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Science 16 July 1976:
Vol. 193. no. 4249, pp. 227 - 229
DOI: 10.1126/science.193.4249.227
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Articles

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

A. J. CAMPILLO 1, V. H. KOLLMAN 1, and S. L. SHAPIRO 1

1 University of California, Los Alamos Scientific Laboratory, Los Alamos, New Mexico 87545

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.

Submitted on January 23, 1976
Revised on April 14, 1976

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Science. ISSN 0036-8075 (print), 1095-9203 (online)