Abstract
Second-order Raman scattering has been observed in the group- semimetals Bi, Sb, and As. Comparison of the spectra in Bi and Sb, which are primarily of even symmetry, with neutron-scattering measurements indicate a predominance of overtone scattering. Variations in the form of the second-order spectra are attributed to differences in the phonon density of states within the group- system. In contrast to Bi and Sb, the optical modes at in As are shifted to relatively higher frequency so that the mode no longer occurs at the minimum of the optic branch. Differences in the vibrational spectra near between As and Bi or Sb are attributed to a decrease in second- or further-neighbor interactions. From the ratio of the second- to first-order scattered intensities the corresponding ratios of average electron—one-phonon to electron—two-phonon deformation potentials are determined.
- Received 3 March 1975
DOI:https://doi.org/10.1103/PhysRevB.12.585
©1975 American Physical Society