Multiple-order Raman scattering by a localized mode

Abstract

Resonant Raman scattering, up to seventeenth order, was observed in additively colored CsI. The Raman spectrum is dominated by a series of sharp, intense, equally spaced lines due to a localized mode associated with the defect. The principal mechanism for broadening of these lines is shown to be the anharmonic decay of the localized mode into two band modes. For the case of anharmonically broadened lines, a criterion is established to distinguish between hot luminescence and resonant Raman scattering. Each of the sharp lines exhibits a side band which resembles the phonon density of states of pure CsI. The intensity of the side bands is relatively constant out to tenth order even though the intensity of the main line decreases as ${(\mathrm{order})}^{\ensuremath{-}1}$. This behavior can be simply explained by the multiplicity of scattering diagrams.