Electron energy-loss near-edge structure in silicate minerals

1992 ◽  
Vol 50 (2) ◽  
pp. 1258-1259
Author(s):  
D W McComb ◽  
R S Payne ◽  
P L Hansen ◽  
R Brydson
Keyword(s):  
Solid State ◽  
Energy Loss ◽  
Electron Energy ◽  
State Energy ◽  
Local Environment ◽  
Edge Structure ◽  
Silicate Minerals ◽  
Two Samples ◽  
Electron Energy Loss ◽  
Careful Processing

Electron energy-loss near-edge structure (ELNES) is an effective probe of the local geometrical and electronic environment around particular atomic species in the solid state. Energy-loss spectra from several silicate minerals were mostly acquired using a VG HB501 STEM fitted with a parallel detector. Typically a collection angle of ≈8mrad was used, and an energy resolution of ≈0.5eV was achieved.Other authors have indicated that the ELNES of the Si L2,3-edge in α-quartz is dominated by the local environment of the silicon atom i.e. the SiO4 tetrahedron. On this basis, and from results on other minerals, the concept of a coordination fingerprint for certain atoms in minerals has been proposed. The concept is useful in some cases, illustrated here using results from a study of the Al2SiO5 polymorphs (Fig.l). The Al L2,3-edge of kyanite, which contains only 6-coordinate Al, is easily distinguished from andalusite (5- & 6-coordinate Al) and sillimanite (4- & 6-coordinate Al). At the Al K-edge even the latter two samples exhibit differences; with careful processing, the fingerprint for 4-, 5- and 6-coordinate aluminium may be obtained.

The Use of ELNES for Microanalysis

1999 ◽  
Vol 5 (S2) ◽  
pp. 664-665
Author(s):  
A.J. Craven ◽  
M. MacKenzie
Keyword(s):  
Electron Microscopy ◽  
Energy Loss ◽  
Electron Energy ◽  
Analytical Electron Microscopy ◽  
Local Environment ◽  
Edge Structure ◽  
Similar Shape ◽  
Analytical Electron ◽  
Electron Energy Loss ◽  
Combining Information

The performance of many materials systems depends on our ability to control the distribution of atoms on a nanometre or sub-nanometre scale within those systems. This is as true for steels as it is for semiconductors. A key requirement for improving their performance is the ability to determine the distribution of the elements resulting from processing the material under a given set of conditions. Analytical electron microscopy (AEM) provides a range of powerful techniques with which to investigate this distribution. By combining information from different techniques, many of the ambiguities of interpretation of the data from an individual technique can be eliminated. The electron energy loss near edge structure (ELNES) present on an ionisation edge in the electron energy loss spectrum reflects the local structural and chemical environments in which the particular atomic species occurs. Thus it is a useful contribution to the information available. Since a similar local environment frequently results in a similar shape, ELNES is useful as a “fingerprint”.

Electron energy loss near edge structure

1989 ◽  
Vol 47 ◽  
pp. 384-385
Author(s):  
Xudong Weng ◽  
Peter Rez
Keyword(s):  
Solid State ◽  
Energy Loss ◽  
Electron Energy ◽  
Golden Rule ◽  
Scattering Method ◽  
Edge Structure ◽  
Densities Of States ◽  
Dipole Selection Rule ◽  
Multiple Scattering Method ◽  
Electron Energy Loss

In inner shell absorption spectroscopy, the near edge structure (NES) up to 30 eV above threshold is a prominent solid state effect. It is well known that electron energy loss spectroscopy is advantageous for the study of light elements, like carbon, nitrogen, oxygen, and fluorine. Due to the complexity of the near edge region, it is only recently that a significant amount of research have been carried out to extract information on the solid state effects.The theory to interpret the near edge structure is based on Fermi’s Golden rule. Two methods have been derived which give different and complimentary physical pictures about the inner shell excitation process. Single electron band structure techniques have been successfully applied to the interpretation of x-ray near edge structure. using the projected densities of states (DOS) of L±1 characterpermitted by the dipole selection rule. The multiple scattering method views the near edge structure (XANES) [2.3] as coming from the interference between the outgoing ejected electron wave and renections from neighboring atoms.

Combined ab-initio and N-K, Ti-L2,3, V-L2,3 electron energy-loss near edge structure studies for TiN and VN films

2007 ◽  
Vol 98 (11) ◽  
pp. 1060-1065 ◽  
Author(s):  
Boriana Rashkova ◽  
Petr Lazar ◽  
Josef Redinger ◽  
Raimund Podloucky ◽  
Gerald Kothleitner ◽  
...  
Keyword(s):  
Energy Loss ◽  
Ab Initio ◽  
Electron Energy ◽  
Edge Structure ◽  
Electron Energy Loss

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.

scholarly journals Electron Energy-Loss Near-Edge Structure of Metal-Alumina Interfaces

1995 ◽  
Vol 6 (1) ◽  
pp. 19-31 ◽  
Author(s):  
Christina Scheu ◽  
Gerhard Dehm ◽  
Harald Müllejans ◽  
Rik Brydson ◽  
Manfred Rühle
Keyword(s):  
Energy Loss ◽  
Electron Energy ◽  
Edge Structure ◽  
Structure Of Metal ◽  
Electron Energy Loss

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.

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