Water-binding solid scintillators: Synthesis, emission properties, H-3 andC-14 counting

Spectral and time-resolved fluorescence properties as well as relative fluo rescence quantum yields of carbodiimide derivatives of 2,5-diphenyloxazole (PPO) (prepared by H2S elimination from the corresponding thioureas), of so me intermediates in the preparation, and of several other PPO derivatives w ere investigated in solution and in the solid state to test their suitabili ty as solid scintillators. The carbodiimides reacted slowly with water unde r 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 H-3 and C-14 counting. Bot h the chemically and the absorptive water-binding scintillators proved capa ble of counting H-3 and C-14 decay, and open a way to the counting of aqueo us samples by solid scintillators without a drying step.