Time and frequency dependence of nearly resonant light scattered from collisionally perturbed atoms

Abstract

We generalize previous theories of collisional redistribution of near-resonance radiation to the case of a time-dependent incident intensity. In the absence of saturation the relation between the incident and the scattered spectrum is given by a time-dependent redistribution function. In the special case of an incident pulse with an exponential rise and decay we evaluate the time-dependent strength of the Rayleigh or Raman scattering and of the fluorescence. We pay special attention to the restriction on the time resolution resulting from the spectral resolution that is necessary to observe separately the two peaks in the scattered spectrum.