Session K28 - Clusters: Nanophase and Supported.
MIXED session, Wednesday afternoon, March 19
Room 4300E, Conv. Center
Techniques have been developed to deposit nanometer-size Au clusters onto the apex of a sharp W tip. This allows the clusters in question to be studied using a field-ion / field emission microscope. The successful deposition of a cluster on the apex of the tip is signaled by a large increase in the field emission current and the appearance of a bright spot on a nearby fluorescent screen. By introducing Argon as an imaging gas, it is sometimes possible to obtain a field-ion image before the cluster is field desorbed. Time lapse studies of the field-ion micrographs allow the positions of edge and corner atoms on the cluster to be identified. In this way we can study the equilibrium structure of nanometer-size annealed, single crystal Au clusters. The FIM micrographs show evidence of a truncated-octahedra (TO) structure. The micrographs also suggest the presence of partially filled shells as well as adatoms/defects on the (100) and (111) facets.