Intensity Dependence of the Fluorescence Lifetime of in vivo Chlorophyll Excited by a Picosecond Light Pulse

Science  16 Jul 1976:
Vol. 193, Issue 4249, pp. 227-229
DOI: 10.1126/science.193.4249.227


New data on intensity-dependent lifetimes indicate that all previous in vivo fluorescence studies of chlorophyll by picosecond techniquies must be reinterpreted. Anomalously short lifetimes result from high-intensity effects due to exciton-excition annihilation processes. Measurements in Chlorella pyrenoidosa with single-pulse, low-intensity excitation indicate a longer "true" lifetime of 650 ± 150 picoseconds.