Resonant first- and second-order Raman scattering in gray tin

Abstract

The first- and second-order Raman scattering by phonons has been investigated in $\alpha -\mathrm{S}\mathrm{n}$ as a function of scattering photon energy. A resonant behavior of both first- and second-order processes has been found near the $E_1+{\Delta }_1$ gap (∼ 1.85 eV) and a resonance of the first-order process near $E_2$ (3.7 eV). The scattering by $2\Gamma \mathrm{}\left(O\right)\mathrm{}$ phonons develops a peak near resonance in a manner similar to that found for Ge and Si. The results are interpreted in terms of two- and three-band scattering processes.