Fluorescence Lifetimes of Chloroplasts, Subchloroplast Particles and Chlorella Using Single Photon Counting

摘要

Lifetimes of chlorophyll fluorescence from spinach chloroplasts, digitonin subchloroplast particles and Chlorella pyrenoidosa were measured using a single photon counting apparatus capable of detecting lifetimes longer than about 0.1 ns. In the absence of actinic illumination or inhibitors, all of the materials investigated exhibited single exponential decays in the range 0.2 to 0.4 ns. Actinic illumination or inhibitors that block Photosystem 2 produce a biphasic fluorescence decay. The fast decay component becomes several times slower, and it is accompanied by a second, slow decay of about 2 ns. The results are interpreted to support the occurrence of transfer of excitation between Photosystem 2 units. (ERA citation 03:015918)