John Machnicki - Academia.edu (original) (raw)
Address: Woodstock, Connecticut, United States
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Papers by John Machnicki
Photochemistry and Photobiology, 1983
Abstract— The temperature dependencies of the primary donor triplet state spectra are presented f... more Abstract— The temperature dependencies of the primary donor triplet state spectra are presented for the phorosynthetic bacteria Rhodopseudomonas sphaeroides wild type. GIC and R26. The data suggest that energy transfer from the primary donor triplet state to the reaction center carotenoid is dependent on the type of carotenoid present, reversible in the case of strain GIC, and best understood by a model depicting the kinetic processes that can occur between two potential energy surfaces; one representing the state 3BChl2*Car and the other representing BChl23Car*. Furthermore, it is shown that the onset of spin lattice relaxation in the primary donor triplet is most likely coupled to the same energy vibrational mode as that which promotes triplet state energy transfer from the primary donor to the reaction center carotenoid
Photochemistry and Photobiology, 1982
Abstract— The triplet state spectra of anaerobically grown cells of Rhodopseudomonas sphaeroides ... more Abstract— The triplet state spectra of anaerobically grown cells of Rhodopseudomonas sphaeroides GIC and R. sphaeroides wild type and aerobically grown cells of R. sphaeroides wild type were examined under reducing and non-reducing conditions at 100 K. by electron paramagnetic resonance (EPR). Large differences in the zero field splitting parameters, |D| and |E| of the triplets are seen to arise in the different preparations. The spectra are assigned to the triplet states of carotenoids, some of which are closely associated with the reaction center and others are contained in the light harvesting complex. Taken together with the triplet state data on Rhodospirillum rubrum wild type previously published the trends in the zero field splitting parameters can be understood in terms of the extent of electron derealization in carotenoids of varying length.
Photochemistry and Photobiology, 1984
Abstract— The orientation of the principal magnetic axes of the reaction center carotenoid from R... more Abstract— The orientation of the principal magnetic axes of the reaction center carotenoid from Rps. sphaeroides wild type is presented. The parameters needed to simulate the observed carotenoid triplet state spectra indicate that the carotenoid adopts a planar structure within the reaction center. A high degree of geometrical and structural specificity is shown to exist for this carotenoid molecule.
Photochemistry and Photobiology, 1983
Abstract— The temperature dependencies of the primary donor triplet state spectra are presented f... more Abstract— The temperature dependencies of the primary donor triplet state spectra are presented for the phorosynthetic bacteria Rhodopseudomonas sphaeroides wild type. GIC and R26. The data suggest that energy transfer from the primary donor triplet state to the reaction center carotenoid is dependent on the type of carotenoid present, reversible in the case of strain GIC, and best understood by a model depicting the kinetic processes that can occur between two potential energy surfaces; one representing the state 3BChl2*Car and the other representing BChl23Car*. Furthermore, it is shown that the onset of spin lattice relaxation in the primary donor triplet is most likely coupled to the same energy vibrational mode as that which promotes triplet state energy transfer from the primary donor to the reaction center carotenoid
Photochemistry and Photobiology, 1982
Abstract— The triplet state spectra of anaerobically grown cells of Rhodopseudomonas sphaeroides ... more Abstract— The triplet state spectra of anaerobically grown cells of Rhodopseudomonas sphaeroides GIC and R. sphaeroides wild type and aerobically grown cells of R. sphaeroides wild type were examined under reducing and non-reducing conditions at 100 K. by electron paramagnetic resonance (EPR). Large differences in the zero field splitting parameters, |D| and |E| of the triplets are seen to arise in the different preparations. The spectra are assigned to the triplet states of carotenoids, some of which are closely associated with the reaction center and others are contained in the light harvesting complex. Taken together with the triplet state data on Rhodospirillum rubrum wild type previously published the trends in the zero field splitting parameters can be understood in terms of the extent of electron derealization in carotenoids of varying length.
Photochemistry and Photobiology, 1984
Abstract— The orientation of the principal magnetic axes of the reaction center carotenoid from R... more Abstract— The orientation of the principal magnetic axes of the reaction center carotenoid from Rps. sphaeroides wild type is presented. The parameters needed to simulate the observed carotenoid triplet state spectra indicate that the carotenoid adopts a planar structure within the reaction center. A high degree of geometrical and structural specificity is shown to exist for this carotenoid molecule.