Electron energy loss spectroscopy of a {111} oriented aluminum single crystal☆

Abstract Recently, the electron energy loss spectroscopy (ELS) and secondary electron spectroscopy (SES) of the interaction of oxygen with polycrystalline aluminum were reported for primary energies in the range 30 ⩽ E p ⩽ 250 eV. Two new transitions were resolved in the ELS spectra (one at 4 eV for clean aluminum and the other at 12 eV for oxide-covered aluminum) for low primary energies ( E p ≈ 30 eV). In this paper we report on experiments utilizing a {111} oriented single crystal of aluminum that confirm the existence of these loss peaks for low primary energies and show that the 4 eV peak position for pure aluminum depends on the primary beam energy. This suggests that this low energy loss peak is due to direct nonvertical inter- and intraband transitions which differs from the previous assignment.