Quasielastic light scattering in silicon

A dominant, broad central mode in the Brillouin spectrum of silicon was fir st reported by Sandercock in 1978. This feature was later ascribed to a two -phonon difference scattering process. However, the issue of quasielastic s cattering in silicon has remained a major outstanding problem in Brillouin scattering, because similar central modes in other materials have commonly displayed two components. A second, broader quasielastic mode has been meas ured and is reported here.