Phonon excitations in low-energy-electron scattering from solid Ar, Kr, and Xe films: Direct observation of conduction-band density of states

High-resolution low-energy-electron scattering (1--14 eV) from multilayer solid films of Ar, Kr, and Xe is reported for various energy losses and angles of incidence. We show that the scattered-electron intensity arising from multiple scattering on phonons, measured as a function of the incident energy, reproduces the conduction-band density of states calculated recently for rare-gas solids by Bacalis et al.$---- Using a simple multiple-scattering analysis we conclude that, under appropriate experimental conditions, this results from probing the inverse total mean free path of an electron propagating into the bulk of a film.