THEORETICAL STUDY OF THE RESONANCE RAMAN SCATTERING FROM A MOLECULAR SYSTEM. EFFECTS OF VIBRONIC AND NONADIABATIC COUPLINGS.

A theory of the resonance Raman scattering (RRS) from a molecular system in which the vibronic levels of the resonance state are perturbed by both the Herzberg-Teller vibronic and the nonadiabatic coupling is developed. By using the time-independent Green-function formalism, an expression for the RRS is derived in the three-electronic-state model. The RRS cross-sections obtained are classified into four types: the pure RRS cross-section, independent of the coupling mode: the vibronically induced one, the nonadiabatically induced one, and the interference term. Assuming that the molecular system consists of a totally symmetric mode characterized by a displaced harmonic oscillator, with a nontotally symmetric mode as the inducing mode, analytical expressions for the relevant RRS cross-sections of the n//s-th order vibrational transition for the totally symmetric mode are derived.