The Thickness Dependence of Energy Loss Spectra

1982 ◽  
Vol 40 ◽  
pp. 486-487
Author(s):  
M. Sarikaya ◽  
P. Rez
Keyword(s):  
Energy Loss ◽  
Multiple Scattering ◽  
Core Loss ◽  
Single Scattering ◽  
Low Loss ◽  
High Loss ◽  
Loss Analysis ◽  
Scattering Spectrum ◽  
Exact Procedure ◽  
Quantitative Analyses

One factor limiting energy loss analysis is the effect of multiple scattering on core loss edge shapes. Multiple scattering distorts fine structures, leads to incorrect quantitative analyses and even affects analysis of extended fine structure (EXELFS). Two procedures for extracting the single scattering spectrum from a spectrum showing the effects of multiple scattering have been proposed. Johnson and Spence derive the single scattering profile by taking the logarithm of the fourier transformed spectrum. If all scattering angles are accepted by the spectrometer this is an exact procedure. Leapman and Swyt have had some success assuming that multiple scattering imposes low loss structure on the high loss part of the spectrum. It is of interest to know how stable these procedures are with thickness and whether the logarithmic deconvolution can be used in thicker specimens than the method described by Leapman and Swyt.

Background Fitting in the Low-Loss Region of Electron Energy Loss Spectra

1990 ◽  
Vol 48 (2) ◽  
pp. 56-57
Author(s):  
C P Scott ◽  
A J Craven ◽  
C J Gilmore ◽  
A W Bowen
Keyword(s):  
Energy Loss ◽  
Multiple Scattering ◽  
Simple Form ◽  
Single Scattering ◽  
Low Loss ◽  
Characteristic Energy ◽  
Normal Method ◽  
Fitting In ◽  
Electron Energy Loss ◽  
Electron Energy Loss Spectra

The normal method of background subtraction in quantitative EELS analysis involves fitting an expression of the form I=AE-r to an energy window preceding the edge of interest; E is energy loss, A and r are fitting parameters. The calculated fit is then extrapolated under the edge, allowing the required signal to be extracted. In the case where the characteristic energy loss is small (E < 100eV), the background does not approximate to this simple form. One cause of this is multiple scattering. Even if the effects of multiple scattering are removed by deconvolution, it is not clear that the background from the recovered single scattering distribution follows this simple form, and, in any case, deconvolution can introduce artefacts.The above difficulties are particularly severe in the case of Al-Li alloys, where the Li K edge at ~52eV overlaps the Al L2,3 edge at ~72eV, and sharp plasmon peaks occur at intervals of ~15eV in the low loss region. An alternative background fitting technique, based on the work of Zanchi et al, has been tested on spectra taken from pure Al films, with a view to extending the analysis to Al-Li alloys.

A Practical Method for Removing Plural Scattering from Core Edges in EELS

1981 ◽  
Vol 39 ◽  
pp. 196-197
Author(s):  
R.D. Leapman ◽  
C.R. Swyt
Keyword(s):  
Core Loss ◽  
Practical Method ◽  
Electron Excitation ◽  
Single Scattering ◽  
Low Loss ◽  
High Loss ◽  
The Core ◽  
Electron Energy Loss ◽  
Electron Excitations ◽  
Electron Energy Loss Spectra

Core edges in electron energy loss spectra are generally complicated by thickness effects involving plural inelastic scattering. The fine structure can be modified and errors can be caused in quantitation based on measured edge intensities. Sometimes plural scattering can confuse even identification of elements. In this paper we describe a practical method for eliminating these difficulties.We derive the single scattering distribution, assuming valence electron excitation is small in the core loss region, a reasonable approximation for edges above 100 or 200 eV and for thicknesses of a few hundred Å. We can then separate the spectrum into a “high loss” region H(E) consisting of core edges (less background) and a “low loss” region L(E) containing the zero loss peak, plasmons and one-electron excitations.

scholarly journals Energy loss separation in NiFeMo compacts with smoothed powders according to Landgraf’s and Bertotti’s theories

2021 ◽  
Author(s):  
Denisa Olekšáková ◽  
Peter Kollár ◽  
Miloš Jakubčin ◽  
Ján Füzer ◽  
Martin Tkáč ◽  
...  
Keyword(s):  
Energy Loss ◽  
Mechanical Treatment ◽  
Positive Impact ◽  
Core Loss ◽  
Low Frequency ◽  
Treatment Method ◽  
Effective Dimension ◽  
Loss Analysis ◽  
Innovative Method ◽  
Individual Particles

AbstractThis submitted paper presents the detailed description of the energy loss separation for dc and ac low-frequency magnetic fields of NiFeMo (supermalloy) compacted powder prepared by innovative method of smoothing the surfaces of individual particles. The positive impact of mechanical treatment method on domain wall displacement is explained on the basis of Landgraf approach for dc loss analysis, and the effective dimension for eddy current in ac magnetic field is explained according to Bertotti approach for core loss analysis.

Empirical Identification of Uranium Oxides and Fluorides Using Electron Energy-loss Spectroscopy in the Transmission Electron Microscope

1999 ◽  
Vol 5 (6) ◽  
pp. 437-444 ◽  
Author(s):  
Stephen B. Rice ◽  
Hazel H. Bales ◽  
John R. Roth ◽  
Allen L. Whiteside
Keyword(s):  
Energy Loss ◽  
Electron Energy ◽  
Electron Energy Loss Spectroscopy ◽  
Contaminated Soils ◽  
Core Loss ◽  
Uranium Oxides ◽  
Low Loss ◽  
Electron Dose ◽  
Core Losses ◽  
Electron Energy Loss

Abstract: A set of uranium compound particles relevant to contaminated soils and other environmental concerns surrounding uranium bioavailability were studied by electron energy-loss spectroscopy (EELS). Core-loss EELS results suggest that uranium 4+ compounds have an energy loss resolvable from 6+ compounds. Shoulders on the uranium O4,5 edge further distinguish UO2 from UF4. Low-loss characteristics distinguish carbon-free uranium oxide specimens on holey substrates. In the presence of carbon, correction techniques must be applied. Uranium oxides, fluorides, and minerals show a tendency toward reduction of uranium toward 4+ under the beam. The electron dose required to achieve the transformation from 6+ to 4+ is more severe than that usually required to obtain satisfactory spectra, but the possibility for reduction should be considered. The conditions for low-loss analysis need not be as vigorous as those for core losses, and can be done without altering the valence of most oxides.

Image-Spectroscopy: New Developments and Applications

1999 ◽  
Vol 5 (S2) ◽  
pp. 618-619 ◽  
Author(s):  
P.J. Thomas ◽  
P.A. Midgley
Keyword(s):  
Spectroscopic Analysis ◽  
Core Loss ◽  
Compositional Analysis ◽  
Single Scattering ◽  
Electron Spectroscopic Imaging ◽  
Low Loss ◽  
Step Size ◽  
New Developments ◽  
Analysis Techniques ◽  
Image Spectroscopy

The ability of modern TEMs to acquire a series of energy filtered images opens up new possibilities in energy loss compositional analysis. In particular, an electron spectroscopic imaging (ESI) series may be treated as a 2-D array of spectra whose resolution is dictated by the step size of the image series, as illustrated in Fig (a). This allows standard spectroscopic analysis techniques to be used on the extracted ‘image-spectra’, such as the removal of plural scattering by deconvolution. Examples of this are given in Fig (b) and (c), which show how Fourier-log and Fourier-ratio deconvolution can be used to recover the single scattering distribution (SSD) from both the low-loss and core-loss regions from a Cr specimen. A pure elemental sample is ideal for testing the validity of such analysis techniques for quantitative compositional mapping, and more details of this method will be published elsewhere. Further, for many simple metal systems, such as steels and alloys, and for simple semiconductors it is possible to model the plasmon contribution using a simple Drude-Lorentz model.

Highly Automated Electron Energy-Loss Spectroscopy Elemental Quantification

2014 ◽  
Vol 20 (3) ◽  
pp. 798-806 ◽  
Author(s):  
Raman D. Narayan ◽  
J. K. Weiss ◽  
Peter Rez
Keyword(s):  
User Interface ◽  
Energy Loss ◽  
Electron Energy ◽  
Electron Energy Loss Spectroscopy ◽  
Single Scattering ◽  
Ease Of Use ◽  
Low Loss ◽  
Wide Range ◽  
Fitting Algorithm ◽  
Electron Energy Loss

AbstractA model-based fitting algorithm for electron energy-loss spectroscopy spectra is introduced, along with an intuitive user-interface. As with Verbeeck & Van Aert, the measured spectrum, rather than the single scattering distribution, is fit over a wide range. An approximation is developed that allows for accurate modeling while maintaining linearity in the parameters that represent elemental composition. Also, a method is given for generating a model for the low-loss background that incorporates plural scattering. Operation of the user-interface is described to demonstrate the ease of use that allows even nonexpert users to quickly obtain elemental analysis results.

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.

Probing the Chemical Structure in Diamond-Based Materials Using Combined Low-Loss and Core-Loss Electron Energy-Loss spectroscopy

2014 ◽  
Vol 20 (3) ◽  
pp. 779-783 ◽  
Author(s):  
Paolo Longo ◽  
Ray D. Twesten ◽  
Jaco Olivier
Keyword(s):  
Energy Loss ◽  
Electron Energy ◽  
Electron Energy Loss Spectroscopy ◽  
Core Loss ◽  
Amorphous Region ◽  
Low Loss ◽  
Plasmon Energy ◽  
Carbon Structure ◽  
Experimental Conditions ◽  
Electron Energy Loss

AbstractWe report the analysis of the changes in local carbon structure and chemistry caused by the self-implantation of carbon into diamond via electron energy-loss spectroscopy (EELS) plasmon energy shifts and core-edge fine structure fingerprinting. These two very different EELS energy and intensity ranges of the spectrum can be acquired under identical experimental conditions and nearly simultaneously using specially designed deflectors and energy offset devices known as “DualEELS.” In this way, it is possible to take full advantage of the unique and complementary information that is present in the low- and core-loss regions of the EELS spectrum. We find that self-implanted carbon under the implantation conditions used for the material investigated in this paper creates an amorphous region with significant sp2 content that varies across the interface.

scholarly journals Elemental Mapping of Labeled Biological Specimens at Intermediate Energy Loss in an Energy-Filtered TEM acquired using a Direct Detection Device

2020 ◽  
Author(s):  
Ranjan Ramachandra ◽  
Mason R. Mackey ◽  
Junru Hu ◽  
Steven T. Peltier ◽  
Nguyen-Huu Xuong ◽  
...  
Keyword(s):  
Energy Loss ◽  
Lower Energy ◽  
Direct Detection ◽  
Core Loss ◽  
Intermediate Energy ◽  
High Signal ◽  
Experimental Conditions ◽  
High Loss ◽  
The Core ◽  
Elemental Maps

ABSTRACTThe multi-color or single-color EM that was developed previously, by the pseudo-colored overlay of the core-loss or high-loss EFTEM elemental map/s of the lanthanide onto the conventional image, the lanthanide chelates conjugated to diaminobenzidine being sequentially deposited as a result of selective oxidization by orthogonal photosensitizers / peroxidases. The synthesis of the new second generation lanthanide DABs, which contains 4 times more lanthanide per DAB, gives significant signal amplification and enabling collection of elemental maps at much lower energy-loss regions more favorable. Under the same experimental conditions, acquiring EFTEM elemental maps for the lanthanides at the lower energy-loss of N4,5 edge instead of the core-loss M4,5 edge, provides ~4x increase in signal-to-noise and ~2x increase in resolution. The higher signal at the N4,5 edge, also allows for more sophisticated technique of EFTEM spectrum Image for the acquisition of elemental maps with very high signal fidelity.

Retrieval of the single loss spectrum with Johnson-Spence method

1986 ◽  
Vol 44 ◽  
pp. 720-721
Author(s):  
Xudong Weng
Keyword(s):  
Energy Loss ◽  
Cross Sections ◽  
Additional Assumption ◽  
Relaxation Times ◽  
Single Scattering ◽  
Energy Gain ◽  
Low Loss ◽  
Multiple Data ◽  
Pass Through ◽  
Electron Energy Loss

A method using fourier transform and logarithm for the retrieval of the single scattering electron energy loss spectrum from the experimental multiple data has been described and used previously. However, the uniqueness of this method is proved only under an additional assumption that no energy gain processes occur as the incident electron pass through the specimen. This proof is adopted in the later review papers. In this paper we prove the uniqueness without such an assumption, although in comparison with the energy loss processes, the energy gain processes usually have negligible differential cross sections, provided the relaxation times for the excitation inside the specimen are short enough with respect to the amount of energy loss. Also we shall compare deconvolution methods for the low loss region.

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