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Optical Engineering

Photomultiplier tube gain suppression: a new method for the sequential measurement of fluorescence and phosphorescence
Author(s): Liqun Yang; Daniel McStay; Alan J. Rogers; Peter J. Quinn
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Paper Abstract

A technique for the sequential measurement of fluorescence and phosphorescence depolarization is reported. The technique is based on a newly developed photomultiplier gain-suppression technique. The gain-suppression characteristics of the circuit are studied by applying a constant level of incident light. To demonstrate this new technique, a solid sample ofthetriplet probe eosin is excited by a pulsed, frequency-doubled Nd:YAG laser; the resulting orthogonally polarized emissions are collected by two balanced photomultipliers (PMT5). The gains of the PMTs are suppressed for the duration of the fluorescence emission, and subsequently returned to normal, to maintain the fluorescence and phosphorescence signals at the same level. The suppression of the gain is controlled by a specially designed dual-channel PMT gain-suppression circuit. The signals from the PMTs are recorded by two digital oscilloscopes, one set at a fast sampling rate to measure the static fluorescence anisotropy, the other set at a slow sampling rate to measure the slow phosphorescence depolarization. The anisotropy values can then be deduced from the two sets of recordings.

Paper Details

Date Published: 1 February 1993
PDF: 7 pages
Opt. Eng. 32(2) doi: 10.1117/12.60698
Published in: Optical Engineering Volume 32, Issue 2
Show Author Affiliations
Liqun Yang, King's College London (United Kingdom)
Daniel McStay, Robert Gordon Institute of Technology (United Kingdom)
Alan J. Rogers, King's College London (United Kingdom)
Peter J. Quinn, King's College London (United Kingdom)

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