J.G. McCarty

Stanford University, Palo Alto, CA, United States

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Publications (8)2.94 Total impact

  • J.G. McCarty, R.J. Madix
    Journal of Catalysis. 06/1977; 48(s 1–3):422–426.
  • J.G. McCarty, R.J. Madix
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    ABSTRACT: A study of the adsorption/desorption behavior of CO, H2O, CO2 and H2 on Ni(110)(4 × 5)-C and Ni(110)-graphite was made in order to assess the importance of desorption as a rate-limiting step for the decomposition of formic acid and to identify available reaction channels for the decomposition. The carbide surface adsorbed CO and H2O in amounts comparable to the clean surface, whereas this surface, unlike clean Ni(110), did not appreciably adsorb H2. The binding energy of CO on the carbide was coverage sensitive, decreasing from 21 to 12 as the CO coverage approached 1.1 × 1015 molecules cm−2 at 200K. The initial sticking probability and maximum coverage of CO on the carbide surface were close to that observed for clean Ni(110). The amount of H2, CO, CO2 and H2O adsorbed on the graphitized surface was insignificant relative to the clean surface. The kinetics of adsorption/desorption of the states observed are discussed.
    Surface Science. 01/1976; 54(1):121–138.
  • J.G. McCarty, R.J. Madix
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    ABSTRACT: The adsorption/desorption behavior of formic acid from a monolayer of graphite carbon on Ni(110) was studied using AES, LEED and flash desorption spectroscopy. Formic acid adsorbed at 165 K did not form multilayers of adsorbate. Instead, due to strong hydrogen-bonding interactions the formic acid formed a two-dimensional condensed phase on the surface and exhibited zero-order desorption kinetics initially for a 30-fold change in initial coverage. The zero-order desorption rate constant was kd = 1018 exp[−68.2 kJ mol−1/RT]s−1, suggesting a desorption transition state with nearly full translational and rotational freedom on the surface. The desorption kinetics and the coverage limit were consistent with the formation of a surface polymer-monomer equilibrium.
    Surface Science 01/1976; · 1.87 Impact Factor
  • Surface Science. 03/1974; 42(1):329–330.
  • J. Falconer, J. McCarty, R. J. Madix
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    ABSTRACT: Mass spectrometric flash desorption methods were used to study the formic acid decomposition following adsorption at 37°C on clean nickel (110). The surface cleanliness was verified by AES and LEED. Flash desorption of preadsorbed DCOOH showed no H2, HD, or H2O peaks, indicating that the acid hydrogen desorbed immediately upon formic acid adsorption. Isothermal decomposition showed that a surface explosion occurred to form CO2 and D2. The kinetics of the explosion were consistent with a mechanism the rate of which was dependent on the local surface concentration of formate complexes and bare metal atoms. The first-order rate constant for the DCOOH decomposition was 1.6×1015 exp {-26.6(kcal/gmole)/RT}sec-1.
    Japanese Journal of Applied Physics 01/1974; 13(S2):525. · 1.07 Impact Factor
  • J. McCarty, J. Falconer, R.J. Madix
    Journal of Vacuum Science and Technology 01/1974; 11(1):266-266.
  • Journal of Catalysis. 11/1973; 31(2):316–318.
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    ABSTRACT: The flash decomposition of adsorbed formic acid on clean Ni〈110〉 produced H2O, CO, H2, and CO2 peaks. The CO decomposition peak appeared at much higher temperatures than the H2 or CO2 decomposition peaks; it was identical to the flash desorption peak of adsorbed CO. The H2O peak was observed at temperatures well below the H2 and CO2 decomposition peaks. The H2 and CO2 decomposition peaks were identical and quite narrow. The insensitivity of the peak temperature of H2 and CO2 to initial coverage and the detailed peak shapes were inexplicable by simple mechanisms; they were suggestive of an autocatalytic decomposition. The hydrogen decomposition peak occurred at a much higher temperature than the flash desorption peak of H2.The initial sticking probability of formic acid was near unity at room temperature. Low exposures to formic acid produced CO and surface oxidation. The sticking probability of H2 was quite temperature sensitive, increasing from 0.01 to 0.5 between 50 and −25 °C; it was immeasurable on a carbon-covered surface. The initial sticking probability of CO was 0.7 ± 0.2. Decomposition of CO2 to adsorbed CO and O occurred with a probability of 0.15 per incident CO2 molecule.
    Journal of Catalysis. 08/1973; 30(2):235–249.