Charge transfer processes in atom-molecule collision ...Paulo Limão-Vieira, F Ferreira da Silva and G García Department of Physics, Universidade NOVA de Lisboa, Portugal and Consejo

Charge transfer processes in atom-molecule collision experiments

Charge transfer processes in atom-molecule

collision experiments

1

IAEA Technical MeetingVienna, 20 December 2016

Paulo Limão-Vieira, F Ferreira da Silva and G García

Department of Physics, Universidade NOVA de Lisboa, Portugaland

Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain


2

The Atomic and Molecular Collisions Laboratory

Asst. Prof. Filipe Ferreira da Silva

Dr. Krystyna Regeta, Post-Doc

PhD students:

Mr. Tiago Cunha, PT

Ms. Emanuele Lange, BR

Ms. Mónica Mendes, PT

Ms. Alexandra Loupas, PT

Ms. Rebeca Meißner, D

Technicians:

Mr. João Faustino

Mr. Afonso Moutinho

Funding through several schemes:

IF-FCT IF/00380/2014 UID/FIS/00068/2013

FY2016 JSPS Invitation Fellowship

PD/00193/2012

http://www.royalsoc.ac.uk/

http://www.royalsoc.ac.uk/


3

Our most close collaborations

CSIC – Madrid, ES

Gustavo García

University of Innsbruck, AT

Paul Scheier

Stephan Denifl

Sophia University – Tokyo, JP

Hiroshi Tanaka

Masamitsu Hoshino

Flinders University, AU

Michael Brunger

Université de Lyon, FR

Marie Christine Bacchus

Czech Academy of Sciences, CZ

Juraj Fedor


4

Data for plasma applications

• Japan-Portugal-Spain-Australia (from 2003):

GeF4; SiF4, CF4; BF3; C4F6; CF3Cl; CF2Cl2; CFCl3; 1,3-C4F6, c-C4F6 and 2-C4F6;CCl4; F2CO; C2F4

COS; CS2;H2O; CH4; SiH4; GeH4; C6H6; CH3F; CH3Cl; CH3Br; CH3I; O2

• UK-Portugal (2006):CF3I, C2F4 and CFx (x = 1 - 3) radicals

• Elastic DCS; ICS; Total Cross Sections (experiment and theory);• Electronic Excitation (experiment and theory) / high-resolution VUV

spectroscopy


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Motivation Negative ion formation

Introduction

electron transfer

ion-pair formation

Experimental set-up

Results

acetic acid pyrimidines nitromethane

Conclusions

Overview


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Motivation

Collisional ionisation processes between atoms A and molecules BC

A + BC

A+ + BC– (1) IPF by charge transfer

A– + BC+ (2) IPF by charge transfer

A+ + B– + C (3)IPF by charge

transfer/dissociative IPF

A+ + (B + C) + e– (4) Ionisation

AB+ + C + e– (5)Chemiionisation w/

rearrangement

AB+ + C– (6)Chemiionisation w/

rearrangement

AB + C+ + e– (7)Chemiionisation w/

rearrangement

ABC+ + e– (8) Associative ionisation

A + B+ + C– (9)Collision induced polar

dissociation


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Motivation

Studying chemical reactions – understand radiation induced damage;Collisional excitation and dissociation;Site- and bond-selectivity (pyrimidines, purines, imidazole);The role of the collision complex – pathways;Competitive (even concerted) fragmentation mechanisms in pyrimidinesand purines.

Negative ions formation from molecular targets

[K+ + AB–]*

K+ + AB– K+ + A– + B K+ + A + B– K + AB*

Electron transfer in atom-molecule collisions:

Kohyp + AB


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Motivation

access to parent molecular states which are not accessible in EA (statespositive EA);role of vibrational excitation of the parent neutral molecule - collisiondynamics

DEA - resonances;direct and statistical dissociation;


9

Elab ≤ 1keV

The crossed molecular

beam setup in Lisbon


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Complex internal rearrangement yielding OH-

Meneses, Widmann, Cunha, Gil, da Silva, Calhorda and PLV. Phys. Chem. Chem. Phys. (2017) DOI: 10.1039/c6cp06375f

0,00

0,25

0,50

0,75

1,00

0,00

0,25

0,50

0,75

1,00

0 5 10 15 20 25 30 35 40 45 50 55 60 65

0,00

0,25

0,50

0,75

1,00

CH3COOHa)

c)

b)

Inte

nsi

ty (

arb

. u

nits

)

CH3COOD

Mass (m/z)

CD3COOH

CH3COO–

CH3COO–

CD3COO–

OH–

OH–

OH–

OD–

OD– / CD3–

CH3–

CH3–

CDH–

Elab = 100 eV

π*C=O →σ*OH (?)


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Almeida, Antunes, Martins, Eden, Silva, Nunes, Garcia and PLV Phys. Chem. Chem. Phys. 13 (2011) 15657

Ptasinska et al. J. Chem. Phys. 123 (2005) 124302

0 10 20 30 40 50 60 70 80 90 100 110 120

0.0000

0.0043

0.0086

0.0129

0.0172

0.0215

0.0258

C4H

2N

2O

2

-

C4H

3N

2O

2

-

C2H

-

H- O

-

NCO-

Inte

nsity (

a.u

.)

Mass (a.m.u)

Uracil vs K0

Hyper (100 eV)


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Site- and bond-selectivity

6-dimethyladenine

9-methyl adenine1-methyl thymine 3-methyl uracil


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Autodetachment suppression &Coulombic complex stabilization


14Almeida, Kinzel, Silva, Puschnigg, Gschliesser, Scheier, Denifl, Garcia, Gonzalez and PLV, Phys. Chem. Chem. Phys. 15 (2013) 11431


15Ferreia da Silva, Matias, Almeida, García, Ingólfsson, Flosadóttir, Ómarsson,Ptasinska, Puschnigg, Scheier, PLV, Denifl J. Am. Soc. Mass. Spectrom. 24 (2013) 1787


16Antunes, Almeida, Martins, Mason, García, Maneira, Nunes and PLV. Phys. Chem. Chem. Phys. 12 (2010) 12513

K + CH3NO2 and K + CD3NO2uncertainty ≈ 20%


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Conclusions

• site– and bond–selective mechanism in purines;

• the electron donor can greatly affect the chemical pathways of the reaction(e.g. CH3NO2);

• compared to an isolated TNI formed by free electron capture, the anion inthe vicinity of a K+ favours dissociation rather than autodetachment;

• K+ may delay autodetachment, allowing for intramolecular electrontransfer

• Branching ratios (uncertainties up to 20%) and the collision dynamics;

• Provide K+ energy loss profiles.

Documents

Charge transfer processes in atom-molecule collision ...Paulo Limão-Vieira, F Ferreira da Silva and G García Department of Physics, Universidade NOVA de Lisboa, Portugal and Consejo