Resonant scattering of light by slowly fluctuating localized electrons

The effect of slow fluctuations on resonant scattering of light by localized electrons is considered in the systems with a central peak. The cases of excitation in the regions of broad phonon wing of the absorption spectrum and of zero‐phonon line are discussed. It is shown that the spectrum of resonant scattering essentially depends on the fluctuation amplitude ≪ 0 and rate γ as well as on the radiative damping rate γ. In particular, in case γ ≪ γ ≪ ε 0 (limit of nearly static fluctuations), at an excitation in the region of zero‐phonon line, the resonant emission line becomes fluctuationally broadened by ε 0 (γ/2γ) 1/2 . In glasses at T → O this broadening mechanism should be dominant as its contribution decreases slowly with temperature (∼ T 2 ).