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Title: Electron-stimulated reactions in layered CO/H2O films: Hydrogen atom diffusion and the sequential hydrogenation of CO to methanol

Low-energy (100 eV) electron-stimulated reactions in layered H2O/CO/H2O ices are investigated. For CO trapped within approximately 50 ML of the vacuum interface in the amorphous solid water (ASW) films, both oxidation and reduction reactions are observed. However for CO buried more deeply in the film, only the reduction of CO to methanol is observed. Experiments with layered films of H2O and D2O show that the hydrogen atoms participating in the reduction of the buried CO originate in region from ~10 – 40 ML below the surface of the ASW films and subsequently diffuse through the film. For deeply buried CO layers, the CO reduction reactions quickly increase with temperature above ~60 K. We present a simple chemical kinetic model that treats the diffusion of hydrogen atoms in the ASW and sequential hydrogenation of the CO to methanol that accounts for the observations.
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Journal Article
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Journal Name: Journal of Chemical Physics, 140(20):Article No. 204710
Research Org:
Pacific Northwest National Laboratory (PNNL), Richland, WA (US)
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Country of Publication:
United States