Ionic Raman Effect. II. The First-Order Ionic Raman Effect

Abstract

A theory previously developed for 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 has been applied to the calculation of the scattering efficiency of a pure crystal having a first-order electric dipole moment and cubic anharmonicity in the potential energy. The requirements on crystal symmetry for a nonvanishing scattering efficiency are developed, and it is shown that only noncentrosymmetric crystals can exhibit the effect. The symmetries of the ionic Raman tensor are presented for the 21 crystal classes lacking a center of inversion. A numerical estimate of the scattering efficiency is given for the case of gallium arsenide.