The adsorption of oxygen on the (100) surface was studied using low-energy electron diffraction and high-resolution electron energy loss spectroscopy. Room temperature adsorption of oxygen gave a diffuse c(2 x 2) low-energy electron diffraction pattern and several vibrational loss features, with the most intense peak at 35meV. Upon annealing to 600C both the c(2 x 2) low-energy electron diffraction pattern and the high-resolution electron energy loss spectroscopy loss features became much sharper. Annealing to 700C produced a sharp (2 x 1) low-energy electron diffraction pattern and strong changes in the high-resolution electron energy loss spectrum including a large decrease in intensity of the 35meV peak. The work function of the 2 x 1 structure was 0.9eV lower than that of the c(2 x 2) structure while Auger measurements showed that the oxygen coverage was the same. The results were explained in terms of possible oxygen adsorption sites.

Oxygen Adsorption Sites on the PrB6(100) and LaB6(100) Surfaces. Yamamoto, N., Rokuta, E., Hasegawa, Y., Nagao, T., Trenary, M., Oshima, C., Otani, S.: Surface Science, 1996, 348[1-2], 133-42