Dynamic light scattering in gold colloids prepared by laser ablation in water

Laser ablation of solid targets in liquid environment is emerging as a new and interesting technique to prepare a plenty of nanoparticles and other nanostructures directly in thecolloidal form. This procedure is considered environmental friendly, thus producing nanomaterialswith low energy consumption and free of any residual by-products, typical of other chemical approaches. Most of the works actually reported in literature making use of the so called Pulsed Laser Ablation in Liquids (PLAL) are devoted to the production of silver and gold sols by using nanosecond as well as femtosecond laser ablation procedures. In this work we intend to present some results obtained using polarized and depolarized dynamic light scattering on gold colloids prepared by PLAL in water. This technique allows the measurement of translational diffusivity forthe nanopartilces, while depolarised scattering yields (simultaneously) the characterisation of translational and rotational diffusivities, thus giving information on the size and shape of the nanoparticles directly in the liquid state. Particular emphasis will be devoted to the laser fluencedependence. The data obtained are compared with electron and atomic force microscopy which, even though much more appealing at the nano scale, do not account for particle-particle and particle-liquid interactions like brownian motion, solvation or the presence of charges at theclusters’ surface.