RECONSTRUCTION PHENOMENA AT GOLD ELECTROLYTE INTERFACES - AN IN-SITU STM STUDY OF AU(100)/

The structure of Au(100) surfaces in contact with aqueous solutions ha s been studied by in-situ scanning tunnelling microscopy. It is shown that the surface topography of flame annealed Au(100) sensitively depe nds on the sample preparation as well as on the electrochemical pretre atment. Flame annealed Au(100) surfaces are reconstructed and it is de monstrated under which conditions this initial (thermally induced) rec onstruction is preserved during and after contact with the electrolyte . Once the initial reconstruction of a gold surface has disappeared, e .g. due to specific adsorption of anions, a potential induced reconstr uction may take place, usually at potentials clearly negative with res pect to the potential of zero charge. As a consequence, the surface st ructure of an Au(100) electrode is potential dependent and structural changes may occur within the potential region chosen for an electroche mical experiment. The kinetics and a mechanistic model of the structur al transition are briefly discussed.