Oxygen adsorption on LaB₆ (100) and (111) surfaces

The adsorption of oxygen on LaB₆ (100) and (111) surfaces has been studied with high resolution electron energy loss spectroscopy (HREELS). In the HREELS spectra of the clean (100) surface, only one peak at 14 meV is observed, while two intense peaks appear at 16 and 27 meV in the spectra of the clean (111) surface. Oxygen adsorption on the (111) surface is quite different from the (100) surface: oxygen attacks the surface framework of boron on the (111) surface even at room temperature, resulting in the formation of a complex structure including B-O bonds, while the superstructure with only La-O bonds is formed on the (100) surface at room temperature. Only after heating to above 700°C, a B-O bond is formed on the (100) surface.