Surface Interactions

Gold is inert in its bulk form, but an effective catalyst when supplied as a nanoparticle. We are investigating the adsorption process for organic molecules on gold surfaces that present the same surface features as gold nanoparticles. The energetics of the binding as well as the chemical reactivity of the adsorbed species are computational targets. Our current focus is on adsorbed amines. These studies will lead to direct calculations involving gold nanoparticles.

We are interested in the interaction of metal, semiconductor and magnetic clusters with surfaces. In these computational studies we attempt to answer questions about the relationship of cluster geometry to the nature and functionality of the final surface film. In one example, the energetics and surface relaxation of silver adatoms and clusters on graphite were investigated using an ab initio density functional theory description; a package called PLATO (Package for Linear-combination of Atomic Type Orbitals), developed by Steven Kenny at the University of Loughborough in the UK. The energy landscape sketched along [110] indicates that atom/cluster mobility on the graphite surface is very high. These results were consistent with the available experimental data from scanning tip microscopy. Other studies on graphite have examined gold atoms and dimers (with results similar to those for silver), as well as larger gold clusters which exhibit variable orientations with respect to the surface. We have also explored the lability of these clusters on the surface. Current work is directed towards the examination of semiconductor clusters (ZnS and ZnO) on surfaces such as graphite and metal oxides, including various crystal orientations of MgO and ZnO.

We have begun studies on the growth of ZnO crystals on zirconium or gold surfaces, as well as the interaction of organic molecules,especially thiols, with nanotubes of various diameters.