Vibrationally-resolved photoelectron spectroscopy and photoelectron circular dichroism of bicyclic monoterpene enantiomers

Ganjitabar, Hassan; Hadidi, Rim; Garcia, Gustavo A.; Nahon, Laurent; Powis, Ivan

Abstract

The photoionization of four chiral bicyclic monoterpene isomers, α-pinene, β-pinene, 3-carene and sabinene — all commonly found constituents in essential natural oils — has been studied using synchrotron radiation and compared to recent findings for the cyclic isomer limonene. Slow photoelectron spectra (SPES) are recorded between threshold and an energy of 10.5 eV. In the case of limonene, α -pinene, and 3-carene, vibrational structure is observed in the ground ionic state and attributed to a C=C double bond stretching in the cation, using Franck-Condon vibrational band simulations. The photoelectron circular dichroism (PECD) is examined for specific enantiomers of these terpenes, and vibrational modification of the forward-backward photoelectron asymmetry detected by PECD can be tentatively identified, even when the corresponding SPES is unstructured. Large chiral asymmetry factors are found at low binding energies for the pinenes and 3-carene, with α -pinene in particular displaying a 37% forward-backward photoelectron asymmetry, believed to be a record chiroptical asymmetry for randomly-oriented, non-interacting molecules.

Citation

Ganjitabar, H., Hadidi, R., Garcia, G. A., Nahon, L., & Powis, I. (2018). Vibrationally-resolved photoelectron spectroscopy and photoelectron circular dichroism of bicyclic monoterpene enantiomers. Journal of Molecular Spectroscopy, 353, 11-19. https://doi.org/10.1016/j.jms.2018.08.007

• Journal Article Type: Article
• Acceptance Date: Aug 22, 2018
• Online Publication Date: Aug 23, 2018
• Publication Date: Nov 30, 2018
• Deposit Date: Aug 29, 2018
• Publicly Available Date: Aug 24, 2020
• Journal: Journal of Molecular Spectroscopy
• Print ISSN: 0022-2852
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 353
• Pages: 11-19
• DOI: https://doi.org/10.1016/j.jms.2018.08.007
• Keywords: Physical and Theoretical Chemistry; Spectroscopy; Atomic and Molecular Physics, and Optics
• Public URL: https://nottingham-repository.worktribe.com/output/1051552
• Publisher URL: https://www.sciencedirect.com/science/article/pii/S0022285218301759
• Contract Date: Aug 30, 2018