Extracting the Ag surface and volume loss functions from reflection electron energy loss spectra

Reflection electron energy loss spectra have been measured for silver using incoming electrons with energies between 5 and 40 keV, in a surface and volume-sensitive geometry. Bulk and surface loss functions are extracted from these data and various consistency checks are applied to the obtained loss functions. Depositing minute amounts of Al onto the Ag surface causes a severe reduction in surface features. The intensity of the surface feature seems now to increase as the probe energy is increased. A mechanism by which this can occur is discussed. The relation between the bulk loss function and the dielectric function is discussed, and a comparison with the results of transmission electron energy loss spectra and optical data is made.