Scattering of Radiation from Interacting Atoms

The resonance fluorescence of a system of two identical, interacting atoms is investigated when the atoms are separated by distances that are large compared with atomic size. We consider the interactions between the atoms and the radiation field and the electrostatic interaction between the atoms, and find that the line shape of the emitted radiation consists of two peaks whose amplitude, separation, and width are functions of the internuclear distance $R$ of the atoms. The peaks are distinct at smaller separations, and, as $R$ increases, rapidly merge to the characteristic line shape of a single, isolated atom.