Bulk versus surface effects in normal photoemission from Cu(110) in the range32≤hν≤160eV

Synchrotron radiation in the 32-160-eV range was used to elucidate the role of bulk and surface effects in normal photoemission from the valence bands of a Cu(110) crystal. A dramatic resonance in the $s-p$ band was observed for photon energies $h\nu =43-52\mathrm{}$ eV. We have used this resonance and the energy dependence of the spectra to study the role of surface-induced broadening of the momentum component perpendicular to the surface ($k_{\perp }$). Our results strongly contradict previous interpretations of lower-energy studies in terms of a one-dimensional density of states along $k_{\perp }$. We find that normal photoemission, applied over a sufficient energy range, can be used to map the initial-state bulk band structure.