Controlling the formation of Au nanoparticles using functionalized molecular buffer layers

Nanoparticles of gold are produced by evaporation of gold atoms onto functionalized self-assembled monolayers (SAMs). SAMs of dodecanethiol (DT) and mercaptoundecanoic acid (MUA) on Au(1 1 1) are used as substrates and the gold particles are imaged with a scanning tunneling microscope. Gold atoms evaporated on DT monolayers diffuse rapidly to the interface between the molecular layer and the gold substrate where they form two-dimensional islands of 1 ML in height. In the case of monolayers of MUA, the strong interaction between evaporated gold and the acid group of the molecule gives rise to effective pinning of the gold atoms on top of the molecular layer and leads to the growth of three-dimensional gold nanocrystals.