AVS 58th Annual International Symposium and Exhibition
    Surface Science Division Monday Sessions
       Session SS2-MoM

Paper SS2-MoM9
Molecular Beam Scattering of CO and CO2 on CuOx Nanoclusters Supported on Silica Fabricated by Electron Beam Lithography

Monday, October 31, 2011, 11:00 am, Room 110

Session: Surface Chemical Dynamics
Presenter: Mallikharjunarao Komarneni, North Dakota State University
Authors: M. Komarneni, North Dakota State University
U. Burghaus, North Dakota State University
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Adsorption dynamics of CO and CO2 on 12 nm CuOx nanoclusters supported on silica are studied by molecular beam scattering. Samples are fabricated by electron beam lithography. Scanning electron microscopy, auger electron spectroscopy, and x-ray photoelectron spectroscopy are used to characterize the sample. Cu clusters which are nearly metallic, partially oxidized, and fully oxidized are prepared by varying the sample treatment. The initial adsorption probability, S0, of both CO and CO2 decreased with an increase in impact energy, Ei, and adsorption temperature, Ts, which is consistent with non-activated molecular adsorption. S0 of CO approaches the values obtained for copper single crystals for Ei of 0.4 eV. This is a result of the so-called capture zone effect, where CO molecules are trapped on the support and subsequently diffuse to the metal clusters. S0 of CO2 is larger than for single crystals. The differences in S0 for metallic and oxidic clusters can be explained by deviations in the mass matching. In-contrast with CO2, S0 of CO on metallic clusters is slightly larger than that of oxidic clusters. At low Ei and Ts, coverage dependent adsorption probabilities, S(Θ), of CO and CO2 on metallic clusters obeyed precursor-mediated Kisliuk-like dynamics. At large Ei, Langmuirian-like dynamics is seen for CO which is less pronounced for CO2 on metallic clusters.