resulting from these gases, the electron-impact ionization cross
sections (Qion) of fluoroketone (C6F12O and C5F10O) and fluoronitrile (C4F7N and C3F5N) are
calculated by Complex Scattering Potential-ionisation contribution (CSP-ic) method [3,4].
Figure1. Qion for e- C5F10O scattering
We have shown in figure 1 the present Qion for e- C5F10O scattering compared with the data of
Zhong et al [2]. We have also calculated the total inelastic cross sections (Qinel) and summed
of total excitation cross sections (ΣQexc.) using the Spherical Complex Optical Potential
(SCOP) method [3]. We propose to present all the results in detail at the conference.
References [1] Wang, F et al., IEEE Transactions on Dielectrics and Electrical Insulation 26(5), 1693-1700 (2019).
[2] L.Zhong et al., 2018 Plasma Sources Sci. Technol. 27, 095005 (2018).
[3] Limbachiya et al., Mol. Phys. 113 (1), 55-62 (2015).
[4] Vinodkumar et al., Int. J. of Mass Spect. 339, 16-23 (2013).
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PP-10
Ab initio study of structure, spectroscopic constants and thermal
properties of an ozone depleting reaction
Gargi Nandi* and T. K Ghosh
Department of Physics, Diamond Harbour Women’s University
Sarisha, South 24-Pgs, West Bengal-743368, India * [email protected]
Recently, there is a scientific and public interest grown up about the climatic change and there
by the environmental threat on the earth. The key factors responsible for this are the excessive
emission of Carbon Dioxide (CO2), Chloroflurocarbons (CFCs) and halogenated compounds,
which causes depletion of ozone layer in the atmosphere. The stratospheric ozone plays an
important role by absorbing most of the ultraviolet sunlight. Increasing concentrations of
hazardous chemicals, biomass burning, surface pollution and several other factors decrease the
ozone layer in stratosphere in different ways. So, it became an important tusk to find out a
complete phase out of these systems in ozone depletion. One of the ozone depleting reaction
is
X + O3 XO + O2 (X=Cl, Br, I).
However, experimental investigations are available for these systems, theoretical
investigations are limited in literature. In this report, ab initio calculations have been done to
investigate various minimum energy geometries and transition state geometries of this ozone
depleting reaction using an extensive correlation consistent basis set. Geometries and
frequencies have been identified at the MP2 level of theory. The energetics has been studied
at the Configuration Interaction level of theory. Several spectroscopic properties are calculated
and are compared with the available experimental data. IRC calculations are going on to find
the possible reaction pathway.
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PP-11
Dissociation dynamics of multiply charged CO2 under impact of slow and
highly charged ions
S. Srivastav1*, D. Sharma1 and B. Bapat1 1Indian Institute of Science Education and Research, Homi Bhabha Road, Pune 411008
When one or more electrons are removed from a neutral molecule, the molecular ion may
dissociate into its fragments. For the long time, CO2 molecule has been a simple and prototype
system to investigate the triple fragmentation [1-4]. Here, we are studying the triple
fragmentation of CO23+ ion under strong perturbation created by slow and highly charged ions
(HCI). Perturbation strength is parametrized by Sommerfeld parameter which is defined by the
ratio of projectile charge (q) and its velocity (v). Highly charged ions, Ar(1-16)+ with energy
from 5kev/q to 25kev/q, are obtained by newly installed electron beam ion source (EBIS) at
IISER Pune.
Depending on the states accessed by the molecule in perturabtion, molecular ion CO23+ follows
two types of dissociation pathways: ‘concerted’ and ‘sequential’. We separated and studied
these two breakup pathways with the help of Dalitz plot and Newton diagram [1]. We observed
the kinetic energy release (KER) distribution and trying to look at the effect of different
projectile charge and different velocity of projectile on KER. In HCI, capture is one of the
dominant ionization mechanism along with the direct ionization and in principle these two
mechanisms can be tuned by choosing projectile of suitable charge and velocity. We also have
designed cylindrical deflector post collision charge state analyzer to separate these two
ionization mechanisms to further investigate dissociation dynamics of multiply charged
molecular ions.
References
[1] Neumann N, Hant D, Schmidt L. Ph. H, Titze J, Jahnke T, Czasch A, Schoffler M. S., Kreidi K, Jagutzki O,
Schmidt-Bocking H, and Dorner R, Phys. Rev. Lett. 104, 103201 (2010).
[2] Khan A, Tribedi L. C, and Misra D, Phys. Rev. A 92, 030701(R) (2015).
[3] Yan S, Zhu X. L, Zhang P, Ma. X, Feng W. T, Gao Y, Xu, S, Zhao Q. S, Zhang S. F, Guo D. L, Zhao D. M,
Zhang R. T, Huang Z. K, Wang H. B, and Zhang X. J, Phys. Rev. A 94, 032708 (2016).
[4] Tezuka H, Takahashi K, Matsumoto J, Karimi R, Sanderson J H, and Shiromaru H, J. Phys. B 51, 035202
(2018).
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PP-12
Electron beam ion trap/source for ion–molecule collisions in the non-
perturbative regime
B. Bapat1*, D. Sharma1 and S. Srivastav1
1 Indian Institute of Science Education and Research, Homi Bhabha Road, Pune 411008
Among the variety of ion sources, the electron beam ion trap/source, which works on the
principle of magnetic compression of an intense electron beam, creating a significant space
charge potential and enhancing the rate of collisional ionisation, has the advantage of
producing ions with very high charge states at low energies [1]. Low energy, highly charged
projectiles are of great importance in exploring the response of molecules to slow, but heavy
perturbations. The typical ‘interaction time’ of a projectile with a molecule is taken to be a/v,
where a is the nominal size of the molecule and v is the projectile speed. When this time is
comparable to the vibrational time scales of molecules, we move significantly away from the
perturbative regime, requiring the use of non-perturbative quantum mechanical treatments to
predict the outcome of such collisions [2].
To investigate such collisions, one needs projectile energies of the order 10 keV/amu and
variable charge states. These are well provided by an ion source such as EBIS/T, with suitable
acceleration. The source at IISER Pune is based on a thermionic electron emitter and
permanent magnets for compression of the electron beam [3]. The complete source is raised to
a positive potential between 10–30 keV, allowing the extraction of 10–30 keV/q beams. Charge
states upto Ar 16+ can be produced and extracted. The distribution of charge states in the
source/trap can be controlled by changing the conditions in the trap, viz. the electron flux,
electron energy, trapping time and pressure. The trap can be operated in the pulsed mode or a
continuous,‘leaky’ mode. A Wien Filter with an aperture of 1.0 mm is employed to separate
the charge states before the ions enter the beam line. The beamline consists of an einzel lens
and an electrostatic quadrupole deflector, which couples downstream to the collision chamber.
The ion beam crosses an effusive gas jet in the collision chamber. Analysis of the collision
fragments is done by a multi-coincidence of an ion momentum spectrometer. Projectile ions
that have undergone charge change in the collision are separated by a cylindrical sector charge
state analyser. This will be a user facility soon.
References
[1] Donets E D , Rev. Sci. Instrum. 69, 614 (1998).
[2] Lüdde H J, Spranger T, Horbatsch M and Kirchner T , Phys. Rev. A 80, 060702R (2009).
[3] Schmidt M, Zschornack G, Kentsch U and Ritter E, Rev. Scient. Instr. 85 ,02B704 (2014).
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PP-13
Orientation effect in multiple ionisation of OCS under proton and C2+
impact at 50 keV
D. Sharma1*, B. Bapat1, P. Bhatt2 and C. P. Safvan2 1 Indian Institute of Science Education and Research Pune, Homi Bhabha Road, Pune 411008
2 Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067
Under the impact of charged particles, one or multiple electrons can be removed from the target
molecule. Depending on the electronic state of transient molecular ion, it can be stable or
dissociate into it’s fragments. Dissociation of multiply ionised triatomic or large molecules can
proceed via concerted (all the bonds break simultaneously) or sequential (step wise process)
pathways. The method of Newton diagram and Dalitz plot have been widely used [1,2] to
separate the dissociation channels. Recently, a new representation based on angular correlation
of fragments has been used by Rajput et al [3].
Furthermore, the electronic cloud of a molecule is not spherical symmetric. Therefore, in ion-
molecule collisions, the multiple ionisation is expected to depend on the orientation of the
molecule with respect to incident projectile. In recent papers [4,5], we have discussed the
angular distribution of fragments from dissociation of multiply ionised CO molecule. Together
with anisotropy, asymmetry in the distribution was observed, owing to the heteronuclear nature
of CO molecule. Furthermore, it was shown that orientation effect is a function of interaction
strength of the projectile which is parameterized by Sommerfeld parameter k = q/v, where q
and v are the charge and velocity of projectile in atomic units. When a diatomic molecular ion
is formed in a dissociative state, the dissociation products move apart along the straight line
defined by the internuclear axis of the molecule. The orientation of the molecule can be
determined from momentum vectors of fragment ion. The case is simple for two body
dissociation of triatomic molecule, but for three body breakup, the measurement of this angle
is difficult because of the mixing of sequential and concerted channels. Even for a pure
concerted channel, the asymptote angle between the fragments is different from the actual bond
angle of the molecule because of mutual repulsion of the fragments ions.
Here, we present an experimental study of dissociation dynamics of OCS molecule under
proton and C2+ impact at 50 keV such that the interaction strength is 0.70 (k < 1) for proton
and 4.86 (k >1) for C2+. The experiment was performed at low energy ion beam facility
(LEIBF) at Inter University Accelerator Center, New Delhi. For a particular dissociation
channel, angular distribution of the fragments and kinetic energy release has been measured.
Strong orientation effect is observed under proton impact as compare to C2+ impact.
Experimental results are further compared with the case of diatomic molecules and earlier
studies of triatomic molecules.
References
[1] Neumann N, Hant D, Schmidt L P H, Titze J, Jahnke T, Czasch A, Schöffler M S, Kreidi K, Jagutzki O,
Schmidt-Böcking H and Dörner R, Phys. Rev. Lett. 104(10), 103201 (2010).
[2] Khan A, Tribedi L C and Misra D, Phys. Rev. A 96(1), 012703 (2017).
[3] Rajput J, Severt T, Berry B, Jochim B, Feizollah P, Kaderiya B, Zohrabi M, Ablikim U, Ziaee F,Raju P K,
Rolles D, Rudenko A, Carnes K D, Esry B D and Ben-Itzhak I, Phys. Rev. Lett. 120(10), 103001 (2018).
[4] Sharma D, Bapat B, Bhatt P and Safvan C P, Journal of Physics B: Atomic, Molecular and Optical Physics
51, 195202 (2018).
[5] Sharma D, Bapat B, Bhatt P and Safvan C P, Journal of Physics B: Atomic, Molecular and Optical Physics
52, 115201 (2019).
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PP-14
Electron interaction with Para-Benzoquinone(C6H4O2) and
Naphthoquinone(C10H6O2)
Dhaval Chauhan1* and Chetan Limbachiya1
1 The M.S. University of Baroda, Vadodara – 390001
We report theoretical results of electron driven processes for Para-Benzoquinone(C6H4O2) and
Naphthoquinone(C10H6O2) molecules over a wide energy range from ionization potential
(IP) to 5000 eV.
Quinone and its derivatives such as Para-Benzoquinone(C6H4O2) and Naphthoquinone
(C10H6O2) play a vital role in numerous electrochemical reactions for energy transduction and
storage, such processes include respiration and photosynthesis [1]. For example, fast proton-
coupled electron transfer between primary and secondary quinones in green plants triggers the
rapid charge separation of chlorophyll molecules, achieving unparalleled photosynthesis with
near-unity quantum yield. In addition, quinone-rich polymers such as eumelanin and
polydopamine show unique optical and electrical properties (e.g., strong broadband
absorbance or a switching response to external stimuli), mostly arising from their chemically
disordered structures [2]. Understanding the unique features of quinone and its derivatives can
provide solutions to the construction of bio-inspired systems for energy harvesting and
conversion [3,4]. Applications of this, in energy-harvesting and storage systems, such as
artificial photosynthetic platforms, rechargeable batteries, pseudo-capacitors, phototransistors,
plasmonic light harvesting platforms, and dye-sensitized solar cells [4,5].
The present study is aimed to provide reliable elastic, inelastic and ionization cross sections
data for electron scattering from para-benzoquinone and Naphthoquinone which are used in
many electrical and optical properties. So, we employ Spherical Complex Optical Potential
(SCOP) and Complex Scattering Potential – ionization contribution (CSP-ic) methods to study
the electron induced processes [6].
References: [1] D.B. Jones et al, The J. Chem. Phys. 148, 204305 (2018).
[2] D.B. Jones et al, The J. Chem. Phys. 145, 164306 (2016).
[3] B. Huskinson, M. P. Marshak, C. Suh, S. Er, M. R. Gerhardt, C. J. Galvin, X. Chen, A. Aspuru-Guzik, R.
G. Gordon and M. J. Aziz, Nature 505, 195 (2014).
[4] Y. Ding and G. Yu, Angew. Chem., Int. Ed. 55, 4772 (2016).
[5] E. Son, J, Kim, K. Kima and C.Park, J. Mater. Chem. A 4,11179 (2016).
[6] Yogesh Thakar et. al, Planetary and Space science 168,95-103 (2019).
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PP-15
Electron impact elastic scattering cross section from acetylene
Dibyendu Mahato1*, Lalita Sharma1 and Rajesh Srivastava1
1 Department of physics, IIT Roorkee, Uttarakhand, INDIA
Electron scattering elastic cross section data from small hydrocarbon molecule, Acetylene
(C2H2) is very important to understand the plasma and modeling plasma. Also C2H2 is an
important molecule in astrophysics environment. There are few measurements and
theoretical calculations have been reported with different techniques. We have obtained our
e-C2H2 cross section calculation by using an analytic expression of static potential using the
STO-6G Gaussian wave function. We have evaluated the interaction of C-H or H-H by
solving the Gaussian integration through Euler angle rotation for a fixed molecular frame. A
non-relativistic Schrödinger equation has been solved to obtained the e-C2H2 scattering cross
sections. Our DCS results for acetylene are shown in figure 1 and compared with the
available theoretical and experimental results [1,2]. Our results show excellent agreement
with previous experiments and theory.
Figure 1. Electron impact differential cross section from Acetylene for incident electron
energies 80eV (a) and 150 eV(b)
Reference
[1] Song M Y, Yoon J S, Cho H, Karwasz G P, Kokoouline V, Nakamura Y and Tennyson J, J. Phys. Chem.
Ref. Data 46.1, 013106 (2017)
[2] Iga I, Lee M T, Rawat P, Brescansin L M and Machado L E, Eur. Phys. J. D 31, 45 (2004)
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PP-16
Electron impact excitation cross-sections of magnesium for plasma
applications
S S Baghel1*, S Gupta1, R K Gangwar2 and R Srivastava1
1 Indian Institute of Technology Roorkee 2 Indian institute of Technology Tirupati
Electron impact excitation cross-sections has significant application in plasma modelling [1].
In the present work, we calculate the electron impact excitation cross-section of Magnesium
for Plasma applications from its ground state into 34 different energy levels corresponding to
configuration 3s3p, 3s4s, 3s3d, 3s4p, 3s5s, 3s4d, 3s5p, 3s6s, 3s5d, 3s6p and also from levels
of configuration 3s3p into 3s4s, 3s5s, 3s6s, 3s3d, 3s4d, 3s5d for electron energy from threshold
to 500 eV. We use Relativistic distorted wave (RDW) theory for calculation of cross-
sections[2]. The ground and excited states of magnesium is represented through Multi
Configuration Dirac-Fock (MCDF) wave functions and obtained through GRASP2K code[3].
The calculated oscillator strength for various allowed transitions of Magnesium from its
ground as well as excited states is also compared of Magnesium to that of NIST[4].
References [1] Boffard J B, Lin C C and DeJoseph C A, J. Phys. D. Appl. Phys., 37 R143 (2004)
[2] Baghel S S, Gupta S, Gangwar R K and Srivastava R, Plasma Sources Sci. Technol., 28 115010 (2019)
[3] Jönsson P, He X, Froese Fischer C and Grant I P, Comput. Phys. Commun., 177 597 (2007)
[4] Kramida A ., Ralchenko Y, Reader J and Team N A (2018) NIST: Atomic Spectra Database ( version 5.6.1)
NIST At. Spectra Database (ver. 5.6.1), [Online]. Available https//physics.nist.gov/asd [2019, Dec 20]. Natl.
Inst. Stand. Technol. Gaithersburg, MD.
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PP-17
Study of the nature of impurity transport coefficients using separate
atomic databases in the ADITYA tokamak
A. Bhattacharya1,*, J. Ghosh2, M. B. Chowdhuri2, P. Munshi1 and the ADITYA team2
1 Indian Institute of Technology Kanpur, Kalyanpur, Kanpur–208016, Uttar Pradesh, India 2Institute for Plasma Research, Gandhinagar, Bhat–382428, Gujarat, India
Analysis of impurity transport in the tokamak plasma and their contributing factors, through
experiments and modeling, has been an important topic of tokamak research for more than a
decade [1, 2]. Impurity elements are the non–fuel species in tokamak plasma that are mainly
generated towards the plasma boundary, near the wall and limiters/divertors of the system,
which gradually enter into the main plasma and can lead to either radiation losses or plasma
dilution disrupting the tokamak operations. Temporal evolutions and radial distributions of the
impurity ions in tokamak are numerically obtained by solving the radial impurity transport
equation [3]. The radial impurity transport equation for tokamak plasma is a set of non–linear,
parabolic, diffusion–convection–reaction equation, coupled through its source (reaction) term
and the distributions of all ionization states of an impurity element are simultaneously obtained
numerically. A novel approach of numerically solving the radial impurity transport equation
with a semi–implicit method has recently been discussed in literatures [4, 5] and will be
featured in this presentation. The presentation will further show the comparison between the
experimental [6] and simulated radial emissivity profiles of the 650.024 nm (2p3p3D3–2p3d3F4)
O4+ (visible) spectral line for both (inboard/outboard) regions of the ADITYA tokamak (ro=
0.25 m, R= 0.75 m, Bt,o= 0.75 T), installed at the Institute for Plasma Research (IPR)
Gandhinagar, India. The simulated radial (inboard/outboard) emissivity profiles of the O4+
transition have been determined using the (inboard/outboard) O4+ number densities obtained
from the semi–implicit form of the radial impurity transport equation and the 650.024 nm
Photon Emissivity Coefficient (PEC) data from two separate databases namely the Atomic
Data and Analysis Structure (ADAS) database and the National Institute for Fusion Science
(NIFS) database, Japan. The (inboard/outboard) impurity diffusion coefficient, although an
input to the linearized numerical form of the radial impurity transport equation, is also the
outcome of the study and is decided based on the simulated emissivity profiles which best
represents (‘best–fit’) the experimentally obtained (650.024 nm) emissivity data. A difference
in the natures of the radial impurity diffusivity profiles, corresponding to the best–fit simulated
emissivity profiles, is observed when the two separate aforementioned PEC databases are used
[5, 7]. The difference in the radial (inboard/outboard) emissivity profile and thereby the
(inboard/outboard) impurity diffusivity profile occurs due to the differences in the atomic
processes (transitions) considered while calculating the excitation rate coefficients in the two
databases (ADAS and NIFS) [7] and will be addressed in the presentation. Analytical (model–
based) calculations featured in the presentation will further validate the factors contributing to
the anomalous nature of impurity diffusivity conjectured by the simulation profiles
corresponding to the two (ADAS and NIFS) databases.
References [1] C. Angioni et al., Physics of Plasmas 14, 055905 (2007)
[2] B. A. Grierson et al., Physics of Plasmas 22, 055901 (2015)
[3] R. Dux, and A. G. Peeters, Nuclear Fusion 40 (10), 1721–1729 (2000)
[4] A. Bhattacharya, P. Munshi, J. Ghosh, M. B. Chowdhuri, Journal of Fusion Energy 37 (5), 211–237 (2018)
[5] A. Bhattacharya, J. Ghosh, M. B. Chowdhuri, P. Munshi, I. Murakami, and the Aditya team, Plasma and
Fusion Research 14, 1403155 (2019)
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PP-18
C-R model for Ar-CO2 mixture plasma using reliable fine structure
cross sections
Neelam Shukla1, Reetesh Gangwar2 and Rajesh Srivastava1
1Department of Physics, Indian Institute of Technology Roorkee, Roorkee-247667, India 2Department of Physics, Indian Institute of Technology Tirupati, Tirupati-517506, India
The carbon dioxide (CO2) gas plasma are very interesting due to its application in numerous
fields such as plasma polymerization, etching, deposition, etc. In order to achieve efficient
processing in a specific application, it is important to understand the discharge-kinetics by
employing the appropriate diagnostic approach. The inert gas optical emission spectroscopy
approach is very suitable for diagnostic of these plasmas. It can provide information about
electron temperature and density which are key parameters to monitor in any plasma mediated
processing. In this light the Ar is the most preferred choice due to its relatively lower cost.
Moreover the addition of Ar gas in CO2 plasmas also assist in maintaining the discharge at
relatively lower power. It is mainly due to the fact that the ionization energy of Ar is lower
than the CO2 molecules.
However, in order to extract plasma parameters, the OES measurements need to be coupled
with a suitable collisional radiative (CR) model. Using our calculated relativistic cross-
sections, we developed a fine structure resolved CR model for Ar atom. In the present study,
we applied our CR model to study the discharge-kinetics of Ar/CO2 mixture plasma. The OES
measurements are taken from a recent study reported by Martinez et al. [1]. They reported the
OES measurements of Ar/CO2 (20-80%) gas mixture plasma. In the present work, we have
modified our pure Ar inert gas CR model and applied it to study the measurements reported
by Martinez et al. [1]. Previously, we have also extended our model to other inert gas mixture
plasmas [2, 3]. The further modeling results along with discussion shall be presented during
the conference.
References [1] Martinez et. al., J. Phys. D: Appl. Phys. 47, 335206 (2014)
[2] Shivam et al., Spectrochimica Acta part B, 149 203-213 (2018)
[3] Priti et al., J. Quant. Spectrosc. Radiat. Transfer 187, 426 (2017)
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PP-19
Modeling the tunneling reaction 𝑵𝑯𝟐+ + 𝑯𝟐 → 𝑵𝑯𝟑
+ + 𝑯 at interstellar
temperature by variational transition state theory
M. Salvi1*, Raghunath O. Ramabhadran2 and S. Sunil Kumar1
1Department of Physics, IISER Tirupati, Tirupati-517507, Andhra Pradesh, India 2Department of Chemistry, IISER Tirupati, Tirupati-517507, Andhra Pradesh, India
Nitrogen-containing molecules form a class of the key species in the chemistry of the
interstellar medium [1]. The reaction of interest, 𝑁𝐻2+ + 𝐻2 → 𝑁𝐻3
+ + 𝐻, is an important step
in the pathway of gas-phase formation of ammonia by hydrogen abstraction. The current study
contributes to a better understanding of nitrogen chemistry in the interstellar medium. The rate
coefficient for this gas-phase reaction is addressed by using variational transition state theory
(VTST). Møller-Plesset (MP2 & MP2(full)) and coupled cluster single double (CCSD &
CCSD(full)) levels of theory have been employed for the calculation. The study demonstrates
the necessity of incorporating quantum effects such as tunneling and zero-point energy for
modeling the reaction 𝑁𝐻2+ + 𝐻2 → 𝑁𝐻3
+ + 𝐻.
Figure 1. Relative energy diagram of species involved in the reaction calculated in MP2/aug-
cc-pVTZ level of theory.
The computed rate coefficient monotonically decreased from 𝑘𝑁𝐻2+(25 K) = 1.05 ×
10−9 cm3mol−1s−1 to 𝑘𝑁𝐻2+(298 K) = 1.26 × 10−9 cm3mol−1s−1 as temperature is
increased. Comparison of the calculated rate coefficient with the experimentally determined
values [2] confirms that the reaction proceeds by tunneling through a potential barrier.
References [1] Eric Herbst, D J DeFrees, and A D McLean, ApJ 321, 898-906 (1987).
[2] S Rednyk, Š Roučka, A Kovalenko, T D Tran, P Dohnal, R Plašil, and J Glosík, A&A 625, A74 (2019).
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PP-20
Electron scattering from HCNO
Paresh Modak1, Nafees Uddin1,*, and Bobby Antony1
1Indian Institute of Technology (Indian School of Mines) Dhanbad *[email protected]
HNCO is a very interesting target since it contains the four basic life-forming chemical
elements. As such, it has been attracting attention as a possible prebiotic precursor [1] in
formation of the peptide bond. Its presence has been confirmed in a number of interstellar
environments: interstellar clouds [2], young stellar objects [3], molecular outflows [4], and
comets [5]. In the interstellar space, the ultraviolet light, x-rays, and cosmic rays interact with
interstellar icy grains that serve as reservoirs for chemical species, and an avalanche of
secondary electrons is produced. Therefore, the electron-induced processes of this molecule is
of high astrophysical interest. In the present study, we made direct investigation of elastic and
inelastic processes for e-HCNO scattering employing UK R-matrix [6] formalism.
References [1] L. Song and J. Kastner, Phys. Chem. Chem. Phys. 18, 29278 (2016)
[2] B. E. Turner, R. Terzieva, and E. Herbst, Astrophys. J. 518, 699 (1999).
[3] S. E. Bisschop, J. K. Jorgensen, E. F. van Dishoeck, and E. B. M. de Wachter, Astron. Astrophys 465,
913 (2007)
[4] N. J. Rodriguez-Fernandez, M. Tafalla, F. Gueth, and R. Bachiller, Astron. Astrophys 516, A98 (2010).
[5] D. C. Lis, J. Keene, K. Young, et al., Icarus 130, 355 (1997).
[6] L.A.Morgan, J.Tennyson, and C.J.Gillan,Comput. Phys. Commun. 114, 120-128 (1998)
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PP-21
Pulse width effect on the ionization and dissociation of
methyl iodide in the intense femtosecond laser field
Arnab Sen1*, Bhas Bapat1, Ram Gopal2 and Vandana Sharma3 1Indian Institute of Science Education and Research, Pune 411008, India
2Tata Institute of Fundamental Research, Hyderabad 500107, India 3Indian Institute of Technology Hyderabad, Kandi 502285, India
The ionization rate of the diatomic molecule in an intense laser field has been observed to be
enhanced for inter-nuclear separation greater than it’s equilibrium bond length ’RE’. This
specific inter-nuclear separation is known as ’critical’ bond length ’Rc’, where the HOMO
(Highest occupied molecular orbital) and LUMO (Lowest unoccupied molecular orbital) starts
to overlap in the presence of the laser field [1]. Previous results on diatomic molecules showed
that the typical ’Rc’ could be two to three times greater than the ’RE’. Several experiments
have been performed on diatomic molecules to understand the ionization mechanism and the
dissociation dynamics by changing various parameters such as intensity, pulse width of the
laser field. It has been observed that enhanced ionization dominates for larger pulse duration
(~ 100fs) and suppressed for few-cycle pulses (~ 10fs), as the molecular ion does not have
sufficient time to reach ’Rc’ within the duration of the pulse. To follow the appearance of the
enhanced ionization and investigate its molecular origin, it would be better to vary the pulse
duration from few-cycle to multi-cycle regime. Few experiments of this kind have been done
for diatomic molecules and small polyatomic molecules having simple geometry, such as CO2
[1], which has a linear molecular geometry. For polyatomic molecules with critical geometry
the ionization mechanism and dissociation pathways remain matter of interest. Here in this
work we have irradiated intense (~ 1012 W/cm2) laser pulse of 800nm on CH3I molecule,
which has a tetrahedral geometry. We have varied the pulse width from 25fs to 1200fs to
understand the ionization mechanism and the dissociation pathways in a systematic manner.
Being a large molecule the vibrational time period of the C-I bond is quite large(~100fs), so
we can easily consider the C-I bond to be frozen for the pulse duration of 25fs. We have used
velocity map imaging techniques [3] to collect all the fragmented ions. Here we have closely
looked into the fragments originating from the ’Coulomb Explosion’ pathways, such as from
CH3I++ → CH3+ + I+ and CH3I+++ → CH3
+ + I++. Coulomb explosion in molecules is extensively
studied to understand different dissociation pathways and to reconstruct the molecular structure
at the moment of the explosion. The measured kinetic energy of the fragmented ions
originating from Coulomb explosion processes has been observed to decrease with increasing
pulse duration, which is a clear indication of increasing bond length. Molecules in laser field
undergo rotation and align itself along the laser polarization axis, it is known as dynamical
alignment. The observed angular distribution of the fragmented ions confirms the ’dynamical
alignment’ and with increasing pulse width molecules become more aligned. Interestingly, we
have also seen C+, CH+ and CH2+ fragments in coincidence with I+ and I++, and the yield of C+,
CH+ and CH2+ fragments increase with increasing pulse duration. From the kinetic energy
distribution of these fragments we can confirm they are coming from further dissociation of
CH3+. The possible reason for increasing further dissociation of CH3
+ fragment could be due
to the increasing geometric distortion on the molecular ion as it gets aligned with increasing
pulse width.
References [1] Bocharova. Irina, Karimi. Reza, Penka. Emmanuel F.,Brichta. Jean-Paul, Lassonde. Philippe, Fu. Xiquan,
Kieffer. Jean-Claude and Bandrauk, Andr´e D. and Litvinyuk. Igor, Sanderson, Joseph, L´egar´e,
Franc¸ois, Phys. Rev. Lett. 107, 063201 (2011).
[2] Zuo, T. and Bandrauk, A. D., Phys. Rev. A 52, R2511 (1995).
[3] Gopal,R. and Sen,A. and Sahu,S. R. and Venkatachalam,A. S. and Anand,M. and Sharma,V., Review
of Scientific Instruments 89, 086107(2018)
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PP-22
Double slit projectile wave interference at slow and intermediate
electron transfer collisions
Md A. K. Azad Siddiki1, Nrisimhamurty Madugula2, M.A. Rehman1, M.R. Chowdhury1,
L.C. Tribedi1 and Deepankar Misra1*
1Tata Institute of Fundamental Research, Mumbai-400005, India 2 University of Florida, FL 32611, USA
We have performed a series of electron capture experiments for various low projectile
velocities (vp) ranging between 0.35 a.u. and 1 a.u. with diatomic molecules like H2, N2 and
O2, using COLd Target Recoil Ion Momentum Spectroscopy (COLTRIMS) [1]. The
measurements are carried out at the Electron Cyclotron Resonance Ion Accelerator (ECRIA)
facility [2], TIFR. The prime focus of these experiments is to investigate the fundamental
concept of wave-particle duality at high perturbation regime. The very small de Broglie
wavelength (λdB ~ 10 fm) corresponding to incoming projectile wave scatters on both the
centres of the target molecules. During capture there is a change in de Broglie wavelength
which manifests the interference effect. The molecular dissociation happens in tens of
femtoseconds compare to molecular rotation which is in picoseconds. Therefore, the axial
recoil approximation is valid during dissociation. The quantum mechanical interference effects
are manifested, in the present experiment, as the variations of transfer excitation cross sections
with respect to the molecular orientations. This can be modelled as follows [3, 4]:
,
where A and V are free parameters. Here, δϕ is the phase shift between two projectiles de
Broglie waves which interact with both the molecular centres. Details of the measurements
will be presented.
References [1] Arnab Khan et al, RSI 86(4):043105 (2015).
[2] A. N. Agnihotri et al, Phys. Scr. T 144, 014038 (2011).
[3] H. T. Schmidt et al, PRL 101, 083201 (2008).
[4] D. Misra et al, PRL 102, 153201 (2009).
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PP-23
Mercury hydroxide as a promising triatomic molecule to probe P, T-odd
interactions
R. Mitra1,2, V. S. Prasannaa1* and B. K. Sahoo1, X. Tong2, M. Abe3 and B. P. Das4
1 Atomic, Molecular, and Optical Physics Division, Physical Research Laboratory, Navrangpura,
Ahmedabad-380009, India 2 Indian Institute of Technology Ganhinagar, Palaj, Gandhinagar-382355, India
3Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan-430071, China 4Department of Chemistry, Tokyo Metropolitan University, Tokyo-1930397, Japan
5Department of Physics, Tokyo Institute of Technology, Tokyo-1528550, Japan
In the quest to find a favourable triatomic molecule for detecting the parity- and time-reversal
violating electric dipole moment of an electron (eEDM), we identify mercury hydroxide
(HgOH) as an extremely attractive candidate from both experimental and theoretical
viewpoints. Our calculations show that there is a four-fold enhancement in the effective electric
field of HgOH as compared to the recently proposed ytterbium hydroxide (YbOH) [1] for
eEDM measurement. Thus, in the (010) bending state associated with the electronic ground
state, it could provide better sensitivity than YbOH from a theoretical point of view. We have
also investigated the potential energy curve and permanent electric dipole moment of HgOH,
which lends support for its experimental feasibility. Moreover, we propose that it is possible
to laser cool the HgOH molecule by adopting the same technique as that in the diatomic polar
molecule, HgF, as shown in [2].
References [1] I. Kozyryev, and N. R. Hutzler, Phys. Rev. Lett. 119, 133002 (2017). [2] Z. Yang, J. Li, Q. Lin, L. Xu, H. Wang, T. Yang, and J. Yin, Phys. Rev. A 99, 032502 (2019).
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PP-24
Electron interaction with Fluorocompounds for application in plasma
sciences
Smruti Parikh1* and Chetan Limbachiya1 1 The M.S. University of Baroda, Vadodara-390 001
Studies on collisions of electrons with various radicals and molecules have remained an
important subject of interest since long. Interest in these collisions arises in view of the
applications of relevant cross-section data in various pure and applied sciences [1,2]. Electron
induced ionization and other processes determine the density and reactivity of low-temperature
technological plasmas. In general the electron induced processes, including ionization as a
dominant inelastic channel at intermediate and high energies, play important roles in plasma
processing, aeronomy and in biological systems. Electron-impact cross sections for molecular
targets, including their radicals, are important in developing plasma reactors and testing
various plasma processing gases [3]. The aim of this effort is to build the quantitative analysis
for electron interaction processes with molecules relevant to plasma processing, such as CFx
(x=1 to 4), C2F4, C3F8, C3F6, C6F6, etc.
We report study on various total cross-sections for collisions of electrons in the energy from
threshold to 5000 eV for these plasma molecules. Spherical complex optical potential (SCOP)
formalism [4] is employed to evaluate total elastic cross-section,Qel and total cross-section, QT.
Total ionization cross sections, Qion, are derived from total inelastic cross sections, Qinel, using
our complex spherical potential – ionization contribution (CSP-ic) method [5].
References
[1] N.J. Mason, J.M. Gingell, N.C. Jones, L. Kaminski, Phil. Trans. R. Soc. Lond. A 357, 1175 (1999).
[2] H. Deutsch, K. Becker, S. Matt, T.D. Maerk, Int. J. Mass Spectrom, 197, 37 (2000), and references therein.
[3] J. -S. Yoon, M. J. Brunger et. al., Journal of Physical and Chemical Reference Data 39, 033106 (2010).
[4] Yogesh Thakkar et. al., Planetary and Space science 168,95-103(2019).
[5] K. N. Joshipura and N. J. Mason, Cambridge University Press, (2019).
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PP-25
A comparative analysis of non-relativistic and relativistic calculations of
electric dipole moments and polarizabilities of heteronuclear alkali dimers
R. Mitra1,2, V. S. Prasannaa1* and B. K. Sahoo1 1 Physical Research Laboratory, Atomic, Molecular and Optical Physics Division, Navrangpura,
Ahmedabad-380009, India 2 Indian Institute of Technology Gandhinagar, Palaj, Gandhinagar-382355, Gujarat, India
We analyze the molecular electric dipole moments (PDMs) and static electric dipole
polarizabilities of heteronuclear alkali dimers in their ground states by employing coupled-
cluster theory, both in the non-relativistic and four-component relativistic frameworks. The
roles of electron correlations as well as relativistic effects are demonstrated by studying them
at different levels of theory, followed by a comprehensive treatment of error estimates. We
compare our obtained values with the previous non-relativistic calculations, some of which
include lower-order relativistic corrections, as well as with the experimental values, wherever
available. We find that the PDMs are sensitive to relativistic effects, as compared to
polarizabilities. We show that consideration of relativistic values of PDMs improves
significantly the isotropic Van der Waals C6 coefficients of the investigated alkali dimers over
the previously reported non-relativistic calculations. The dependence of dipole
polarizabilites on molecular volume is also illustrated.
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PP-26
Characterizing Laguerre-Gaussian pulses using angle-resolved attosecond
streaking
Irfana N. Ansari1*, Deependra S. Jadoun1 and Gopal Dixit1*
1 Department of Physics, Indian Institute of Technology Bombay, Mumbai, India
* [email protected], [email protected]
Light can carry orbital angular momentum, along with the spin angular momentum, due to
their spatial structure. The presence of this extra angular momentum has been exploited
extensively such as for nanoparticle trapping, quantum state engineering in Bose-Einstein
condensates, and chiral recognition in molecules. Here, we have proposed a method to directly
characterize the orbital angular momentum of the Laguerre-Gaussian (LG) pulse. The
technique, called as attosecond streaking, involves photo-emission of an electron from the
hydrogen atom by XUV- LG pulse, which are then deflected in angular spatial directions by
circularly polarized IR pulse. We have shown that the units of orbital angular momentum
present in LG pulse is directly reflected in the angle-resolved streaking spectra.
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PP-27
Theoretical investigation of various inelastic processes of e-CO2 scattering
S. Vadhel1, M. Vinodkumar2 and P. C. Vinodkumar1
1 Department of Physics, Sardar Patel University, Vallabh Vidyanagar, Gujarat, India 2 V. P. & R. P. T. P. Science College, Vallabh Vidyanagar, Gujarat, India
Carbon dioxide (CO2) is vital component of planetary atmosphere and is found in abundance
particularly in the atmosphere of Venus and Mars. On the contrary, even though the
concentration of CO2 in earth’s atmosphere is small, it is the most noteworthy greenhouse gas
on Earth’s atmosphere. Electron impact scattering study of CO2 is widely used in gaseous
discharges or low-temperature plasma devices and in CO2 laser etc. Because of its importance
it has been studied both theoretically [1] as well as experimentally [2].
In the present work, we compute electron impact collision cross sections for e-CO2 scattering
over a wide range of impact energies starting from 0.01 eV to 5000 eV. Such a wide energy
range encompasses many interaction phenomenon which are predicted in terms of quantitative
cross sections. Since a single theoretical formalism is insufficient for modelling all these
phenomenon, we have used unification of two theoretical methods viz. R-matrix [3] and
spherical complex optical potential (SCOP) methods [4, 5]. The detailed results will be
presented in the conference.
Acknowledgement: Mr. Sagar Vadhel and Dr. Minaxi Vinodkumar acknowledges DST-SERB, New
Delhi for major research project [EMR/2016/000470] for financial support under which part of this
work is carried out.
References [1] Yukikazu Itikawa, J. Phys. Chem. Ref. Data 31, 749 (2002)
[2] Czeslaw Szmytkowski, Antonio Zecca, Grzegorz Karwasz, Stefan Oss, Krzysztof Maciggt, Bratislav
MarinkoviC, Roberto S Brusa and Rolly Grisenti, J. Phys. B: At. Mol. Phys. 20, 5817-5825 (1987)
[3] J. Tennyson, Phys. Rep. 491, 29 (2010)
[4] M. Vinodkumar, H. Desai, P. Vinodkumar. RSC Adv 5(31), 24564 (2015)
[5] Minaxi Vinodkumar, Chetan Limbachiya, Hardik Desai and P. C. Vinodkumar, Phys. Rev A 89, 062715
(2014)
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PP-28
Relativistic coupled-cluster calculations of electric dipole polarizability of
Al and In
Ravi Kumar1 and B. K. Mani1
1 Department of Physics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi, India.
High precision calculation of electric dipole polarizability, α, plays important role in the study
of optical properties of materials, atom-electron scattering, interatomic potential, collision
induced spectral shifts, atomic clocks, and discrete symmetry violations [1-5]. Accurate
theoretical data of α for open-shell atomic systems is rare due to complicated electron
correlations and relativistic effects. In this context, we have developed methods based on
perturbed relativistic coupled-cluster (PRCC) theory for the properties calculation of one-
valence atoms or ions which accounts for electron correlation effects to all orders in
perturbation. In this work, we employ this method to calculate α for the ground states (p1/2 and
p3/2) of Al and In atoms. Results from this study will be useful in developing the new frequency
standards and will also provide important inputs to discrete symmetry violating atomic
experiments.
References
[1] T. M. Miller and B. Bederson, Adv. At. Mol. Phys. 13, 1 (1977).
[2] T. M. Miller and B. Bederson, Adv. At. Mol. Phys. 25, 37 (1988)
[3] D. P. Shelton and J. E. Rice, Chem. Rev. (Washington, D.C.) 94, 3 (1994).
[4] K. D. Bonin and V. V. Kresin, Electric-Dipole Polarizabilities of Atoms, Molecules and Clusters (World
Scientific, Singapore, 1977).
[5] M. S. Safronova, U. I. Safronova and S. G. Porsev, Phys. Rev. A 87, 032513 (2013).
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PP-29
Ion-pair dissociation dynamics in electron collision with
carbon dioxide probed by velocity slice imaging
Narayan Kundu*, Anirban Paul and Dhananjay Nandi
Indian Institute of Science Education and Research Kolkata, Mohanpur, WB-741246.
In low-energy electron-molecule interaction, dissociative electron attachment (DEA:
energy ≤ 15 eV) and ion-pair dissociation (IPD: 15 eV ≤ energy ≤ 100 eV) are the two well
established inelastic phenomena. IPD occurs when the incident electron partially transfers its
kinetic energy to the molecule and leaves it to one of the neutral super-excited ion-pair states
which ultimately dissociates into a cation and an anion. The dissociation dynamics of these
super-excited states with internal energy greater than the first ionization potential energy of
that particular molecule in the ionization endurance are much different from those of the lower
ordinary states excited below about ionization thresholds [1] and such states can be accessed
by either electron or photon collisions with the isolated molecules.
In electron collision with CO2 the ion-pair states can give rise to momentum matched anion
and cation products,
Figure 1. (a) Ion yield curve of O-/CO2, (b) Velocity slice image at 25 eV incident electron
energy & (c) Kinetic energy distributions of O- ions at different incident electron energies.
Only O- formation channel has been studied using time of flight (TOF) mass spectroscopy
in combination with the highly differential velocity slice imaging (VSI) technique. The ion
yield curve (1.a) of O-/CO2 shows that the threshold energy value of IPD is about 17.2 eV
which matches well with thermo-chemically obtained value (18.06 eV) [2]. The VSI (1.b) at
25 eV incident electron energy dictates that most of the O- ions are produced near zero kinetic
energy. No additional variation in kinetic energy distributions (1.c) of O- ions at different
incident electron energies demand only one major process is involved for anion formation. To
study the symmetry of associated ion-pair states, angular distribution (AD) of O- ions are fitted
using the formula given by Van Brunt [3]. Two ion-pair states π and Ʃ have been identified
based on best fitting of AD measurements.
References [1] Y. Hatano, Journal of Electron Spectroscopy and Related Phenomena.119, 107 (2001).
[2] Erman, Karawajczyk and Rachlew-K, Chem. Phys. Lett. 215, 173 (1993).
[3] R. J. Van Brunt, J. Chem. Phys. 60, 3064 (1974).
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PP-30
Differential cross section for positron-biomolecules interaction
Nidhi Sinha* and Bobby Antony
Atomic and Molecular Physics Lab, Department of Physics,
Indian Institute of Technology (ISM) Dhanbad, India
In recent years medical sciences have seen increasing use of positrons in their diagnostic
techniques. Most popular among these methods are positron emission tomography (PET) [1]
and positherapy [2]. Positron-biomolecule interaction thus becomes important and calls for a
proper investigation on such systems, especially in the low energy region. In this work we have
picked two important molecules, pyridine and pyrimidine. Differential cross section (DCS) for
these molecules are presented at different energies ranging from 1 to 20 eV.
Figure 1. Differential cross section of pyrimidine at 1 eV and 20 eV. Solid line:present
results and spheres: Palihawadana et al. [4]
For the present calculations, spherical complex optical potential (SCOP) formalism [3] is used
to compute the differential elastic cross section. Considering the molecular nature of the target
we have adopted effective potential method (EPM) to encompass the molecular structure in
our computations. This approach is introduced for the first time in our work and as can be seen
from figure 1 gives excellent results even at lowest impact energies. Under this approach we
have generated the molecular potential by adding the potential from various scattering centers
available in the molecule. Partial wave analysis is then done to compute the desired cross
section. SCOP method is well known for producing reliable results at intermediate to high
energies. However, modification of SCOP with EPM have extended this range in the low
energies as well. For pyridine no previous data was found for DCS, while for pyrimidine
experimental cross section of Palihawadana et al. [4] are available. The experimental data is
reported for six different energies and present results show very good agreement at each
energy.
References [1] J. Hooker and R. Carson, Annu. Rev. Biomed. Eng. 21, 551-581 (2019).
[2] R. M. Moadel, R. H. Weldon, E. B. Katz, P. Lu, J. Mani, M. Stahl, M. D. Blaufox, R. G. Pestell, M. J.
Charron, and E. Dadachova, Cancer Res. 65, 698–702 (2005).
[3] N. Sinha and B. Antony, J. App. Phys. 123, 124906 (2018).
[4] P. Palihawadana, R. Boadle, L. Chiari, E. Anderson, JR. Machacek, M. Brunger, S. Buckman, J. Sullivan,
Phys Rev A 88(1), 012717 (2013).
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PP-31
Quantum coherence in dissociative electron attachment: isotope effect
S. Swain1, E. Krishnakumar2 and V. S. Prabhudesai1*
1 Tata Institute of Fundamental Research, Mumbai 400005 India 2 Raman Research Institute, Bengalure 560080 India
Dissociative electron attachment (DEA) to H2 has shown the generation of quantum coherence
among negative ion resonances as manifested in the inversion symmetry breaking in the
angular distribution of the H ion [1]. This asymmetry in the angular distribution shows an
isotope effect. The resonant electron attachment to D2 shows the directionally preferred anion
ejection but the overall asymmetry is different in comparison to its lighter isotope (H2). This
is attributed to different dissociation time, which affects the relative phase of two interfering
channels as well as their amplitudes. Conventionally, HD has been treated as a heteronuclear
diatom as the two isotopes have different masses making the center of mass of the molecule
displaced from the midpoint. This is also seen as the energy difference in the dissociative
ionization [2] as well as anion dissociation limits. In such a scenario, what happens to the
interference observed in DEA?
We have measured the velocity slice images (VSI) [3] of H− & D− arising from DEA to HD
around the 14 eV resonance. Both the anions show asymmetry in the angular distribution which
are identical. The backward anion ejection is preferred over the forward one with respect to
the incident electron direction. The asymmetry increases with increase in electron energy.
From this result we confirm that the incident electron is unable to distinguish between H and
D atom of HD molecule and it behaves like a homonuclear diatom.
Figure 1. Velocity sliced images of H− & D− from DEA to HD at 14.5eV electron energy.
In this poster we will describe our results and compare them with those from H2 and D2.
References [1] E. Krishnakumar, V. S. Prabhudesai, N. J. Mason, Nat. Phys. 14, 149 (2018).
[2] E. Charron, A. Giusti-Suzor, F. H. Mires, Phys. Rev. Lett. 75, 2815 (1995).
[3] D. Nandi, V. S. Prabhudesai, E. Krishnakumar, A. Chatterjee, Rev. Sci. Instrum. 76, 053107 (2005).
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PP-32
Angular distribution of H- from dissociative electron attachment to H2 at
10eV
S. Swain1, E. Krishnakumar2 and V. S. Prabhudesai1*
1 Tata Institute of Fundamental Research, Mumbai 400005 India 2 Raman Research Institute, Bengalure 560080 India
Dissociative Electron Attachment (DEA) to H2 is important to astrophysics [1] as well from
basic electron collision point of view. It has been studied by many groups over several decades
in terms of absolute cross section and angular distributions. Three distinct peaks [2] have been
obtained in DEA to H2 at 4eV, 10eV and 14eV. They are identified as due to i) the lowest
attractive ground X2Ʃu+ anion state (4eV process), ii) the repulsive B2Ʃg
+ state (7-13eV process)
and iii) coherent contribution from 2Ʃg+ and 2Ʃu
+ states (14eV process). The 4eV and 14 eV
processes are extensively studied by many groups in terms of absolute cross-section and
angular distribution as the anion fragments are having less kinetic energy (<1eV). The 4eV
resonance is found to show strong temperature dependence [3]. The DEA signal at 14eV is
found to show signature of coherent superposition of two resonances [4] of opposite parity.
The resonance around 10 eV appears as a broad peak due to a steep slope of the potential
energy curve of the underlying anion state in the Frank-Condon region. This resonance
dissociates into H− (1s2) and H (n=1). As the threshold for this dissociation channel is around
3.75eV, the kinetic energies of H– resulting from this resonance ranges from 1.5 – 4.5eV. M
Tronc et al. [5] have measured the angular distribution using conventional turn table technique
in limited angular range. Measuring the angular distribution using recently developed VSI
technique for such a fast moving light ions is a challenge as the measurements are carried out
in the presence of transverse magnetic field used for collimating the electron beam. We have
carried out these measurements using our recently developed VSI spectrometer [6] and figure
1 shows one such VSI image.
Figure 1. Velocity Sliced Images of H− from DEA to H2 at 10eV.
In this poster we will report the kinetic energy and angular distributions of the H− ions
obtained for this resonance in detail.
References [1] S. C. Glover, D. W. Savin, A. K. Jappasen, Astrophys. J. 640, 553 (2006)
[2] E. Krishnakumar, S. Denfl, I. Cadez, S. Markelj, N. J. Mason, Phys. Rev. Lett. 106, 243201 (2011).
[3] M. Allan, S.F. Wong, Phys. Rev. Lett. 41, 1791 (1978).
[4] E. Krishnakumar, V. S. Prabhudesai, N. J. Mason, Nat. Phys. 14, 149 (2018).
[5] M. Tronc, F. Fiquet-Fayard, C Schermann, J. Phys. B: At. Mol. Phys. 10, 305 (1977).
[6] K. Gope, V. Tadsare, V.S. Prabhudesai, E. Krishnakumar, Euro. Phys. J. D. 71, 323017 (2017)
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PP-33
Electron ionization cross sections of C2H4 molecule
Pawan Kumar Sharma1* and Rajeev Kumar2
1Research Scholar, Department of Physics, D. J. College, Baraut, Baghpat, Uttar Pradesh, India
250611 2Asst. Prof. Department of Physics, D. J. College, Baraut, Baghpat, Uttar Pradesh, India-250611
1*[email protected],[email protected]
In this paper we have investigated partial and total electron impact ionization cross sections of
C2H4 molecule [1] by using modified Jain-Khare semi-empirical approach Partial integral
ionization cross sections corresponding to various cations formed during the electron impact
shows good agreement with available data and sum of all partial ionization cross sections give
us total ionization cross sections that again show good agreement with available data. Besides
integral ionization cross sections, first time we have evaluated partial and total single
differential cross sections, and double differential cross sections for the ionization of C2H4
molecule [2]. No other results are available for single differential cross sections and double
differential cross sections to compare the present results calculated.
References [1] Toshio IBUKI, Glyn COOPER and C.E. BRION, J. Chemical Physics 129, 295-309(1989)
[2] Rajeev Kumar, Journal of Applied Mathematics & Physics, 3,1671-1678(2015)
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PP-34
Laser cooling and trapping of neutral 87Rb atoms
Raj Kumar, Neeraj Singh, Anju Pal, Navpreet Kaur and Ajay Wasan*
Department of Physics, Indian Institute of Technology Roorkee, India
We demonstrate ongoing experiment to construct a laser cooling and trapping system which
consists three pairs of orthogonally intersecting counter-propagating laser beams and a pair
of anti-Helmholtz coil, i.e., magneto-optical trap (MOT), in which atoms are trapped where
magnetic field is zero. The installation of the MOT system is mainly divided into two
categories, vacuum system installation and optical components arrangement setup. Once the
atomic cloud of 87Rb atoms are produced, we have used two types of imaging techniques for
characterizing the atomic cloud. The first technique is the fluorescence imaging for MOT
loading measurement and second is the absorption imaging for number density and
temperature of atomic cloud measurement.
Figure 1. Schematic diagram of MOT and atomic cloud.
The number of atoms in the trap N = (1.04 ± 0.27) × 106 and the trap volume V = (2.98 ± 0.3)
× 10-2 mm3. The temperature of atomic cloud is T = 128 ± 24 µK. In future, we will trap single
Rb atoms for Quantum Computing.
References [1] L. Isenhower, E. Urban, X. L. Zhang and M. Saffman, Phys. Rev. Lett. 104, 010503 (2010).
[2] J. Dalibard and C. Cohen-Tannoudji, J. Opt. Soc. Am. B 6 (11), 2023-2045 (1989).
[3] P.D. Lett, R. N. Watts, W. D. Phillips and H. J. Metcalf, Phys. Rev. Lett. 61 (2), 169 (1988).
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PP-35
Angle dependence of WES photoionization time delay from
atoms trapped in a negatively charged cage
S. Banerjee1,* and P. C. Deshmukh2
1Department of Physics, Indian Institute of Technology Madras, Chennai, Tamil Nadu 600036, India
2Department of Physics, Indian Institute of Technology Tirupati, Tirupati, 517506, India *[email protected]
The dynamics of electrons inside atoms and molecules can now be understood in time-domain
due to developments in ultrafast laser technology over the last decade. Techniques like
RABBITT, attoseconds streaking, attoclock etc. have enabled researchers to look into detailed
dynamics of the photoionization process on the attosecond time scale. The theory of time delay
was developed by Wigner [1], Eisenbud [2], and by Smith [3] in the context of potential
scattering. Photoionization, being considered as half scattering process [4], can also be dealt
with applying the same theory. The Wigner-Eisenbud-Smith (WES) photoionization time
delay, being the energy derivative of phase of the complex photoionization matrix element,
provides significant information about electron correlations in the atomic system. The time
delay spectrum carries prominent signatures near Cooper minima [5], autionization resonances
[6] etc. The present study aims at investigating the WES time delay and its angle dependence
for the photoionization from the outer subshells of noble gas atoms confined inside anionic
fullerene cage. Endohedral fullerenes, being the nanoformations of interest in basic and applied
sciences, are important candidates for spectroscopic studies, which has motivated this work. A
few reports on the time delay for photoionization from confined atom [7] and endohedral
anions [8] are available. The present work reports angle dependence of the WES time delay in
the photoelectron yield from such systems.
References [1] E. P. Wigner, Phys. Rev. 98, 145 (1955).
[2] L. Eisenbud, The Formal Properties of Nuclear Collisions, Ph.D. thesis, Princeton University (1948).
[3] F. T. Smith, Phys. Rev. 118, 349 (1960).
[4] P. C. Deshmukh, D. Angom and A. Banik, Invited article in DST-SERC-School publication (NAROSA),
9-28 (2011).
[5] S. Saha, A. Mandal, J. Jose, H. R. Varma, P. C. Deshmukh, A. S. Kheifets, V. K. Dolmatov and S. T.
Manson, Phys. Rev. A 90, 053406 (2014).
[6] P. C. Deshmukh, A. Kumar, H. R. Varma, S. Banerjee, S. T Manson, V. K. Dolmatov and A. S. Kheifets,
J. Phys. B 51, 065008 (2018).
[7] P. C. Deshmukh, A. Mandal, S. Saha, A. S. Kheifets, V. K. Dolmatov and S. T. Manson, Phys. Rev. A
89, 053424 (2014).
[8] A. Kumar, H. R. Varma, P. C. Deshmukh, S. T. Manson, V. K. Dolmatov and A. Kheifets, Phys. Rev. A
94, 043401 (2016).
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PP-36
Theoretical investigation on electron impact with halogen diatomic
molecule X2 (X = F, Cl, Br, I)
Hitesh Yadav1*, Minaxi Vinodkumar2, Chetan Limbachiya3 and P. C. Vinodkumar1
1 Department of Physics, Sardar Patel University, Gujarat, India - 388120 2 Electronics Department, V. P. & R. P. T. P. Science College, Gujarat, India – 388120
3 Department of Applied Physics, The M. S. University Baroda, Gujarat, India - 390002
Halogens are reactive species; hence their experimental investigation is difficult and involves
large uncertainty [1]. Halogen atoms together with their diatomic molecule play an important
role in variety of physical and chemical processes such as plasma physics, troposphere
chemistry etc. Thus, the theoretical study plays an important role in the case of halogen
molecules.
Literature survey [2-4] reveals that electron impact scattering on F2, Cl2 has been extensively
studied at low to intermediated energy range up to few hundred eV only. But the study related
to Br2 and I2 are rare and only one or two cross-sections on electron impact is reported [2].
Also, the total scattering cross section of these diatomic halogens are very limited. In this
scenario, we try to provide the theoretically estimated cross-sections on electron impact with
these halogen molecules from 0.1 eV to 5000 eV, using two different theoretical formalisms:
1) R-matrix via Quantemol-N [5] which uses the UK based R-mol codes for low energy (0.1
eV to 20 eV) and 2) Spherical Complex Optical Potential (SCOP) formalism [6] for cross-
sections beyond the ionization threshold of the respective target to 5000 eV.
Figure 1. Total scatting cross section of Cl2 molecule.
In figure 1. we present a sample result for the total scattering cross section of Cl2 molecule
starting from 0.1 eV to 5000 eV. The present result qualitatively represents the earlier reported
data, but it overestimates the low energy cross section below 5 eV. And beyond 5 eV the
present result is in overall in good agreement with the data available in the literature. The detail
analysis of the work will be presented at the conference.
Dr. Minaxi Vinodkumar acknowledges DST-SERB, New Delhi for Major research project
[EMR/2016/000470] for financial support under which part of this work is carried out.
References [1] T. R. Hayes, R. C. Wetzel and R. S. Frund, Phys. Rev. A 35, 578 (1987).
[2] G. Raju (2012). Gaseous Electronics. Boca Raton: CRC Press, https://doi.org/10.1201/9781315217437
[3] L. G. Christophorou and J. K. Olthoff, J. Phys. Chem. Ref. Data, 28, 131-169 (1999).
[4] Gregório and Pitchford, Plasma Sources Sci. Technol. 21, 032002 (2012).
[5] H. Yadav, M. Vinodkumar, C. Limbachiya and P. C. Vinodkumar, J. Phys. B: 51, 045201 (2018).
[6] H. Yadav, H. Bhutadia, D. Prajapati, H. Desai, M. Vinodkumar and P. C. Vinodkumar, AIP Conference
Proceedings 1953, 140106 (2018): doi: 10.1063/1.503328.
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PP-37
Dissociative electron attachment dynamics to nitrogen dioxide
Anirban Paul1,2, Dipayan Biswas1 and Dhananjay Nandi1*
Indian Institute of Science Education and Research Kolkata.
Mohanpur, WB-741246
Dissociative electron attachment (DEA) and ion pair dissociation (IPD) are two low-energy
electron-molecule collision processes producing anionic fragments. DEA is a two-step
resonant process predominantly observed in case of low-energy (~0-15 eV) electron collision
with molecules. In the first step incoming electron is attached with the parent molecule forming
a temporary negative ion (TNI) that may dissociate into fragments in the second step.
𝑨𝑩 + 𝒆− → (𝑨𝑩−)∗ → 𝑨 + 𝑩−
We are studying dissociative electron attachment to Nitrogen dioxide (NO2) that plays an
important role in upper atmosphere, as the main source of Ozone in troposphere. It is also the
precursor of nitric acid.
Abouaf et al.[1] reported three DEA peaks of O- ion at 1.8, 3.5 and 8.5eV in dissociative
electron attachment to NO2. Using a velocity slice imaging (VSI) spectrometer we have
measured the angular distribution and kinetic energy distribution of O- ions formed at around
~8.5eV resonance peak.
(a) (b) (c)
Fig. 1. (a) Velocity slice image at 8.6eV incident electron energy (b)kinetic energy distributions
of O- ions at different incident electron energies and (c) Angular distribution of O- ion at 8.6eV
incident electron energy.
We have found that most of the O- ions around this DEA peak are produced with very low near
zero kinetic energy. We have also measured the angular distribution of the O- ions and fitted
the curve with the formula given by Ram [2] and the best fit is observed for A1 B2 transition.
References [1] R. Abouaf, R. Paineau, F. Fiquet-Fayard, J. Phys. B: Atom. Molec. Phys. 9, 303-314 (1976).
[2] N. B. Ram, Dissociation dynamics in polyatomic molecules due to electron attachment, Tata Institute of
Fundamental Research (PhD thesis, 2010).
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PP-38
Initial results from the 22-pole ion trap experimental set-up
Roby Chacko1, N. R. Behera1, S. Dutta1 and G. Aravind1*
1 Dept of Physics, Indian Institute of Technology Madras, Chennai - 600036
An experimental setup using 22-pole radio-frequency (RF) ion trap [1] has been developed,
which can be used to study ion interactions at low temperature and low-density regime. Two
different types of ion sources are employed for ion production. These are, Electron-impact ion
source (EIS) [2] and pulsed supersonic expansion plasma ion source. The former is found to
be more efficient compared to the later. Both positive and negative ions are produced via
electron-impact ionization and secondary electron attachment, respectively, using EIS. The
ions are perpendicularly extracted using a beam-bender and guided into the quadrupole mass
spectrometer (QMS) for the mass selection. Mass spectra of both positive and negative ions
from ionized SF6 gas are observed. We used Helium as a carrier with a small admixture of
CH3I to produce negative ions via dissociative electron attachment, using EIS. The mass
spectra of the same are also observed. We have built our own 22-pole RF trap, mounted next
to QMS, to trap ions. Eventually, we have successfully trapped positive ion fragments of SF6
gas at room temperature. In this poster, we shall represent the first mass spectra, produced
using EIS and results of trapping of positive ions fragments ionized SF6 gas. The experiments
to be done in future shall be discussed in the same poster.
Negative ion mass spectra obtained with ionized SF6 gas
References [1] D. Gerlich, Phys. Scr. T59, 256-263 (1995).
[2] L. G. Christophorou (Ed.). Electron-Molecule Interactions and Their Applications (Vol. 1).
Academic Press. p. 6-11. (1984).
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PP-39
Study of reaction kinetics of O + XO → X + O2
S. Naskar* and T. K. Ghosh
Department of physics, Diamond harbour women’s University
Sarisha; D.H. Road; South 24 Parganas; West Bengal- 743368. India
Ab initio calculation have been performed to investigate the reaction kinetics of the ozone
depleting reaction O + XO → X + O2. The atmospheric ozone plays a beneficial role by
absorbing ultraviolet rays coming from the sun. The excessive emission of green house gases
like carbon dioxide (CO2), chloroflurocarbons (CFC) etc. are responsible for ozone depletion
in atmosphere and thereby causing global warming, several hazardous effects on human being
and climate worldwide.
One of the important ozone depleting reaction is
O + XO → OXO or XOO
→X + O2 (X= Cl, Br, I)
We investigate various minimum energy geometries, transition state geometries, of the above
ozone depleting reaction O + XO → X + O2 from theoretical point of view. Using an extensive
correlation consistent basis sets geometries and frequencies have been obtained at the Moller-
Plesset perturbation theory (MP2). QCISD(T) method is used to obtained the energy value.
The spectroscopic properties of different species are calculated and compared with the
available data. To know details about these complexes and their effectiveness in ozone
depletion layer, our data may be helpful.
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PP-40
Spectroscopic properties of divalent lead halides
S. Ghosh# and T. K. Ghosh
Department of Physics, Diamond Harbour Women’s University
Sarisha, DH Road, South 24-Pgs, West Bengal-743368, India #[email protected]
For a long time, there is a scientific interest about the divalent Lead halides (PbX2; X=F, Cl,
Br & I) because of their useful applications due to high ionic conductivity in the development
of semiconductor devices, discharge lamps etc. They are used in infrared devices because they
have good application potentials and large diffraction efficiency. PbF2 plays an importance role
in therapeutic application & it is useful because of its transparent nature. In fabrication of
extremely efficient solar cell PbI2 is a pioneer material. In high-energy photon detector for
gamma rays & X-rays, PbI2 is used due to its wide band gap. PbCl2 and PbBr2 have strong
application potential and so they are used specially in infrared devices. The decomposition
effect of lead halides are used in photographic processes because they are decomposed by light
at high temperature.
In this article, Ab initio calculations are done to pursue minimum energy geometries, vibration
frequency, dissociation energies and various spectroscopic properties of divalent lead halides
(PbX2; X=F, Cl, Br & I) using an extensive basis set. The structural parameters and vibrational
frequencies have been studied at the MP2 level of theory. Energy values are obtained at the
QCISD(T) level of theory at their MP2 optimized geometry. Theoretical calculations of these
systems are limited, because of the concerned heavy atoms. From this perspective, our
computed data may deliver information in future.
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PP-41
Camphor doped helium nano-droplets in soft X-ray radiation
S. Sen1†, S. Mandal2, R. Gopal3, R. Richter4, M. Mudrich5, V. Sharma1# and S. Krishnan6* 1 Indian Institute of Technology Hyderabad, Kandi 502285, India
2 Indian Institute of Science Education and Research, Pune 411008, India 3 Tata Institute of Fundamental Research, Hyderabad 500107, India
4 Elettra-Sincrotrone Trieste, Basovizza, 34149 Trieste, Italy 5 Department of Physics and Astronomy, Aarhus University, 8000 Aarhus C, Denmark
6 Indian Institute of Technology Madras, Chennai 600036, India †[email protected] #[email protected] *[email protected]
Helium nano-droplets has been widely used for spectroscopic studies of doped
atomic/molecular species, as it is a weakly interacting matrix for the dopant [1]. In this work,
we studied the interaction of Camphor, an interesting volatile compound, doped helium nano-
droplets with monochromatic soft X-ray radiation (synchrotron radiation) around the C 1s
edge. The photo-electrons and photo-ions generated are studied with coincidence time-of-
flight mass spectrometry (PEPICO) and velocity map imaging(VMI) techniques.
Preliminary analysis suggests, that although the fragmentation pattern of the Camphor
molecule is similar to the previously reported study [2], the ratio of larger fragments is
enhanced in case of the droplets as compared to the gas phase fragmentation. Further, the
photo-ion energy spectra suggest that there is a mass dependent relative decrease in the energy
and the velocity of fragments ejected from droplets from the corresponding gas phase
fragment, as has been previously reported for the SF6 molecule [3,4].
Figure 1. a] Mass spectrum of Camphor doped He nano-droplet and gas phase Camphor.
b] Photo-fragment Energy spectra of gas-phase and droplet specific Camphor fragments.
References [1] D. Buchta et al, J. Phys. Chem. A 117, 4394−4403 (2013).
[2] R.B. de Castilho et al, Rapid Commun. Mass Spectrom. 28, 1769–1776 (2014).
[3] D. S. Peterka et al, J. Phys. Chem. B 110, 19945-19955 (2006).
[4] A. Braun and M. Drabbels, J. Chem Phys. 127, 114303 (2007).
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PP-42
Significance of dynamic quadrupole polarizabilities on the determination
of magic wavelengths of the clock transitions in the alkaline-earth metal
ions
Mandeep Kaur1, Sumeet1, B K Sahoo2 and Bindiya Arora1
1 Guru Nanak Dev University, Amritsar, Punjab-143005, India.
2 Atomic, Molecular and Optical Physics division, Physical Research Laboratory, Navrangpura,
Ahmedabad -380009, India
The role of dynamic quadrupole polarizabilities in the accurate determination of magic
wavelengths of the clock transitions in Ca+, Sr+ and Ba+ alkaline-earth metal ions is
investigated. The scalar and tensor components of dynamic polarizabilities were obtained
using the sum-over-states approach, for which a large number of electric quadrupole matrix
elements were obtained by employing relativistic coupled-cluster theory. The deviations in
these magic wavelengths from our earlier reported values in [1-3], that were evaluated
accounting only for the dynamic dipole polarizabilities in the above clock transitions, are
reported. These changes are shown with reference to small and large applied electric field-
gradients in the experiments. Additional magic wavelengths are revealed when the ratio of the
electric field-gradient to electric field strength exceeds 0.1 in atomic units. Based on these
findings, we propose the use of high electric field-gradient for strong optical trapping of the
aforementioned alkaline-earth metal ions.
Figure 1. Total dynamic polarizability of the ground state and metastable 3D5/2 state for
Ca+ ion. The crossings of curves for two states represent the Magic Wavelengths.
References
[1] J. Kaur, S. Singh, B. Arora, B. K. Sahoo, Phys. Rev. A 92, 031402® (2015). [2] S. Singh, M. Kaur, B. Arora, B. K. Sahoo, Phys. Rev. A 98, 013406 (2018). [3] B. Arora, B. K. Sahoo, Phys. Rev. A 86, 033416 (2012).
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PP-43
Electron impact ionization cross section of atoms and molecules using
binary-encounter-Bethe model
Piyush Sinha1,* and Shivani Gupta
1Dept. of Physics, HNB Garhwal University, BGR Campus, Pauri
Many frontier areas of research such as material analysis, environmental protection, radiation
science, atmospheric physics, plasma diagnostics and astrophysics require data of electron
impact ionization cross section of molecules. Many experimentalists and theoreticians have
compiled the inner shell ionization cross sections data of different molecules by electron
impact. Kim et al had proposed a Binary Encounter Dipole (BED) and Binary Encounter Bethe
(BEB) models to calculate theoretically the electron impact ionization of atoms and molecules.
The approach has proved to be quite successful for the inner shell ionization cross section of
atoms and molecules. The analytical formula of BEB model employs a scaling term involving
the energy of incident particle, binding energy of the target and the kinetic energy of the target.
In the present investigation we have modified the said scaling term and have computed the K-
shell ionization cross sections of various atoms and molecules by electron impact. The results
in the form of the ratios of K-shell ionization cross section to the total ionization cross section
of the molecules in the energy range up to 5000 eV and for atoms up to 1 GeV have been
compared with the available experimental data which show satisfactory agreement.
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PP-44
Photoelectron velocity map imaging spectroscopy facility for probing
astrophysical anions
Saroj Barik and G. Aravind*
Department of Physics, Indian Institute of Technology Madras, Chennai, India
We have successfully built and tested a photoelectron velocity map imaging spectroscopy
setup in our lab. A supersonic discharge ion source employed to produce different kind of
negative ions. The ions are perpendicularly extracted and mass separated by a linear time of
flight mass spectrometer. The desired anion is photo detached in source region of VMI which
is achieved by synchronizing the laser with the anion of interest. The photo detached electrons
are extracted by VMI electrodes which are detected by a position sensitive detector. From the
observed data we can extract the kinetic energy and angular distribution of ejected
photoelectrons. The setup is calibrated using iodine and oxygen anions. We are performing
photoelectron spectroscopy on couple of astrophysical molecules. The result will be presented
in the conference.
Figure 1. Photoelectron spectra of oxygen anion obtained with 355nm photon.
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PP-45
Probing molecular chirality via laser-induced electronic fluxes
Sucharita Giri1,2 , Alexandra Maxi Dudzinski2,3,
Jean Christophe Tremblay2,4 and Gopal Dixit1,*
1 Department of Physics, Indian Institute of Technology Bombay, Mumbai 400076 India 2 Institut für Chemie und Biochemie, Freie Universität Berlin, 14195 Berlin, Germany
3 Institut NEEL CNRS/UGA UPR2940, 38042 Grenoble cedex 9, France 4 Laboratoire de Physique et Chimie Théoriques, CNRS-Université de Lorraine, 57070 Metz, France
The present work focuses on understanding the conditions required to modify the chirality
during ultrafast electronic motion by bringing enantiomers out-of-equilibrium. Different
kinds of ultrashort linearly-polarised laser pulses are used to drive an ultrafast charge
migration process by the excitation of a small number of low-lying excited states from the
ground electronic state of S- and R-epoxypropane. Control over chiral electron dynamics is
achieved by choosing the different orientations of the linearly polarised pulse. We find that
chirality breaking electric fields are only possible in oriented molecules, and that charge
migration remains chiral when the polarisation of the field lies in the mirror plane defining
the enantiomer pair, or when it is strictly perpendicular to it. Ultimately, the presence or the
absence of a mirror symmetry for the enantiomer pair in the external field determines the
chiral properties of the charge migration process.
Figure 1. (a) Charge distribution difference and (b) corresponding electronic fluxes (blue arrows)
for both the S- and R-enantiomers during field-free charge migration, at different times after the laser
pulse linearly polarized in the yz-plane.
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PP-46
Penning spectroscopy of ionic molecular cluster in He nanodroplets
Suddhasattwa Mandal1*, Ram Gopal2, Robert Richter3, Marcello Coreno3, Alessandra
Ciavardini3, Alessandro D’Elia4, Bhas Bapat1, Marcel Mudrich5, Vandana Sharma6 and
Sivarama Krishnan7#
1 Indian Institute of Science Education and Research Pune, Pune – 411008, Maharashtra, India 2 Tata Institute of Fundamental Research Hyderabad, Hyderabad – 500107, Telangana, India
3 Elettra-Sincrotrone Trieste, Strada Statale 14-km 163.5, 34149 Basovizza, Trieste, Italy 4 University of Trieste, Department of Physics, 34127 Trieste, Italy
5 Aarhus University, 8000 Aarhus C, Denmark 6 Indian Institute of Technology Hyderabad, Sangareddy – 502285, Telangana, India
7 Indian Institute of Technology Madras, Chennai – 600036, Tamil Nadu, India
* [email protected] # [email protected]
He nanodroplets are traditionally used as nanoscale-sized sub-Kelvin cryostats for hosting
foreign atoms and molecules for high-resolution spectroscopy over a wide spectral range from
infrared to vacuum ultraviolet, where the host He matrix remains transparent to these
radiations. However, when being photoexcited to 1s2p droplet excitation band by 21.6 eV
photon, the host He droplets can ionize the embedded species through inter-atomic relaxation
process known as Penning ionization. We have used this Penning ionization in He droplet to
study the electronic structure and ionization dynamics of ionic molecular cluster of RbI, doped
in He droplet by employing electron-ion coincidence technique using a velocity map imaging
and time of flight spectrometer, operating in tandem. Penning ionization of RbI is evident from
the ion-yield curve of RbI+ as a function of photon energy shown in Fig.1.
Figure 1. RbI+ ion-yield as a function of photon energy. The shaded yellow band shows the
1s2p droplet excitation band.
Although, recent report with acene doped He droplet [1] suggested Penning electron
spectroscopy may be inefficient in revealing the electronic structure of the dopant due to
scattering of Penning electrons with the droplet environment, similar study with acetylene
doped droplet by our group [2] shows otherwise. This work with RbI dopant affirms Penning
electron spectroscopy as a useful spectroscopic tool to investigate the quantum structure of the
dopant in He nanodroplet.
References [1] M. Shcherbinin et al., J. Phys. Chem. A 122, 1855−1860 (2018)
[2] S. Mandal et al [under preparation]
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PP-47
Electron interactions with plasma processing gases
Rakesh Bhavsar1,*, Yogesh Thakar1 and Chetan Limbachiya2
1M.N. College, Visnagar-384315, Gujarat, India. 2The M.S. University of Baroda-390001, Vadodara, Gujarat, India.
*E-mail: [email protected]
We have computed inelastic, ionization and excitation cross sections for plasma processing
gases such as TiClx , x = 1,2,3,4[1-2] from ionization threshold to 5 keV. Here we have used
Spherical Complex Optical Potential (SCOP) [3] to compute total inelastic cross sections Qinel
and have used Complex Scattering Potential – ionization contribution (CSP-ic)[4] model to
compute total ionization cross sections Qion and summed total excitation cross sections ∑Qexc.
Comparison of our results are done with available experimental as well as theoretical results
and noticed good agreement wherever available. Total excitation cross sections are presented
first time.
References [1] V. Tarnovsky, R. Basner, M. Schmidt, K. Becker, Int. J. Mass Spectrom 208, 1-5(2001).
[2] R. Basner, M. Schmidt, K. Becker, V. Tarnovsky, H.Deutsch, Thin solid Films 374, 291-297(2000).
[3] M. Swadia et al., Molecular Physics 115, 2521-2527 (2017).
[4] Y. Thakar et al., Planetary and Space Science 168, 95-103(2019).
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PP-48
Design of a Penning trap setup for lifetime studies of metastable states in
atomic ions Deepak Chhimwal1*, S. Kumar2, L. Nair1, W. Quint3, C.P. Safvan2 and M. Vogel3
1 Jamia Millia Islamia University, Jamia Nagar, New Delhi
2 Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 3GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany
In this abstract, we present the design of a compact open-endcap cylindrical Penning trap with
permanent magnets as a tool for enabling isolation and manipulation of the charged particles
from an ECR ion source in a well-controlled environment in order to study the lifetime of the
forbidden metastable transitions in highly charged atomic ions example 2P1/2 state of F-like
Ar9+. The proposed experimental setup will allow to benchmark corresponding radiative
lifetime measurements with high significance and with broad range of ion species.
Figure 1. Left: Sectional view of the setup with cryogenic and Penning trap at the centre.
Right: Penning trap assembly with trap electrodes and magnet for ion
confinement.
The experimental setup consists of a mechanically compensated open-endcap cylindrical
Penning trap with an additional capture electrode on either ends. It has an inner radius of
ρ0=4.5mm half endcap separation of z0=3.7mm and gap size between ring and endcap electrode
of zg=0.5mm. We chose specific value of ρ0/z0=1.22mm [1] to make the anharmonic
coefficient of trap potential C4 zero. The electrical insulation between electrodes is provided
by sapphire rings and sapphire blocks. One of the endcap electrodes is split into two segments
to allow magnetron cooling and also for ion cyclotron frequency detection. The Ring segment
is equipped with two, diametrically opposite 3.5 mm holes for detection of fluorescence light.
The complete electrode stack is mounted on three parallel rods. The trap is placed at the
magnetic field centre of a permanent-magnet assembly. The permanent magnet (REM NdFeB)
provides the field strength of the order of 1T for operation of the trap in an appropriate way
[2]. Measurements show that the magnetic field in the region of ± 2.5mm around the trap centre
has homogeneity better than 1%. The trap itself and its cryo-electronics are cooled to liquid
helium temperature by the helium cryo-cooler which maintains 10 K at the magnet, the trap
and the attached electronics as shown in figure 1.
References [1] Sugam Kumar etal, Phys. Scr. 94, 075401 (2019)
[2] V. Gomer etal, Appl. Phys. B 60, 89 (1995)
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PP-49
Electron and positron impact ionization cross sections of nitrogen
molecules
Kamlesh Kumar Jat1 and Ghanshyam Purohit1*
1 Department of Physics, University College of Science, Mohanlal Sukhadia University,
Udaipur-313001, India
*[email protected], [email protected]
Ionization of targets such as atoms, ions, and molecules by charged projectiles such as
electrons/positrons has been studied from a long time and has various applications; few may
be listed as diagnostics of fusion plasmas, modeling of physics and chemistry related to
atmosphere, understanding the effect of ionizing radiation on biological tissues etc. The
detailed information about this kind of collision processes are obtained from the triple
differential cross sections (TDCS) obtained through the coincidence study, which has been of
interest since the pioneering work of Ehrhardt group [1]. Coincidence study of TDCS has been
of particular interest since it provides full information about the collision dynamics and
momentum vectors of all the free particles involved in the ionization are determined.
Good amount of ionization cross section studies have been reported for the atomic targets [2].
From last decade the molecular targets have also been studied for the ionization processes [2,
3] as well as electron momentum spectroscopy studies [4]. We report the results of our recent
work on calculation of electron and positron impact ionization cross sections based on distorted
wave Born approximation formalism (DWBA) for N2 molecules [5]. We will review briefly
the status of charged particle ionization processes from nitrogen molecules in different
geometrical and kinematical conditions. We will discuss the salient features of TDCS which
are projectile charge dependent.
References [1] H. Ehrhardt, K. H. Hesselbacher, K. Jung, and K. Willmann, J. Phys. B 5, 1559 (1972).
[2] D. H. Madison and O. Al-Hagan, J. At. Mol. Opt. Phys. 2010, 367180 (2010).
[3] E. Ali, K. Nixon, A. J. Murray, C. G. Ning, J. Colgan and D. Madison, Phys. Rev. A 92, 042711 (2015).
[4] N. Watanabe, S. Yamada and M. Takahashi, Phys. Chem. Chem. Phys. 20, 1063 (2018).
[5] G. Purohit and D. Kato, J. Phys. B: At. Mol. Opt. Phys. 51, 135202 (2018).
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PP-50
Electron induced processes on plasma relevant materials – Be and W
atoms
Kailash Chandra Dhakar and Ghanshyam Purohit*
Department of Physics, University College of Science, Mohanlal Sukhadia University, Udaipur-
313001, India
*[email protected], [email protected]
The ionization cross sections are essential in the modeling of plasma in fusion research.
Beryllium (Be) is one of the materials which is directly exposed to the plasma components in
the International Thermonuclear Experimental Reactor (ITER) [1]. Formation of gas-phase
Be in various charge states and of hydrides of Be, takes place when the erosion of Be walls
occurs in contact with the hot plasma containing hydrogen and its isotopes. Electron collision
processes on the beryllium and its charged states play an important role in the fusion edge and
diverter plasmas. The tungsten (W) and tungsten based materials have also been recommended
as one of the materials to be used as plasma facing components for the International
Thermonuclear Experimental Reactor (ITER) [1], and it is also been used in the number of
current tokamaks such as JET, ASDEX-Upgrade and DIII-D. Electron induced processes are
prevalent in such magnetic fusion devices in a wide range of energies.
We will review and discuss electron induced processes on Be and W atoms. Total cross
sections have been reported for the Be and W atoms and their charged states [2-5]. We will
report the electron impact total cross sections for Be and W atoms in this communication [6].
The cross sections have been calculated in the distorted wave approximation using potential
generated by Hartree-Fock methods [7-8].
References [1] G. Federici, Phys. Scr. T 124, 1 (2006).
[2] J. Colgan, S. D. Loch and M. S. Pindzola, Phys. Rev. A 68, 032712 (2003)
[3] S. D. Loch, J. A. Ludlow, M. S. Pindzola, A. D. Whiteford and D. C. Griffin, Phys. Rev. A 72, 052716 (2005).
[4] M. S. Pindzola, S. D. Loch and A. R. Foster, J. Phys. B: At. Mol. Opt. Phys. 50, 095201 (2017).
[5] F. Blanco, F. Ferreira da Silva, P. Limao-Vieira and G. Garcia, Plasma Sources Sci. Technol. 26, 085004
(2017).
[6] G. Purohit, D. Kato and I. Murakami, Plasma and Fusion Research 13, 3401026 (2018).
[7] R. D. Cowan, The Theory of Atomic Structure and Spectra (University of California Press, Berkeley, 1981).
[8] A. Bar-Shalom et al., J. Quant. Spec. Radiat. Transf. 71, 169 (2001).
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PP-51
Exploring quasi molecular phenomenon using heavy ion heavy atom
collisions
R. Gupta1,2, C. V. Ahmad1,2, K. Chakraborty1,2, D. Swami3, G. Sharma4 and P. Verma1*
1 Department of Physics, Kalindi College, University of Delhi, New Delhi-110008 2 Department of Physics and Astrophysics, University of Delhi , New Delhi-110007
3 Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi-110067 4Department of Physics, Government Engineering College, Ajmer, Rajasthan-305001
During a close and adiabatic heavy ion heavy atom collision, with a decrease in inter-nuclear
distance, the inner shell electrons adjust continuously and adiabatically to the combined time
varying two center nuclear potential of the collision partners. A transient collision molecule or
quasi-molecule is formed for the inner shell electrons during the collision. Such a quasi-
molecule has a united atomic charge ZUA=Z1+Z2 (subscript 1 for projectile and 2 for target)
and if Z1 and Z2 are such that ZUA ≥ 100, superheavy elements can be explored [1,2].
Investigation of projectile energy and target thickness dependence of inner shell ionization
cross sections of 73≤Z2≤83 targets irradiated by 70-120 MeV Agq+ (5≤q≤12) ions have been
recently performed using the 15UD Pelletron at Inter University Accelerator Centre (IUAC),
New Delhi. The collision induced X-Rays from both collision partners were measured using
solid state detectors (see Figure 1). X-Ray energy shifts and altered intensity ratios, indicating
the presence of spectator vacancies, have been observed giving evidence of multiple ionization
of target atoms [3,4]. Additionally, X-Ray production cross sections and target to projectile
intensity ratios have shown enhancements when observed as a function of target atomic
number Z2. These observations can be understood qualitatively within the framework of quasi
molecular phenomenon [1,2]. This considers formation of transient quasimolecules, for the
inner shell electrons during the collision, with united atomic number 120≤ZUA≤130 for the
present collision systems, such that the inner shells of the collision partners become coupled
to each other through correlations with energy levels of corresponding ZUA. These have been
studied using diabatic correlation diagrams for Ag-Z2 (73≤Z2≤83) combinations to understand
the experimental observations.
Figure 1. X-Ray spectrum of 120 MeV Ag9+ on 50 µg/cm2 Au target.
References
[1] J. S. Greenberg et al. High-Energy Atomic Physics—Experimental. In: Bromley D.A. (eds) Treatise on
Heavy-Ion Science. Springer, Boston, MA (1985).
[2] P. Verma et al., NIM B 245, 56–60 (2006); Rad. Phys. and Chem. 75, 2014–2018 (2006); Phys. Scr. T144,
014032 (2011).
[3] W. Uchai et al., J. Phys. B: At. Mol. Phys. 18, L389-L390 (1985).
[4] P. Verma et al., Physica. Scripta. 61, 335 (2000); J. Phys.: Conf. Ser. 875, 092029 (2017).
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PP-52
Detailed collisional radiative model for laser produced Zn plasma
Shivam Gupta1*, Reetesh Kumar Gangear2 and Rajesh Srivastava1
1 Department of Physics, Indian Institute of Technology Roorkee, Roorkee, India 2 Department of Physics, Indian Institute of Technology Tirupati, Tirupati, India
An intricate collisional radiative (CR) model is developed including all the important processes
for the laser induced zinc plasma. The electron impact excitation and de-excitation of several
fine structure levels of Zn play a dominant role in the laser induced plasma and their cross-
sections are needed. In view of this, an extensive calculation is performed to obtain the electron
impact excitation cross-sections of the large number of fine structure transitions of zinc atom.
The cross-sections of Zn are calculated and presented for the excitations from its ground state
4s2 (J=0) as well as from the 4s4p excited state to the various fine structure levels of different
excited states using fully relativistic distorted wave theory. In the calculation relativistic multi-
configuration bound target atomic wave functions are obtained through GRASP2K program
using 4s2, 4s4p, 4s5s, 4s5p, 4s4d, 4s6s, 4s6p, 4s5d, 4s7s and 4s7p configuration state functions
while the projectile incident and scattered electron distorted wave functions are obtained by
solving the relativistic Dirac equations. Further, the calculated cross-sections are incorporated
in the CR model for the plasma characterization as the various rate coefficients are linked
through their corresponding cross-sections. The model gives the state population distribution
of the fine structure energy levels of the neutral Zn atom considered in the model and from
which the intensities of the line emissions are obtained. The calculated intensities from the CR
model for the four emission lines (334.5 nm, 468 nm, 472 nm, and 481 nm) are matched with
the spectroscopic measurements [1] and the plasma parameters viz. electron density (ne) and
electron temperature (Te) are evaluated. The plasma parameters are calculated at different
ambient pressures in the range of 0.05–10 Torr [2].
References [1] N Smijesh, Reji Philip, J Appl Phys 114, 093301, (2013).
[2] S. Gupta, R. K. Gangwar, R. Srivastava, Plasma Sources Sci Technol 28, 095009 (2019).
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PP-53
Saturated absorption spectroscopy of molecular iodine for frequency
stabilization of 739 nm laser
Lakhi Sharma1, 2, A. Roy1, 2, S. Panja1, 2 and S. De3,*
1 CSIR- National Physical Laboratory, Dr. K. S. Krishnan Marg, New Delhi-110012, India 2 Academy of Scientific and Innovative Research (AcSIR), Ghaziabad-201002, India
3 Inter-University Centre for Astronomy and Astrophysics, Post Bag 4, Ganeshkhind, Pune-411007,
India
Frequency stabilization of lasers is essential in many atomic, molecular and optical physics
experiments. Our experiment aims at developing a singly trapped, laser cooled Ytterbium ion
(171Yb+) based optical frequency standard at 467 nm. Ion cooling is obtained by driving the 2S1/2 ↔
2P1/2 transition using 369.5 nm (νC) beam which is obtained from a second harmonic
generation (SHG) laser at fundamental frequency of 739 nm. Additionally, νC + 2.1 GHz and
νC + 14.7 GHz are also used in the process. For probing the said transition, the 739 nm laser
therefore has to be frequency stabilized which is done with respect to molecular iodine (I2)
reference. In this work, we discuss the saturated absorption spectroscopy (SAS) of I2 for
stabilization of the 739 nm ECDL laser. The SAS optical set-up is shown in Figure 1(a). On
focusing counter-propagating pump and probe beams of power 10.6 mW and 1.5 mW
respectively into a 30 cm long Iodine (I2) vapor cell heated to 420oC with a cold finger at 30oC,
and scanning the laser frequency from 405.65395 THz to 405.65518 THz, we obtain the
molecular iodine Doppler free spectroscopy as shown in Figure 1(b). The pump beam is double
passed through an 80 MHz AOM before entering the vapor cell. For effective detection of the
weak signals, the pump is frequency modulated at 60 kHz using the AOM and the signal from
the photodiode is demodulated using a Lock-in Amplifier. As can be seen, six Doppler free
features are present in this region centered at 739.03475 nm, 739.03421 nm, 739.03394 nm,
739.03367 nm, 739.03341 nm and 739.03314 nm and they overlap well with their derivatives
in the lock signal. The Full width at half maximum (FWHM) for these peaks are approximately
13 MHz, 24 MHz, 31 MHz, 17 MHz, 29 MHz and 16 MHz, respectively. As compared to the
measured Doppler broadened width of ≈ 930 MHz at 420oC, the Doppler free spectra obtained
by this technique is of the order of a few tens of MHz. Using Pound-Drever Hall technique,
the laser’s frequency can be locked with respect to the Doppler free features 1, 4 or 6, which
is in progress.
Figure 1: (a) Optical set-up for SAS of I2, (b) I2 SAS profile (red) with Doppler free peaks
marked 1 – 6 with the corresponding Error signal at modulation frequency 60 kHz (blue).
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PP-54
Strong field ionization from atoms and nano-tips in structured
beams Abhisek Sinha1 , Debobrata Rajak2 , Sanket Sen1, Ram Gopal2 and Vandana Sharma1*
1IIT Hyderabad, Sangareddy, Telangana 2TIFR Hyderabad, Gopanpally, Telangana
Studies of strong field ionization of atoms have revealed the existence of a plateau in the photo
electron spectra (PES)[1-4]. This was attributed to the rescattering of electrons from the parent
ion and has been successfully described by the Simple Man’s Model (SMM)[5]. This model
along with the strong field approximation, could adequately describe cut offs of the energy
spectra in atoms. The same model is used to describe the ionization in metal nano tips. In the
following work, we obtained the total electron yield as a function of the intensity of the beam.
Furthermore, we used LG beams to compare the total yield with Gaussian beams.
The experimental setup consists of a time-of-flight spectrometer. Laser light is focused on the
gas jet and the emitted electrons are detected using a MCP detector. The time of flight of the
electrons are recorded and the yield is then calculated. The same experiment is then repeated,
but this time replacing the gas target by a metal nano tip.
When fitted with the equation
𝑊 = 𝛼𝑛𝐼𝑛
where, 𝑊 is the photoelectron yield. 𝛼𝑛 is the cross-section for n photon ionization and I is the
intensity, we see that there is a difference in the value of n at metal nano tips for Gaussian and
LG beams. The same is not true when we go to atomic scales as the value of n is seen to be the
same in both the types of beams for Argon.
References [1] Allen, Les, et al. "Orbital angular momentum of light and the transformation of Laguerre-Gaussian laser
modes." Physical Review A 45.11, 8185 (1992).
[2] Paulus, G. G., et al. "Plateau in above threshold ionization spectra." Physical review letters 72.18, 2851
(1994).
[3] Becker, W., et al. "The plateau in above-threshold ionization: the keystone of rescattering physics." Journal of
Physics B: Atomic, Molecular and Optical Physics 51.16, 162002 (2018).
[4] Paulus, Gerhard G., et al. "Rescattering effects in above-threshold ionization: a classical model." Journal of
Physics B: Atomic, Molecular and Optical Physics 27.21, L703 (1994).
[5] Muller H. G., and van Linden van den Heuvell B. “Multiphoton Processes”. Proceedings of ICOMP 4 ed. S. J.
Smith and P. L. Knight (Cambridge: Cambridge University Press) pp 25–34”(1988)
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PP-55
Iron impurity behavior in the ADITYA tokamak
S. Patel1,*, A.K. Srivastava1, M. B. Chowdhuri2, R. Manchanda2, A. Bhattacharya4,
J. V. Raval3, U. Nagora2, P. K. Atrey2, R. L. Tanna2, J. Ghosh2,3 and ADITYA Team2
1Pandit Deendayal Petroleum University, Raisan, Gandhinagar 382007, India
2Institute for Plasma Research, Gandhinagar 382428, India 3HBNI, Anushakti Nagar, Mumbai 400094, India
4Indian Institute of Technology Kanpur, Kanpur 208016, India
Iron (Fe) impurity behaviour and transport in ADITYA tokamak plasma has been investigated
by modeling the observed VUV spectral lines at 28.41 nm from Fe14+, and 33.54 nm and 36.08
nm from Fe15+. It has been observed that the intensities of the Fe emissions decrease with an
increase in plasma electron density. The observed spectral emission and the intensity ratio of
Fe14+ and Fe15+ impurity ions from two discharges having relatively low and high plasma
density are modeled using a one-dimensional impurity transport code STRAHL It shows that
the observed spectral line emission can be simulated using the same ratio of the convective
velocity to the diffusion coefficient v/D radial profile, but with two different iron concentration
values. The ratio v/D varies from the value of -0.22 m−1 at the plasma normalized radius 𝜌 =
0.2 to a maximum value of -0.35 m−1 at 𝜌 = 0.6. The obtained diffusion coefficient for Fe
impurity ion in the core region is well explained in using neo-classical transport in the Pfirsch–
Schluter regime. While the diffusion coefficient in the edge region, which is large by two
magnitudes as compared to core region is explained using ion temperature gradient turbulence.
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PP-56
Electron partial wave analysis of electron scattering from argon atoms
David Joseph and Naveen Chahal
Department of Physics,
Guru Jambheshwar University of Science and Technology, Hisar, Haryana125001
Email: [email protected]
Electron scattering is important in many physical process in Physics, especially the electron induced
excitations in laser systems and semiconductors. It is also important in plasma temperature
measurements. Argon atom having about eight laser transitions is technologically interesting atomic
system. Relativistic Partial wave analysis has been used to study the scattering from central interaction
potential V(r) using the ELSEPA code developed by F Salvat, A Jablonski and C Powell [1]. Semi
empirical correlation polarization potential is used to get the interaction between the electrons with the
atomic states for energies less than 10KeV. To simulate the processes experimentally, we have been
setting up a scattering chamber 80 cms ID and 53 cms height and with four ports (Fig:1). This has been
shielded using the nu-metal covering. A goniometer is being designed for incorporating the electron
gun, angle resolved goniometer, and the Cylindrical mirror Analyzer (CMA). Argon gas will be used
as the target Angle resolved studies will be undertaken to study processes like e-2e collision [2],
excitation process -all in a spectroscopic point of view [3]. A schematic picture of the experimental set
up is shown below (fig:2). The electron gun will be collinear to the faraday cup. The scattered flux will
be collected and analyzed by a CMA and MCA module. Plane wave analysis will be used to analyze
the experimental data obtained
Fig 2 Schematic diagram of the collision Fig:1 Scattering chamber which is being set up experiential set up
References [1] F Salvat, A Jablonski and C Powell, Compute Science Communications 165, 157 (2005)
[2] Y Khajuria and D N Tripathi Phys Rev A 59, 1197 (1999)
[3] R K Singh, Thesis, BHU, “Electron –Impact processes in Gaseous and solid targets at keV energies (2002)
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PP-57
High harmonic generation in bichromatic inhomogeneous
pulses
Ankur Mandal1,2,* and Pranawa C. Deshmukh2,3
1Department of Physics, Indian Institute of Science Education and Research Mohali,
Manauli, 140306, India 2Department of Physics, Indian Institute of Science Education and Research Tirupati,
Tirupati, 517507, India 3Department of Physics, Indian Institute of Technology Tirupati,
Tirupati, 517506, India *[email protected]
Chirp pulse amplification and high harmonic generation (HHG) accelerated the studies on light
matter interaction in atomic scale resolution [1, 2]. The intuitive mechanism as described by
three step model provides a playground for modifying the harmonic production [3, 4]. Many
schemes have been implemented both theoretically and experimentally to enhance and extend
the cut-off frequency.
Spatial inhomogeneity of the interacting electromagnetic radiation occur spontaneously in
nanostructures. This allows experimentalists to achieve about three order of magnitude field
enhancement hence a low intensity access to attoscience [5].
Here we show the interaction of atom with two-color infra-red femtosecond field with spatial
inhomogeneity.
Figure 1: Harmonic spectrum for bichromatic spatially inhomogeneous electromagnetc fields
(red dashed) for relative phase difference in the two color fields, ∅ = 0. Corresponding
homogeneous cases are shownin blue line.
In Fig. 1 one sample plot is presented where we can see substantial increment of cut-off. This
incrementis highly sensitive to the relative phase of the two color fields. Maximum
enhancement of the cut-off is observed at zero relative phase difference in the two color fields.
References [1] R. Pazurek et al, Rev. Mod. Phys. 87, 765 (2015).
[2] F. Krausz and M. Ivanov, Rev. Mod. Phys. 81, 163 (2009).
[3] P. B. Corkum, Phys. Rev. Lett. 71, 1994 (1993).
[4] C. Winterfeldt et al, Rev. Mod. Phys. 80, 117 (2008).
[5] S. Kim et al, Nature 453, 757 (2008).
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PP-58
Electron-impact cross sections of isovalent AlCl & AlF molecules from
0.1~eV to 5~keV
S. Kaur1*, A. Bharadvaja2 and K. L. Baluja3 1 SGTB Khalsa College, Department of Physics, University of Delhi, Delhi -7, India
2 Bhaskaracharya College of Applied Sciences, Department of Physics, University of Delhi, Delhi-75. 3 (Formerly) Department of Physics and Astrophysics, University of Delhi, Delhi - 7, India
Closed-shell diatomic molecules, with the univalent aluminium have been detected in
astrophysical environments as exemplified by the Aluminium monofluoride (AlF) and
Aluminium monochloride (AlCl) species. They become quite stable at high temperatures in
the gas phase [1]. AlF lines have been observed in the spectra of umbrae of sunspots [2] and
both AlCl and AlF have been detected in the envelope of the carbon-rich star IRC +10216 [3].
Thus AlCl and AlF being astrophysically very viable we have studied the electron-impact cross
sections of isovalent AlCl & AlF molecules from 0.1~eV to 5~keV
The study of electron-molecule collision is of crucial importance in the understanding and
modelling of natural and technological plasmas, astrophysical processes, planetary
atmospheres and many other fields [4]. This essentially means that a comprehensive set of
accurate electron- molecule collision cross section data is required over a wide range of energy
values.
The ab-initio R-matrix approach is used in one energy domain (less than the ionization
potential) whereas the semi ab-initio Single Center Expansion (SCE) formalism in other
energy domain (ionization threshold to 5 keV). The molecular wavefunctions of the targets are
obtained from the multi-center expansion of the Gaussian-type orbitals within single
determinant Hartree-Fock self-consistent field scheme. The multipole expansion of the target
at center of mass includes the dipole and quadrupole terms. In SCE approach, potentials are
approximated by their local behaviour. The potential included to model the interactions
consists of static, correlation-polarization and exchange effects.
The electron impact ionization cross sections and the excitation cross sections are obtained
using the Binary-Encounter-Bethe model and the R-matrix approach respectively. The electron
excitation cross sections include contributions from both spin-allowed and spin forbidden
transitions. The elastic and inelastic cross sections are summed to obtain the total cross
sections. The elastic, total and momentum transfer cross sections obtained from two
approaches match smoothly near ionization threshold. Further, we also compute the differential
cross sections. The SCE study is also performed in different models. This helped in
understanding the effect of dipole moment and polarization in the scattering problem.
References [1] S. Petrie, J. Phys. Chem. A 102, 7834 (1998)
[2] S. P. Bagare, K. B. Kumar, N. Rajamanickam , Sol. Phys. 234, 1 (2006)
[3] M. Ag´undez, J. P. Fonfr´ia, J. Cernicharo, C. Kahane, F. Daniel, M. Gu´elin, A&A 543, A48 (2012)
[4] Y. Itikawa, Molecular Processes in Plasmas Collisions of Charged Particles with Molecules, (Springer 2007)
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PP-59
Positron impact ionization cross sections from pentane isomers
Vardaan Sahgal1, A. Bharadvaja1, S. Kaur2* and K. L. Baluja3
1 Bhaskaracharya College of Applied Sciences, University of Delhi, Delhi-75. 2 SGTB Khalsa College, Department of Physics, University of Delhi, Delhi -7, India
3 (Formerly) Department of Physics and Astrophysics, University of Delhi, Delhi - 7, India
The elementary particles like electron and positron are used as projectiles in the scattering
phenomenon. Though positron is an antiparticle of electron, its collision physics greatly differs
from electron due to the non-applicability of Pauli Exclusion principle. The positron impact
ionization may result in either in the direct ionization of target or may result in positronium
formation. The latter is absent in case electron is taken as projectile.
Though several methods exist to estimate electron impact ionization cross sections [1,2], no
such methods seems to exist for positron impact ionization process. We present a simple
analytic formula based Binary Encounter formalism to estimate positron impact ionization
cross sections from pentane isomers. A very good agreement is observed with the available
results [3]. The results for pentane isomers are presented. However, the work is in progress to
further simplify the expression without compromising on results.
References [1] Y.-K. Kim and M. E. Rudd, Phys. Rev. A 50, 3954 (1994).
[2] H Deutsch, H, K. Becker, R. Basner, M. Schmidt, M and T.D. Mark. J. Phys. Chem. A 102, 8819 (1998).
[3] N. Sinha and B. Antony, Molecular Physics 117:18, 2527, (2019).
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PP-60
New ultrafast laser and instrumentation facility at PRL Ahmedabad for
femtosecond and attosecond science
R. K. Kushawaha*, Madhusudhan P, Rituparna Das, Pranav Bhardwaj, Swetapuspa
Soumyashree, Pooja Chandravanshi and Nimma Vinitha
Physical Research Laboratory, Ahmedabad
New CEP stabilized ultrafast laser (25fs, 800nm, 10mJ at 1KHz & 3.6mJ at 5KHz), Multi-
plate Velocity Map Imaging Spectrometer, Grating-eliminated no-nonsense observation of
ultrafast incident laser light e-fields (GRENOUILLE) and Spectral Phase Interferometry for
Direct Electric-field Reconstruction (SPIDER) have been installed and functional at new
femtosecond laser lab in PRL Ahmedabad. This is unique lab in India in term of facility. This
lab is established in cleanroom (ISO 7, 10000 grade) with temperature (± <0.05 degree
Centigrade) and humidity (50 ± 5 RH). All optical equipments are installed on optical tables
which are installed on anti-vibration floor isolation area. Recently a femtosecond pump-probe
experiment has been for molecular alignment similar to this reference [1, 2]. In This
conference, recent results on molecular alignment on N2 and CO2 using ultrafast pulses will be
presented. We solved the time dependent Schrodinger equation for CO2 alignment in field-free
case. The result is shown in figure 1. The experimental and theoretical results will be presented
in this conference.
Figure 1. Theoretical result on CO2 alignment with respect to polarization axis using
femtosecond pulses in pump-probe spectroscopy.
References [1] Henrik Stapelfeldt, REVIEWS OF MODERN PHYSICS 75, (2003)
[2] Xiaoming Ren, Varun Makhija, Hui Li, Matthias F. Kling, and Vinod Kumarappan Phys. Rev. A 90, 013419
(2016)
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PP-61
Edge temperature and density measurements in ADITYA-U Tokamak
with helium spectral line intensity ratio
Tanmay Macwan*1,2, Sharvil Patel1,3, Nandini Yadava1,4, Ritu Dey1, Kaushlender Singh1,2,
Suman Dolui1,2, Rohit Kumar1, Suman Aich1, Malay B Choudhary1, Ranjana Manchanda1,
R. L. Tanna1, K. A. Jadeja1, K. M. Patel1 and J. Ghosh1,2
1 Institute for Plasma Research, Gandhinagar 382 428 2 Homi Bhabha National Institute, Anushakti Nagar, Mumbai 400 085
3Pandit Deendayal Petroleum University, Gandhinagar 382 007 4The National Institute of Engineering, Mysuru, 570 008
*Email: [email protected]
Edge tokamak plasma is known to be highly turbulent which causes the particle transport
across the equilibrium magnetic field. The turbulence is caused by the inherent gradients in
density and temperature profiles of the tokamak plasma. This edge turbulence is dominated by
various drift wave turbulence which causes fluctuations in the floating potential, density and
temperature [1]. In order to characterize these fluctuations and the corresponding modes, one
needs an accurate measurement of the edge plasma parameters such as floating potential,
density and temperature. These can be measured by a Langmuir probe, which provides the
localized measurements. However, this is an intrusive method. Measurement of edge
temperature by helium spectral line intensity ratio method is a non-intrusive technique, which
can complement the Langmuir probe measurements. The Helium singlet-singlet spectral line
ratio (667.8/728.1 nm) is sensitive to density, whereas the singlet-triplet spectral line ratio
(728.1/706.5 nm) is sensitive to temperature [2]. Using these ratios, we have estimated the
ADITYA-U tokamak edge plasma density and temperature during flat-top phase of discharge.
These helium spectral lines are monitored using a photo-multiplier tube detector with
wavelength interference filter during helium gas puffing into edge region of tokamak. The
analysis for number of discharges shows that the edge temperature is about 7-15 eV and the
edge density is 31918 101105 m . These results are in agreement with the Langmuir probe
measurements.
References [1] X Garbet et al., Plasma Phys. Control. Fusion 46, B557 (2004)
[2] M Griener et al., Plasma Phys. Control. Fusion 60, 025008 (2018)
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PP-62
Neutral and impurity influx measurement from limiter and wall of
Aditya-U tokamak
Nandini Yadava1, J. Ghosh2, M. B. Chowdhuri2, R. Manchanda2, Sripathi Punchithaya K1, 3,
Ismyil3, N. Ramaiya1, Ritu Dey2, Tanmay Macwan2, S. Patel4, R. L. Tanna2 and Aditya-U
team2
1The National Institute of Engineering, Mysuru 570008, India 2Institute for Plasma Research, Bhat, Gandhinagar 382 428, India
3Manipal Institute of Technology, MAHE, Manipal 576 104, Karnataka, India 4Pandit Deendayal Petroleum University, Raisan, Gandhinagar, 382 007, Gujarat, India
The understanding of the tokamak edge plasma is very much crucial to achieve the better core
plasma [1]. The hydrogen fuel particle and major impurities entering into the edge plasma
through plasma-surface interaction modify the edge dynamic through the various atomic and
molecular processes. Then the plasma density control and impurity contamination of the
plasma is determined by the influxes of those from the surrounding surfaces. Considering that,
in Aditya-U tokamak, which is having plasma major and minor radius of 0.75 and 0.25,
respectively, particle and carbon and oxygen impurities influxes have been measured using
PMT based spectroscopic diagnostics made of light collecting lens known as collimating beam
probe, optical fiber, interference filter, and PMT detector. The Hα emission at 656.3 nm from
neutral hydrogen, spectral lines at 464.7 from C2+ and 441.6 nm from O1+ ions have been
routinely monitored through various lines of sight terminating on the bottom wall and inboard
side toroidal belt limiter. After converting these signals into the absolute number of emitted
photons, the influxes have been estimated using the atomic data known as S/XB ratio, which
is basically the information on the number of photons emitted by the particle before ionizing.
This quantification has been done for both wall and toroidal belt limiter to understand their
relative contribution in the total influxes into the Aditya-U tokamak plasma.
References [1] P.C. Stangeby and G.M. McCracken, Plasma boundary phenomena in tokamaks, Nuclear Fusion 30.7, 1225
(1990).
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PP-63
Diffraction of proton beams by an optical crystal: Kapitza-Dirac effect for
plasma ions with spin
Sushanta Barman and Sudeep Bhattacharjee
Department of physics, Indian Institute of Technology- Kanpur, Kanpur 208016, India
E-mail : [email protected], [email protected]
The Kapitza-Dirac effect is an example of the wave-particle duality of matter, which consists
of the diffraction of material particles by standing wave of light and is analogous to the
diffraction of light by a material grating in optics. Kapitza and Dirac first predicted this
quantum mechanical effect in 1933 [1] for electron beams. In this effect, matter waves get
diffracted by an optical crystal formed by the standing waves of light where the regions of
maximum intensity of the standing wave act like the crystal planes. It is realized that the
diffracted beams are coherent to each other. Hence this type of set-up is important in the
interferometric systems for the coherent mixing of momentum states [2]. Using this effect,
matter-wave interferometers, experiments related to general relativity [3], gravitational waves
[4], and the fine structure constant [5] can be performed with much higher accuracy. The
interaction of matter-wave of charged particles with the standing waves of electromagnetic
radiations, can be used as a testing ground of non-perturbative quantum dynamical systems
[6].
The diffraction of proton beams obtained from plasmas, by an optical crystal formed by
standing waves of laser (Nd: YAG, λ = 532 nm) is studied by simulating the Gaussian wave
packets associated with the incoming protons. The protons interact with the pondermotive
potential of the optical crystal, due to the nonlinear electromagnetic fields in the standing
waves of laser. From the simulation results of the probability distribution, it is observed that
the charged particles get accumulated at some equidistant positions in the transverse direction,
which results in the diffraction patterns. Experiments will be carried out to observe the
diffraction by the optical crystal for proton beams extracted from a microwave plasma system.
It will be interesting to observe the dependence of the diffraction pattern on the spin
polarization states of the proton beams. The results of the spin evolution in the optical crystal
in the presence of external perturbations such as electrostatic and magnetostatic fields will be
presented.
References [1] P. L. Kapitza and P. A. M. Dirac, Proc. Camb. Phil. Soc. 29, 297-300, (1933).
[2] C. Adams, M. Sigel, and J. Mlynek, Phys. Rep. 240, 143-210, (1994).
[3] Qingqing Hu, Jun Yang, Yukun Luo, Aiai Jia, Chunhua Wei, and Zehuan Li, Optik 131, 632 - 639 (2017)
[4] R. Colella, A. W. Overhauser, and S. A. Werner, Phys. Rev. Lett. 34, 1472-1474 (1975).
[5] Rym Bouchendira, Pierre Cladé, Saïda Guellati-Khélifa, François Nez, and François Biraben, Phys. Rev.
Lett. 106, 080801 (2011).
[6] Batelaan H., Rev. Mod. Phys. 79, 929-941, (2007).
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PP-64
Electron impact excitation of highly charged iso-electronic series of Ge like
Ba, Te, Sn, Cd ions
P. Malker1 and L. Sharma1* 1Indian Institute of Technology Roorkee
Atomic structure and collisional properties of the highly charged atomic ion have great
importance in many areas of science and technology such as laser physics, plasma physics and
astrophysics [1]. Since experimental studies on these systems are very limited, the requirement
of atomic data is mostly fulfill by reliable theoretical methods. Moreover, the relativistic and
QED effects play important role in the study of highly charged heavy ions. Therefore, in order
to attain reliable results, these effects must be taken into account. Further, such studies become
even more challenging for open shell Ge-like ions as there are several fine-structure levels in
the ground state.
There are only a few theoretical investigations for atomic structure properties of highly charged
Ge-like ions. For example, recently Hao et al. reported excitation energies, transition rates and
wavelengths for transitions from ground 4s24p2 to excited 4s4p3 and 4s24p4d states of Ge-like
Te, Xe and Ba ions [2]. However, there are no results reported for electron impact excitation
cross sections of the transitions considered in this work. In the present work we have performed
extensive calculations of cross sections for electron impact excitation of Ge-like Ba XXV, Te
XXI, Sn XIX, Cd XVII, ions using fully relativistic distorted wave (RDW) method. We have
considered fine-structure transitions between the ground state having configuration 4s24p2 and
the excited states with configurations 4s4p3 and 4s24p4d. The reliability of our bound state
wavefunctions is ascertained by comparing our results for excitation energies and oscillator
strengths of the transitions with the available theoretical results for Ba XXV and Te XXI of
Hao et al. [2]. The initial and final state wavefunctions of the target ion is taken as multi-
configuration Dirac Fock wavefunction [3]. The continuum wavefuncton for
projectile/scattered electron is obtained by solving Dirac equation using spherically averaged
potential of the ion is initial/final state of the ion as distortion potential. Thus, relativistic effects
are incorporated in a consistent manner in our calculations. Finally, we obtained cross sections
for all the 67 dipole allowed transitions considered in the present work. We have also provided
fitting of our cross sections with the analytical form so that these can be used easily in plasma
models. The detailed results will be presented in the conference.
Reference
[1] J. D. Gilaspy, J. Phys. B: At. Mol. Opt. Phys. 34, R93 (2001).
[2] L. H. Hao, X. P. Kang, and J. J. Liu. Journal of Applied Spectroscopy, Vol. 84, No. 2, May, 2017 (Russian
Original Vol. 84, No. 2, March–April, 2017).
[3] F.A. Parpia, C. Froese Fischer, I.P. Grant, Comput. Phys. Commun. 94, 249 (1996).
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PP-65
Dynamics of dissociative electron attachment to ethanol
S. Das1, S. Swain1 and V. S. Prabhudesai1*
1 Tata Institute of Fundamental Research, Mumbai 400005 India
Functional group dependence present in dissociative electron attachment (DEA) allows
selective bond breaking in molecules as a function of electron energy, which holds enormous
potential for practical application like controlled chemical reaction [1]. In this context, there
has been extensive efforts to understand the DEA dynamics that leads to the functional group
dependent site selectivity. One such functional group in organic molecules, which is common
to many biologically relevant molecules is a hydroxyl group. Ethanol or ethyl alcohol is one
of the simpler alcohols that can be studied for these DEA dynamics. So far, DEA measurement
on ethanol based on mass spectrometric studies have reported formation of H−, O−, OH−, C2H5−
ions [2,3,4]. Only one report describing momentum images for heavier ions [5] have concluded
that the production of O– results from a double dehydrogenation of the negative ion resonance
formed after electron attachment. In our study, we have measured the H– as the most
dominating anionic product of DEA having peaks in the ion yield curve at 6.5 eV, 8 eV and
9.5 eV. As can be seen from fig 1. using partially deuterated ethanol (C2H5OD), we have
identified the origin of the 6.5 eV and 8 eV peaks from the O-H site whereas the 9.5 eV peak
is found to be from the C-H site.
Figure 1. Comparison of normalized ion yield curve for H− from ethanol (black square) and D−
(red circles) and H− (blue triangles) from deuterated ethanol
We have carried out the momentum imaging of these ions using velocity slicing technique
and unraveled the dynamics that leads to these selective channels. In this poster we will
present the details of these dissociation channels as well that for the OH− channel.
References [1] V. S. Prabhudesai, A. H. Kelkar, D. Nandi, E. Krishnakumar, Phys. Rev. Lett. 95, 143202 (2005).
[2] M. Orzol, I. Martin, J. Kocisek, I. Dabkowska, J. Langer, E. Illenberger, Phys. Chem. Chem. Phys. 9, 3424 (2007).
[3] B. C. Ibănescu, M. Allan, Phys. Chem. Chem. Phys. 11, 7640 (2009).
[4] V. S. Prabhudesai, D. Nandi, A. H. Kelkar, E. Krishnakumar, J. Chem. Phys. 128, 154309 (2008).
[5] X-D. Wang, C.-J. Xuan, W.-L. Feng, S. X. Tian, J. Chem. Phys. 142, 064316 (2015).
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PP-66
Effect of background static gas on momentum images in velocity slice
imaging of dissociative electron attachment
S. Das1, S. Swain1 and V. S. Prabhudesai1*
1 Tata Institute of Fundamental Research, Mumbai 400005 India
Velocity slice imaging technique is one of the commonly used techniques for momentum
imaging of photodissociation dynamics of molecules. The introduction of this technique for
measuring the momentum distribution of fragment anions produced in low energy electron
collision experiments has revolutionized the understanding of the dissociative electron
attachment (DEA) process [1]. Due to its ability of measuring the angle dependence of the
fragment products it has been very useful in determining the symmetries of the anion
resonances. This has enabled identifying new resonances [2], distinguishing different
overlapping resonances [3] and identifying symmetry based dynamics of the resonances [4].
Usually, in these experiments, effusive molecular beam has been used as the source of the
target molecules in the ultrahigh vacuum chamber where the electron beam is made to cross at
right angles. Such a source of molecules also causes significant contribution from the
background as the effused gas eventually occupies the chamber volume, increasing the
background gas (here we call static gas) pressure which is determined by the effective pumping
speed of the vacuum pumps and the flow rate of the effused gas. In such a scenario, the electron
beam traverses significant length of path through this static gas, which contributes substantially
to the momentum image obtained. As can be seen from figure 1, the contribution of the static
gas affects the quality of the momentum image.
(a) (b) (c)
Figure 1. Momentum images obtained for H− from ethanol from the (a) crossed beam
where the static gas also contributes (b) pure static gas in the absence of molecular beam
and (c) pure crossed beam contribution obtained by subtracting the images
In this poster, we will discuss this effect and its detailed analysis.
References [1] D. Nandi, V. S. Prabhudesai, E. Krishnakumar, A. Chatterjee, Rev. Sci. Instrum. 76, 053107 (2005).
[2] V. S. Prabhudesai, D. Nandi, E. Krishnakumar, J. Phys. B At. Mol. Opt. Phys. 39, L277 (2006).
[3] K. Gope, V. S. Prabhudesai, N. J. Mason, E. Krishnakumar, J. Phys. B At. Mol. Opt. Phys. 49, 015201
(2016).
[4] E. Krishnakumar, V. S. Prabhudesai, N. J. Mason, Nat. Phys. 14, 149 (2018).
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PP-67
Theoretical investigation of the electronic structure of HgH+
R. Bala1,*, H. S. Nataraj1, M. Kajita2 and M. Abe3
1 Department of Physics, Indian Institute of Technology Roorkee, Roorkee -247667, India
*[email protected], [email protected] 2 National Institute of Information and Communications Technology, Koganei, Tokyo 184-8795,
Japan
[email protected] 3 Department of Chemistry, Tokyo Metropolitan University, 1-1 Minami-Osawa, Hachioji, Tokyo
192-0397, Japan
A rotational transition X1Σ (J, F) = (0, 1/2) → (1, 1/2) in the 202HgH+ ion has recently been
proposed for frequency standard, in the terahertz region, with an uncertainty below 10-15 [1].
To study the systematic shifts induced in a clock transition (which is a result of the coupling
of states with neighboring electronic, vibrational and rotational states), an accurate knowledge
of spectroscopic constants and molecular properties of the ground and excited states of this
molecular ion is necessary [1]. Except the spectroscopic constants of ground and first excited
electronic state of Σ symmetry [2], there are no other experimental results available for 202HgH+. The available theoretical results are also limited only to the spectroscopic parameters
of the electronic ground-state at the non-relativistic and quasi-relativistic levels [3-5]. In this
context, we have performed 4-component relativistic calculations and obtained potential
energy curves, dipole moment curves, diatomic constants, vibrational and rotational
parameters for the ground and a few low-lying excited states of this ion. The configuration
interaction (CI) method limited to single- and double-excitations is employed together with the
quadruple zeta basis sets. The details of our theoretical investigation together with the results
will be presented in the conference.
References
[1] M. Kajita, R. Bala, M. Abe, J. Phys. B (Under review).
[2] G. Herzberg, Spectra of Diatomic Molecules, Second Edition (D. Van Nostrand), May 1950.
[3] N. S. Mosyagin, A. V. Titov, E. Eliav, and U. Kaldor, arXiv:physics/0101047v4 [physics.chem-ph].
[4] G. Ohanessian, M. J. Brusich, and W. A. Goddard , J. Am. Chem. Soc. 112, 7179 (1990).
[5] U. Häussermann , M. Dolg, H. Stoll, H. Preuss, P. Schwerdtfeger, and R .M. Pitzer, Molecular Physics 78,
1211 (1993).
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PP-68
Analysis of visible spectra in tungsten ions observed from electron beam
ion trap
Priti1, Daiji Kato2,3, Izumi Murakami2,4, Hiroyuki A. Sakaue2 and Nobuyuki Nakamura1
1Institute of Laser Science, University of Electro-communications, Tokyo, 182-8585 Japan 182-8585
2National Institute for Fusion Science, Toki, Gifu 509-5292, Japan 3Department of Advanced Energy Engineering Science, Kyushu University, Fukuoka 816-8580,
Japan 4Department of Fusion Science, SOKENDAI, Toki, Gifu 509-5292, Japan
Atomic data of few times ionized tungsten have great importance due to its prospective
application in diagnostics of edge plasma of the ITER [1]. A large fraction of the divertor
plasmas are expected to contain tungsten ions in charge states mainly from three to fifteen
times ionized (WIV-WXVI). Therefore, emission lines from these tungsten ions are a very
useful tool to determine their concentration, the influx of tungsten sputtered from the wall to
the core plasma and to assess power loss. In addition, the visible transitions of WIX and WX
are the potential candidate for optical atomic clocks. These transitions are supposed to be very
sensitive to the α variation due to level crossing of 4f and 5p levels [2]. However, the candidate
transitions have yet to be experimentally identified.
In literature, to date there are no lines reported for these two ions in the visible region [3].
Therefore, to fill this void visible spectra of WVIII to WX tungsten ions have been recorded
using Compact electron beam ion trap (CoBIT) by our group [4]. To identify the observed
spectra from CoBIT, a fine structure resolved collisional radiative (CR) model is developed.
Electron impact excitation, de-excitation, and radiative decay are taken into account in the rate
balance equation. Since electron density is small (1010cm-3), other recombination processes
viz. radiative recombination, three-body recombination and dielectronic recombination is
ignored in the model. To ensure the identification of lines done by the CR model we have also
performed the accurate calculation of transition energies and transition probabilities within
multi configurational Dirac-Fock using the GRASP2018 [5]. We found that most of the
observed lines are from M1 transitions between lower-lying stares of these ions. Details of the
model and analysis will be presented in the conference.
References [1] J. Clementson et. al., Atoms 3, 407 (2015)
[2] J C Berengut et. al., Phys. Rev. Lett. 105, 120801 (2010)
[3] A. E. Kramida et. al., Data Nucl. Data Tables 95, 305 (2009)
[4] M. Mita et. al., Atoms 5, 13 (2017)
[5] C. Froese Fischer, et. al., Computer Physics Communications 237, 184 (2019)
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PP-69
Strongly coupled plasma effect on excitation energies and transition data of
Ca VI
Sunny Aggarwal1,a, Arun Goyal1,b and Man Mohan2
Department of Physics, Shyamlal College, University of Delhi, Delhi-110032, India.
Department of Physics and Astrophysics, University of Delhi, Delhi-110007, India [email protected]
The main goal of the present study is to analyze and estimate the plasma screening effect on
excitation energies and transition data for Ca VI (P-like Ca) under the influence of strongly
coupled plasma. We have employed an ion sphere model (ISM) in flexible atomic code (FAC)
to study and analyze plasma effect in atomic structure. We have presented shift in excitation
energies of lowest 13 levels belonging to the configurations 3s23p3 and 3s3p4 at electron
densities ranges 1022 - 1024 cm-3 under plasma environment. We have also studied transition
wavelengths, transition rates and oscillator strengths at electron densities ranges
1022 - 1024 cm-3 under plasma environment.
8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications
PP-70
Plasma screening effect on excitation energies and transition data of
P-like Zn
Arun Goyal1,a , Sunny Aggarwal1,b, Narendra Singh1 and Man Mohan2
Department of Physics, Shyamlal College, University of Delhi, Delhi-110032, India.
Department of Physics and Astrophysics, University of Delhi, Delhi-110007, India [email protected]
The main goal of the present study is to analyze and estimate the plasma screening effect on
excitation energies and transition data for P-like Zn under the influence of strongly coupled
plasma. We have employed an ion sphere model (ISM) in flexible atomic code (FAC) to study
and analyze plasma effect in atomic structure. We have presented shift in excitation energies
of lowest 20 levels at electron densities ranges 1022 - 1024 cm-3 under plasma environment. We
have also studied transition wavelengths, transition rates and oscillator strengths at electron
densities ranges 1022 - 1024 cm-3 under plasma environment.