The initiation and characterization of single bimolecular reactions with ascanning tunneling microscope

A scanning tunneling microscope (STM) operating at 9 K in ultrahigh vacuum was used to initiate a bimolecular reaction between isolated hydrogen sulfi de and dicarbon molecules on the Cu(001) surface. The reaction products eth ynyl (CCH) and sulfhydryl (SH) were identified by inelastic electron tunnel ing spectroscopy (STM-IETS) and by sequentially removing hydrogen atoms fro m an H2S molecule using energetic tunneling electrons. For comparison, the thermal diffusion and reaction of H2S and CC at 45 K and H2O and CC at 9 K were also observed.