On the theory of nonradiative transitions in optical excitation of gaseous media

A new approach and a theoretical model for describing experimentally observed nonradiative effects are considered. Nonradiative transitions in an ensemble of polyatomic molecules are interpreted as conversion of absorbed energy of optical radiation to energy of thermal translational motion of gas molecules. The model includes explicit account for intermolecular interactions. The form of the corresponding model Hamiltonian in the approximation of pairwise interactions of molecules and methods for its calculation are proposed. It is shown that all required matrix elements of the theory are easy to calculate, and the method is suitable for both qualitative and quantitative analysis of nonradiative effects. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 67, No. 3, pp. 289–295, May–June, 2000.