Collisional perturbation of resonance fluorescence from atoms in a strong monochromatic driving field

We treat the problem of collisional perturbation of resonance fluorescence by means of a fully quantum-mechanical master equation approach based on the Fano-Zwanzig projection operator method. We suppose monochromatic irradiation at arbitrary intensity and consider mainly the two-state atom approximation. In the weak-coupling case, defined by assuming that the collision operator does not depend on the coupling with the exciting field, we recover results of previous work, valid beyond the restrictions of the impact limit. (orig.)