Encapsulated Fluorescent Ag NPs as Novel Indicators for High-Energy Ionizing Radiation

Abstract : Reverse micelles (RMs) containing aqueous solutions of Ag+ ions in their core produce fluorescent Ag nanoclusters (NCs), upon exposure to gamma irradiation. The fluorescence spectra of the NCs evolves over days to weeks after the exposure, and usually show large increases in intensity. Responses of as high as 4 x 105 CPS/Gy were reached. A dosage of as low as 0.5 Gys (10% of the lethal dosage for humans) produces NCs having fluorescence intensities significantly higher than background. The RMs can be employed in novel gamma radiation detectors with appearance of fluorescence indicating that radiation was once present. In applications involving detection of fissile materials, the evolution of the fluorescence spectra over time may provide additional information about the radiation source. A two-phase liquid system is used for RM formation in a simple procedure. This synthesis method may be adapted to produce NCs from many other metal ions.