Resonant Raman scattering versus luminescence

Abstract

We study the competition, in the light scattering spectrum, between electronic resonant Raman scattering and luminescence, on a simple three-level model due to Takagahara et al., where electrons are assumed to couple, in the intermediate state, with a field of localized « phonons ». The model can be solved exactly. We show that the relative weight of Raman versus luminescence peaks is controlled by a single memory parameter γb /Γ — where γb and Γ are the damping rates of the intermediate electronic state and of the phonons. If γb/Γ >> 1, memory is quasi-perfect, and the spectrum is purely Raman; in the opposite limit luminescence predominates. For γb/Γ ∼ 1, both structures are present, as well as anomalous satellites characteristic of « hot » luminescence.