Nucleation Control of Size and Dispersity in Aggregative Nanoparticle Growth. A Study of the Coarsening Kinetics of Thiolate-Capped Gold Nanocrystals

The thermal coarsening (180 °C) of decanethiolate-capped Au nanocrystals is studied at various tetraoctylammonium bromide concentrations. The coarsening kinetics are determined by measuring nanocrystal size distributions (CSDs) as a function of time. The results are shown to be consistent with aggregative nucleation and growth. For each kinetic trial, the time dependence of the aggregative nucleation rate is extracted from the early time CSDs and fitted by a Gaussian profile. The height of the profile is the maximum nucleation rate, Γ max, and the 2σ width is the time window for nucleation, Δ t n . These nucleation parameters are shown to control the final mean size and size distribution of the coarsened nanocrystals. The coarsening kinetics are influenced by tetraoctylammonium bromide concentration because the nanocrystals are partially electrostatically stabilized.