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

Abstract

Fast photovoltage measurements are a valuable tool for the study of trapping of excitation energy, kinetics of charge separation, and relative distances of intermediary accepters in the photosynthetic reaction center. Recent advances of both, the technique and the data analysis have not been described before. Here, in a first article of this sequence, we describe a theoretical model of the primary photosynthetic reactions and the computer analysis of transient photovoltage as well as of fluorescence data. The model assumes free energy migration between photosynthetic units and takes into account specific effects of high energy excitation like the acceleration of the trapping kinetics, the quenching of the excited state by oxidized reaction centers, and the nonlinear process of exciton-exciton annihilation. Furthermore, the finite duration of the picosecond flashes is considered. The approximations involved in this model are discussed with respect to different functional antenna organizations. In a second article of this sequence we describe the experimental set-up, calibration procedures and the application of the present theory to experimental data. (C) 1995 John Wiley & Sons, Inc.