UNDERPOTENTIAL DEPOSITION AND ELECTROCRYSTALLIZATION OF METALS - AN IN-SITU SCANNING-TUNNELING-MICROSCOPY STUDY WITH LATERAL ATOMIC-RESOLUTION

The formation of well ordered 2D metal adsorbate layers in the underpo tential range and 3D metal deposits in the overpotential range on fore ign substrates has been studied in the model system Ag(hkl)/Pb2+ by in situ scanning tunnelling microscopy (STM) under defined potential con trol with lateral atomic resolution. The results are compared to elect rochemical, morphological, in situ EXAFS and GIXS investigations. In s itu STM provides an excellent atomic view of the initial steps of unde r potential deposition (UPD) and electrocrystallization of lead onto ( 100) and (111) silver single-crystal faces. The results indicate a Str anski-Krastanov mechanism of 3D nucleation and growth in this system.