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in creator/contributor: "Tollin, G"  
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Free radicals in biological energy conversion: EPR studies of model systems. Final report. [Mechanism of chlorophyll participation in photosynthesis]

Description: Energy conversion in photosynthesis is known to proceed via light-induced one-electron transfer reactions involving chlorophyll and electron donors and acceptors. Although the chemical identities of all of the components have not as yet been elucidated, considerable evidence has been accumulated which points to quinones (Q) as primary electron acceptors in both green plants and bacterial photosynthesis. Furthermore, it has been established that the initial photoprocess leads to the formation of… more
Date: August 31, 1976
Creator: Tollin, G.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Environmental effects on electron transfer from chlorophyll triplet to quinone: role of dielectric constant, viscosity and quinone structure in cellulose acetate films

Description: The effects of environmental parameters on chlorophyll triplet quenching and electron transfer to quinones have been investigated in a system consisting of donor and acceptor incorporated into a cellulose acetate film which was subsequently exposed to solvent. Triplet quenching by a diffusional mechanism was found to occur in the dry film, with steric effects being a major determinant of quencher effectiveness. No formation of separated radicals was found under these conditions, probably becaus… more
Date: January 1, 1981
Creator: Cheddar, G. & Tollin, G.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Direct observation of electron transfer across a lipid bilayer: laser photolysis of an asymmetric vesicle system containing chlorophyll, methyl viologen, and EDTA

Description: Electron transfer across lipid bilayer vesicle walls was examined by laser flash photolysis to determine the mechanisms of charge transport across the membrane. The discussion is restricted to vesicles whose walls contain phosphatidylcholine, chlorophyll a, and valinomycin. (ACR)
Date: January 1, 1980
Creator: Ford, W.E. & Tollin, G.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Chlorophyll-quinone photochemistry in liposomes: mechanisms of radical formation and decay

Description: Laser flash photolysis has been used to investigate the mechanism of formation and decay of the radical species generated by light induced electron transfer from chlorophyll a triplet to quinone in egg phosphatidyl choline bilayer vesicles. Chlorophyll triplet quenching by quinone is controlled by diffusion occurring within the bilayer membrane and reflects bilayer viscosity. Radical formation via separation of the intermediate ion pair is also inhibited by increased bilayer viscosity. Cooperat… more
Date: January 1, 1980
Creator: Hurley, J.K. & Tollin, G.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Chlorophyll photochemistry in condensed media: triplet state quenching and electron transfer to quinone in cellulose acetate films

Description: Chlorophyll a was incorporated into cellulose acetate films and the triplet decay and electron transfer to p-benzoquinone in aqueous solution was studied using laser flash photolysis and ESR. The triplet was found to decay by first order kinetics with the same rate constant regardless of chlorophyll concentration, but the yield was concentration dependent. This is due to quenching at the ground and/or singlet state levels. In the presence of quinone, the triplet is quenched and, when the quinon… more
Date: January 1, 1979
Creator: Cheddar, G.; Castelli, F. & Tollin, G.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Delayed Light Emission in Green Plant Meterials:Temperature-Dependence and Quantum Yield

Description: The discovery of the delayed light emission of plant materials by Strahler and Arnold in 1951 has stimulated a good deal of interest in this rather remarkable property. The emitted light has been shown to be due to an electronic transition between the first excited singlet state of chlorophyll and the ground state. At room temperature, a luminescence is observable from about 0.01 seconds to several minutes after excitation. Thus, the electronic transition cannot be rate-determining and the proc… more
Date: July 1, 1958
Creator: Tollin, G.; Fujimori, E. & Calvin, M.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Action and Emission Spectra of the Luminescence of Green PlantMaterials

Description: The action and emission spectra of the delayed light emission from Chlorella, Nostoc, and spinach chloroplasts have been measured. The action spectra for Chlorella and for spinach chloroplasts are quite similar to the absorption spectra of these materials. The action spectrum for Nostoc, on the other hand, shows a relatively low activity for chlorophyll and carotenoids and a high activity for phycocyanin. The emission spectra of these materials demonstrates that the luminescence is the result o… more
Date: December 29, 1957
Creator: Tollin, G.; Fujimori, E. & Calvin, Melvin
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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