The vacuum ultraviolet absorption spectra of norbornadiene : vibrational analysis of the singlet and triplet valence states of norbornadiene by configuration interaction and density functional calculations
Abstract
A synchrotron-based vacuum ultraviolet absorption spectrum (VUV) of norbornadiene (NBD) is reported, and the extensive vibrational structure obtained has been analysed. The previously known 5b13s-Rydberg state has been reinterpreted by comparison with our recent high resolution photoelectron spectral (PES) analysis of the X2B1 ionic state. Additional vibrational detail in the region of this Rydberg state is observed in its VUV spectrum, when compared with the PES 2B1 ionic state; this is attributed to underlying valence state structure in the VUV. Valence and Rydberg state energies have been obtained by configuration interaction (CI) and time dependent density functional theoretical methods (TDDFT). Several low-lying singlet valence states, especially those which arise from ππ* excitations, conventionally termed NV1 to NV4, have been examined in detail. Their Franck-Condon (FC) and Herzberg-Teller (HT) profiles have been investigated and fitted to the VUV spectrum. Estimates of the experimental 00 band positions have been made from these fits. The anomaly of observed UV absorption by the 1A2 state of NBD is attributed to HT effects. Generally the HT components are less than 10% of the FC terms. The calculated 5b13s lowest Rydberg state also shows a low level of HT components. The observed electron impact spectra of NBD have been analysed in detail in terms of triplet states.
Citation
Palmer , M H , Hoffmann , S V , Jones , N C , Coreno , M , de Simone , M , Grazioli , C & Aitken , R A 2021 , ' The vacuum ultraviolet absorption spectra of norbornadiene : vibrational analysis of the singlet and triplet valence states of norbornadiene by configuration interaction and density functional calculations ' , The Journal of Chemical Physics , vol. 155 , no. 3 , 034308 . https://doi.org/10.1063/5.0053962
Publication
The Journal of Chemical Physics
Status
Peer reviewed
ISSN
0021-9606Type
Journal article
Rights
Copyright © 2021 Author(s). Published under an exclusive license by AIP Publishing. This work has been made available online in accordance with publisher policies or with permission. Permission for further reuse of this content should be sought from the publisher or the rights holder. This is the author created accepted manuscript following peer review and may differ slightly from the final published version. The final published version of this work is available at https://doi.org/10.1063/5.0053962
Collections
Items in the St Andrews Research Repository are protected by copyright, with all rights reserved, unless otherwise indicated.