Relationship between the geometry of the excited state of vanadium oxides anchored onto SiO sub 2 and their photoreactivity toward CO molecules
- Univ. of Maine, Orono (United States)
- Univ. of Osaka (Japan)
The phosphorescence spectrum of vanadium oxide anchored onto SiO{sub 2} shows well-resolved vibrational fine structure at 77 K. Franck-Condon analysis of the phosphorescence indicates that the internuclear equilibrium distance between oxygen and vanadium ions of V {double bond} O vanadyl groups as emitting sites of V/SiO{sub 2} catalyst anchored onto SiO{sub 2} is larger by 0.12 {angstrom} in its charge-transfer excited triplet state than in its ground state. UV irradiation of the catalyst in the presence of CO leads to the formation of CO{sub 2} (photoreduction of the catalyst) and adsorption of CO. In this former photoreaction, a good linear relationship between the yields of photoformed CO{sub 2} and the yields of phosphorescence is observed. Since photoformation of CO{sub 2} is accompanied by the removal of oxygen from the catalyst, both theoretical Franck-Condon analysis and experimental results indicate not only that the charge-transfer excited state of the surface vanadyl group of the catalyst plays a significant role in the photoreaction but also that an elongation of the internuclear distance between vanadium and oxygen ions in the excited state of the vanadyl groups may be associated with the easier photoreduction of the catalyst with CO.
- OSTI ID:
- 7252895
- Journal Information:
- Journal of Physical Chemistry; (United States), Journal Name: Journal of Physical Chemistry; (United States) Vol. 95:22; ISSN 0022-3654; ISSN JPCHA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400102 -- Chemical & Spectral Procedures
400201* -- Chemical & Physicochemical Properties
400500 -- Photochemistry
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CATALYST SUPPORTS
CHALCOGENIDES
CHEMICAL REACTIONS
DATA
ELECTROMAGNETIC RADIATION
ENERGY LEVELS
EXCITED STATES
EXPERIMENTAL DATA
INFORMATION
LUMINESCENCE
MOLECULAR STRUCTURE
NUMERICAL DATA
OXIDES
OXYGEN COMPOUNDS
PHOSPHORESCENCE
PHOTOCHEMICAL REACTIONS
RADIATIONS
REDUCTION
SILICON COMPOUNDS
SILICON OXIDES
TRANSITION ELEMENT COMPOUNDS
ULTRAVIOLET RADIATION
VANADIUM COMPOUNDS
VANADIUM OXIDES
VIBRATIONAL STATES