title: Influence of cationic surfactants on the formation and surface oxidation states of gold nanoparticles produced via laser ablation.
abstract: We report on the time evolution of gold nanoparticles produced by laser ablation in the presence of the cationic surfactants cetyltrimethylammonium bromide (CTAB) and cetyltrimethylammonium chloride (CTAC) in aqueous solution. The broader applicability of a laser-induced nanoparticle formation kinetic model previously developed by us for the case of anionic surfactants in aqueous solution [ J. Phys. Chem. C 2010 , 114 , 15931 - 15940 ] is shown to also apply in the presence of cationic surfactants. We explore the surface properties of the nanoparticles produced in the presence of the cationic surfactants via synchrotron X-ray photoelectron spectroscopy (XPS). The XPS data indicate that at CTA(+) concentrations approximating the aqueous critical micelle concentration Au(III) is present on the nanoparticle surface. Such oxidation is not observed at (i) lower CTA(+) concentrations, (ii) in the presence of an anionic surfactant, or (iii) in the case of pure water as a solvent.
authors.affiliation: Department of Chemistry, The University of Adelaide , Adelaide SA 5005, Australia.
authors.forename: Yuen-Yan
authors.initials: YY
authors.lastname: Fong
authors.forename: Jason R
authors.initials: JR
authors.lastname: Gascooke
authors.forename: Bradley R
authors.initials: BR
authors.lastname: Visser
authors.forename: Hugh H
authors.initials: HH
authors.lastname: Harris
authors.forename: Bruce C C
authors.initials: BC
authors.lastname: Cowie
authors.forename: Lars
authors.initials: L
authors.lastname: Thomsen
authors.forename: Gregory F
authors.initials: GF
authors.lastname: Metha
authors.forename: Mark A
authors.initials: MA
authors.lastname: Buntine