A theory is presented of the Raman scattering of infrared light by the modulation of the ionic contribution to the polarizability of a crystal by the displacements of the atoms from their equilibrium positions. It is applied to the calculation of the scattering efficiency for the scattering of light by the localized vibration modes due to ${\mathrm{H}}^{-} U$ centers in Ca${\mathrm{F}}_2$. The results of these calculations indicate that such scattering should be readily observable when a CO or He-Ne laser is used as the source of incident light.

• Received 22 June 1970

DOI:https://doi.org/10.1103/PhysRevB.2.4294