Detection of Ultrafast Process in the Energy and Electron Transfer Dynamics in the Photosystem I Reaction Center

Abstract

Fluorescence dynamics of photosystem I reaction center over a femtosecond to nanosecond time range was observed by using both the fluorescence up-conversion (FUC) technique and the streak camera (SC). Simultaneous analysis of the data of both FUC and SC resulted in determination of the time dependent fluorescence spectrum, in which the wavelength dependence of the sensitivity is corrected. The observed data could be well reproduced based on a kinetic model assuming three fluorescent compartments and one dark compartment. The parameter set estimated by the fitting suggests that the entire fluorescence decay was determined by the rate of the energy transfer step from the red chlorophyll-a pool to the primary charge donor.