Comparative analysis of intramolecular interactions in trans-stilbene and 1,4-distyrylbenzene

We have analyzed the intensity distributions in fine-structure fluorescence and fluorescence excitation spectra of trans-stilbene in n-hexane at 4.2 K. Modeling the spectra by representing each of the vibronic transitions by a zero-phonon line and a phonon wing with certain parameters (widths, Debye-Waller factors) made it possible to determine relative intensities of vibronic transitions. The parameters of Franck-Condon and Herzberg-Teller interactions, which form the fine-structure spectra of stilbene, have been calculated and compared with previously obtained parameters of intramolecular interactions in 1,4-distyrylbenzene.