Dark and Bright Field experimental images of Au nanoparticles passivated with dodecanothiol.

1. Passivating Au Nanoparticles With Alky-Thiol Molecules Dhiraj K. Sardar, University of Texas at San Antonio, DMR 0934218 In the design of new nanotechnology devices, the study of the interaction between nanoparticles and different types of ligands has been a very important topic. The control of the adsorption and structural changes on ligand passivated gold (Au) nanoparticles are of primary importance to the design of biocompatible materials, biosensors, and catalysts. Gold nanoparticles are easily coated through organic molecular self-assembly, particularly with thiol molecules due to the strong interaction between sulfur and gold atoms. Self-assembled monolayers have been intensively studied, at the experimental and theoretical levels, on extended gold (111) surfaces; however, the adsorption of thiolates on gold adatoms is energetically more stable than adsorption on flat surfaces. Therefore, a model that allows us to have a better understanding about some fundamental structural aspects of passivated Au nanoparticles is of great importance. A new theoretical model has been developed to study the final packing, structural defects and stability of the nanoparticles that are passivated with alky-thiol molecules. Our modeling results are comparable with experimental results. Theoretical models of Au icosahedral nanoparticles ( ~25 nm) surrounded by two different alky-thiol molecules (mercaptobenzoic acid and dodecanothiol). Dark and Bright Field experimental images of Au nanoparticles passivated with dodecanothiol.