University of Oulu

Powis, I., Menzies, R., Holland, D., Trofimov, A., Skitnevskaya, A., Gromov, E., Antonsson, E., Patanen, M., Nicolas, C., Miron, C. (2018) Photoionization dynamics of cis-dichloroethene from investigation of vibrationally resolved photoelectron spectra and angular distributions. Journal of Chemical Physics, 149 (7), 074305. doi:10.1063/1.5042216

Photoionization dynamics of cis-dichloroethene from investigation of vibrationally resolved photoelectron spectra and angular distributions

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Author: Powis, I.1; Menzies, R. C.1; Holland, D. M. P.2;
Organizations: 1School of Chemistry, University of Nottingham, Nottingham NG7 2RD, United Kingdom
2Daresbury Laboratory, Daresbury, Warrington, Cheshire WA4 4AD, United Kingdom
3Laboratory of Quantum Chemistry, Irkutsk State University, Karl Marx Str. 1, 664003 Irkutsk, Russia
4Favorsky’s Institute of Chemistry, SB RAS, Favorsky Str. 1, 664033 Irkutsk, Russia
5Theoretische Chemie, Physikalisch-Chemisches Institut, Universität Heidelberg, Im Neuenheimer Feld 229, 69120 Heidelberg, Germany
6Synchrotron SOLEIL, L’Orme des Merisiers, Saint-Aubin, BP 48, 91192 Gif-sur-Yvette, France
7Current address: Physical Chemistry, Freie Universität Berlin, Takustr. 3, D-14195 Berlin, Germany
8 Nano and Molecular Systems Research Unit, Faculty of Science, University of Oulu, P.O. Box 3000, 90014 Oulu, Finland
9Current address: LIDYL, CEA, CNRS, Universit ́ e Paris-Saclay, CEA Saclay, 91191 Gif-sur-Yvette, France
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 2.9 MB)
Persistent link:
Language: English
Published: American Institute of Physics, 2018
Publish Date: 2018-08-30


The influence of vibronic coupling on the outer valence ionic states of cis-dichloroethene has been investigated by recording photoelectron spectra over the excitation range 19–90 eV using plane polarized synchrotron radiation, for two polarization orientations. The photoelectron anisotropy parameters and electronic state branching ratios derived from these spectra have been compared to theoretical predictions obtained with the continuum multiple scattering approach. This comparison shows that the photoionization dynamics of the à ²B₂, B̃ ²A₁, C̃ ²A₂, and D̃ ²B₁ states, all of which are formed through the ejection of an electron from a nominally chlorine lone-pair orbital, exhibit distinct evidence of the Cooper minimum associated with the halogen atom. While retaining a high degree of atomic character, these orbital ionizations nevertheless display clear distinctions. Simulations, assuming the validity of the Born-Oppenheimer and the Franck-Condon approximations, of the X̃ ²B₁, à ²B₂, and D̃ ²B₁ state photoelectron bands have allowed some of the vibrational structure observed in the experimental spectra to be assigned. The simulations provide a very satisfactory interpretation for the X̃ ²B₁ state band but appear less successful for the à ²B₂ and D̃ 2B₁ states, with irregularities appearing in both. The B̃ ²A₁ and C̃ ²A₂ state photoelectron bands exhibit very diffuse and erratic profiles that cannot be reproduced at this level. Photoelectron anisotropy parameters, β, have been evaluated as a function of binding energy across the studied photon energy range. There is a clear step change in the β values of the à ²B₂ band at the onset of the perturbed peak intensities, with β evidently adopting the value of the B̃ ²A₁ band β. The D̃²B₁ band β values also display an unexpected vibrational level dependence, contradicting Franck-Condon expectations. These various behaviors are inferred to be a consequence of vibronic coupling in this system.

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Series: Journal of chemical physics
ISSN: 0021-9606
ISSN-E: 1089-7690
ISSN-L: 0021-9606
Volume: 149
Article number: 074305
DOI: 10.1063/1.5042216
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.