MEASUREMENT OF VERY SHORT FLUORESCENCE LIFETIMES BY SINGLE-PHOTON COUNTING

Measurement of very shoft fluorescence lifetimes by the single-photon technique is made possible by an improved fluorescence lifetime system. Fluorescence lifetimes of 4. 94 plus or minus 0. 07 nsec for anthracene in cyclohexane, 640 plus or minus 30 psec for diphenyl butadiene in cyclohexane, and 90 plus or minus 30 psec for erythrosin in water were determined. Complications in the analysis of lifetime data introduced by intrinsic fluorescence and phosphorescence processes in commonly used absorption filters are discussed. Certain ″blind spots″ are found in the electronic pulse pileup rejection schemes most commonly used in photon counting.