A Nanosecond Photon-Counting Fluorimetric System Using a Modified Multichannel Vernier Chronotron

Abstract

A new time-resolved photon-counting instrument with high data-gathering efficiency is described. The principle of operation is based on the measurement of the nanosecond temporal distribution of the emitted photon burst during the short duration of transient emission. The instrument is characterized by the unique capabilities of a modified vernier chronotron with plural coincidence circuits and serial-timing data memories, which serve as an efficient multichannel event-time analyzer of 1.5-ns time resolution. The data-gathering efficiency is improved by a factor of 20 or more in comparison with that of the conventional single-photon counting method. In regular operation, the time history of transient emission for the period of 144 ns is obtained; and for phenomena with longer duration, the time-scale expansion mode of operation is provided. To demonstrate the whole system performance, a fluorescence decay curve of 1-ppm quinine sulfate in 0.1-N H2SO4 is presented.