Laser and Pulse Radiolytically Induced Colloidal Gold Formation in Water and in Water-in-Oil Microemulsions

Article abstract of DOI:10.1021/ja00347a011

Reduction of HAuCl4 has been investigated pulse radiolytically in water and in water-in-oil microemulsions.Rate constants have been determined for Au(3+) + e_aq^- -> Au(2+), 2Au(2+) -> Au(3+) + Au(+), and Au(+) +R(-*) -> Au⁰ + R (where R(*-) is an unidentified radical).On the longer time scale formation of colloidal gold, nAu⁰ ->(Au⁰)n, has been observed.Rate of colloidal gold formation has also been studied in the bombardment of HAuCl4 solutions by 353-nm 60-mJ 3 - 5-ns laser pulses.Hydrodynamic diameters and polydispersities of empty and colloidal-gold-containing microemulsions have been determined by dynamic laser light scattering to be 150 and 220 Angstroem, respectively.Morphologies of colloidal gold have been determined by electron micrography.There are a number of advantages of forming colloidal particles in microemulsions.Under identical conditions a greater amount of colloidal particles is formed than that in water.Colloidal gold particles formed in microemulsions are smaller and more uniform than those obtained in homogeneous solutions.