AG CU(111) - AN INCOMMENSURATE RECONSTRUCTION STUDIED WITH SCANNING-TUNNELING-MICROSCOPY AND SURFACE X-RAY-DIFFRACTION/

We present the first results of a combined scanning tunneling microsco py (STM) and surface X-ray diffraction (SXRD) study of Ag monolayer de posited on Cu(111). The STM images of Ag monolayer show a periodic fra me of triangles, 4 or 5 atomic row wide with 1 or 3 atoms protruding i n the centre respectively. Away from the triangles, the corrugation of the atomic rows is about 0.05 Angstrom while the depth of the triangl es is about 0.5 Angstrom. SXRD shows an ''average'' Ag surface unit ce ll (9.43 x 9.43) times the Cu(111) surface unit cell without rotation in good agreement with STM observations.