FAST PHOTOVOLTAGE MEASUREMENTS IN PHOTOSYNTHESIS .1. THEORY AND DATA EVALUATION

Fast photovoltage measurements are a valuable tool for the study of tr apping of excitation energy, kinetics of charge separation, and relati ve distances of intermediary accepters in the photosynthetic reaction center. Recent advances of both, the technique and the data analysis h ave not been described before. Here, in a first article of this sequen ce, we describe a theoretical model of the primary photosynthetic reac tions and the computer analysis of transient photovoltage as well as o f fluorescence data. The model assumes free energy migration between p hotosynthetic units and takes into account specific effects of high en ergy excitation like the acceleration of the trapping kinetics, the qu enching of the excited state by oxidized reaction centers, and the non linear process of exciton-exciton annihilation. Furthermore, the finit e duration of the picosecond flashes is considered. The approximations involved in this model are discussed with respect to different functi onal antenna organizations. In a second article of this sequence we de scribe the experimental set-up, calibration procedures and the applica tion of the present theory to experimental data. (C) 1995 John Wiley & Sons, Inc.