A Study of the Electronic Structure Near Individual Dislocations in Diamond by Energy-Loss Spectroscopy

1989 ◽  
Vol 162 ◽  
Author(s):  
J. Bruley ◽  
P. E. Batson
Keyword(s):  
Energy Loss ◽  
Local Density ◽  
Threshold Energy ◽  
Defect States ◽  
Surface Layers ◽  
Edge Structure ◽  
Spatially Resolved ◽  
The Difference ◽  
Electron Energy Loss ◽  
Electron Energy Loss Spectra

ABSTRACTSpatially resolved electron energy-loss spectra recorded from very small volumes of diamond containing individual dislocations show extra intensity within the band-gap just below the 1s to bulk conduction band threshold energy, when compared to spectra recorded from neighboring defect free regions. This is interpreted as direct evidence for the presence of vacant defect states associated with the dislocation structure. The contribution of the π* states from the surface layers to this region of the spectra is completely removed by calculating the difference between the spectra recorded on and off the defect. A comparison is drawn between the measured near edge structure and calculations of local density of states reported in the literature.

Investigations of the chemistry and bonding at niobiumsapphire interfaces

1994 ◽  
Vol 9 (10) ◽  
pp. 2574-2583 ◽  
Author(s):  
J. Bruley ◽  
R. Brydson ◽  
H. Müllejans ◽  
J. Mayer ◽  
G. Gutekunst ◽  
...  
Keyword(s):  
Energy Loss ◽  
Basal Plane ◽  
Molecular Beam ◽  
Structural Model ◽  
Edge Structure ◽  
Spatially Resolved ◽  
Two Samples ◽  
Metal Ceramic ◽  
Electron Energy Loss ◽  
Atomistic Structure

Spatially resolved electron energy-loss data have been recorded at the interface between niobium and sapphire (α-Al2O3), a model metal/ceramic couple. The spatial-difference technique is used to extract interface specific components of the energy-loss near-edge structure (ELNES), which are dependent on the chemistry and bonding across the interface. Multiple scattering calculations of aluminum, oxygen, and niobium clusters were performed to simulate the measured Al L2,3 ELNES. Two samples fabricated by different techniques were examined. The first interface was made by diffusion bonding pure crystals. Its interface spectrum is identified with tetrahedral coordination of the Al ions at the interface. The calculations match the experimental edge structures, supporting the notion of aluminum to niobium metal bonding and concurring with a structural model in which the basal plane of sapphire at the interface is terminated by a full monolayer (i.e., 67% excess) of aluminum. The second sample was produced by molecular beam epitaxy. The spectrum of this interface is consistent with an atomistic structure in which the interfacial basal plane of sapphire is terminated by oxygen. An unoccupied band of states within the band gap of Al2O3 is observed, signifying chemical bonding between metal and ceramic.

The Effect of Local Symmetry on Atomic Resolution EELS Near-Edge Structures: Predictions for Grain Boundaries In NiAl

2000 ◽  
Vol 6 (S2) ◽  
pp. 186-187
Author(s):  
D. A. Pankhurst ◽  
G. A. Botton ◽  
C. J. Humphreys
Keyword(s):  
Energy Loss ◽  
Electron Energy ◽  
Local Density ◽  
Spherical Aberration ◽  
Core Loss ◽  
Atomic Scale ◽  
Atomic Resolution ◽  
Atomic Column ◽  
Edge Structure ◽  
Electron Energy Loss

It has been demonstrated that electron energy loss spectrometry (EELS) can be used to probe the electronic structure of materials on the near-atomic scale. The electron energy loss near edge structure (ELNES) observed after the onset of a core edge reflects a weighted local density of final states to which core electrons are excited by fast incident electrons. Lately ‘atomic resolution EELS’ and ‘column-by-column spectroscopy’ have become familiar themes amongst the EELS community. The next generation of STEMs, equipped with spherical aberration (Cs) correctors and electron beam monochromators, will have sufficient spatial and energy resolution, along with the superior signal to noise required, to detect small changes in the ELNES from atomic column to atomic column.Core loss ELNES provides information about unoccupied states, but the structure observed in spectra is sensitive to changes in the underlying occupied states, and thus to the bonding in the material.

Near-edge structure in electron-energy-loss spectra of MgO

1986 ◽  
Vol 33 (1) ◽  
pp. 22-24 ◽  
Author(s):  
Th. Lindner ◽  
H. Sauer ◽  
W. Engel ◽  
K. Kambe
Keyword(s):  
Energy Loss ◽  
Electron Energy ◽  
Edge Structure ◽  
Electron Energy Loss ◽  
Electron Energy Loss Spectra

Microscopic Analysis of Twin Grain Boundaries in Alumina

2001 ◽  
Vol 7 (S2) ◽  
pp. 312-313
Author(s):  
S. Nufer ◽  
A.G. Marinopoulos ◽  
S. Fabris ◽  
C. Elsässer ◽  
W. Kurtz ◽  
...  
Keyword(s):  
Energy Loss ◽  
Electron Energy ◽  
Density Functional ◽  
Local Density ◽  
Boundary Segregation ◽  
Microscopic Analysis ◽  
Structural Defects ◽  
Beam Diameter ◽  
Spatially Resolved ◽  
Electron Energy Loss

Extended structural defects in α-Al2O3 (alumina), a technologically important, complex ceramic material were quantitatively analyzed with respect to grain boundary segregation, atomic and electronic structures using spatially resolved electron energy-loss spectroscopy (EELS), energy dispersive X-ray spectroscopy (EDS) and first-principles local-density-functional (LDFT) calculations. in this study the results of analytical investigations will be compared with the outcome of LDFT calculations.The analytical measurements were performed with a dedicated scanning transmission electron microscope (TEM) VG HB501UX, operating at 100 kV and with a typical beam diameter of lnm. For the spatially resolved EELS a parallel electron energy-loss spectrometer (Gatan model 666) with an energy resolution of better than 0.8 eV was used. For the chemical analysis an EDS system (Noran-Gresham with a Si(Li) detector and a Norvar window) was applied. The detection limit of the EDX system for measuring interface excess is in the range of 0.3 atoms/nm2.

Electron-energy-loss spectra of silicon carbide of 4H and 6H structures

1991 ◽  
Vol 49 ◽  
pp. 736-737
Author(s):  
D. R. Liu ◽  
S. S. Shinozaki ◽  
J. U. Hangas ◽  
K. Maeda
Keyword(s):  
Silicon Carbide ◽  
Energy Loss ◽  
Electron Energy ◽  
Power Law ◽  
Background Subtraction ◽  
Minute Amount ◽  
The Difference ◽  
Electron Energy Loss ◽  
Electron Energy Loss Spectra ◽  
Made In

The properties of silicon carbide can be tailored with addition of various sintering aides. It is desirable to understand the microstructure of these materials as related to their properties. For example, there is a debate whether there is some Be at all in the 4H structure of SiC doped with BeO. It is very difficult to use the conventional EELS quantification procedure to investigate the Be presence of minute amount in SiC. In any spectrum collected from SiC doped with BeO, the huge Si-L23 edge at 100 eV would extend well above 200 eV and make it impossible to identify a small Be-K edge at 111 eV. However, progress has been made in solving this problem as reported in the present paper. A spectrum from SiC with the BeO additive is compared with a spectrum from SiC without BeO, and the difference of the two spectra starting at 111 eV, if present, should be the Be-K edge signal. Thus, one does not have to fit the background before the Be-K edge with the usual power law A.E-r, and the background subtraction error is greatly reduced.

Investigations on electronic structure of YMnO3 by electron energy loss spectra and first-principle calculations

2019 ◽  
Vol 34 (4) ◽  
pp. 339-344
Author(s):  
S. Wang ◽  
J. Cai ◽  
H. D. Xu ◽  
H. L. Tao ◽  
Y. Cui ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Energy Loss ◽  
Experimental Spectrum ◽  
X Ray Diffraction ◽  
Edge Structure ◽  
Transmission Electron ◽  
The Individual ◽  
Electron Energy Loss ◽  
Electron Energy Loss Spectra ◽  
Good Agreement

Crystal structure and electronic structure of YMnO3 were investigated by X-ray diffraction and transmission electron microscopy related techniques. According to the density of states (DOS), the individual interband transitions to energy loss peaks in the low energy loss spectrum were assigned. The hybridization of O 2p with Mn 3d and Y 4d analyzed by the partial DOS was critical to the ferroelectric nature of YMnO3. From the simulation of the energy loss near-edge structure, the fine structure of O K-edge was in good agreement with the experimental spectrum. The valence state of Mn (+3) in YMnO3 was determined by a comparison between experiment and calculations.

scholarly journals Comparison Between the Experimentally Determined Orientation Dependence of the Near Edge Structure in Electron Energy Loss Spectra from Graphite with Present Theoretical Formulations

2006 ◽  
Vol 12 (S02) ◽  
pp. 1198-1199
Author(s):  
A Liu ◽  
N Zaluzec
Keyword(s):  
Energy Loss ◽  
Electron Energy ◽  
Orientation Dependence ◽  
Edge Structure ◽  
Electron Energy Loss ◽  
Electron Energy Loss Spectra

Extended abstract of a paper presented at Microscopy and Microanalysis 2006 in Chicago, Illinois, USA, July 30 – August 3, 2005

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