Spectroscopic ellipsometric investigation of clean and oxygen covered copper single crystal surfaces

Spectroscopic ellipsometric measurements (400–820 nm) have been performed on clean and oxygen covered Cu(110) and Cu(111) surfaces in an AES-LEED UHV system. The complex dielectric functions of the clean surfaces were calculated from measurements between room temperature and 600 K. In contrast with Cu(111), for the Cu(110) surface the ellipsometric parameters Δ and Ψ depend on the azimuth of the plane of incidence of the light beam. Such an anisotropy was also found for the changes in Δ and Ψ measured upon adsorption of oxygen to coverages corresponding with approximately 1/2 and 1 monolayer. To explain the results, several models are discussed, in which changes with substrate optical properties are taken into account.