SIMS and TDS study of the reaction of water and oxygen on Pt(111)

Abstract

The reaction of H216O with 18O on Pt(111) was investigated using temperature programmed static secondary ion mass spectrometry (TPSSIMS), SSIMS and thermal desorption spectroscopy (TDS). The TPSSIMS behavior of the H3O+ and H318O+ signals, after coadsorption of the reactants at 95 K, indicates that the isotopic exchange rate increases sharply at temperatures above 130 K. At 150 K, hydroxyl formation is indicated by a sharp drop in the H3O+ and a similar sharp increase in the H318O+ signals. Using TDS, the overall stoichiometry of the reaction was determined to be 2H2O(a)+O(a)→ 3 OH(a)+H(a). SSIMS data suggest that at least two kinds of hydroxyls are formed and that they do not interconvert at 160 K. © 1982.