The Theory of Raman Scattering by Impure Crystal. The Resonance Case

摘要

The resonance Raman spectrum of an impure crystal is analyzed in the adiabatic and Condon approximations with allowance for the anharmonicity of the lattice vibrations but neglecting variations in force constants in various electron states. The spectral intensities are calculated for two cases: (1) the incident light frequency omega being in the region of pure-electron transition and (2) omega falling in the region of the phonon wing, assuming the Stokes-shifts are appreciable. In the latter case, a quasi-linear structure of the spectrum may be observed, which makes it possible to use the resonance Raman spectra for studying the dynamics of impurity centers with appreciable Stokes-shifts.