  By making use of the Green function concept of quantization of the
electromagnetic field in Kramers--Kronig consistent media, a rigorous quantum
mechanical derivation of the rate of intermolecular energy transfer in the
presence of arbitrarily shaped, dispersing, and absorbing material bodies is
given. Applications to bulk material, multi-slab planar structures, and
microspheres are studied. It is shown that when the two molecules are near a
planar interface, then surface-guided waves can strongly affect the energy
transfer and essentially modify both the (F\"{o}rster) short-range $R^{-6}$
dependence of the transfer rate and the long-range $R^{-2}$ dependence, which
are typically observed in free space. In particular, enhancement (inhibition)
of energy transfer can be accompanied by inhibition (enhancement) of donor
decay. Results for four- and five-layered planar structures are given and
compared with experimental results. Finally, the energy transfer between two
molecules located at diametrically opposite positions outside a microsphere is
briefly discussed.
