Measurement of the fluorescent lifetimes of Chlorella and Porphyridium in weak light

The fluorescent lifetimes of Chlorella and Porphyridium were measured by determining the emission time distribution of fluorescent photons following excitation by a flash lamp. A lifetime of 0.6 ± 0.2 nsec was determined for both species exposed to light of an average intensity less than 1 erg/sec per cm2. No lifetime greater than 1 nsec with a relative yield greater than 10% was found. © 1967.