In this paper, the method to determine the absolute Raman cross section comparing the Raman intensity with that of the longitudinal Brillouin lines has been extended to the case of systems with low Brillouin separation. Here, we present an experimental determination of the cross section for two-phonon Raman scattering in potassium chloride. The spectra have been collected using, as a frequency analyzer, a high-resolution monochromator, which allows the detection under the same experimental conditions of both the sharp Brillouin line and the weak Raman signal.

• Received 30 November 1990

DOI:https://doi.org/10.1103/PhysRevB.43.14268