Photostimulated luminescence and dynamics of AgI and Ag nanoclusters in zeolites

The photoluminescence and photostimulated luminescence of Ag and AgI nanoclusters formed in zeolite-Y are studied using fluorescence spectroscopy. The photoluminescence spectra of AgI nanoclusters show emission from both AgI as well as Ag nanoclusters which are present in small amounts in the AgI nanoclusters, while in the photostimulated luminescence, only the emission of Ag clusters is observed. While the photoluminescence from both Ag and AgI particles displays subnanosecond and microsecond lifetimes, the emission from photostimulated luminescence shows very short, picosecond lifetimes. A model which ascribes the photostimulated luminescence to recombination of electrons trapped in the zeolite with Ag in close proximity to the trap site is proposed. The appearance of strong photostimulated luminescence with short decays in these systems demonstrates that nanoparticles have potential for digital storage and medical radiology applications.