Semiclassical theory of vibrational Raman intensities

A semiclassical theory of the vibrational Raman effect based on the idea of different time scales for the electronic and nuclear motions is given. The proposed model gives a physical insight into the polarizability theory intuited by Placzek, the role of the electronic polarizability being that of the perturbation which induces first-order transition of the nuclei between vibrational levels. Extension of the semiclassical theory to the resonance Raman effect is made for the case where the intermediate states are, or may be represented by, a vibrational continuum. The specific case of the parallel components of the 0 {→} 1 and 0 {→} 2 Raman transitions in H₂⁺ is considered.