Shape Controlled Growth Of Noble Metal Nanocrystals

Michael Bockstaller, Materials Science and Engineering

Gold nanocrystals have attracted tremendous interest because of their particular optical properties (determined by the plasmon resonance) as well as the bio-inert characteristics of gold. Applications such as contrasting agents, nanoscopic heat sources for cancer treatment, sensors and many more have been postulated or demonstrated. Fundamental to all these application is the plasmon resonance that determines the optical properties of the gold crystals - and that has been shown to be intimately related to the particles size and shape. Despite the progress in controlling the growth of gold nanocrystals that mechanism and thus the relevant parameters that control size and shape of the resulting nanocrystals is essentially not understood. The hypothesis of this proposal (based on preliminary results of the PI) is that before the initiation of the nucleation event a polymeric precursor salt-complex forms in the solution and it is the characteristics of this precursor that determines the final particle characteristics.

This project will focus on the elucidation of the interrelationship between reaction conditions, precursor state and final particle morphology. Starting point will be the established Schiffrin-method for synthesizing gold nanocrystals. Students will prepare precursor solutions and apply light scattering and viscometry methods to identify the precursor polymers (size and shape) in solution. Subsequently, particle growth will be initiated (by addition of a reducing agent) and the resulting particle characteristics determined by electron microscopy (in collaboration with a graduate student). If successful, this project will open new avenues for controlling process conditions for gold particle growth and potentially open up new application areas of shape controlled metal nanocrystals.