Enhanced stability of gold colloids produced by femtosecond laser synthesis in aqueous solution of CTAB.

Femtosecond laser ablation of gold in an aqueous solution of cetyl trimethylammonium bromide (CTAB) is shown to produce nanoparticle suspensions with superior colloidal stability compared to other surfactants, with shelf lives exceeding 2 months even at low concentrations of CTAB, below 1 mM. CTAB also helps control nanoparticle size with mean diameters of 6.3, 5.6, and 4.7 nm obtained in 0.1, 0.5, and 1 mM concentrations of CTAB respectively, compared to 11.9 nm obtained in pure deionized water under same ablation conditions. The size distributions produced with low concentrations of CTAB are comparable to those produced by other surfactants, typically used at high concentrations.