Finite-temperature Green's functions of the fluctuation electromagnetic field of a sphere and spherical layer imbedded in an infinite medium

Exact finite-temperature Green's function are constructed for the long-wave electromagnetic field in a medium with a spherical inhomogeneity by means of an expansion with respect to spherical harmonics. The expansion coefficients are found for the case of an unbounded medium with one spherical particle and for the case of a spherical layer on the surface of a particle imbedded in an infinite medium. These Green's functions can be used to study the physics of finely dispersed systems.