Elastic and Inelastic Low-Energy-Electron Diffraction From Al(100). II. Absolute-Intensity Measurements

Elastic and inelastic low-energy-electron-diffraction (ELEED, ILEED) observation have been made on a clean (100) surface of Al. Measurements on the (10) and (11) elastic-diffraction beams were made using normally incident electrons in the energy range $30\le E\le 170$ eV. Peaks in the energy-loss distribution are seen near 5, 10, 15, 26, and 31 eV, the dominant peaks near 10 and 15 eV corresponding to surface- and bulk-plasmon excitations, respectively. Two types of structure are observed in the inelastic angular profiles: one closely correlated with the structure in the elastic angular profile and the second being substructure corresponding to different ILEED conditions. Absolute intensities of the energy-intensity profiles (as a function of incident energy) for the (10) and (11) elastic and inelastic diffraction beams have been measured. These profiles also show primary and secondary structure. Within the substructure of the angular profiles are the first unambiguous experimental observations of sideband diffraction. A comparison of the experimental results and the theoretical predictions of different models is made.