Surface-induced d-band anisotropy on Cu( [formula omitted

Abstract

Reflectance difference spectroscopy (RDS) was used to study the surface-induced anisotropy of the electronic band structure on Cu(1 1 0) in the energy range between 3 and 5.5 eV. The spectral features in this energy range can be well reproduced by approximating surface dielectric anisotropy by the first derivative of the known bulk dielectric function. In contrast to the conventional ‘derivative model’, however, the different sensitivity to the relevant Cu d-bands to the surface anisotropy has to be respected. The results can be rationalized in a tight-binding picture relating the shift of the surface projected d-bands to the different atomic densities along the in-plane [0 0 1] and [ 1 ̄ 1 0 ] directions, respectively. As a confirmation, the temperature dependence of the RDS features was measured and found to be in good agreement with the thermal shifts of the associated optical transitions.