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Fluorescence Studies on New EpoxypolymerDye Compositions for Ultrafast Wavelength Shifters

Volume 50, Number 12 (Dec. 1996) Page 1545-1552

Liu, Lin-I; Barashkov, Nikolay N.; Novikova, Tamara S.; Palsule, Chintamani P.; Gangopadhyay, Shubhra; Borst, Walter L.

Fast wavelength shifters with fluorescence decay times in the low nanosecond range were prepared from mixtures of various dyes in epoxypolymer compositions on the base of diglycidyl ether of bisphenol-A (DGEBA) with hexahydrophthalic anhydride (HHPA) or trimethoxyboroxine (TMBOX). Three possible sample preparation methods yielding high transmittance and high-fluorescence intensity were compared. The characteristics of the new wavelength shifters were determined with continuous-wave (cw) excitation of the fluorescence and by pulsed-laser excitation, the latter coupled with an analysis of the fluorescence decay times. The cw emission and time-resolved fluorescence spectra of these new wavelength shifters were studied as a function of component concentration in order to optimize the decay times, the emission peaks, and the quantum efficiencies for potential use in high-energy particle detectors. The mean decay times of most of the epoxypolymer-dye mixtures were found to be 2.6-3.1 ns, which is significantly shorter than the wavelength shifters currently in use. We also used fluorescence techniques to study the cure kinetics and fluorescence yields in epoxypolymer-diglycidyl ether of 3',3"-dihydroxy-2,5-diphenyloxadiazole (DGEPOD) compositions.