Coadsorbate induced compression of sulfur overlayers on Re(0001) and Pt(111) by CO
- Center for Advanced Materials, Material Science Division, Lawrence Berkeley Laboratory, Berkeley, California 94720 (United States)
Low coverages of sulfur chemisorbed on the rhenium(0001) and platinum(111) surfaces were studied in UHV by scanning tunneling microscopy (STM) and low-energy electron diffraction (LEED). On both of these surfaces of triangular symmetry the lowest coverage ([approx]0.25 monolayers) ordered structure is [ital p](2[times]2). Exposure of this ordered sulfur overlayer on either surface to low pressures (10[sup [minus]9] Torr) of CO induces compression of the sulfur layer to a structure associated with a higher local coverage and CO chemisorbs in the holes created in the sulfur layer. The reordering was observed by both a change in the LEED pattern and by real space STM imaging of the surface. On the Re surface the new overlayer has (3[radical]3[times]3[radical]3)[ital R]30[degree] symmetry, while on the Pt surface it has ([radical]3[times][radical]3)[ital R]30[degree] symmetry. There was no increase in the amount of sulfur on the surface during this reordering. On both surfaces the overlayers could be returned to the original [ital p](2[times]2) by annealing for several seconds at 600 [degree]C, during which CO desorbs and sulfur atoms reoccupy the vacant metal sites. This phenomenon of the compression of atoms in a strongly chemisorbed layer upon coadsorption of another molecule provides a mechanism for carrying out catalytic reactions on metal surfaces that are covered with strongly chemisorbed layers that do not participate in the reaction.
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 5158568
- Journal Information:
- Journal of Chemical Physics; (United States), Vol. 100:8; ISSN 0021-9606
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
CARBON MONOXIDE
CHEMISORPTION
SULFUR
ANNEALING
CATALYSIS
ELECTRON DIFFRACTION
LAYERS
PLATINUM
RHENIUM
SCANNING ELECTRON MICROSCOPY
TUNNEL EFFECT
ULTRAHIGH VACUUM
CARBON COMPOUNDS
CARBON OXIDES
CHALCOGENIDES
CHEMICAL REACTIONS
COHERENT SCATTERING
DIFFRACTION
ELECTRON MICROSCOPY
ELEMENTS
HEAT TREATMENTS
METALS
MICROSCOPY
NONMETALS
OXIDES
OXYGEN COMPOUNDS
PLATINUM METALS
SCATTERING
SEPARATION PROCESSES
SORPTION
TRANSITION ELEMENTS
360102* - Metals & Alloys- Structure & Phase Studies
400201 - Chemical & Physicochemical Properties
665100 - Nuclear Techniques in Condensed Matter Physics - (1992-)