Relaxation hindrance in nonadiabatic cage reactions

In-cage reactions are considered in the model of two intersecting parabolic terms different in curvature and lifetime. Transitions between the terms are assumed (contact approximation) possible only at the crossing point that is reached due to diffusion along the terms. The non-exponential kinetics of nonactivated reactions and the rate constants of activated reactions following the exponential law have been calculated within the model proposed. The results obtained allow one to connect the nonadiabatic theory (weak interaction) with the Kramers adiabatic theory (strong interaction). It has been found that at strong friction in the nonadiabatic theory as well as in the Kramers theory, the reactions are hindered by relaxation, i.e. the limiting stage is either the reagent activation (diffusion along the first term), or the product relaxation (diffusion along the second term).