Förster migration of electronic excitation between randomly distributed molecules

Abstract

This article deals with the diffusivelike migration of electronic excitation between molecules that are randomly distributed in space. A generalized (non-Markoffian) diffusion equation is obtained, and the generalized diffusion coefficient is expanded to second order in molecular concentration. At early times the mean squared displacement of excitation increases as the 5/6th power of time, instead of the usual first power of time. We conjecture that, at long times, the migration may be described by a conventional (Markoffian) diffusion equation.