Surface optical properties of clean Cu(110) and Cu(110)-(2 x 1)-O

The surface optical and electronical properties of Cu(110) surfaces were st udied by using reflectance anisotropy spectroscopy (RAS) together with angl e-resolved photoemission spectroscopy (ARUPS). On the clean surface, a stru cture in the optical spectra at 2.1 eV is assigned to transitions between o ccupied p-type and unoccupied s-type surface states occurring at the (Y) ov er bar point of the surface Brillouin zone. Ar;other structure at 4.2 eV is associated with a transition at the (X) over bar point between a surface r esonance (occupied) split off from the bulk d bands and a p-derived surface state (unoccupied). The oxygen-induced (2 X 1) surface exhibits a double p eak in the reflectance anisotropy which can be explained partly by transiti ons from oxygen induced d- to empty p-derived states. Surface modified bulk d-states are responsible for parts of the features around 2 eV and feature s at higher energies.