Phase Fluorometer to Measure Radiative Lifetimes of 10−5 to 10−9 Sec

Apparatus to measure radiative lifetimes by the phase-shift method is described. A rotating-wheel, reflection grating modulates light at 60 kc for the measurement of lifetimes of 10−5 to 10−7 sec. An ultrasonic grating is used for modulation at 5.2 Mc to study lifetimes of 10−7 to 10−9 sec. Optical and electronic sources of systematic error have been investigated. Procedures have been developed to minimize systematic errors in the lifetime measurements. Measurements on solid BaPt(CN)4·4H2O are reported. Iodine vapor and solutions of organic molecules also have been studied.