Dresden 2003 – wissenschaftliches Programm

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CPP: Chemische Physik und Polymerphysik

CPP 20: POSTER A

CPP 20.51: Poster

Montag, 24. März 2003, 19:00–21:00, ZEU/250

Transient EPR Study of Photoexcited Triplet States in Photosystem II — •Peizhu Tian and Dietmar Stehlik — Institute for Experimental Physics, Free University Berlin, Arnimallee 14, D-14195 Berlin

Time resolved EPR of photoexcited triplet states have been performed in various photosystem II (PS II) preparations. Based on Zero-Field-Splitting parameters, spin polarization pattern and kinetics of the individual triplet species as well as spectra simulation, at least three triplet species (³Chl, ³P680 and ³Car) have been identified and separated. The ³P680 is generated through charge recombination of the first radical pair P680⁺Pheo⁻ in reaction center; ³Car is formed through triplet energy transfer from ³Chl as part of independent photocycle started with excitation of ¹Chl and ISC to ³Chl. In addition, the localization of ³P680 on a monomeric Chl molecule at low temperature and delocalization on one or more molecules at high temperature can be demonstrated in all functional PSII samples studied. The results of functional PS II core and non-functional D1D2 complex are compared.