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Title: Electron-stimulated reactions in layered CO/H{sub 2}O films: Hydrogen atom diffusion and the sequential hydrogenation of CO to methanol

Low-energy (100 eV) electron-stimulated reactions in layered H{sub 2}O/CO/H{sub 2}O ices are investigated. For CO layers buried in amorphous solid water (ASW) films at depths of 50 monolayers (ML) or less from the vacuum interface, both oxidation and reduction reactions are observed. However, for CO buried more deeply in ASW films, only the reduction of CO to methanol is observed. Experiments with layered films of H{sub 2}O and D{sub 2}O show that the hydrogen atoms participating in the reduction of the buried CO originate in the region that is 10–50 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 to account for the observations.
Authors:
;  [1] ; ;  [2] ;  [3] ;  [3]
  1. Physical Sciences Division, Pacific Northwest National Laboratory, MSIN K8-88, P.O. Box 999, Richland, Washington 99352 (United States)
  2. School of Chemistry, The University of Manchester, Manchester M13 9PL (United Kingdom)
  3. (United Kingdom)
Publication Date:
OSTI Identifier:
22304341
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 140; Journal Issue: 20; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; CARBON MONOXIDE; DIFFUSION; ELECTRONS; FILMS; HEAVY WATER; HYDROGEN; HYDROGENATION; METHANOL; OXIDATION; SOLIDS; SURFACES