SCANNING TUNNELING MICROSCOPY AND QUARTZ CRYSTAL MICROBALANCE STUDIES OF AU EXPOSED TO SULFIDE, THIOCYANATE, AND N-OCTADECANETHIOL

Atomic resolution STM images of Au(111) treated with solutions of Na2S, H2S, or NaSCN display patterns of atoms in the shape of squares with nearest-neighbor distances of 0.27 +/- 0.3 nm. QCM data demonstrate that Au dissolves in aqueous solutions of sulfide and thiocyanate with O2 present. The square pattern observed is ascribed to images of Au atoms on a reconstructed Au(111) surface caused by dissolution of Au by sulfide or thiocyanate. n-Octadecanethiol/Au(111) surfaces damaged by the STM tip display a similar square pattern, indicating removal of Au atoms by the tip in a manner analogous to the dissolution process observed for sulfide or thiocyanate.