Applications of Electron Energy Loss Spectroscopy in Materials Science

1980 ◽  
Vol 38 ◽  
pp. 86-89
Author(s):  
Ondrej L. Krivanek
Keyword(s):  
Energy Loss ◽  
Electron Energy ◽  
Energy Resolution ◽  
Materials Science ◽  
Magnetic Shielding ◽  
Dark Count ◽  
Object Plane ◽  
Electron Energy Loss Spectrometer ◽  
Electron Energy Loss ◽  
Loss Range

The electron energy loss spectrometer developed at Berkeley differs from most other ones in four ways: 1) it uses the projector lens crossover as the spectrometer entrance object plane, 2) its magnet is asymmetric so that the entrance object is de-magnified about 5x, 3) it counts electrons admitted through the energy-selecting slit singly at rates up to 20MHz while adding zero dark count, and 4) it fits neatly at the back of the available leg space of the electron microscope, and requires no substantial alterations to the microscope. The energy resolution attainable routinely at any primary voltage is 3eV over an energy loss range 0 to 1keV, as illustrated by resolving the π* transition on the K-edge of amorphous carbon (Fig. 1). The 3 eV limit comes mainly from 120Hz stray magnetic fields (the 60Hz component has been compensated out). Fast scanning of the spectrum improves the resolution to 1eV (Fig. 2). This indicates that with proper magnetic shielding of the electron flight path, especially in the microscope viewing chamber which is made out of brass, the energy resolution attainable with the spectrometer will be limited only by the energy spread of the primary beam.

A New High Performance Electron Energy Loss Spectrometer for use with Monochromated Microscopes

2001 ◽  
Vol 7 (S2) ◽  
pp. 908-909
Author(s):  
H.A. Brink ◽  
M. Barfels ◽  
B. Edwards ◽  
P. Burgner
Keyword(s):  
Energy Loss ◽  
Electron Energy ◽  
Energy Resolution ◽  
Optical Design ◽  
Electron Source ◽  
High Voltage Power Supply ◽  
Electron Energy Loss Spectrometer ◽  
Electron Microscopes ◽  
Electron Energy Loss ◽  
Better Than

A new type of electron energy loss spectrometer for use with monochromated microscopes is presented. The energy resolution of the spectrometer is better than 0.100 eV. A completely new electron optical design with a number of extra optical elements and advanced tuning software makes it possible to correct spectrum aberrations to 4th order, which increases sensitivity and collection angles. New high-stability electronics make it possible to maintain energy resolution over a period of several minutes in a practical laboratory environment.The energy resolution of Transmission Electron Microscopes (TEMs) equipped with electron energy loss spectrometers is determined by a combination of the energy spread of the electron source, the stability of the microscope’s high voltage power supply, and the energy resolution of the spectrometer. Commercial microscopes usually employ electron sources with an energy distributions of around 0.5 eV or more (FWHM), limiting the energy ultimate energy resolution that can be achieved. Recently FEI constructed a special 200 kV TEM with a built-in monochromator which makes it possible to monochromize the electron source to better than 0.100 eV. A prototype of the presented spectrometer has been installed on this microscope.

Element analysis with the imaging electron energy loss spectrometer of the zeiss EM 902

1986 ◽  
Vol 44 ◽  
pp. 600-601
Author(s):  
J. Bihr ◽  
A. Rilk ◽  
W.I. Miller
Keyword(s):  
Energy Loss ◽  
Electron Energy ◽  
Electron Spectroscopic Imaging ◽  
Element Analysis ◽  
X Ray ◽  
Electron Energy Loss Spectrometer ◽  
Elemental Maps ◽  
Electron Energy Loss ◽  
Electron Energy Loss Spectra ◽  
Loss Range

An imaging electron energy loss spectrometer can be used to produce elemental maps with highest spatial resolution by Electron Spectroscopic Imaging (ESI). Simultaneously, electron energy loss spectra (EELS) can also be recorded. It is therefore simple to combine morphological examinations with the analytical method of electron energy loss spetroscopy (Figs. 2, 3)The electron energy loss spectrometer of the EM 902, used in combination with a suitable electron detector (Fig. 1), provides the possibility of recording electron energy loss spectra over an energy loss range from 0 to 2000 eV. In this way, all elements of the periodic system can be detected via their K, L, M, N or O absorption edges (Fig. 5). Unlike X-ray microanalysis, this technique is especially suitable for detecting light and medium-heavy elements which are of special significance in biological and medical research.

Trends in Electron Energy Loss Spectroscopy

1977 ◽  
Vol 35 ◽  
pp. 228-229
Author(s):  
C. Colliex ◽  
P. Trebbia
Keyword(s):  
Energy Loss ◽  
Electron Energy ◽  
Electron Energy Loss Spectroscopy ◽  
Materials Science ◽  
Analytical Technique ◽  
Recent Developments ◽  
Quantitative Results ◽  
Electron Microscopes ◽  
Electron Energy Loss ◽  
Primary Electrons

The physical foundations for the use of electron energy loss spectroscopy towards analytical purposes, seem now rather well established and have been extensively discussed through recent publications. In this brief review we intend only to mention most recent developments in this field, which became available to our knowledge. We derive also some lines of discussion to define more clearly the limits of this analytical technique in materials science problems.The spectral information carried in both low ( 0<ΔE<100eV ) and high ( >100eV ) energy regions of the loss spectrum, is capable to provide quantitative results. Spectrometers have therefore been designed to work with all kinds of electron microscopes and to cover large energy ranges for the detection of inelastically scattered electrons (for instance the L-edge of molybdenum at 2500eV has been measured by van Zuylen with primary electrons of 80 kV). It is rather easy to fix a post-specimen magnetic optics on a STEM, but Crewe has recently underlined that great care should be devoted to optimize the collecting power and the energy resolution of the whole system.

Parallel Detection of Electron Energy Loss Spectra in Direct Mode

1990 ◽  
Vol 48 (2) ◽  
pp. 82-83
Author(s):  
Eckhard Quandt ◽  
Stephan laBarré ◽  
Andreas Hartmann ◽  
Heinz Niedrig
Keyword(s):  
Energy Loss ◽  
Electron Energy ◽  
Energy Resolution ◽  
Large Angle ◽  
Maximum Energy ◽  
Semiconductor Detectors ◽  
Parallel Detection ◽  
Photodiode Arrays ◽  
Electron Energy Loss ◽  
Electron Energy Loss Spectra

Due to the development of semiconductor detectors with high spatial resolution -- e.g. charge coupled devices (CCDs) or photodiode arrays (PDAs) -- the parallel detection of electron energy loss spectra (EELS) has become an important alternative to serial registration. Using parallel detection for recording of energy spectroscopic large angle convergent beam patterns (LACBPs) special selected scattering vectors and small detection apertures lead to very low intensities. Therefore the very sensitive direct irradiation of a cooled linear PDA instead of the common combination of scintillator, fibre optic, and semiconductor has been investigated. In order to obtain a sufficient energy resolution the spectra are optionally magnified by a quadrupole-lens system.The detector used is a Hamamatsu S2304-512Q linear PDA with 512 diodes and removed quartz-glas window. The sensor size is 13 μm ∗ 2.5 mm with an element spacing of 25 μm. Along with the dispersion of 3.5 μm/eV at 40 keV the maximum energy resolution is limited to about 7 eV, so that a magnification system should be attached for experiments requiring a better resolution.

Stopping-power determination for compound by EELS

1994 ◽  
Vol 52 ◽  
pp. 948-949 ◽  
Author(s):  
David C. Joy ◽  
Suichu Luo ◽  
John R. Dunlap ◽  
Dick Williams ◽  
Siqi Cao
Keyword(s):  
Energy Loss ◽  
Electron Energy ◽  
Electron Energy Loss Spectroscopy ◽  
Materials Science ◽  
Average Energy ◽  
Stopping Power ◽  
Accurate Information ◽  
Power Calculation ◽  
Coulomb Collisions ◽  
Electron Energy Loss

In Physics, Chemistry, Materials Science, Biology and Medicine, it is very important to have accurate information about the stopping power of various media for electrons, that is the average energy loss per unit pathlength due to inelastic Coulomb collisions with atomic electrons of the specimen along their trajectories. Techniques such as photoemission spectroscopy, Auger electron spectroscopy, and electron energy loss spectroscopy have been used in the measurements of electron-solid interaction. In this paper we present a comprehensive technique which combines experimental and theoretical work to determine the electron stopping power for various materials by electron energy loss spectroscopy (EELS ). As an example, we measured stopping power for Si, C, and their compound SiC. The method, results and discussion are described briefly as below.The stopping power calculation is based on the modified Bethe formula at low energy:where Neff and Ieff are the effective values of the mean ionization potential, and the number of electrons participating in the process respectively. Neff and Ieff can be obtained from the sum rule relations as we discussed before3 using the energy loss function Im(−1/ε).

The Influence of Specimen Thickness in Quantitative Electron Energy Loss Spectroscopy

1980 ◽  
Vol 38 ◽  
pp. 112-113
Author(s):  
Nestor J. Zaluzec
Keyword(s):  
Quantitative Analysis ◽  
Adverse Effects ◽  
Energy Loss ◽  
Electron Energy ◽  
Electron Energy Loss Spectroscopy ◽  
Materials Science ◽  
Light Element ◽  
Specimen Thickness ◽  
Element Analysis ◽  
Electron Energy Loss

The application of electron energy loss spectroscopy (EELS) to light element analysis is rapidly becoming an important aspect of the microcharacterization of solids in materials science, however relatively stringent requirements exist on the specimen thickness under which one can obtain EELS data due to the adverse effects of multiple inelastic scattering.1,2 This study was initiated to determine the limitations on quantitative analysis of EELS data due to specimen thickness.

Using Electron Energy-Loss Spectroscopy (EELS) To Study Rare Earth Elements In Natural Crystals

2000 ◽  
Vol 6 (S2) ◽  
pp. 206-207
Author(s):  
Huifang Xu
Keyword(s):  
Rare Earth ◽  
Energy Loss ◽  
Rare Earth Elements ◽  
Electron Energy ◽  
Energy Resolution ◽  
Electron Energy Loss Spectroscopy ◽  
Relative Concentration ◽  
Chemical Properties ◽  
Similar Chemical ◽  
Electron Energy Loss

Because of similar chemical properties of the rare earth elements (Ree), whole series of the Ree may occur in natural Ree-bearing crystals. Relative concentration of the Ree may vary as the crystallization environments change. Electron energy-dispersive spectroscopy (EDS) associated with TEM is unable to resolve Ree and other coexistence elements, such as Ba nd Ti, because of peak overlap and energy resolution (∼ 150 eV) of EDS. Figure A indicate multiple peaks from Ce only. The Cu peaks are from Cu grid holding the specimen. Electron energy-loss spectroscopy (EELS) with energy resolution of < 1 eV is able to resolve all Ree in natural Ree-bearing crystals.Natural carbonate crystals from a Ree ore deposit were investigated by using EELS associated with field emission-gun (FEG) TEM. The crystals are in a chemical series of BaCO3 - Ree(CO3)F [1]. In Figure B, EEL spectra A and B are from Ce-rich and La-rich bastnaesite (Ree(CO3)F), respectively; spectrum D is from cordylite (BaCO3 (Ree(CO3)F); spectrum E is from huanghoite (BaCO3 Ree(CO3)F), spectrum F is from BaCO3; spectrum C is from an unknown Ree-rich phase.

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