Sm. Barnett et al., DECAY OF EXCITED ATOMS IN ABSORBING DIELECTRICS, Journal of physics. B, Atomic molecular and optical physics, 29(16), 1996, pp. 3763-3781
We present calculations of the rates of decay of an excited atom embed
ded in an absorbing dielectric. Decay can occur by spontaneous emissio
n into transverse radiative modes of the electromagnetic field and by
Joule heating via longitudinal coupling of the atom to the dielectric.
The spontaneous emission (transverse) decay rate is modified in a die
lectric, being the free-space rate multiplied by the real part of the
refractive index at the transition frequency of the atom. There is a f
urther modification due to the difference between the macroscopic diel
ectric field and the local field at the position of the atom. In addit
ion there is a longitudinal decay rate which is proportional to the im
aginary part of the dielectric constant and therefore vanishes in non-
absorbing media. We derive expressions for each of these rates of deca
y and discuss the physical mechanisms leading to them.