STM TEM COMPARATIVE-STUDY OF PD CLUSTERS EPITAXIALLY GROWN ON HIGHLY ORIENTED PYROLYTIC-GRAPHITE

Pd clusters in the size range 1-100 nm are grown at high temperature o n HOPG and observed by STM and TEM. These two techniques give compleme ntary information. The morphology of the particles is easily obtained by STM at all sizes, while TEM is limited to the observation of larger clusters. Crystallographic informations (internal structure, facet or ientation, epitaxy) can be obtained on individual particles by TEM, bu t only if the particles are larger than about 5 nm. However the surfac e structure of dusters is only attainable by STM. STM is also more eff icient to detect very small clusters (<1.5 nm).