ELECTRON ENERGY-LOSS SPECTRA OF CLEAN AND GAS-COVERED NI(100) SURFACES

Electron energy-loss spectra have been measured on Ni(100) surfaces, clean and following oxygen and carbon monoxide adsorption, at primary energies of 40-300 eV. The observed peaks at 9.1, 14 and 19 eV in the clean-surface spectrum are ascribed to the bulk plasmon of the 4s electrons, the surface plasmon, and the bulk plasmon of the coupled 3d + 4s electron, respectively, and the weak but sharp peak at 33 eV is tentatively attributed to the localized many-body effect in the final state. Assignments of the loss structures on the gas-covered surfaces have been attempted. © 1979.