University of Oulu

Ivan Powis, Minna Patanen, Egill Antonsson, Christophe Nicolas, Catalin Miron, and David M. P. Holland (2017) Vibration-dependent photoelectron angular distributions and branching ratios observed across the Cooper-minimum region of bromobenzene, Phys. Rev. A 96, 013413,

Vibration-dependent photoelectron angular distributions and branching ratios observed across the Cooper-minimum region of bromobenzene

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Author: Powis, Ivan1; Patanen, Minna2,3; Antonsson, Egill2,4;
Organizations: 1School of Chemistry, University of Nottingham, Nottingham NG7 2RD, United Kingdom
2Synchrotron SOLEIL, l’Orme des Merisiers, Saint-Aubin, BP 48, 91192 Gif-sur-Yvette Cedex, France
3Current address: Nano and Molecular Systems Research Unit, Molecular Materials Research Community, Faculty of Science, P.O. Box 3000, 90014 University of Oulu, Finland
4Current address: Institut für Chemie und Biochemie - Physikalische und Theoretische Chemie, Freie Universität Berlin, Takustr. 3, D-14195 Berlin, Germany
5Current address: Extreme Light Infrastructure-Nuclear Physics (ELI-NP), “Horia Hulubei” National Institute for Physics and Nuclear Engineering, 30 Reactorului Street, RO-077125 Măgurele, Jud. Ilfov, Romania
6Daresbury Laboratory, Daresbury, Warrington, Cheshire WA4 4AD, United Kingdom
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 0.7 MB)
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Language: English
Published: American Physical Society, 2017
Publish Date: 2019-09-26


Vibrational state-resolved photoelectron anisotropy parameters, β, for the ˜X2B1, ˜B2B2, and ˜C2B1 state ionizations of bromobenzene have been recorded at photon energies ranging from 20.5 to 94 eV, thus spanning the region of the expected bromine Cooper minimum (CM). The ˜X state displays no CM and its β value is also independent of vibrational level, in accord with the Franck-Condon approximation. The ˜B and ˜C state β values display the CM to differing degrees, but both show a vibrational dependence that extends to energies well below the obvious CM dip. Calculations are presented that replicate these observations. We thus demonstrate a wide-ranging Franck-Condon approximation breakdown detected in the β anisotropy parameter in the absence of any resonance. Measured and calculated vibrational branching ratios for these states are also presented. Although the ˜B state branching ratios remain constant, in accord with Franck-Condon expectations, the ˜X and (especially) the ˜C state ratios display weak, quasilinear variations across the studied range of photon energy, but with no apparent correlation with the CM position.

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Series: Physical review. A
ISSN: 2469-9926
ISSN-E: 2469-9934
ISSN-L: 2469-9926
Volume: 96
Article number: 013413
DOI: 10.1103/PhysRevA.96.013413
Type of Publication: A1 Journal article – refereed
Field of Science: 114 Physical sciences
Funding: This research was funded by the European Community's Seventh Framework Program (FP7/2007-2013) ELISA under Grant Agreement No. 226716. We are grateful to SOLEIL staff for running the facility and providing beam time (Project No. 20120162).
Copyright information: © 2017 American Physical Society.