  Within the framework of quantization of the macroscopic electromagnetic
field, a master equation describing both the resonant dipole-dipole interaction
(RDDI) and the resonant atom-field interaction (RAFI) in the presence of
dispersing and absorbing macroscopic bodies is derived, with the relevant
couplings being expressed in terms of the surroundings-assisted Green tensor.
It is shown that under certain conditions the RDDI can be regarded as being
governed by an effective Hamiltonian. The theory, which applies to both weak
and strong atom-field coupling, is used to study the resonant energy exchange
between two (two-level) atoms sharing initially a single excitation. In
particular, it is shown that in the regime of weak atom-field coupling there is
a time window, where the energy transfer follows a transfer-rate law of the
type obtained by ordinary second-order perturbation theory. Finally, the
spectrum of the light emitted during the energy transfer is studied and the
line splittings are discussed.
