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 d etermined with inverse photoemission. An intense, Cu-induced surface s tate is found at 0.6 eV above the Fermi level on W(110). It is located in the Sigma(1) band gap. On the stepped W(331) surface there is a si milar state at 0.7 eV. This terrace state shifts down to 0.3 eV when t he coverage of Cu is reduced such that only a single row of Cu atoms r emains at a step edge.