The Role of Surface Modification on Nanoparticle Formation by Atomic Layer Deposition Stacey F. Bent, Department of Chemical Engineering, Stanford University We are carrying out fundamental studies into a novel method for growing catalytically active nanoparticles on surfaces in which the size and average spacing of the nanoparticles can be controlled. The process utilizes chemical modification of the substrate surface combined with atomic layer deposition (ALD). In these experiments, we use self assembled monolayers (SAM) formed from octadecyltrichlorosilane (ODTS) to modify silicon oxide-terminated silicon substrates. The self assembled monolayers are imparted with increasing defect concentrations by intentionally shortening the SAM formation time. These defects, in turn, serve as potential nucleation sites for ALD. The size of the nanoparticles can be controlled by the number of ALD reaction cycles. ALD Process 200 nm Atomic layer deposition of Pt on a substrate modified by a self-assembled monolayer successfully yields nanoparticles if the nucleation sites are constrained.