Theory of Inhomogeneous Gaussian Broadening of Resonance Raman and Coherent Anti-Stokes Raman Scattering Excitation Profiles for Polyatomic Molecules in Solution

Abstract

Reliable quantitative determination of parameters characterizing the time evolution of secondary radiation processes with polyatomic molecules in solutions, such as energy relaxation, elastic solute-bath collisions (dephasing), etc, from experimental data for the absorption spectra and the excitation profiles of the resonance Raman scattering (RRS) and coherent anti-Stokes Raman scattering (CARS) essentially depends on the correct theoretical account of the effects of the medium’s influence on the characteristics for isolated molecules. The medium exerts double influence on the characteristics of both the single-photon spectra of absorption (fluorescence) by molecules in solution and the RRS and CARS excitation profiles (REPs and CEPs): dynamic, of homogeneous nature, i.e. having effect even on a single molecule via the electron-phonon coupling, and static, of essentially inhomogeneous origin, evoked by variations of the local surroundings of each molecule of the ensemble under study.