Comparison of the secondary-electron spectrum with the electron-loss spectrum on pure Al by low-energy electron-reflection spectroscopy

The secondary-electron (SE) spectrum, energy-loss (EL) spectrum, and Auger electron spectrum (AES) for pure Al were measured by low-energy electron-reflection spectroscopy. The SE spectrum taken at primary energies higher than 50 eV is compared to the spectrum at 30 eV when excitation of surface and bulk plasmons is negligible. Both spectra do not change in the peak position and shape. Therefore the contribution of secondary electrons emitted by plasmon decay is negligibly small compared to the contribution of those emitted by the single-electron excitations. Some additional peaks are observed in EL and SE when O2 is sorbed on the surface.