ИСТИНА

Ag- doped bulk oxyfluoride glasses have been prepared by conventional meltquenching method. The photoluminescence excitation and emission spectra of the as-prepared glass cover wide range from 300 to 500 nm and from 400 to 900 nm, respectively, corresponding to the typical spectra of Ag nanoclusters with size less than 1.2 nm [1, 2]. The particular preparation conditions result in a glass with white light luminescence based solely on emission of Ag nanoclusters under excitation in UV [3]. Likewise, the white light generation may be achieved via co-doping with Tm3+ ions emitting in the blue region [4]. The quantum yield of the prepared glasses was found to be up to 70% [1]. The as-prepared glasses were heat-treated at 350 oC (below glass transition temperature) preserving glassy state of the samples. Under heat-treatment the Ag nanoclusters coalesce into the amorphous nanoparticles larger than 2 nm exhibiting a broad surface plasmon absorption band centered at 480 nm in the visible range. These amorphous Ag nanoparticles do not emit light due to the ascribing plasmonic properties. Open aperture z-scan experiments were conducted using 480 nm nanosecond laser pulses. These experiments revealed that the Ag nanoclusters and nanoparticles exhibit non-saturated and saturated non-linear absorption with large non-linear absorption indices, respectively [5]. The prepared glasses may be applied for white light generation under UV excitation, optical limiting and object’s contrast enhancement.