Long range energy transfer by dipole–dipole and exchange interactions in rigid media and in liquids

Abstract

Static quenching by dipole–dipole and exchange mechanisms is discussed in terms of a time dependent radial density function, which describes the distribution of acceptor molecules around donors. The final equations for the time dependence of the donor concentration agree with those derived previously using an alternative technique. The radial density function provides a helpful physical insight into the short comings of the active sphere treatment. The effect of an exchange interaction on diffusion-controlled reactions is discussed, and an analytic equation derived for the increase in the effective encounter distance as the diffusion coefficient decreases. The transition from diffusive to static quenching is discussed, and the two regions linked qualitatively.