FLUORESCENCE STUDIES ON NEW EPOXYPOLYMER-DYE COMPOSITIONS FOR ULTRAFAST WAVELENGTH SHIFTERS

Fast wavelength shifters with fluorescence decay times in the low nano second range were prepared from mixtures of various dyes in epoxypolym er 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 transmittanc e and high-fluorescence intensity were compared, The characteristics o f the new wavelength shifters were determined with continuous-wave (cw ) excitation of the fluorescence and by pulsed-laser excitation, the l atter coupled with an analysis of the fluorescence decay times, The cw emission and time-resolved fluorescence spectra of these new waveleng th shifters were studied as a function of component concentration in o rder 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 t o be 2.6-3.1 ns, which is significantly shorter than the wavelength sh ifters currently in use, We also used fluorescence techniques to study the cure kinetics and fluorescence yields in epoxy-polymer-diglycidyl ether of 3',3 ''-dihydroxy-2,5-diphenyloxadiazole (DGEPOD) compositio ns.