Surface chemistry and growth manipulation of supported metal clusters and hybrid nanostructured materials

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Understanding the chemical processes occurring on surfaces is fundamentally important to many areas of science and technology, including chemical and petrochemical technologies, environmental science, materials research, molecular electronics, and nanotechnology. The proposed work seeks to study the surface chemistry and physics occurring on novel substrates, from metallic clusters (of a few atoms to a few nanometers in size) supported on single-crystal silicon surfaces to nanostructures of transparent conductive oxides (e.g. tin oxide). Our study will focus on adsorbates of biochemical interest, and will follow the evolution of their structures and electronic properties upon adsorption on these substrates and upon stimulation with heat and low-energy electrons. Using specialized tools that allow us to precisely deposit one atom or molecule at a time (i.e. molecular beam epitaxy), we will develop the appropriate growth strategies to obtain a near-monosized distribution of these metal clusters on the silicon substrate. Using a laser ablation technique, we will also be able to build a variety of one-dimensional and two-dimensional nanostructures of transparent conductive oxides. These novel nanomaterials will not only provide important test beds for investigating fundamental processes occurring on their complex surfaces, but also serve as the basic platforms for developing emerging applications in catalysis, biosensing, extended-release drug delivery, solar cell devices and single-nanostructure electronics. We will focus on three general areas of interest: (1) Growth of metal clusters, with special emphasis on how the initial nucleation sites on the silicon support will affect the geometries and structures of the clusters; (2) Interactions of DNA base molecules with metal clusters as a function of cluster size; and (3) Growth manipulation of hybrid nanostructures of bimetallic systems (nanoalloys) and of transparent conductive oxides that are of respective interest to nanocatalysis and nanomagnetics applications and to solar cell applications.