Absorption and resonance Raman spectroscopy of the ~1B_u state of trans-1,3,5-hexatriene including vibronic coupling

摘要

The vibronic coupling between the first excited S_1 (2~1A_g) and the second excited S_2 (1~1B_u) singlet electronic states in spectroscopy of trans-1,3,5-hexatriene molecule is investigated on the basis of a model consisting of two electronic states coupled by two vibrational modes. Employing a perturbation theory that treats the intramolecular couplings in a perturbative manner, the absorption and resonance Raman cross sections and excitation profiles of this molecule are calculated using the time-correlation function formalism. The non-Condon corrections are included in evaluation of cross sections. The multidimensional time-domain integrals that arise in these calculations have been evaluated for the case in which S_0 (1~1A_g)?S_2 (1~1B_u) electronic transition takes place between displaced and distorted harmonic potential energy surfaces. The calculated spectra are in good agreement with the experimental ones.