LIGHT-SCATTERING AS A PROBE OF THERMODYNAMIC QUANTITIES IN A BINARY MIXTURE

We have shown recently how Rayleigh-Brillouin light scattering can be used to extract certain thermodynamic quantities of a binary mixture in an approximate way. An approach which yields exact results is described here, although it requires knowledge of additional thermodynamic data. This information can be obtained either from other experiments or from a thermodynamic model prediction. Since we arc dealing with a model system that can be described by a van der Waals equation of state, that model is preferred here. The results for the osmotic compressibility for a He + Xe mixture obtained this way from the Landau-Placzek ratio are in good agreement with calculations.