Silver nanoparticles: generation and fragmentation by using femtosecond ablation inside of deionised water solution

G.A. TORCHIA, F. VIDELA, D. SCHINCA AND L.B. SCAFFARDI

Foz Iguazu

Workshop; 19th International Laser Physics Workshop (LPHYS’10); 2010

In this work we present the generation and fragmentation of silver nanoparticles (Nps)by using femtosecond (fs) laser ablation focusing on the solid target inside a solution ofdeionised water. In order to do these experiments, we have used a Spectra Physics ChirpedPulse Amplification (CPA) Ti: Sapphire system lasing at 800 nm, 120 fs pulse width, 1 KHzrepetition rate and it can deliver up to 1 mJ of energy per pulse. The generation andfragmentation of silver Nps were conducted by means of different strategies. First of all, silvercolloidal solution in desionised water was obtained by using a direct laser ablation atfundamental wavelength. On the other hand in order to obtain a reduced size for the meanaverage radii corresponding to the silver Nps in the water solution, we have conducted theablation process by using the Second Harmonic (SH) radiation. It was obtained after pass thefundamental fs pulse trough a BBO non linear crystal. By focusing the SH on the silver targetinside the water solution, we obtained the smallest silver Nps solution. This fact can beexplained by taking into account the following points i) the location of the resonance plasmoncorresponding to the fresh silver Nps, which coincides with SH wavelength thus linear and nonlinear absorption can be responsible of the particle reduction by Coulomb repulsion (nanoablation);2) the super-continuum radiation generated in water by blue radiation and thenlineally absorbed by the fresh silver Nps can deliver ablated Nps. In order to identify theparticles sizes distribution, optical extinction spectroscopy was used to fit all optical spectra. Inorder to do that, we additionally have taken into account the oxidation (core-shell structures) forthe resultant silver Nps solution. TEM picture were also used to explore the shape, morphologyand sizes of the Nps obtained in work.