Growth Kinetics of Gold Nanoparticles

We have measured the growth kinetics of gold nanoparticles in real time. Gold nanoparticles were formed from the reduction of gold (III) in aqueous solution and monitored with a stopped-flow reactor equipped with a diode array. The overall reduction of gold (III) occurred in less than 20 [ms]. The growth kinetics was determined from measurements of the plasmon resonance time-dependent wavelength. The peak position and width of the plasmon resonance were found to be sensitive to particle size and to the medium dielectric constant. The maximum peak wavelength shifts toward higher wavelengths with particle size. The results were modeled with Mie’s scattering theory. Excellent agreement between theory and experiment were found in the peak maximum and long wavelength tail, for particle sizes less than 50 [nm]. The dependence of the gold dielectric constant on particle size and the effect of multi-pole interactions must be added if a theoretical path is to be followed.