Oxygen adsorbed on rare earth surfaces

The adsorption of oxygen on the surfaces of the rare earth metals Gd, Nd, and Tb was investigated using VUV photoelectron spectroscopy. As substrates served thin films showing the (0001) surfaces of crystals. This study utilized the technique of circular dichroism in the angular distribution of photoelectrons CDAD. The CDAD asymmetry, determined by the normalized difference of the photoelectron intensities for right and left circularly polarized radiation, is reduced with increasing oxygen exposure. The behavior of the asymmetry of the O 2p induced structure is rather similar for oxygen on neodymium and terbium. On gadolinium, in contrast, the observed feature is different including a change of sign. This observation points to different electronic properties of the adsorbate overlayers.