Theory of low-energy Raman scattering in glasses

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Abstract
We work out a theory of low-energy Raman scattering in glasses. The scattering and the energy transfer are due to interaction of the light with the soft potentials in glasses. We exploit relations between the scattering cross sections at a certain energy transfer, ħω, and the mean free paths of sound and electromagnetic radiation for the frequency ω. A comparison between the theory and experiment is made. An explanation of the boson peak is proposed. We come to a conclusion that the peak may be due to a reconstruction of the low-energy density of states due to interaction between soft harmonic oscillators. The interaction is enhanced with the frequency ω and, as a result, soft harmonic vibrations, localized for comparatively small ω, become extended (but not propagated) for bigger values of ω.