Angle-resolved UPS study of the oxygen-induced 2x1 surface of Cu(110)

The two-dimensional oxygen-induced energy bands of the Cu(110)/2 x 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 <(Gamma)over bar> and (Y) over bar along the [001] direction. A fight-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 X 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.