Surface plasmon excitation at a Au surface by 150-40,000 eV electrons

Abstract

Spectra of electrons with energies between 5 and 40 keV reflected from a homogeneous Au surface have been measured and analyzedto give the normalized distribution of energy losses in a single surface and volume excitation, as well as the total probability for excitationof surface plasmons. The resulting single scattering loss distributions compare excellently in (absolute units) with data from previouswork taken at lower energies (150-3400 eV). An empirical relationship is derived for the total surface excitation probability as a functionof the energy. For high energies the surface scattering zone represents only a small fraction of a typical electron trajectory and henceinterference effects should be small at these energies. Since we find that both the energy dependence of the surface plasmon excitationprobability and the shape of the single scattering loss distributions are the same at high and low electron energies, we conclude that thereis no evidence for interference effects in the entire energy range studied.