Synthesis of silver and gold nanoparticles by pulsed laser ablation for nanoparticle enhanced laser-induced breakdown spectroscopy

Abstract

Chemically pure colloidal suspensions of silver and gold nanoparticles were synthesized by nanosecond pulsed laser ablation of metal plates placed in the ultrapure water. The nanoparticles were analyzed by UV-Vis spectroscopy and electron microscopy. The absorption spectra of silver and gold nanoparticles were basically the same as that of the chemically prepared nanoparticles. The diameter of almost spherically shaped Ag and Au nanoparticles prepared by 40 mJ laser energy was in the range of approximately 20–100 and 20–50 nm, respectively. The microdrops of Ag and Au colloidal solution were deposited on the surface of soda-lime glass and copper to perform nanoparticle-enhanced laser-induced breakdown spectroscopy. The results showed that Au nanoparticles cause much higher spectral enhancement, from both glass and copper targets, as compared to that of Ag nanoparticles. For the given target, type of nanoparticle and laser fluence, the enhancement factor of various spectral lines of an element was not the same. Moreover, the enhancement factor found to decrease with an increase of laser fluence, which is explained in terms of the electric field reduction due to the flow of electrons between two adjacent nanoparticles.