Direct energy transfer in restricted geometries

We study the relaxation of an excited donor due to energy transfer to acceptors embedded in restricted geometries which model different porous structures. We focus on relaxation within spherical and cylindrical volumes and also within fractals. The relaxation of the donor is expressend in terms of a site density function ρ 0 ( r ). Deviations from the known Forster behavior are observed due to the geometrical restrictions.