High-Intensity Laser Irradiation Inducing Au Nanoparticles in Viscous Glycerin

Abstract

We studied the formation of gold nanoparticles (Au NPs) by laser-induced nucleation from HAuCl₄ in viscous glycerin (η = 1,400 mPa s) at a room temperature for the application of laser-drilled screen printing. Femtosecond pulsed laser irradiation at a wavelength of 800 nm and a pulse energy of 5 mJ caused Au NPs with a mean diameter of 4.9 nm at a concentration of 2.5×10^-5 mol dm^-3. The decrease in viscosity by heating the solution at 313 K and the mechanical stirring of the solution during laser irradiation caused the mean diameter and size distribution to become small. The mechanical stirring was effective for the formation of uniform Au NPs with a mean diameter of 3.2 nm. These indicated that successive pulsed laser irradiation induced uniform nucleation reactions of HAuCl₄ to metal Au, melting and fusion among metal Au species, and particle growth through Ostwald ripening. The Au NPs formed in glycerin kept a suspension for at least 1 week without any stabilizing surfactants probably due to low frequency of contacting NPs in viscous glycerin.