Rayleigh-Brillouin spectrum of compressed He, Ne, and Ar. I. Scaling

Abstract

The Rayleigh-Brillouin spectrum of He, Ne, and Ar is reported for 90° scattering at a number of densities spanning the kinetic and hydrodynamic regime. A purely experimental test of scaling is made and it is found that deviations from scaling at high density can be attributed to mean-field effects. At low densities there is evidence that deviations from scaling, which arise from the detailed dependence of the spectrum on the intermolecular potential, are detectable at the few percent level. Some insight into scaling is obtained by comparing the results at low densities with curves predicted from a $3E$ kinetic model and from hydrodynamic theory.