Generation of fluorescent silver nanoclusters in reverse micelles using gamma irradiation: low vs. high dosages and spectral evolution with time

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 evolve over days to weeks after the exposure, and usually show large increases in intensity. Responses of as high as 2.8 × 104 CPS/Gy were reached. A dosage as low as 0.5 Gy (10 % of the lethal dosage for humans) produces NCs having fluorescence intensities 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 and tracking 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. It is likely that this synthesis method may be adapted to produce NCs from other metal ions.