Utilize este identificador para referenciar este registo: http://hdl.handle.net/10400.1/2062
Título: Photochemistry of benzophenone on Ti-MCM-41 surfaces
Autor: Silva, José P. da
Machado, I. F.
Lourenço, J. P.
Ferreira, Luís F. Vieira
Palavras-chave: Luminescence
Surface photochemistry
Diffuse reflectance
Laser flash photolysis
Degradation products
Data: 2006
Editora: Elsevier
Citação: Da Silva, J. P.; Machado, I. F.; Lourenço, J. P.; Ferreira, L. F. V. Photochemistry of benzophenone on Ti-MCM-41 surfaces, Microporous and Mesoporous Materials, 89, 143-149, 2006.
Resumo: Diffuse reflectance and chromatography techniques were used to study three Ti-MCM-41 solid powders, containing 1%, 2.5% and 8% of Ti, and to investigate the photochemistry of benzophenone adsorbed on their surfaces. The observed ground state absorption, luminescence and transient absorption spectra depend on the Ti content of the solid support. The luminescence intensity of the pure powders and of the solids with adsorbed benzophenone decreases with the Ti content. The benzophenone triplet emission was detected in all solids but its half-lives decrease with the Ti content of the support. Hydrogen-bonded excited benzophenone luminescence is also quenched but was detected only on supports with low Ti percentage. Transient absorption reveals the formation of trapped electrons and the presence of ligand-to-metal charge transfer in the pure solids, under 266 nm excitation. Ti aggregates are present in all used solid supports. Triplet–triplet absorption of benzophenone was observed in all solids under argon atmosphere. Transient absorption due to the OH–benzophenone radical was detected in all conditions and increases with the Ti content of the powder. 2-Hydroxybenzophenone and benzoic acid are the major photodegradation products in air-equilibrated conditions.
Peer review: yes
URI: http://hdl.handle.net/10400.1/2062
ISSN: 1387-1811
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