Organization and control of nanoscale structures on Au(111)

We address the formation and characterisation of three different nanoscale systems on single-crystal Au(111) electrode surfaces in aqueous electrolyte solutions. The systems are investigated particularly by single-crystal electrochemistry and in situ scanning tunnelling microscopy (STM). The first system is the amino acid cystine in the adsorbed state. After dissociation of its disulfide bond cystine forms a highly ordered pattern controlled by adsorption via the liberated sulfur atoms and intermolecular hydrogen bonding. Further organisation at three different levels by lateral interactions can be distinguished by the complementary use of single-crystal voltammetry and in situ STM. The second target molecule is the blue single-copper protein azurin which is shown to form monolayers which retain their long-range electron transfer function through the protein in the adsorbed state. The third system constitutes a new case for the use of in situ STM as a tool for manufacturing nanoscale pit structures on the Au(111) surface at small bias voltage. Individually and in combination these data hold perspectives for preparation of atomically planar electrochemical surfaces with controlled functionalisation, orientation of functional biological macromolecules, nanoscale biological sensing, and controlled adsorption sites for enzymes and other reactive molecules.