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

Abstract

The surface optical and electronical properties of Cu(110) surfaces were studied by using reflectance anisotropy spectroscopy (RAS) together with angle-resolved photoemission spectroscopy (ARUPS). On the clean surface, a structure in the optical spectra at 2.1 eV is assigned to transitions between occupied p-type and unoccupied s-type surface states occurring at the $\overline{Y}$ point of the surface Brillouin zone. Another structure at 4.2 eV is associated with a transition at the $\overline{X}$ point between a surface resonance (occupied) split off from the bulk d bands and a p-derived surface state (unoccupied). The oxygen-induced $(2\mathrm{}\times 1)$ surface exhibits a double peak in the reflectance anisotropy which can be explained partly by transitions 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 features at higher energies.