  Radiative heat exchange at the nanoscale presents a challenge for several
areas due to its scope and nature. Here, we provide a thermokinetic description
of microscale radiative energy transfer including phonon-photon coupling
manifested through a non-Debye relaxation behavior. We show that a
lognormal-like distribution of modes of relaxation accounts for this non-Debye
relaxation behavior leading to the thermal conductance. We also discuss the
validity of the fluctuation-dissipation theorem. The general expression for the
thermal conductance we obtain fits existing experimental results with
remarkable accuracy. Accordingly, our approach offers an overall explanation of
radiative energy transfer through micrometric gaps regardless of geometrical
configurations and distances.
