Spectrum of light scattered by a strongly driven atom

A spectrum based on the correspondence principle leads directly to the fundamental dipole moment correlation function for light scattering. We consider the distinction between mean-field scattering (coherent scattering) and scattering by fluctuations (incoherent scattering). We calculate the corresponding spectra from ab initio atomic wave functions associated with (i) a two-level system and (ii) an atom in two situations: while undergoing multiphoton ionization, and during electron-atom scattering.