Relaxation of excited states of an atom in the vicinity of a nanoparticle

Relaxation of an excited state of an atom in the vicinity of a nanoparticle has been described taking into account the rotational degrees of freedom of the atom. The description has been compared with the widely used generalized (vector) two-level model of an atom and the classical oscillator model. Relaxation dynamics of real atoms (excluding the atoms with the angular momenta $J_{m}=1$ and $J_{n}=0$ of the upper and lower levels, respectively) has been found to differ significantly from the predictions of those models.