The Fluorescence and Scintillation Properties of New Oxazoles, Oxadiazoles and Pyrazolines

The advantages of using a secondary solute in plastic and liquid scintillators, and the manner in which such solutes define scintillation performance, are reviewed. Potential secondary solutes of general structure Ar1-X-Ar2-X-Ar1, where X is an oxadiazole, oxazole or 5-phenylpyrazoline group, were synthesized and their spectra1 and scintillation properties were measured. The relationship between the molecular structure of these compounds and their spectral properties is examined. It is postulated that anomalous spectral displacements which were observed can be explained in terms of the distorting effect of the heterocyclic groups on the conjugated system. A procedure is outlined forthedirect measurement of the reabsorption by a solute of its own fluorescence emission. The contribution of reabsorption to light attenuation in practical scintillators is discussed and a model experiment is proposed to determine the extent of this contribution.