Relaxation induced radical pair recombination in micelles

Abstract

We have derived accurate, analytic expressions for the quantum yield and the decay constants of a geminate radical pair reaction in a micelle. The relative diffusive motion of the radicals, intraradical relaxation (both transverse and longitudinal), and homogeneous scavenging are included. The general expression is exact for the assumed diffusion model, but we have also introduced two approximation schemes, called slow and fast mixing, which cover the complete parameter range. The high accuracy of these approximations is demonstrated by comparison with numerically exact results. A simple expression, derived for the limiting case of diffusion controlled recombination through the singlet channel, is compared with the previously introduced semi-phenomenological exponential, two-positional, and supercage models as well as with approximations based on a level population description. This comparison gives insight into the applicability of the approximate models and the physical meaning of the model parameters. The work is based on the general Green's function results derived in our previous paper [Chem. Phys. 260 (2000) 125].