Photoemission spectra and band structures ofd-band metals. V. The (100) and (111) faces of single-crystal copper

Photoelectron energy spectra have been measured on the (100) and (111) surfaces of single-crystal copper in the photon energy range 7. 7-10. 2 eV. The surfaces were prepared by argon-ion sputter-etching and annealing techniques with chemical purity (> 95%) determined by in situ Auger-electron spectroscopy. Model band calculations based on direct transitions predict successfully the relative positions of the uppermost d-band peak and its splitting on the (100) face. For the (100) face at the lowest photon energy, the calculations predict no emission from the d bands, whereas abundant emission is actually observed. The contributions from one of the higher Mahan cones have also been calculated, and are found to be important only for photon energies above 10 eV.