Quasielastic light scattering in silicon

A dominant, broad central mode in the Brillouin spectrum of silicon was first reported by Sandercock in 1978. This feature was later ascribed to a two-phonon difference scattering process. However, the issue of quasielastic scattering 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 measured and is reported here.