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Title: Insights into acetone photochemistry on rutile TiO₂(110). 2. new photodesorption channel with CH₃ ejection along the surface normal

Angle-resolved photon stimulated desorption (PSD) combined with infrared reflection-adsorption spectroscopy and temperature programmed desorption reveal two distinct channels in the photochemistry of acetone on rutile TiO₂(110) surface. During UV irradiation of co-adsorbed oxygen and acetone molecules, methyl radicals (CH₃) are ejected in two different directions: i) normal to the surface and ii) off-normal at ~±66° to the surface normal in the azimuth (i.e. perpendicular to the rows of bridging oxygen and Ti atoms). Both components are relatively narrow and non-cosine, indicating non-thermal evolution of CH₃ radicals. The direction of the “off-normal” PSD component is consistent with orientation of the C–CH₃ bonds in the n²-acetone diolate—a photoactive form of acetone chemisorption on the oxidized TiO₂(110) surface proposed earlier from experimental and theoretical studies. The direction of the “normal” PSD component requires an orientation of a C–CH₃ bond which is not consistent with the n²-acetone diolate structure. The angular distribution of the CH₃ PSD depends on the acetone coverage. The “off-normal” PSD component dominates at lower acetone coverage (< 0.2 ML), but does not increase at higher coverages in accord with the acetone diolate peak intensity in the infrared reflection-absorption spectra. The “normal” PSD component grows with the acetone coverage up tomore » 0.6 ML. The newly discovered “normal” PSD channel is tentatively assigned to a photo-produced n²- acetone enolate as a potential precursor based on the H/D exchange experiments« less
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  1. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Publication Date:
OSTI Identifier:
Report Number(s):
Journal ID: ISSN 1932-7447; 47565; KC0301020; KC0302010
DOE Contract Number:
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Physical Chemistry. C; Journal Volume: 119; Journal Issue: 22
American Chemical Society
Research Org:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org:
Country of Publication:
United States
Environmental Molecular Sciences Laboratory