Influence of adsorbed Bi on the chemisorption properties of Pt(111):H/sub 2/, CO, and O/sub 2/

Journal Article · Wed May 01 04:00:00 EDT 1985 · J. Vac. Sci. Technol., A; (United States)

DOI:https://doi.org/10.1116/1.573317· OSTI ID:5568966

Paffett, M T; Campbell, C T; Taylor, T N

The growth modes and interactions of vapor-deposited Bi on a clean Pt(111) surface and its effects on the chemisorption of H/sub 2/, CO, and O/sub 2/ have been monitored by Auger electron spectroscopy (AES), low-energy electron diffraction (LEED), and thermal desorption mass spectroscopy (TDMS). For submonolayer Bi coverages, LEED patterns were observed to progress with increasing coverage through p(2 x 2), ( 7/8 x 7/8 )R30/sup 0/, p(3 x 3), and p(4 x 4) structures. The Bi TDMS and AES data are consistent with proposed structural models giving absolute coverages of 0.25, 0.33, 0.44, and 0.56, respectively. For submonolayer coverages of this s/sup 2/p/sup n/-type metal, Bi adatoms are strongly repulsive and maximize their spacing subject to the constraints of the Pt(111) sites. This is to be contrasted with d/sup n/s/sup m/-type metals such as Ag, Cu, and Au on Pt(111), which show attractive interactions and coalesce into 2d islands. In chemisorption of small molecules on Pt(111), each Bi adatom blocks about two Pt surface atoms. An ensemble of two adjacent Pt sites is required for both dissociative H/sub 2/ and molecular O/sub 2/ adsorption versus one site for CO adsorption; therefore, uptake of the former adsorbates is much more severely attenuated as theta/sub Bi/ increases.

• Research Organization: Los Alamos National Laboratory, Los Alamos, New Mexico 87545
• OSTI ID: 5568966
• Journal Information: J. Vac. Sci. Technol., A; (United States), Journal Name: J. Vac. Sci. Technol., A; (United States) Vol. 3:3; ISSN JVTAD
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360104* -- Metals & Alloys-- Physical Properties
ADSORPTION
AUGER ELECTRON SPECTROSCOPY
BISMUTH
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON OXIDES
CHALCOGENIDES
CHEMICAL REACTIONS
CHEMISORPTION
COATINGS
COHERENT SCATTERING
DIFFRACTION
ELECTRON DIFFRACTION
ELECTRON SPECTROSCOPY
ELEMENTS
HYDROGEN
METALS
NONMETALS
OXIDES
OXYGEN
OXYGEN COMPOUNDS
PLATINUM
PLATINUM METALS
SCATTERING
SEPARATION PROCESSES
SORPTION
SORPTIVE PROPERTIES
SPECTROSCOPY
SURFACE PROPERTIES
TRANSITION ELEMENTS
VAPOR DEPOSITED COATINGS