Synchrotron radiation photoemission studies of CO chemisorption on Pt/Ta(110) and Ni/Ta(110)
The effect of overlayer structure and electronic density near the Fermi level on CO chemisorption is studied for Pt/Ta(110) and Ni/Ta(110) by angle-resolved synchrotron radiation photoemission spectroscopy. Ni and Pt have distinctly different overlayer growth modes, but undergo similar modification of their valance band d-states when in contact with a Ta surface. Ni agglomerates on Ta(110), while Pt accumulates layer-by-layer. Exposure of an ultra-thin (0 < theta < 2ML) Ni/Ta(110) film to CO causes partial dissociation of the adsorbed CO leading to the coexistence of CO, C and O on the surface. Examination of the data suggests that the fractions of CO adsorbed and dissociated on the surface can be used to determine the amount of Ni clustering on the Ta(110) surface. When the surface is cooled to 80K only molecular CO adsorption is observed. Thick Ni films, also, adsorb molecular CO. Dissociative CO adsorption is observed for submonolayer films of Pt/Ta(110). At Pt coverages greater than a monolayer, molecular CO chemisorption is observed. No CO adsorption, either dissociative or molecular, is observed for monolayer coverages of Pt. Cooling a Pt/Ta(110) monolayer to 80K induces CO molecular adsorption.
- Research Organization:
- Brookhaven National Lab., Upton, NY (USA)
- DOE Contract Number:
- AC02-76CH00016
- OSTI ID:
- 7009075
- Report Number(s):
- BNL-38686; CONF-861019-21; ON: DE87003202
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360104* -- Metals & Alloys-- Physical Properties
BREMSSTRAHLUNG
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CHALCOGENIDES
CHEMICAL REACTIONS
CHEMISORPTION
DISSOCIATION
ELECTROMAGNETIC RADIATION
ELEMENTS
EMISSION
ENERGY LEVELS
FERMI LEVEL
FILMS
LAYERS
METALS
NICKEL
OXIDES
OXYGEN COMPOUNDS
PHOTOEMISSION
PLATINUM
PLATINUM METALS
RADIATIONS
SECONDARY EMISSION
SEPARATION PROCESSES
SORPTION
SPECTRA
SURFACE PROPERTIES
SURFACES
SYNCHROTRON RADIATION
TANTALUM
THIN FILMS
TRANSITION ELEMENTS