Influence of atomic recoil on the spectrum of resonance fluorescence from a two-level atom
M. G. Prentiss, Shaoul Ezekiel · Physical Review A · 1987
By including the effect of atomic recoil, the fluorescence spectrum for a two-level atom can become asymmetric whether the atom is in a uniform field or in a field gradient. This predicted asymmetry in a field gradient accounts for some of the previously observed but hitherto unexplained asymmetry in the fluorescence spectrum.