SCANNING TUNNELING MICROSCOPE AND ATOMIC-FORCE MICROSCOPE STUDY OF EPITAXIALLY GROWN PALLADIUM CRYSTALLITES ON GRAPHITE

Scanning tunneling microscope (STM) and atomic force microscope (AFM) have been applied to the study of an epitaxial growth of Pd on graphit e. Pd deposited at 450-degrees-C nucleates to crystallize and grow epi taxially along the [111] direction. The STM images of the topmost laye r of the (111) face exhibited a long periodic structure with a periodi c distance of about 2.7 nm. Codeposition of Pd and Cu on graphite at 5 50-degrees-C created clear images of the atomic arrangement together w ith the periodic structure. The periodic length was found to exactly c orrespond to a distance of 10 atoms. Auger measurements of each crysta llite showed that its surface layer mostly contains Pd atoms although almost equal amount of Pd and Cu was deposited. The AFM observations a lso showed images with similar periodicity to those from the STM. On t he basis of the STM and the AFM results, the possibility of the recons truction of the surface is discussed.