Synchrotron radiation photoemission studies of CO chemisorption on Pt/Ta(110) and Ni/Ta(110)

Journal Article · Wed Jul 01 04:00:00 EDT 1987 · J. Vac. Sci. Technol., A; (United States)

DOI:https://doi.org/10.1116/1.574353· OSTI ID:6371486

Ruckman, M W; Strongin, M; Pan, X

The effect of overlayer structure and electronic density near the Fermi level on CO chemisorption is studied for Pt or Ni deposited on Ta(110) using angle-resolved synchrotron radiation photoemission spectroscopy. Pt films form two-dimensional pseudomorphic islands at submonolayer coverage, but undergo a structural change to a close-packed Pt(111)-like structure at --0.7 monolayer coverage. Absence of CO induced photoemission features at monolayer coverage suggests that the CO--Pt bond has been weakened and this prevents the retention of CO on a close-packed Pt monolayer at room temperature. Close-packed Pt films three or more layers thick readily chemisorb CO. At liquid-nitrogen temperature, CO is retained on Pt/Ta(110), and photoemission features, such as the CO 4sigma shake-up satellite seen for weakly bonded CO on noble metals, appear for the CO phase chemisorbed on a Pt monolayer. This photoemission feature is absent for CO chemisorbed on thicker Pt films. Photoemission examination of the CO--metal bonding geometry suggests that the CO molecules lie close to the surface normal for both Pt monolayers and the thicker Pt films. From the photoemission data, we conclude that the CO--metal bond strength is reduced for CO--Pt/Ta(110). Comparable studies of CO on Ni/Ta(110) were not possible because the three-dimensional clustering of Ni produced a more complicated surface which had a number of inequivalent CO bonding sites.

• Research Organization: Brookhaven National Laboratory, Upton, New York 11973
• DOE Contract Number: AC02-76CH00016
• OSTI ID: 6371486
• Journal Information: J. Vac. Sci. Technol., A; (United States), Journal Name: J. Vac. Sci. Technol., A; (United States) Vol. 5:4; ISSN JVTAD
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360104* -- Metals & Alloys-- Physical Properties
BREMSSTRAHLUNG
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CHALCOGENIDES
CHEMICAL REACTIONS
CHEMISORPTION
ELECTROMAGNETIC RADIATION
ELEMENTS
EMISSION
ENERGY LEVELS
ENERGY-LEVEL DENSITY
FERMI LEVEL
FILMS
METALS
NICKEL
OXIDES
OXYGEN COMPOUNDS
PHOTOEMISSION
PLATINUM
PLATINUM METALS
RADIATIONS
SECONDARY EMISSION
SEPARATION PROCESSES
SORPTION
SORPTIVE PROPERTIES
SURFACE PROPERTIES
SYNCHROTRON RADIATION
TANTALUM
THIN FILMS
TRANSITION ELEMENTS