University of Oulu

Trofimov, A., Powis, I., Menzies, R., Holland, D., Antonsson, E., Patanen, M., Nicolas, C., Miron, C., Skitnevskaya, A., Gromov, E., Köppel, H. (2018) An experimental and theoretical study of the photoelectron spectra of cis-dichloroethene: Valence shell vertical ionization and vibronic coupling in the low-lying cationic states. Journal of Chemical Physics, 149 (7), 074306. doi:10.1063/1.5033425

An experimental and theoretical study of the photoelectron spectra of cis-dichloroethene : valence shell vertical ionization and vibronic coupling in the low-lying cationic states

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Author: Trofimov, A. B.1,2; Powis, I.3; Menzies, R. C.3;
Organizations: 1Laboratory of Quantum Chemistry, Irkutsk State University, Karl Marx Str. 1, 664003 Irkutsk, Russia
2Favorsky’s Institute of Chemistry, SB RAS, Favorsky Str. 1, 664033 Irkutsk, Russia
3School of Chemistry, University of Nottingham, Nottingham NG7 2RD, United Kingdom
4Daresbury Laboratory, Daresbury, Warrington, Cheshire WA4 4AD, United Kingdom
5Physical Chemistry, Freie Universität Berlin, Takustr. 3, D-14195 Berlin, Germany
6Nano and Molecular Systems Research Unit, Faculty of Science, University of Oulu, P.O. Box 3000, 90014 Oulu, Finland
7Synchrotron SOLEIL, l’Orme des Merisiers, Saint-Aubin, BP 48, 91192 Gif-sur-Yvette, France
8LIDYL, CEA, CNRS, Universit´e Paris-Saclay, CEA Saclay, 91191 Gif-sur-Yvette, France
9Extreme Light Infrastructure-Nuclear Physics (ELI-NP),“Horia Hulubei” National Institute
10Theoretische Chemie, Physikalisch-Chemisches Institut, Universität Heidelberg, Im Neuenheimer Feld 229, 69120 Heidelberg, Germany
Format: article
Version: accepted version
Access: open
Online Access: PDF Full Text (PDF, 2.4 MB)
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Language: English
Published: American Institute of Physics, 2018
Publish Date: 2018-08-31


The valence shell photoelectron spectrum of cis-dichloroethene has been studied both experimentally and theoretically. Photoelectron spectra have been recorded with horizontally and vertically plane polarized synchrotron radiation, thereby allowing the anisotropy parameters, characterizing the angular distributions, to be determined. The third-order algebraic-diagrammatic construction approximation scheme for the one-particle Green’s function has been employed to compute the complete valence shell ionization spectrum. In addition, the vertical ionization energies have been calculated using the outer valence Green’s function (OVGF) method and the equation-of-motion coupled-cluster, with single and double substitutions for calculating ionization potentials (EOM-IP-CCSD) model. The theoretical results have enabled assignments to be proposed for most of the structure observed in the experimental spectra, including the inner-valence regions dominated by satellite states. The linear vibronic coupling model has been employed to study the vibrational structure of the lowest photoelectron bands, using parameters obtained from ab initio calculations. The ground state optimized geometries and vibrational frequencies have been computed at the level of the second-order Møller-Plesset perturbation theory, and the dependence of the ionization energies on the nuclear configuration has been evaluated using the OVGF method. While the adiabatic approximation holds for the X̃ ²B₁ state photoelectron band, the à ²B₂, B̃ ²A₁, and C̃ ²A₂ states interact vibronically and form a complex photoelectron band system with four distinct maxima. The D̃ ²B₁ and Ẽ ²B₂ states also interact vibronically with each other. The potential energy surface of the D̃ ²B₁ state is predicted to have a double-minimum shape with respect to the out-of-plane a₂ deformations of the molecular structure. The single photoelectron band resulting from this interaction is characterized by a highly irregular structure, reflecting the non-adiabatic nuclear dynamics occurring on the two coupled potential energy surfaces forming a conical intersection close to the minimum of the Ẽ ²B₂ state.

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Series: Journal of chemical physics
ISSN: 0021-9606
ISSN-E: 1089-7690
ISSN-L: 0021-9606
Volume: 149
Article number: 074306
DOI: 10.1063/1.5033425
Type of Publication: A1 Journal article – refereed
Field of Science: 114 Physical sciences
116 Chemical sciences
Funding: A.B.T. and A.D.S. gratefully acknowledge Grant No. 4.1671.2017/4.6, from the Ministry of Education and Science of the Russian Federation. D.M.P.H. is grateful to the Science and Technology Facilities Council (United Kingdom) for financial support.
Copyright information: © 2018 The Authors. Published by AIP Publishing.