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Identifying and understanding strong vibronic interaction effects observed in the asymmetry of chiral molecule photoelectron angular distributions

Garcia, Gustavo A.; Dossmann, Heloise; Nahon, Laurent; Daly, Steven; Powis, Ivan

Identifying and understanding strong vibronic interaction effects observed in the asymmetry of chiral molecule photoelectron angular distributions Thumbnail


Authors

Gustavo A. Garcia

Heloise Dossmann

Laurent Nahon

Steven Daly

Ivan Powis



Abstract

Electron-ion coincidence imaging is used to study chiral asymmetry in the angular distribution of electrons emitted from randomly-oriented enantiomers of two molecules, methyloxirane and trifluoromethyloxirane, upon ionization by circularly polarized VUV synchrotron radiation. Vibrationally-resolved photoelectron circular dichroism (PECD) measurements of the outermost orbital ionization reveal unanticipated large fluctuations in the magnitude of the forward-backward electron scattering asymmetry, including even a complete reversal of direction. Identification and assignment of the vibrational excitations is supported by Franck-Condon simulations of the photoelectron spectra. A previously proposed quasi-diatomic model for PECD is developed and extended to treat polyatomic systems. The parametric dependence of the electronic dipole matrix elements on nuclear geometry is evaluated in the adiabatic approximation, and provokes vibrational level dependent shifts in amplitude and phase, to which the chiral photoelectron angular distributions are especially sensitive. It is shown that single quantum excitation of those vibrational modes which experience only a relatively small displacement of the ion equilibrium geometry along the normal coordinate, and which are then only weakly excited in the Franck-Condon limit, can be accompanied by big shifts in scattering phase; hence the observed big fluctuations in PECD asymmetry for such modes.

Citation

Garcia, G. A., Dossmann, H., Nahon, L., Daly, S., & Powis, I. (in press). Identifying and understanding strong vibronic interaction effects observed in the asymmetry of chiral molecule photoelectron angular distributions. ChemPhysChem, 18(5), https://doi.org/10.1002/cphc.201601250R1

Journal Article Type Article
Acceptance Date Dec 14, 2016
Online Publication Date Jan 23, 2017
Deposit Date Dec 16, 2016
Publicly Available Date Jan 23, 2017
Journal ChemPhysChem
Print ISSN 1439-4235
Electronic ISSN 1439-7641
Publisher Wiley
Peer Reviewed Peer Reviewed
Volume 18
Issue 5
DOI https://doi.org/10.1002/cphc.201601250R1
Public URL https://nottingham-repository.worktribe.com/output/839370
Publisher URL http://onlinelibrary.wiley.com/doi/10.1002/cphc.201601250/abstract
Additional Information This is the peer reviewed version of the following article: Identifying and understanding strong vibronic interaction effects observed in the asymmetry of chiral molecule photoelectron angular distributions, Gustavo A. Garcia, Heloise Dossman, Laurent Nahon, Steven Daly, Ivan Powis, ChemPhysChem (2017), which has been published in final form at: http://dx.doi.org/10.1002/cphc.201601250R1. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.
Contract Date Dec 16, 2016

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