Resonant Light Scattering and Luminescence in Weakly Coupled Localized Electron-Phonon System. II

By extending a previous paper such that the condition of the weak coupling limit is relaxed, the relationship between resonant light scattering and luminescence is studied in a localized electron-phonon system with quadratic interaction. The total light scattering spectrum is decomposed into successive terms of S n representing the effect of the n -th order multiple phonon scattering in the intermediate state. It is shown that the line shape of S n changes gradually with n and approaches, for sufficiently large n , the luminescence spectrum. Effects of changes in the electron-phonon interaction strength, sharpness of the phonon density of states and radiative damping on the approach of S n to the luminescence limit are studied. The validity of the approximate calculation employed here is discussed in connection with a sum rule and a comparison of absorption spectra calculated with some different approximation methods.