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 ${\mathrm{nm}}^{\mathrm{-}1}$. 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.