Edge state and terrace state for Cu on W(331) and W(110)

The surface electronic structure of Cu on stepped and flat W(110) is determined with inverse photoemission. An intense, Cu-induced surface state is found at 0.6 eV above the Fermi level on W(110). It is located in the ${\mathrm{\Sigma }}_1$ band gap. On the stepped W(331) surface there is a similar state at 0.7 eV. This terrace state shifts down to 0.3 eV when the coverage of Cu is reduced such that only a single row of Cu atoms remains at a step edge.