Transform method in resonance Raman scattering with quadratic Franck–Condon and Herzberg–Teller interactions

A new method of considering quadratic vibronic interactions and deviations from the Condon approximation in resonance Raman scattering (RRS) is proposed. The method is used for the generalization of the transform law between absorption and Raman excitation profiles, derived earlier for a basic model. In the case of arbitrary mixing of modes with similar frequencies, a simple generalization of the transform law for first‐order RRS is obtained. For an arbitrary change of frequencies without mode mixing the transform law for the nth‐order RRS is given. The equations are valid for an arbitrary number of modes and also take temperature effects into account.