High-resolution normal emission UV-photoelectron spectra and band structure of Cu

Abstract

The energy distribution curves of photoelectrons emitted along the normal direction from Cu (111), (001) and (110) surfaces using unpolarized HeI (hv=21.2 eV) and HeII (hv=40.8 eV, 48.4 eV) radiation incident at 45° to the surface were measured. For the interpretation the band structure as calculated by Janak et al. and by the combined interpolation scheme was used. The high resolution spectra along the [111] and [001] directions show dominant features from direct transitions, indicating strong residualkz conservation, and density of states features, too. The ‘band gap’ emission along the [110] direction using HeI radiation can be explained with direct transitions into ‘evanescent’ states with nearly free electron bands. From the width of the peaks electron escape depths were calculated.