Theoretical aspects of two-photon charge transfer processes in homogeneous condensed systems

The paper presents theoretical models for two-photon processes occurring in homogeneous condensed systems with polyatomic impurity particles. Theoretical calculations were carried out mainly for resonance processes, which make the main contribution to the two-photon processes of absorption and emission of photons. The calculation of the double differential cross section of the processes was carried out using the apparatus of Green's functions of polarization operators of a condensed medium.
Analytical expressions for the kinetic parameters of two-photon processes in condensed systems are obtained. Numerical calculations can be carried out for various model systems.