Ultraviolet Photoemission Spectroscopy study of hydrogen chemisorption and metallic behavior of the niobium (110) surface with palladium overlayers
Ultraviolet Photoemission Spectroscopy (UPS) and bulk hydrogen uptake measurements are used to study bulk and surface hydrogen chemisorption in niobium in an extended temperature range. Predictions of the Dilute Phase Model are verified above room temperature. At lower temperatures hypothesized nucleation of a dense hydride phase at the surface lowers bulk uptake rates drastically. Epitaxial palladium overlayers, known to enhance the bulk hydrogen uptake only above monolayer coverage, are examined in UPS for clues to this behavior. The electronic density of states is found to be insensitive to crystalline structure within the monolayer and is noble-metal-like. Observations of Fano resonance and CO reactivity lead to similar conclusions. Means by which electronic structure can affect hydrogen uptake are discussed. At cryogenic temperatures physisorption of H/sub 2/, O/sub 2/, and Xe gases and distance-dependent shifts are observed. Atomic Pd and Ni are isolated in Xe matrix and studied in UPS. Pd cluster size monitored in transition from atomic to metallic state, initial-state electrostatic and final-state screening shifts in the Xe peaks are separately noted. Reactivity of Ni with N/sub 2/ and Pd with CO and H/sub 2/ in solid matrices are demonstrated.
- Research Organization:
- State Univ. of New York, Stony Brook (USA)
- OSTI ID:
- 6467116
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
Similar Records
Modification of the properties of metal overlayers on Nb(110) and Ta(110)
Interface structures of ordered Fe and Gd overlayers on W(110) from site-specific photoelectron diffraction
Related Subjects
HYDROGEN
CHEMISORPTION
NIOBIUM
HYDRIDATION
SORPTIVE PROPERTIES
DEPOSITS
EMISSION SPECTRA
MEDIUM TEMPERATURE
PALLADIUM
ULTRAVIOLET SPECTRA
CHEMICAL REACTIONS
ELEMENTS
METALS
NONMETALS
PLATINUM METALS
SEPARATION PROCESSES
SORPTION
SPECTRA
SURFACE PROPERTIES
TRANSITION ELEMENTS
360105* - Metals & Alloys- Corrosion & Erosion