Direct detection of electron-hole pairs generated by chemical reactions onmetal surfaces

Non-adiabatic energy dissipation during exothermic chemical reactions on me tal surfaces occurs by creation of electron-hole pairs in the metal. The ex cited charge carriers have been directly detected using metal-silicon (Scho ttky) diodes with ultrathin metal films. The chemically created hot electro ns travel ballistically through the metal film? traverse the Schottky barri er and are detected as a chemicurrent in the diode. Three examples are pres ented, i.e. the adsorption of atomic hydrogen on Ag and Fe and the chemisor ption of molecular oxygen on Ag. The chemicurrent transients upon exposure are related to the kinetics of the surface reaction. The large difference i n the detection efficiency between Ag/Si and Fe/Si diodes is attributed to different conditions at the metal/silicon interface. (C) 2000 Elsevier Scie nce B.V. All rights reserved.