Water-binding solid scintillators: synthesis, emission properties, and tests in 3H and 14C counting.

Spectral and time-resolved fluorescence properties as well as relative fluorescence quantum yields of carbodiimide derivatives of 2.5-diphenyloxazole (PPO) (prepared by H2S elimination from the corresponding thioureas), of some intermediates in the preparation, and of several other PPO derivatives were investigated in solution and in the solid state to test their suitability as solid scintillators. The carbodiimides reacted slowly with water under acidic conditions to yield ureas. These systems were compared with solid mixtures of other PPO derivatives with sodium sulfate as a drying agent, as chemically water-binding solid scintillators in 3H and 14C counting. Both the chemically and the absorptive water-binding scintillators proved capable of counting 3H and 14C decay, and open a way to the counting of aqueous samples by solid scintillators without a drying step.