Scattering of helium atoms by liquid helium

We present results from a new He–liquid-He single-atom effective potential for scattering, obtained from an integration, over the region occupied by the liquid, of a standard Lennard-Jones 6-12 pairwise potential combined with a simple model of the pair-correlation function. The new potential is consistent with (a) the accepted internal energy (the negative of the latent heat) of liquid He, (b) the accepted long-range (-$C_3$/$z^3$ van der Waals) atom-surface interaction potential, and (c) the scattering (reflectivity) data of Edwards et al. Production of excitons (ripplons) at the surface is not necessary to interpret the data. The theory is unsymmetrized; that is, no account is taken of the fact that scattering among identical particles is being considered.