Angle-resolved UPS study of the oxygen-induced 2 × 1 surface of Cu(110)

Abstract

The two-dimensional oxygen-induced energy bands of the Cu(110)/2 × 1−O surface were investigated by angle-resolved ultraviolet photoemission spectroscopy (ARUPS). A new finding in the present report is that the oxygen-derived O 2p y and O 2p z bands cross and hybridize between λ and Ȳ along the [001] direction. A tight-binding band calculation assuming the missing-row reconstruction model was successfully made to reproduce the dispersion of the oxygen-derived bands, including band crossing as well as symmetry characteristics. An ARUPS study on a surface with a very small amount of adsorbed oxygen of about 0.01 ML was also made. An interesting result is that almost the same dispersion as that of the well-ordered 2 × 1−O surface of 0.5 ML is observed. This result indicates that CuO chains directed along the [001] direction grow long enough to apparently give the same dispersion, even in the initial stage of oxygen adsorption.