The physical and chemical characterization of electrochemically reformed silver surfaces

The effects of electrochemically oxidizing and reducing polycrystalline silver foils in aqueous chloride solutions are studied from a physical and chemical standpoint. Scanning electron microscopy indicates that the resulting surface is rough, consisting of nodular formations. Auger electron spectroscopic, secondary ion mass spectrometric and electrochemical results provide clear indication that a highly purified layer of metallic silver of increased surface area and activity is produced by the electrochemical reformation process. No evidence is found for the retention of intense Raman scatterers such as pyridine at these surfaces under ultrahigh vacuum conditions. The implications of the chemical and physical state of the reformed silver foils are discussed in the context of theories which have been proposed to explain the anomalously intense Raman spectra of scatterers adsorbed from solution onto these reformed silver surfaces. The origin of the 240 cm^-1 Raman line commonly observed on electrochemically reformed silver is discussed and assigned to the Ag-Cl^- stretching mode.