Equivalence of Resonance Raman Scattering in Solids with Absorption followed by Luminescence

The method used in a recent paper by Yu, Shen, Petroff, and Falicov to analyze successfully their data on two-phonon resonance Raman scattering in ${\mathrm{Cu}}_{2}$O illustrates the principle that resonance scattering is often equivalent to absorption into a resonant state followed by luminescence from that state. It is shown explicitly for the case considered by Yu et al. that the two descriptions are the same. Other examples from the literature are discussed. It is also shown that the maximum smallness of the resonant-energy denominator is unaffected by the widths of the relevant phonon states.