CONICET | Buscador de Institutos y Recursos Humanos

Metallic clusters are known as few nanometer sized particles made up of subunits which can be atoms of a single element (mono metal), or of several elements (alloys). Their novel chemical and physical properties are dependent only on the number of atoms they contain. These size-dependent properties, which make them suitable for applications in catalysis (1), photoluminescence (2), biomedical (3) and magnetism (4), among others, show significant deviations from their bulk and large nanoparticles (NPs) counterparts.For this reason metal clusters may be considered as new materials covering the intermediate stage between single atoms/molecules and bulk materials.Particularly, silver nanoclusters (Ag NCs) have received much attention as novel fluorophores due to their good photostability, high quantum yield emitters and low toxicity. These properties make them suitable for microscopy settings, with potential biocompatibility and applications to sensoring and bio-labelling when DNA is used as template (5, 6).While there are conventional chemical synthesis methods to generate meta NCs, many of them are adversely affected by the unavoidable contamination of the nanoproduct solution, resulting in aggregation and potential toxicity. In this work, physical method of ultrafast laser ablation as a "green" synthesis approach together with mechanical centrifugation to obtain Ag NCs, simplifying widely the chemical synthesis requirements, is proposed. This new approach starts with a colloid that contains nanosized particles as well as species smaller, managing to obtain colloids with 2 ? 4 atoms NCs by centrifugation. Colloids obtained were analysed by fluorescence spectroscopy and HRTEM, confirming the presence of few atoms Ag NCs. Besides, photocatalytic efficiency of the obtained NCs was studied through degradation of Methylene Blue (MB) when it was mixed with as-prepared or highly centrifuged colloid.