Lifetime measurements of 4-dimethylamino-4′-nitrostilbene fluorescence by picosecond optical amplification

The fluorescence lifetime of 4-dimethylamino-4′-nitrostilbene (DMANS) in benzene and in the mixed solvents of cyclohexanol-methycyclohexane (2 : 5 volume ratio) and cyclohexanol benzene (2 : 5 volume ratio) was found to be ≳1 nsec, 160±40 psec, and 150±40 psec, respectively. The time dependence of the fluorescence intensity after excitation was monitored by the time-resolved gain of a picosecond light beam passing through the sample.