A comparison of the surface electronic structure of Ta(100) and TaC(111) using Auger-photoelectron coincidence spectroscopy

Journal Article · Wed May 01 04:00:00 EDT 1991 · Journal of Vacuum Science and Technology, A (Vacuum, Surfaces and Films); (USA)

DOI:https://doi.org/10.1116/1.577544· OSTI ID:5692228

Hulbert, S L; Kao, C C; Garrett, R F ^[1]; Bartynski, R A; Yang, S ^[2]; Weinert, M ^[3]; Jensen, E ^[4]; Zehner, D M ^[5]

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1. National Synchrotron Light Source, Brookhaven National Laboratory, Upton, New York 11973 (USA)
2. Department of Physics and Astronomy and The Laboratory for Surface Modification, Rutgers University, P.O. Box 849, Piscataway, New Jersey 08855-0849 (USA)
3. Physics Department, Brookhaven National Laboratory, Upton, New York 11973 (USA)
4. Department of Physics, Brandeis University, Waltham, Massachusetts 02254 (USA)
5. Solid State Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (USA)

We present {ital N}{sub 7}{ital VV} (4{ital f}{sub 7/2}5{ital d}5{ital d}) Auger spectra from TaC(111) taken in time coincidence with photoemitted bulk and surface-shifted 4{ital f}{sub 7/2} core-level electrons, and compare these data with self-convolutions of calculated valence band {ital d} densities of states (SCDOS) for the surface (first) and bulk (exponential sum of second, fourth, and sixth subsurface) atomic layers of a 13-layer slab. The Ta 4{ital f} levels of TaC(111) and Ta(100) both exhibit large surface core level shifts, but of opposite sign. Therefore, we compare the TaC(111) data and calculations with analogous {ital N}{sub 7}{ital VV} Auger coincidence spectra and calculated SCDOS that we have previously published for Ta(100). The bulk Ta(100) and surface TaC(111) spectra show favorable agreement with the calculations; the surface Ta(100) and bulk TaC(111) spectra, on the other hand, exhibit marked disagreement with the calculations. These discrepancies are consistent with and provide added support for the presence of our proposed{sup 1} surface-to-bulk (bulk-to-surface) interatomic Auger decay mode which adds a bulk (surface) contribution to the surface (bulk) Auger line shape of Ta(100) (TaC(111)). These conclusions are supported by comparison of our data to incoherent sums of bulk and surface SCDOS.

• DOE Contract Number: AC02-76CH00016; AC05-84OR21400
• OSTI ID: 5692228
• Journal Information: Journal of Vacuum Science and Technology, A (Vacuum, Surfaces and Films); (USA), Journal Name: Journal of Vacuum Science and Technology, A (Vacuum, Surfaces and Films); (USA) Vol. 9:3; ISSN JVTAD; ISSN 0734-2101
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360104* -- Metals & Alloys-- Physical Properties
360204 -- Ceramics
Cermets
& Refractories-- Physical Properties
AUGER ELECTRON SPECTROSCOPY
CARBIDES
CARBON COMPOUNDS
COINCIDENCE METHODS
COUNTING TECHNIQUES
D STATES
ELECTRON SPECTROSCOPY
ELECTRONIC STRUCTURE
ELEMENTS
ENERGY LEVELS
METALS
PHOTOELECTRON SPECTROSCOPY
REFRACTORY METAL COMPOUNDS
SPECTROSCOPY
TANTALUM
TANTALUM CARBIDES
TANTALUM COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS