Supported metal clusters and cluster-substrate interaction studied by scanning tunneling microscopy

Miscellaneous · Wed Jan 01 00:00:00 EST 1992

OSTI ID:7169125

Xhie, J

This dissertation is concerned with an experimental study of supported metal clusters and cluster-substrate interaction. The geometric and electronic structures of platinum and cobalt clusters on graphite, the effects of clusters on graphite substrate, and the influences from the substrate to clusters were investigated by scanning tunneling microscopy. A topographic study of adatoms and small clusters of platinum and cobalt on highly-oriented pyrolytic graphite was performed both in air and in ultra-high vacuum. The samples were prepared by vapor deposition on the graphite surface. Stable images of adatoms and small clusters on graphite were obtained with atomic resolution. The adsorption sites of adatoms and clusters on the surface as well as the bond lengths and bond angles of cluster were determined. Various superstructures on graphite were found near the adsorbed clusters, or generally near defects. The superstructures are localized in small areas near the clusters and decay within a distance of 2-5 nm into the graphite lattice. Among many graphite substrates being studied, anomalous giant lattices were observed on three of the samples. They exhibited hexagonal symmetry with lattice constants of 1.7 nm, 2.8 nm, 3.8 nm and 6.6 nm. Atomic resolution of graphite was obtained simultaneously. By introducing small rotations of the top graphite layer relative to the underlying single crystal, a complete description layer relative to the underlying single crystal, a complete description is developed to account for all the features displayed by the STM images. In addition to the giant and atomic lattices, a supergiant lattice was observed. Cobalt particles on the surface were also imaged and were found on the top sites of the giant lattice.

• Research Organization: Hawaii Univ., Honolulu, HI (United States)
• OSTI ID: 7169125
• Resource Relation: Other Information: Thesis (Ph.D.)
• Country of Publication: United States
• Language: English

Related Subjects

74 ATOMIC AND MOLECULAR PHYSICS
36 MATERIALS SCIENCE
COBALT
ELECTRONIC STRUCTURE
MICROSCOPY
SURFACE PROPERTIES
PLATINUM
CHEMICAL BONDS
CRYSTAL LATTICES
GRAPHITE
SUBSTRATES
TUNNEL EFFECT
CARBON
CRYSTAL STRUCTURE
ELEMENTAL MINERALS
ELEMENTS
METALS
MINERALS
NONMETALS
PLATINUM METALS
TRANSITION ELEMENTS
664000* - Atomic & Molecular Physics- (1992-)
360102 - Metals & Alloys- Structure & Phase Studies