Analysis of sound propagation in xenon near the critical point

Existing ultrasonic and light-scattering data on sound propagation are analyzed, both in terms of a relaxing viscosity as calculated by Kawasaki, and in terms of relaxing heat capacities as calculated by Mistura. The two theories are examined and found to be quite different, but neither theory is found to be capable of accounting for the data, although disagreement with Kawasaki's theory is much more pronounced. Although not in agreement with theory, a frequency-dependent viscosity very similar to that required to account for the observed ultrasonic dispersion and attenuation is found to yield anomalous Brillouin spectra in excellent agreement with those observed near the critical point.