Au nanoparticles are inorganic nanoparticles that have very unique properties, which give them a wide variety of applications such as bio-labels, diode lasers, and solar cells to name a few. The field of nanoparticle research has seen dramatic growth in recent years. Several theories have been proposed and some widely accepted about nucleation and growth of nanoparticles but it has yet to be confirmed experimentally if nanoparticles form by the nucleation theory. According to the theory it takes less energy to start forming a shell around existing nanoparticle rather than form a new core. In this project a Ag shell was grown at a slow rate around Au nanoparticles. Ag was chosen to grow around the Au nanoparticles because they have nearly identical lattice structures. Due to their similar lattice structures it takes very little energy for the Ag to form a shell around the Au nanoparticle. The amount of energy it takes for Ag nanoparticles to nucleate as opposed to growing a shell was determined by monitoring plasmon absorption of Au cores, Au/Ag core/shell composites, and forming isolated Ag particles. The results of the experiments showed that shell growth does require lower amounts of heat and time of exposure than that of nucleation of new cores. This provides first experimental evidence that Ag nanoparticles form according to the classic theory of nucleation.

Ag nanoparticle nucleation vs. shell growth

249th National Meeting (2015)

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