University of Oulu

M. Patanen, A. R. Abid, S. T. Pratt, A. Kivimäki, A. B. Trofimov, A. D. Skitnevskaya, E. K. Grigoricheva, E. V. Gromov, I. Powis, and D. M. P. Holland, "Valence shell photoelectron angular distributions and vibrationally resolved spectra of imidazole: A combined experimental–theoretical study", The Journal of Chemical Physics 155, 054304 (2021)

Valence shell photoelectron angular distributions and vibrationally resolved spectra of imidazole : a combined experimental–theoretical study

Saved in:
Author: Patanen, M.1; Abid, A. R.1,2; Pratt, S. T.3;
Organizations: 1Nano and Molecular Systems Research Unit, Faculty of Science, University of Oulu, P. O. Box 3000, 90014 Oulu, Finland
2Molecular and Condensed Matter Physics, Uppsala University, Ångströmlaboratoriet, 752 37 Uppsala, Sweden
3Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, USA
4MAX IV Laboratory, Lund University, P. O. Box 118, 22100 Lund, Sweden
5Laboratory of Quantum Chemical Modeling of Molecular Systems, Irkutsk State University, Karl Marx Str. 1, 664003 Irkutsk, Russia
6Favorsky’s Institute of Chemistry, SB RAS, Favorsky Str. 1, 664033 Irkutsk, Russia
7Max-Planck Institute for Medical Research, Jahnstrae 29, 69120 Heidelberg, Germany
8School of Chemistry, The University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom
9Daresbury Laboratory, Daresbury, Warrington, Cheshire WA4 4AD, United Kingdom
Format: article
Version: accepted version
Access: open
Online Access: PDF Full Text (PDF, 2.6 MB)
Persistent link:
Language: English
Published: American Institute of Physics, 2021
Publish Date: 2021-08-18


Linearly polarized synchrotron radiation has been used to record polarization dependent valence shell photoelectron spectra of imidazole in the photon energy range 21–100 eV. These have allowed the photoelectron angular distributions, as characterized by the anisotropy parameter β, and the electronic state intensity branching ratios to be determined. Complementing these experimental data, theoretical photoionization partial cross sections and β-parameters have been calculated for the outer valence shell orbitals. The assignment of the structure appearing in the experimental photoelectron spectra has been guided by vertical ionization energies and spectral intensities calculated by various theoretical methods that incorporate electron correlation and orbital relaxation. Strong orbital relaxation effects have been found for the 15a’, nitrogen lone-pair orbital. The calculations also predict that configuration mixing leads to the formation of several low-lying satellite states. The vibrational structure associated with ionization out of a particular orbital has been simulated within the Franck–Condon model using harmonic vibrational modes. The adiabatic approximation appears to be valid for the X 2A″ state, with the β-parameter for this state being independent of the level of vibrational excitation. However, for all the other outer valence ionic states, a disparity occurs between the observed and the simulated vibrational structure, and the measured β-parameters are at variance with the behavior expected at the level of the Franck–Condon approximation. These inconsistencies suggest that the excited electronic states may be interacting vibronically such that the nuclear dynamics occur over coupled potential energy surfaces.

see all

Series: Journal of chemical physics
ISSN: 0021-9606
ISSN-E: 1089-7690
ISSN-L: 0021-9606
Volume: 155
Issue: 5
Article number: 054304
DOI: 10.1063/5.0058983
Type of Publication: A1 Journal article – refereed
Field of Science: 114 Physical sciences
116 Chemical sciences
Funding: D.M.P.H. acknowledges the Science and Technology Facilities Council (United Kingdom) for financial support. S.T.P. was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences, and Biosciences, under Contract No. DE-AC02-06CH11357. A.B.T., E.V.G., E.K.G., and A.D.S. acknowledge Grant No. FZZE-2020-0025 from the Ministry of Science and Higher Education of the Russian Federation. A.D.S. also acknowledges the Russian Foundation for Basic Research for the support under Project No. 19-03-00947. M.P. acknowledges the Academy of Finland for financial support. A.R.A. acknowledges the Horizon 2020 program I4Future for financial support (Grant Agreement No. 713606). The University of Nottingham High Performance Computing Facility provided computational resources partially supporting this investigation. The authors acknowledge MAX IV Laboratory for time on Beamline FinEstBeAMS under Proposal No. 20190182. Research conducted at MAX IV, a Swedish National User Facility, was supported by the Swedish Research Council under Contract No. 2018-07152, the Swedish Governmental Agency for Innovation Systems under Contract No. 2018-04969, and Formas under Contract No. 2019-02496.
EU Grant Number: (713606) I4FUTURE - Novel Imaging and Characterisation Methods in Bio, Medical, and Environmental Research and Technology Innovations
Copyright information: Published under an exclusive license by AIP Publishing. This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. The article appeared in The Journal of Chemical Physics 155, 054304 (2021) and may be found at