Density fluctuations in liquid argon. II. Coherent dynamic structure factor at large wave numbers

Experimental results of the coherent dynamic structure factor S(k,{ω}), obtained by inelastic neutron scattering, are presented for liquid argon at three densities along the 120-K isotherm. The wave numbers k, covered by the experiment, range from 38 to 72 nm^-1. The transition of S(k,{ω}) to its free-gas behavior (the limit for k{→}{∞}) is compared with theoretical calculations. It appears that the experimental results can be described satisfactorily by theoretical calculations for a Lennard-Jones system, whereas the large-k expansion for a hard-spheres system fails to describe the present argon results.