Picosecond fluorescence kinetics of the primary processes in isolated photosynthetic reaction centers from the purple bacterium Rb. sphaeroides

The primary processes of energy transfer and charge separation in isolated reaction centers of photosynthetic bacteria have recently been the subject of intense investigation (1). So far basically all of the kinetic measurements characterizing these processes have been carried out employing transient absorption techniques in the picosecond and femtosecond time range. In contrast, very few time-resolved fluorescence studies are available where the charge separation kinetics has been resolved (2,3). In view of the controversy about the exact mechanism of the primary electron transfer processes (see 1 for details) application of methods which are complementary to transient absorption is highly desirable. We present here a fluorescence kinetics study on isolated reaction centers of the purple bacterium Rb. sphaeroides.