Phase Identification and Mapping Based on Valence Loss EELS and ELNES

2009 ◽  
Vol 17 (3) ◽  
pp. 16-19
Author(s):  
R.D. Twesten
Keyword(s):  
Electronic Structure ◽  
Energy Loss ◽  
Elemental Composition ◽  
Elemental Analysis ◽  
Core Loss ◽  
Core Shell ◽  
Phase Identification ◽  
X Ray ◽  
Response Information ◽  
Electron Energy Loss

Much of analytical TEM is based on elemental analysis of core-shell ionizations and their role in electron energy-loss spectroscopy (EELS) and energy-dispersive X-ray spectroscopy (EDS). In these techniques, integrals of the primary or secondary ionization signals (typically over many tens of eV in energy) are used to measure and map the elemental composition of probed sample areas.In contrast, present-day STEM EELS systems are able to reveal spectral details with resolution in the range 0.1-1.0 eV. This means that EELS provides access to electronic structure and response information that goes beyond the simple elemental composition information of the integrated core-loss signals.

Signal/Noise Ratio and Elemental Detectivity by Eels

1982 ◽  
Vol 40 ◽  
pp. 488-489
Author(s):  
R. F. Egerton
Keyword(s):  
Energy Loss ◽  
Electron Energy ◽  
Elemental Analysis ◽  
Electron Energy Loss Spectroscopy ◽  
Emission Spectroscopy ◽  
X Ray ◽  
Signal Noise ◽  
Characteristic Signal ◽  
Noise Ratio ◽  
Electron Energy Loss

An important parameter governing the sensitivity and accuracy of elemental analysis by electron energy-loss spectroscopy (EELS) or by X-ray emission spectroscopy is the signal/noise ratio of the characteristic signal.

Effects of bond character on the electronic structure of brownmillerite-phase oxides, Ca2B′xFe2−xO5 (B′ = Al, Ga): an X-ray absorption and electron energy loss spectroscopic study

2009 ◽  
Vol 19 (48) ◽  
pp. 9213 ◽  
Author(s):  
Andrew P. Grosvenor ◽  
Farshid Ramezanipour ◽  
Shahab Derakhshan ◽  
Christian Maunders ◽  
Gianluigi A. Botton ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Energy Loss ◽  
Spectroscopic Study ◽  
Electron Energy ◽  
X Ray ◽  
Electron Energy Loss ◽  
X Ray Absorption ◽  
Bond Character

Theory of Electron Energy Loss Spectroscopy and its Application to Threading Edge Dislocations in GaN

2001 ◽  
Vol 693 ◽  
Author(s):  
C. J. Fall ◽  
R. Jones ◽  
P. R. Briddon ◽  
A. T. Blumenau ◽  
T. Frauenheim ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Energy Loss ◽  
Electron Energy ◽  
Electron Energy Loss Spectroscopy ◽  
Core Loss ◽  
Extended Defects ◽  
Low Loss ◽  
Defect Accumulation ◽  
Edge Dislocations ◽  
Electron Energy Loss

AbstractThe electronic structure of dislocations in GaN is controversial. Several experimental techniques such as carrier mobility studies and cathodoluminescence experiments have indicated that dislocations are charged while theoretical studies point to intrinsic states and/or point defect accumulation along the core as a source of electrical activity. Electron Energy Loss Spectroscopy (EELS) studies have the ability to probe the electronic structure of extended defects. Here we report rst principles calculations of the EELS spectrum applied to edge dislocations in GaN. It is found that the electrostatic potential at N atoms in the vicinity of the dislocation varies by the order of a volt and casts doubt on any simple interpretation of core loss spectroscopy. On the other hand, low loss spectroscopy leads directly to detailed information about any gap states. The low loss spectrum obtained by the theory is in good agreement with recent experimental work and indicates that threading dislocations in p-type GaN possess acceptor levels in the upper half of the gap.

Electron energy-loss and soft X-ray emission spectroscopy of electronic structure of MgB4

2017 ◽  
Vol 253 ◽  
pp. 58-62
Author(s):  
Yohei Sato ◽  
Taiki Saito ◽  
Kohei Tsuchiya ◽  
Masami Terauchi ◽  
Hiroki Saito ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Energy Loss ◽  
Electron Energy ◽  
Emission Spectroscopy ◽  
X Ray ◽  
Electron Energy Loss

A simple parameterization scheme for inner-shell cross sections

1988 ◽  
Vol 46 ◽  
pp. 532-533
Author(s):  
R.F. Egerton
Keyword(s):  
Solid State ◽  
Energy Loss ◽  
Cross Section ◽  
Cross Sections ◽  
Elemental Analysis ◽  
Incident Energy ◽  
Core Loss ◽  
Dipole Oscillator ◽  
Electron Energy Loss ◽  
Hand Calculator

Quantitative elemental analysis by electron energy-loss spectroscopy requires values of core-loss cross section σ(β,Δ) integrated up to a scattering angle β and over an energy range Δ above the ionization threshold. Such cross sections can be calculated using atomic models [1-3], neglecting solid-state effects. They can also be determined experimentally [4,5], but only for particular values of β,Δ and incident energy E0. By representing σ(β,Δ) in terms of an integrated dipole oscillator strength f(Δ) which is independent of β and E0, we realize two advantages: (1) measurements on solids can be directly compared with one another and with theory, and (2) values of σ(β,Δ) for K, L and M edges can be derived from tabulated values of f(Δ) by use of a hand calculator or a very short computer program.

Elemental Analysis of thin Films Using Inner Shell Electron Energy Losses

1976 ◽  
Vol 34 ◽  
pp. 414-415
Author(s):  
D. E. Johnson ◽  
M. Isaacson
Keyword(s):  
Thin Films ◽  
Energy Loss ◽  
Electron Energy ◽  
Elemental Analysis ◽  
Large Fraction ◽  
Fluorescence Yield ◽  
Detection Sensitivity ◽  
X Rays ◽  
X Ray ◽  
Electron Energy Loss

The use of electron energy loss spectroscopy (ELS) for elemental analysis of thin films holds considerable promise. This technique has definite advantages in comparison with energy dispersive X-ray spectroscopy (EDS) for two fundamental reasons. First, the detection sensitivity is independent of the fluorescence yield, since for each inner shell excitation an energy loss electron exists as opposed to only a finite probability that an excitation will result in a X-ray emitted. Second, the information carrying energy loss electrons are contained in a small solid angle about 0° scattering angle as opposed to the resulting X-rays which are emitted uniformly over 4Π steradians. This means that a large fraction of the energy loss electrons can be detected (up to ∼90%) compared to only a small fraction (∼1%) of the emitted X-rays with an EDS system.

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