Aggregative growth in the size-controlled growth of monodispersed gold nanoparticles.

This article describes the findings of an investigation of the aggregative growth mechanism for the formation of gold nanoparticles in aqueous solutions under ambient conditions with high monodispersity (2% RSD) over a wide range of particle sizes (10-100 nm). The utilization of the gold nanoparticles synthesized by this simple, reproducible growth mechanism has recently been demonstrated for establishing the size correlation for the surface plasmon resonance optical and surface-enhanced Raman scattering spectroscopic properties. The particle size, morphology, and optical properties of the nanoparticles produced at different stages of the growth processes were determined as a function of control parameters such as the reaction time and seed/precursor concentrations. The results have allowed us to establish a quantitative correlation between the growth size and the seed/precursor concentrations for the precise control of nanoparticle sizes. The kinetic measurements have demonstrated a polycrystalline character for the grown particles, a bimodal size distribution in the early stage of growth, sigmoidal kinetic behavior for the growth, and a correlation of the nucleation parameters with the particle size and distribution. These findings provided important indicators for the operation of an aggregative growth mechanism in the particle size growth and have important implications in understanding interparticle aggregation and coalescence in nanoparticle formation and growth under similar conditions.