KINETIC AND SPECTROSCOPIC FEATURES OF SOME CAROTENOID TRIPLET STATES: SENSITIZATION BY SINGLET OXYGEN |
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Authors: | Michael A J Rodgers Anne L Bates |
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Institution: | Center for Fast Kinetics Research, University of Texas at Austin, Austin, TX 78712, U.S.A. |
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Abstract: | Abstract— Triplet-triplet absorption spectra of a series of carotenoid pigments in benzene solution have been determined by pulse radiolysis experiments. The natural lifetimes in deaerated solution have also been measured. They fall in the range 2–10 µ s as found for other carotenoids under similar conditions. Pulsed laser (337 nm) excitation of benzene solutions containing oxygen, carotenoid and a photosensitized molecule (anthracene) showed the generation of absorption spectra of the triplet states. These absorptions decayed by first order kinetics in such a way as to indicate that they were formed in reactions with singlet oxygen, itself generated by interaction with the anthracene triplet state. Bimolecular rate constants for energy transfer from O*2 (1△g), to carotenoid have been evaluated. |
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