ATOMIC-RESOLUTION ON SMALL 3-DIMENSIONAL METAL-CLUSTERS BY STM

Small, three-dimensional Pd clusters (d < 5 nm) deposited under UHV on two different single crystal surfaces (graphite and MoS2) are imaged with atomic resolution, both in air and in UHV, using scanning tunneli ng microscopy (STM). We show that a complete characterization of the m orphology of the cluster can be achieved: three-dimensional shape; azi muthal orientation on the substrate; and arrangement of atoms on later al facets. These results are in good agreement with those obtained fro m TEM observations on large particles (d > 10 nm). Some limitations of STM for such studies are discussed. (C) 1997 Elsevier Science B.V.