The method of quasi-stationary distribution functions in the diffusion theory of chemical reactions

The diffusion theory of two- and three-particle reacting systems, whose basic principles were formulated by Kramers (1940), is presented in a systematic manner. Formulas for a wide class of chemical reactions are obtained by solving kinetic equations asymptotically with respect to time. In the context of the Kramers model, dissociation (recombination) rate constants are determined for diatomic molecules, and a study is made of the dynamics of three-particle reacting systems. The agreement between theoretical and experimental data is found to be good for two-particle reactions and satisfactory for three-particle reactions. The applicability limits of the theory are analyzed, and ways to refine the theory are discussed.