Strong vibronic coupling in the first excited singlet state of diphenylhexatriene by an asymmetric low-frequency mode

Autor:	Wolfgang Werncke, S. Hogiu, M. Pfeiffer, A. Kummrow, A. Lau
Rok vydání:	1998
Předmět:	Diphenylhexatriene Coupling General Physics and Astronomy Low frequency Photoexcitation symbols.namesake chemistry.chemical_compound Vibronic coupling chemistry symbols Physical and Theoretical Chemistry Atomic physics Raman spectroscopy Doppler broadening Line (formation)
Zdroj:	Chemical Physics Letters. 295:56-62
ISSN:	0009-2614
DOI:	10.1016/s0009-2614(98)00935-x
Popis:	Raman studies of diphenylhexatriene in the first excited singlet state evidence strong vibronic coupling between two close 1Bu/2Ag states. The geometrical change after photoexcitation contains a dominant contribution of a low-frequency mode with bu symmetry near 40 cm−1. This mode is identified as a relatively strong line in the Raman spectrum. Vibronic coupling mainly affects two CC stretching Raman bands near 1700 cm−1. A two-dimensional effective potential for the lowest excited singlet state is derived which models the coupling between the coordinate of the 40 cm−1 mode and the CC stretching coordinate, thereby explaining the occurrence of the two bands and their strong solvent shift. The model gives, in the zero gap limit, a double-well potential for the CC stretching coordinate, due to the pseudo-Jahn–Teller effect. Modulation of this potential by the low-frequency cycle explains the spectral broadening observed in the Raman spectra.
Databáze:	OpenAIRE
Externí odkaz:	https://explore.openaire.eu/search/publication?articleId=doi_________::946b178c03f9d2c6837043a08dca327b https://doi.org/10.1016/s0009-2614(98)00935-x Zobrazit plný text záznamu Full Text from ScienceDirect