Vibronic coupling in polyenes: The frequency increase of the active CC ag stretching mode in the absorption spectra

Abstract

The adiabatic vibronic couplings due to the ag CC stretching modes between the lowest electronic states of a few polyenes have been obtained by quantum mechanical calculations. Their effects on the frequencies of the inducing modes in S0, S1 and S2 are evaluated together with the degree of Duschinsky mixing. Excellent agreement is found between theoretical results and the frequency shifts observed comparing absorption and emission spectra. © 1986.