Metastable quenching spectroscopy as a surface electronic probe of clean and adsorbate covered single crystal metal surfaces
Metastable He/sup */ (2/sup 1/S and 2/sup 3/S) beams were used to probe the electronic properties of clean and adsorbate-covered nickel surfaces. The metastable atoms collide with the surface and electronically transfer their excitation energy causing electron ejection. On a clean nickel surface, the metal is resonantly ionized and the ion is subsequently Auger neutralized. On metal surfaces of low work function or on adsorbate-covered surfaces, deexcitation can proceed via Auger deexcitation. The energy distributions obtained by these two deexcitation paths are comparable to those obtained by ion neutralization (INS) or by optical excitation (UPS), respectively. The metastable quenching technique is much more surface sensitive than UPS, since there is no background due to primary electron emission from the metal, which dominates the UPS spectrum. The competitive nature of the deexcitation paths is discussed for oxygen-covered NI(111) and CO-covered NI(110). Enhanced back-donation from a Ni surface to the 2..pi../sup */ orbital of CO was observed for a potassium-precovered Ni(111) surface. Metastable quenching spectra for Xenon absorbed on potassium recovered Ni(111) indicate the presence of localized charge-transfer from potassium to the surface.
- Research Organization:
- California Univ., Santa Barbara (USA)
- OSTI ID:
- 6922054
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ATOMIC BEAMS
ELECTRON PROBES
HELIUM
NICKEL
SURFACES
ADSORPTION
AUGER EFFECT
CARBON MONOXIDE
DE-EXCITATION
METASTABLE STATES
MONOCRYSTALS
OXYGEN
POTASSIUM
ALKALI METALS
BEAMS
CARBON COMPOUNDS
CARBON OXIDES
CHALCOGENIDES
CRYSTALS
ELEMENTS
ENERGY LEVELS
ENERGY-LEVEL TRANSITIONS
EXCITED STATES
FLUIDS
GASES
METALS
NONMETALS
OXIDES
OXYGEN COMPOUNDS
PROBES
RARE GASES
SORPTION
TRANSITION ELEMENTS
656003* - Condensed Matter Physics- Interactions between Beams & Condensed Matter- (1987-)