ANALYTICAL SOLUTION OF THE PROBLEM ON DIPOLE-DIPOLE RELAXATION OF RADICAL PAIRS WITHIN A MODIFIED MICROREACTOR MODEL

An exact solution of the problem on dipole-dipole relaxation of micell ized radical pairs is derived within a modified microreactor model whi ch allows for the possibility of radical attraction to the micelle wal l. If radicals are attracted only weakly, the results closely agree wi th Steiner's data gained by numerical modeling of motion of two radica ls by the Monte Carlo method. As revealed by analysis of the general s olution, an attracting wall may cause an apparent increase in the mice lle radius. It is suggested that the exact solution be approximated by a sum of two weighted terms, the solution for a micelle with an inert wall and the solution for a radical diffusing solely on the surface. The two-term approximation provides a good fit to the exact solution, whenever the diffusion coefficients on the surface and in the bulk ass ume close values.