Untersuchung über den einfluss von adsorbierten gasen auf die elektronen-energieverlust-spektren einer Ni(110)-oberfläche

Electron energy loss spectra on a (110) nickel surface exhibit characteristic changes upon adsorption of H₂, CO and O₂. The clean surface shows only the surface and bulk plasmon losses at 8 eV and 18 eV respectively. Adsorption of CO produces two new loss peaks at 13.5 eV and 5.5 eV. Loss peaks due to hydrogen adsorption at 15 eV and 7.5 eV show a strong correlation with the well known adsorption characteristics of this system. The oxygen induced losses are different for chemisorbed O on Ni and NiO. In any case the chemisorption-induced losses are well established for primary energies below 120eV. In the loss spectra with higher excitation energies only a drastic decrease of the surface plasmon loss peak-height is visible. If the new losses can be attributed to one-electron excitations from molecular orbital levels due to the chemisorption bond, with assumptions of the final state of the excited electron a determination of the postition of these levels can be made. In case of CO and H₂ reasonable results are evaluated.