An Incommensurate Reconstruction Studied with Scanning Tunnelling Microscopy and Surface X-Ray Diffraction

We present the first results of a combined scanning tunneling microscopy (STM) and surface X-ray diffraction (SXRD) study of Ag monolayer deposited on Cu(111). The STM images of Ag monolayer show a periodic frame of triangles, 4 or 5 atomic row wide with 1 or 3 atoms protruding in the centre respectively. Away from the triangles, the corrugation of the atomic rows is about 0.05 A while the depth of the triangles is about 0.5 A. SXRD shows an "average" Ag surface unit cell (9.43 x 9.43) times the Cu(111) surface unit cell without rotation in good agreement with STM observations.