Measurement of the decay of fluorescence

A fluorometer to measure the rate of decay of fluorescence of mean life between 3 and 30 nanoseconds is described. The apparatus is a modification of that of Bailey and Rollefson. The following lifetimes (in nanoseconds) have been measured for 10-5M solutions freed of oxygen: anthracene in benzene 4.0, anthracene in ethanol 5.5, 9, 10-diphenyl anthracene in ethanol 9.2, acridone in ethanol 14.4, acridone in water 15.7, quinine sulphate in 10-2M HNO3 20.8. The sensitivity is 0.05 and the accuracy 0.2 nsec.