Microscopic approach to correlation-induced frequency shifts

A microscopic model for the origin of the source correlations responsible for Wolf shifts is proposed. To illustrate the main features of the phenomenon of these correlation-induced frequency shifts, a simple atomic system consisting of a pair of identical two-level atoms interacting with each other via the dipole-dipole interaction is considered. Effects of the finite temperature of the source are also included. For this microscopic model, the far-zone spectrum for two different experimental situations is calculated. The red and blue frequency shifts of the spectrum can be understood in terms of the dipole-dipole interaction. The magnitude of the shifts depends on the strength of the dipole-dipole interaction. The dependence of the frequency shifts on the temperature of the radiating source is also given