Quantized media with absorptive scatterers and modified atomic emission rates

Modifications in the spontaneous emission rate of an excited atom that are caused by extinction effects in a nearby dielectric medium are analyzed in a quantummechanical model, in which the medium consists of spherical scatterers with absorptive properties. Use of the dyadic Green function of the electromagnetic field near a dielectric sphere leads to an expression for the change in the emission rate as a series of multipole contributions for which analytical formulas are obtained. The results for the modified emission rate as a function of the distance between the excited atom and the dielectric medium show the influence of both absorption and scattering processes.

Research highlights
► Absorption and scattering processes in a medium may cooperate in modifying the emission rate of an excited atom in its vicinity.
► Explicit expressions for the decay rate permit a detailed analysis of the behaviour of the emission rates for arbitrary distances between the atom and the medium.
► The effects of absorption and of scattering are qualitatively different, when the atom approaches the medium.