Preparation of noble metal nanoparticles by ultrasound assisted laser ablation in liquid

Abstract

The preparation of silver and gold nanoparticles by ablation of a high purity targets immersed in deionized water in presence of ultrasonic waves is reported. The laser used is an excimer laser emitting 20 ns pulses at 193 nm. The geometrical arrangement, in particular the thickness of the liquid layer above the target surface, is crucial in order to efficiently ablate the target. The effect of the laser fluence on the size and shape of the synthesized nanoparticles was investigated. The experiments reveal that the production of nanoparticles is significantly enhanced in the presence of the ultrasound field. The obtained nanoparticles were characterized by Transmission Electron Microscopy (TEM) and UV-Vis spectroscopy. This latter technique confirms the formation of nanometric size particles, according to the observation of the characteristic surface plasmon resonances of silver at 410 nm and gold at 530 nm, with the SPR bandwidth being dependent on the preparation conditions. Flocculation of metal nanoparticles is observed after a few days.