OXYGEN ADSORPTION SITES ON THE PRB6(100) AND LAB6(100) SURFACES

摘要

The adsorption of oxygen on the LaB6(100) and PrB6(100) surfaces has been studied with low energy electron diffraction (LEED) and high resolution electron energy loss spectroscopy (HREELS). Room temperature adsorption of oxygen gives a diffuse c(2x2) LEED pattern and several vibrational loss features with the most intense peak at 35 meV. Upon annealing to 600 degrees C both the c(2x2) LEED pattern and the HREELS loss features become much sharper. Annealing to 700 degrees C produces a sharp (2x1)LEED pattern and strong changes in the HREEL spectrum including a large decrease in intensity of the 35 meV peak. The work function of the 2x1 structure is 0.9 eV lower than that of the c(2x2) structure while Auger measurements show that the oxygen coverage is the same. The results are discussed in terms of possible oxygen adsorption sites. References: 55