Variations in Duschinsky rotations in m-fluorotoluene and m-chlorotoluene during excitation and ionization

Davies, Alexander R.; Kemp, David J.; Warner, Lewis G.; Fryer, Elizabeth F.; Rees, Alan; Wright, Timothy G.

Abstract

We investigate Duschinsky rotation/mixing between three vibrations for both m-fluorotoluene (mFT) and m-chlorotoluene (mClT), during electronic excitation and ionization. In the case of mFT, we investigate both the S1 → S0 electronic transition and the D0+ ← S1 ionization, by two-dimensional laser-induced fluorescence (2D-LIF) and zero-electron-kinetic energy (ZEKE) spectroscopy, respectively; for mClT, only the D0+ ← S1 ionization was investigated, by ZEKE spectroscopy. The Duschinsky mixings are different in the two molecules, owing to shifts in vibrational wavenumber and variations in the form of the fundamental vibrations between the different electronic states. There is a very unusual behavior for two of the mFT vibrations, where apparently different conclusions for the identity of two S1 vibrations arise from the 2D-LIF and ZEKE spectra. We compare the experimental observations to the calculated Duschinsky matrices, finding that these successfully pick up the key geometric changes associated with each electronic transition and so are successful in qualitatively explaining the vibrational activity in the spectra. Experimental values for a number of vibrations across the S0, S1, and D0+ states are reported and found to compare well to those calculated. Assignments are made for the observed vibration-torsion (“vibtor”) bands, and the effect of vibrational motion on the torsional potential is briefly discussed.

Citation

Davies, A. R., Kemp, D. J., Warner, L. G., Fryer, E. F., Rees, A., & Wright, T. G. (2020). Variations in Duschinsky rotations in m-fluorotoluene and m-chlorotoluene during excitation and ionization. Journal of Chemical Physics, 152(21), https://doi.org/10.1063/5.0009391

• Journal Article Type: Article
• Acceptance Date: May 12, 2020
• Online Publication Date: Jun 1, 2020
• Publication Date: Jun 7, 2020
• Deposit Date: Jun 3, 2020
• Publicly Available Date: Jun 4, 2020
• Journal: Journal of Chemical Physics
• Print ISSN: 0021-9606
• Electronic ISSN: 1089-7690
• Publisher: AIP Publishing
• Peer Reviewed: Peer Reviewed
• Volume: 152
• Issue: 21
• Article Number: 214303
• DOI: https://doi.org/10.1063/5.0009391
• Keywords: Physical and Theoretical Chemistry; General Physics and Astronomy
• Public URL: https://nottingham-repository.worktribe.com/output/4569857
• Publisher URL: https://aip.scitation.org/doi/10.1063/5.0009391
• Additional Information: This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in Journal of Chemical Physics and may be found at https://doi.org/10.1063/5.0009391