DILS Spectral Moments of Argon At Room Temperature up to the Triple-Point Liquid Density

The DILS (Depolarized Interaction-induced Light Scattering) spectrum of argon has been measured along the T = 298 K isotherm over a range of densities between the critical and the triple-point liquid density. From these spectra, which where extended down to frequencies as low as 15 GHz, absolute values of the zeroth and second moments have been derived. The results are reported as a function of density and compared to molecular-dynamics simulations for a realistic model of argon. It is shown that, within the experimental errors, the pair approximation for both the potential and the polarizability anisotropy is valid for this system.