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Valence shell electronically excited states of imidazole and 1-methylimidazole

Holland, D. M.P.; Shaw, D. A.; Townsend, D.; Powis, I.


D. M.P. Holland

D. A. Shaw

D. Townsend

I. Powis


The absolute photoabsorption cross section of imidazole, and that of 1-methylimidazole, have been measured from threshold up to 10.8 eV using synchrotron radiation. For each molecule, the absorption spectrum exhibits several broad bands due to transitions into excited valence states and some sharp structure associated with Rydberg states. Assignments have been proposed for some of the observed absorption bands using calculated transition energies and oscillator strengths. Quantum defect analyses have also helped guide these assignments. Natural transition orbital plots indicate that many of the electronically excited states have a mixed Rydberg/valence character. This mixing leads to irregularities in both the transition energies and the relative intensities of the absorption bands ascribed to Rydberg states. The vibrational progressions belonging to some of the Rydberg states have been interpreted using simulations of the corresponding cation’s vibrational structure obtained within the Franck-Condon model employing harmonic frequencies and normal modes.


Holland, D. M., Shaw, D. A., Townsend, D., & Powis, I. (2022). Valence shell electronically excited states of imidazole and 1-methylimidazole. Molecular Physics,

Journal Article Type Article
Acceptance Date Sep 3, 2022
Online Publication Date Sep 22, 2022
Publication Date Sep 22, 2022
Deposit Date Sep 26, 2022
Publicly Available Date Sep 23, 2023
Journal Molecular Physics
Print ISSN 0026-8976
Electronic ISSN 1362-3028
Publisher Taylor and Francis
Peer Reviewed Peer Reviewed
Keywords Physical and Theoretical Chemistry, Condensed Matter Physics, Molecular Biology, Biophysics
Public URL
Publisher URL
Additional Information This is an Accepted Manuscript of an article published by Taylor & Francis in Molecular Physics on 22/09/2022, available at:


This file is under embargo until Sep 23, 2023 due to copyright restrictions.

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