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

Abstract

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.