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

Conference · Sun Jan 01 04:00:00 EST 1984

OSTI ID:6215143

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), (..sqrt..3 x ..sqrt..3)R30/sup 0/, p(3 x 3), and p(4 x 4) structures. The Bi TDMS and AES data are consistent with 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 vs one site for CO adsorption; therefore, uptake of the former adsorbates is much more severely attenuated at theta/sub Bi/ increases.

• Research Organization: Los Alamos National Lab., NM (USA)
• DOE Contract Number: W-7405-ENG-36
• OSTI ID: 6215143
• Report Number(s): LA-UR-84-3488; CONF-841218-11; ON: DE85003725
• 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 MONOXIDE
CARBON OXIDES
CHALCOGENIDES
CHEMICAL REACTIONS
CHEMISORPTION
COHERENT SCATTERING
DEPOSITS
DESORPTION
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