Structure and composition of adsorbed layers formed by sequential exposure of Pt(100) and Pt(111) to pairs of compounds: Solvents and electrolytic substances

Studies are reported of the interaction of vapor of typical polar solvents and electrolytes at electrodes having Pt(111) or Pt(100) single-crystal surfaces: water, pyridine, acetonitrile, dimethyl-sulfoxide, hydrogen bromide, iodine, sulfur dioxide, acrylic acid, and ammonia. Exposure was extended from low pressures (about 10^?5 Torr) to pressures approaching the vapor pressure of the pure liquid. The results indicate that these typical electrochemical materials adsorb strongly to the clean Pt surface but once adsorbed tend not to react with each other. However, analysis of LEED patterns and Auger intensities suggests that exposure of an adsorbed layer of solvents such as dimethylsulfoxide to iodine results in adsorption of the halogen and molecular re-orientation of the adsorbed solvent.