INSITU SCANNING TUNNELING MICROSCOPY OF UNDERPOTENTIAL DEPOSITION IN AQUEOUS-SOLUTION .3. SILVER ADLAYERS ON AU(111)

The underpotential deposition (UPD) of Ag has been investigated on a Au(III) surface in an aqueous sulfuric acid solution using an electrochemical scanning tunneling microscope (ESTM). Real-space images of the substrate surface ot Au(111) are acquired before initiating the UPD. The (square-root 3 X square-root 3)R30-degrees structure can be seen after the formation of the first UPD layer. Individual close-packed Ag atoms have also been resolved on a completely filled Ag layer. It is concluded that the first close-packed Ag layer is epitaxially formed OR the Au(111).