Theoretical Studies of Two-Photon Absorption Processes. I. Molecular Benzene

Abstract

The theory of two‐photon transitions is extended to include vibronic‐coupling effects. The theory of symmetry‐forbidden two‐photon transitions is applied for the theoretical study of excitations in benzene. The introduction of vibronic‐coupling effects implies that the transition probability should be temperature dependent. A definite assignment of the electronic states of benzene can be obtained from theoretical predictions of the intensity ratios, the vibrational structure, and the polarization dependence for two‐photon absorption cross sections in this system.