Competition between annihilation and trapping leads to strongly reduced yields of photochemistry under ps-flash excitation

Autor(en): Wulf, K
Trissl, HW
Stichwörter: ANTENNA; ENERGY-TRANSFER; KINETICS; photochemical yield; photosynthesis; PHOTOSYNTHETIC MEMBRANES; Photosystem I; Photosystem II; PHOTOSYSTEM-II; Plant Sciences; PRIMARY CHARGE SEPARATION; PURPLE BACTERIA; RHODOSPIRILLUM-RUBRUM; Rps-viridis; Rs-rubrum; SYSTEM; TIME SCALE
Erscheinungsdatum: 1996
Herausgeber: KLUWER ACADEMIC PUBL
Journal: PHOTOSYNTHESIS RESEARCH
Volumen: 48
Ausgabe: 1-2
Startseite: 255
Seitenende: 262
Zusammenfassung: 
Excitation of photosynthetic systems with short intense flashes is known to lead to exciton-exciton annihilation processes. Here we quantify the effect of competition between annihilation and trapping for Photosystem II, Photosystem I (thylakoids from peas and membranes from the cyanobacterium Synechocystis sp.), as well as for the purple bacterium Rhodospirillum rubrum. In none of the cases it was possible to reach complete product saturation (i.e. closure of reaction centers) even with an excitation energy exceeding 10 hits per photosynthetic unit. The parameter a: introduced by Deprez et al. ((1990) Biochim. Biophys. Acta 1015: 295-303) describing the competition between exciton-exciton annihilation and trapping was calculated to range between approximate to 4.5 (PS II) and approximate to 6 (Rs. rubrum). The rate constants for bimolecular exciton-exciton annihilation ranged between (42 ps)(-1) and (2.5 ps)(-1) for PS II and PS I-membranes of Synechocystis, respectively. The data are interpreted in terms of hopping times (i.e. mean residence time of the excited state on a chromophore) according to random walk in isoenergetic antenna.
ISSN: 01668595
DOI: 10.1007/BF00041016

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