Structure and stability of silver nanoparticles in aqueous solution produced by laser ablation

Silver nanoparticles were produced by laser ablation of a metal silver plat e in aqueous solutions of surfactants, CnH2n+1SO4Na (n = 8, 10, 12, 16). Th e nanoparticles thus produced were characterized by electron microscopy and UV-visible absorption spectroscopy. The abundances of the nanoparticles be fore and after centrifugation were measured as a function of the surfactant concentration. The concentration dependence of the abundance implies that the surfactant coverage and the charge state on the nanoparticle surface ar e closely related to the stability of the nanoparticles in the solutions. T he nanoparticles tend to be aggregated when the coverage is less than unity , while they are very stable when the surface is covered with a double laye r of the surfactant molecules.