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 (
Revised: July 28, 2015 |
Published: June 4, 2015
Citation
Petrik N.G., M.A. Henderson, and G.A. Kimmel. 2015.Insights into Acetone Photochemistry on Rutile TiO2(110). 2. New Photodesorption Channel with CH3 Ejection along the Surface Normal.Journal of Physical Chemistry C 119, no. 22:12273-12282.PNNL-SA-108621.doi:10.1021/acs.jpcc.5b02478