Surface characterization study of Ag, AgO, and Ag2O using x-ray photoelectron spectroscopy and electron energy-loss spectroscopy

Electron energy-loss spectra (ELS) have been obtained from polycrystalline Ag metal, AgO powder, and Ag2O powder using primary electron-beam energies ranging from 100 to 2000 eV. These samples were characterized using x-ray photoelectron spectroscopy (XPS) to determine the compositions and chemical species in their near-surface regions. The ELS spectra obtained from these three materials are significantly different, implying that ELS is a useful technique for distinguishing between Ag metal, AgO2 and Ag2O or analyzing mixtures of these species. Such an analysis is difficult using techniques including XPS or Auger-electron spectroscopy because spectral features of these species are quite similar and closely spaced. The ELS spectral features consist of losses due to the formation of surface and bulk plasmons and interband transitions. An attempt has been made in this study to assign the processes responsible for the ELS features observed in the spectra. This interpretation win be improved as the electronic structures of Ag metal, AgO, and Ag2O are better understood.