Brillouin Scattering with Neutrons from Liquid Lead and Some Other Materials

In Brillouin scattering the wave-vector transfer Q of the scattering process is equal to the wave-vector q of collective excitations. In the case of neutrons the kinematical limitation restricts the range of momentum and energy transfer. Investigations on liquid Pb, Rb and Cs are reviewed. Molecular liquids CO and D2O have been studied also. Water has been investigated by Brillouin scattering with X-rays with very high energy resolution. The latter technique has the advantage that there is no kinematical limitation. Two different groups have interpreted the experimental results on water in different ways. After 40 years of Brillouin scattering, this technique remains very fruitful for the study of liquids and amorphous materials, both with neutrons and with X-rays.