ANGLE-RESOLVED PHOTOEMISSION-STUDY OF OXYGEN-CHEMISORPTION ON GD(0001)

The initial stages of oxidation and the electronic structure of chemis orbed oxygen on Gd(0001) thin films have been studied by angle-resolve d photoelectron spectroscopy. Dissociative chemisorption of oxygen occ urs with initial exposures and is followed by formation of a more comp lex surface oxide of Gd. The symmetry of oxygen-induced states has bee n identified. Initial oxygen chemisorption occurs through bonding to t he Gd(0001) surface via the p(x,y) derived oxygen states. The surface work function decreases with initial oxygen adsorption. The electronic structure induced by oxygen and the work function change indicate tha t the chemisorbed oxygen layer is below the plane of the Gd(0001) surf ace layer.