Self-assembled nanostructure of Au nanoparticles on a self-assembled monolayer

We investigated self-assembled nanostructure of Au nanoparticles (AuNPs) on a dithiol-inserted self-assembled monolayer (SAM) using scanning tunneling microscopy (STM). Phosphine-stabilized AuNPs were immobilized on the SAM covering an Au(1 1 1) surface by the dithiol anchoring bridges. The phosphine-stabilized AuNPs were transformed to dithiol-stabilized AuNPs by a ligand exchange reaction. The additional phosphine-stabilized AuNPs were attached to the dithiol-stabilized AuNPs on the SAM surface. The dithiol-stabilized AuNPs act as nuclei of stepwise reactions for forming self-assembled nanostructure of AuNPs. We observed a variety of nanostructures of AuNPs using STM.