Scanning-tunneling-microscopy study of the surface diffusion of sulfur on Re(0001)

Journal Article · Fri Jan 15 04:00:00 EST 1993 · Physical Review, B: Condensed Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.47.2320· OSTI ID:6948159

Dunphy, J C ^[1]; Sautet, P; Ogletree, D F; Dabbousi, O; Salmeron, M B ^[2]

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1. Center for Advanced Materials, Material Science Division, Lawrence Berkeley Laboratory, Berkeley, California 94720 (United States) Department of Physics, University of California, Berkeley, Berkeley, California 94720 (United States)
2. Center for Advanced Materials, Material Science Division, Lawrence Berkeley Laboratory, Berkeley, California 94720 (United States)

Low coverages of sulfur chemisorbed on the rhenium (0001) surface were studied by scanning tunneling microscopy (STM). At one-quarter monolayer coverage, sulfur forms a [ital p](2[times]2) ordered overlayer, consistent with low-energy electron-diffraction results. At lower coverages, some of the sulfur forms small islands of the [ital p](2[times]2) structure. Between the islands, sulfur atoms diffuse over the surface as a lattice gas. In our conditions, the residence time of the sulfur atoms in each site is comparable to the STM scan rate, which gives rise to an apparently noisy image. However, a spatial corelation function was used to determine that this apparent noise is due to diffusing sulfur that maintains a local [ital p](2[times]2) order. This order is due to a weak attractive interaction between the diffusing atoms at twice the Re lattice spacing and a repulsive interaction at closer distances. The strength of the attractive interaction was measured by fitting the results of the correlation function to an Ising model of the interaction of sulfur atoms on the surface. The energy barrier to diffusion was calculated from the sulfur residence time, and compares well with an extended Hueckel calculation.

• DOE Contract Number: AC03-76SF00098
• OSTI ID: 6948159
• Journal Information: Physical Review, B: Condensed Matter; (United States), Journal Name: Physical Review, B: Condensed Matter; (United States) Vol. 47:4; ISSN PRBMDO; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360606* -- Other Materials-- Physical Properties-- (1992-)
ATOM TRANSPORT
CHEMICAL REACTIONS
CHEMISORPTION
CRYSTAL MODELS
CRYSTALS
DIFFUSION
ELEMENTS
ISING MODEL
MATHEMATICAL MODELS
METALS
MONOCRYSTALS
NEUTRAL-PARTICLE TRANSPORT
NONMETALS
RADIATION TRANSPORT
RHENIUM
SEPARATION PROCESSES
SORPTION
SULFUR
TRANSITION ELEMENTS