Sound absorption and dispersion as a function of density near the critical point of xenon

Abstract

Sound velocity and absorption have been measured at frequencies of 0.6, 1, and 3 MHz for xenon along the liquid-vapor coexistence curve and along several near-critical isotherms. By simultaneously measuring the dielectric constant, the local density was determined at the level in the fluid where the ultrasonic results were obtained. The shape of the coexistence curve obtained from dielectric data gave a critical exponent $\ensuremath{\beta}$ of 0.357 \ifmmode\pm\else\textpm\fi{} 0.002. The critical sound absorption and dispersion have been analyzed in terms of our modification of Fixman-Kawasaki theory. It is shown that both absorption and dispersion data can be described in terms of a single reduced frequency. The thermodynamic sound-velocity values needed in the analysis of dispersion have been calculated from the linear-model parametric equation of state.