Electron energy-loss spectroscopy from polar ZnO surfaces

Reflection electron energy-loss spectra (ELS) in the 2–30-eV range were obtained from ZnO ($000\overline{1}$)O and (0001)Zn faces. Measurements were performed on atomically clean surfaces and on surfaces subjected to different treatments, including exposures to atomic hydrogen and molecular oxygen. The spectra were compared with ELS, UPS, XPS and UV reflection results obtained by other investigators. An identification of the observed electronic transitions is attempted.