Growth and electronic structure of Nb and Ta films on Pd and their interaction with CO
The growth of Nb and Ta films on Pd(111) and their modification of CO chemisorption are studied using UPS, LEED, and low energy ion scattering (LEIS). At 300K LEIS shows significant amounts of Pd in the top layer even after more than a monolayer of Nb or Ta is deposited. This is in contrast to Pd on Nb or Ta(110) where a Pd monolayer completely covers the substrate. UPS shows that the surface electronic structure at monolayer Nb or Ta coverage resembles that of a Pd monolayer on Nb or Ta(110) and is characterized by strong Pd 4d emission 1-4 eV below Ef and a low density of states at Ef. Molecular CO adsorption is observed at submonolayer coverage, there is negligible CO adsorption at monolayer coverage and dissociative CO adsorption starts at greater than monolayer coverage. It is concluded that the deposited Nb and Ta monolayers intermix with the Pd(111) substrate and it is also shown that this behavior can be understood by examining the energies of the system. 17 refs., 2 figs.
- Research Organization:
- Brookhaven National Lab., Upton, NY (USA)
- DOE Contract Number:
- AC02-76CH00016
- OSTI ID:
- 6873111
- Report Number(s):
- BNL-41761; CONF-881002-11; ON: DE89001104
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360102* -- Metals & Alloys-- Structure & Phase Studies
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CHALCOGENIDES
CHEMICAL ANALYSIS
CHEMICAL REACTIONS
CHEMISORPTION
COHERENT SCATTERING
DEPOSITION
DIFFRACTION
ELECTRON DIFFRACTION
ELECTRONIC STRUCTURE
ELEMENTS
FILMS
INTERFACES
ION SCATTERING ANALYSIS
LAYERS
METALS
MIXING
NIOBIUM
NONDESTRUCTIVE ANALYSIS
OXIDES
OXYGEN COMPOUNDS
PALLADIUM
PLATINUM METALS
SCATTERING
SEPARATION PROCESSES
SORPTION
SURFACES
TANTALUM
THIN FILMS
TRANSITION ELEMENTS