Picosecond Time Resolved Fluorescence of Chlorophyll in Vivo

The published data concerning the fluorescence kinetics of chlorophyll a in various photosynthetic species are reviewed. The effects of singlet‐singlet and singlet‐triplet annihilation induced by excessively high incident light intensities are discussed and related to the changes produced in the fluorescence lifetimes and quantum yields. We also review the fluorescence lifetimes of Chlorella pyrenoidosa and spinach chloroplast fragments under a variety of experimental conditions; these measurements were performed at single pulse excitation intensities of less than 5 × 1013 photons cm–2 where distortion due to annihilation processes is negligible. Evidence for and against a time dependent rate equation for energy migration will be discussed with reference to the authors' work on in vitro systems.