Epitaxial Ag ultra-thin films grown on Cu(111) were studied by scanning tunnelling microscopy and angle-resolved photoemission spectroscopy. In the sub-monolayer range, the spectroscopic measurements reveal the existence of two parabolic dispersive surface bands associated with the Cu terraces and the Ag islands suggesting the lateral confinement of the electronic states. A thickness dependence of the surface-state energy was evidenced. Moreover, the two well-known atomic reconstructions (moiré and triangular superstructures which depend on the preparation temperature) lead to different surface state energies. Photoemission spectra also reflect the transition from the metastable moiré structure into the triangular one. These results clearly demonstrate the strong sensitivity of the surface-state energy to the in-plane atomic structure.

Modification of Shockley States Induced by Surface Reconstruction in Epitaxial Ag Films on Cu(111). A.Bendounan, H.Cercellier, Y.Fagot-Revurat, B.Kierren, V.Y.Yurov, D.Malterre: Physical Review B, 2003, 67[16], 165412 (10pp)