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

Abstract

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.

Authors:
; ;  [1]; ;  [2];  [3];  [4];  [5]
  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)
Publication Date:
OSTI Identifier:
5692228
DOE Contract Number:  
AC02-76CH00016; AC05-84OR21400
Resource Type:
Journal Article
Journal Name:
Journal of Vacuum Science and Technology, A (Vacuum, Surfaces and Films); (USA)
Additional Journal Information:
Journal Volume: 9:3; Journal ID: ISSN 0734-2101
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; TANTALUM; ELECTRONIC STRUCTURE; TANTALUM CARBIDES; AUGER ELECTRON SPECTROSCOPY; COINCIDENCE METHODS; D STATES; PHOTOELECTRON SPECTROSCOPY; CARBIDES; CARBON COMPOUNDS; COUNTING TECHNIQUES; ELECTRON SPECTROSCOPY; ELEMENTS; ENERGY LEVELS; METALS; REFRACTORY METAL COMPOUNDS; SPECTROSCOPY; TANTALUM COMPOUNDS; TRANSITION ELEMENT COMPOUNDS; TRANSITION ELEMENTS; 360104* - Metals & Alloys- Physical Properties; 360204 - Ceramics, Cermets, & Refractories- Physical Properties

Citation Formats

Hulbert, S L, Kao, C C, Garrett, R F, Bartynski, R A, Yang, S, Weinert, M, Jensen, E, and Zehner, D M. A comparison of the surface electronic structure of Ta(100) and TaC(111) using Auger-photoelectron coincidence spectroscopy. United States: N. p., 1991. Web. doi:10.1116/1.577544.
Hulbert, S L, Kao, C C, Garrett, R F, Bartynski, R A, Yang, S, Weinert, M, Jensen, E, & Zehner, D M. A comparison of the surface electronic structure of Ta(100) and TaC(111) using Auger-photoelectron coincidence spectroscopy. United States. doi:10.1116/1.577544.
Hulbert, S L, Kao, C C, Garrett, R F, Bartynski, R A, Yang, S, Weinert, M, Jensen, E, and Zehner, D M. Wed . "A comparison of the surface electronic structure of Ta(100) and TaC(111) using Auger-photoelectron coincidence spectroscopy". United States. doi:10.1116/1.577544.
@article{osti_5692228,
title = {A comparison of the surface electronic structure of Ta(100) and TaC(111) using Auger-photoelectron coincidence spectroscopy},
author = {Hulbert, S L and Kao, C C and Garrett, R F and Bartynski, R A and Yang, S and Weinert, M and Jensen, E and Zehner, D M},
abstractNote = {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.},
doi = {10.1116/1.577544},
journal = {Journal of Vacuum Science and Technology, A (Vacuum, Surfaces and Films); (USA)},
issn = {0734-2101},
number = ,
volume = 9:3,
place = {United States},
year = {1991},
month = {5}
}