The Detection of Transmitted Energy Loss Electrons for Elemental Analysis

1975 ◽  
Vol 33 ◽  
pp. 236-237
Author(s):  
D. E. Johnson ◽  
M. Isaacson
Keyword(s):  
Energy Loss ◽  
Elemental Analysis ◽  
Detection Efficiency ◽  
Collection Efficiency ◽  
Incident Beam ◽  
Light Elements ◽  
Beam Direction ◽  
X Ray ◽  
Transmitted Energy

Elemental analysis by means of energy loss electrons transmitted through thin specimens has the potential of being a very useful technique for the microanalysis of light elements (e.g. 1-5). The advantages of the energy loss technique over x-ray detection have been discussed in detail in ref. 1. They are basically, the lack of dependence of the detection efficiency on the fluorescent yield (which decreases rapidly with decreasing Z) and the possibility of increased collection efficiency of the energy loss electrons (which are concentrated at relatively small angles with respect to the incident beam direction).

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.

A Total reflection X-Ray Spectrograph for Fluorescent Analysis of Light Elements

1968 ◽  
Vol 12 ◽  
pp. 496-505 ◽  
Author(s):  
R. D. Davies ◽  
H. K. Herglotz
Keyword(s):  
Critical Angle ◽  
Incident Angle ◽  
Incident Beam ◽  
Wavelength Dependence ◽  
Light Elements ◽  
X Ray ◽  
Beam Incident ◽  
Open Window ◽  
Angle Of Reflection ◽  
Initial Results

AbstractA novel x-ray spectrograph for the analysis of light elements has been developed based on previous computations and confirming experiments by one of as (H. K. Herglotz). The major components of the instrument are an efficient fluorescent source, a totally reflecting mirror, and an open window photomultiplier. Identification of wavelengths in the range 15 < λ < 80 Å is achieved by the wavelength dependence of the critical angle of reflection of an x-ray beam incident on a suitably chosen low absorption reflector. As the incident angle is increased through the critical angle for a particular wavelength, the reflected beam intensity is sharply reduced; hence, a periodic vibration of the incident beam through a small angular range about the critical angle furnishes a strong a.c. reflected signal characteristic of one narrow wavelength band only.Initial results promise a simple, easy-to-operate instrument for the routine analysis of elements boron to fluorine.

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.

scholarly journals X-ray position-sensitive duo-lateral diamond detectors at SOLEIL

2018 ◽  
Vol 25 (2) ◽  
pp. 399-406 ◽  
Author(s):  
Kewin Desjardins ◽  
Michel Bordessoule ◽  
Michal Pomorski
Keyword(s):  
Collection Efficiency ◽  
Chemical Vapour ◽  
Incident Beam ◽  
Acquisition Time ◽  
Experimental Conditions ◽  
Beam Position ◽  
Charge Collection Efficiency ◽  
Position Resolution ◽  
X Ray ◽  
Position Sensitive

The performance of a diamond X-ray beam position monitor is reported. This detector consists of an ionization solid-state chamber based on a thin single-crystal chemical-vapour-deposition diamond with position-sensitive resistive electrodes in a duo-lateral configuration. The detector's linearity, homogeneity and responsivity were studied on beamlines at Synchrotron SOLEIL with various beam sizes, intensities and energies. These measurements demonstrate the large and homogeneous (absorption variation of less than 0.7% over 500 µm × 500 µm) active area of the detector, with linear responses independent of the X-ray beam spatial distribution. Due to the excellent charge collection efficiency (approaching 100%) and intensity sensitivity (0.05%), the detector allows monitoring of the incident beam flux precisely. In addition, the in-beam position resolution was compared with a theoretical analysis providing an estimation of the detector's beam position resolution capability depending on the experimental conditions (X-ray flux, energy and readout acquisition time).

The Combined Effect of Channelling and Blocking in Electron Energy Loss Spectroscopy

1981 ◽  
Vol 39 ◽  
pp. 190-191
Author(s):  
J. Taftø ◽  
O. L. Krivanek
Keyword(s):  
Energy Loss ◽  
Electron Energy ◽  
Bragg Reflection ◽  
Incident Beam ◽  
Orientation Dependence ◽  
Planar Case ◽  
X Ray ◽  
Crystal Unit Cell ◽  
Electron Energy Loss ◽  
Electron Energy Loss Spectra

Bragg reflection of electrons gives rise to a modulation of the wavefield over the crystal unit cell. Depending on the incident beam direction the electrons may be concentrated at one or another type of atoms or between them. Localized ionization processes will therefore show an orientation dependence, and this will affect the X-ray emission intensities as well as electron energy loss spectra. The energy loss case gives more possibilities for experimental arrangements than the X-ray emission case, in that the direction of not only the incident electron beam, but also that of the exit beam to be analyzed may be selected.Natural MgAl2O4 spinel was studied. The crystals were ground in a mortar and thin areas were analyzed with a Gatan 607 spectrometer attached to a Philips 400T electron microscope operating at lOOkV. The experiments were done for the (400)-planar case where the main atomic planes contain Al2O4. The Mg-atoms are midway between the A12O4 and may be considered as interstitials in this planar case.

EELS Measurements of Carbon and Nitrogen in V(CN) Precipates from HSLA Steel

1981 ◽  
Vol 39 ◽  
pp. 276-277
Author(s):  
Anthony J. Garratt-Reed
Keyword(s):  
Energy Loss ◽  
Electron Energy Loss Spectroscopy ◽  
Analytical Method ◽  
Hsla Steel ◽  
Energy Dispersive ◽  
Light Elements ◽  
Initial Composition ◽  
X Ray ◽  
Carbon And Nitrogen ◽  
Electron Energy Loss

The technique of carbon extraction replication has enabled many workers to obtain useful data on the composition of a variety of precipitates in alloys. When the available analytical method (energy-dispersive X-ray spectroscopy) was limited to detect only those elements heavier than neon the presence in the specimen of the carbon of the replica was not objectionable. With the development of methods to analyze for light elements, such as electron energy-loss spectroscopy (EELS), or energy dispersive X-ray spectroscopy with an ultra-thin window detector occasions arise when analysis for carbon is indicated. In such cases carbon extraction replication is clearly inappropriate.In the present project it was required to study the precipitation of vanadium, presumed to be in the form of carbonitrides, in vanadium HSLA steel. Of particular interest was the ratio of carbon to nitrogen as a function of the specimen history and initial composition. Replicas were therefore made using aluminum.

Recent Developments in Txrf of Light Elements

1995 ◽  
Vol 39 ◽  
pp. 771-779 ◽  
Author(s):  
Christina Streli ◽  
V. Bauer ◽  
P. Wobrauschek
Keyword(s):  
Absorption Edge ◽  
Detection Efficiency ◽  
Fluorescence Analysis ◽  
Total Reflection ◽  
Low Energy ◽  
X Rays ◽  
Light Elements ◽  
Energy Dispersive Analysis ◽  
X Ray ◽  
Recent Developments

Total Reflection X-ray Fluorescence Analysis (TXRF) has been proved to be well suited for the energy dispersive analysis of light elements, as B, C, N, O, F, Na, Mg,.,. using a special spectrometer. It is equipped with a Ge(HP) detector offering a sufficient detection efficiency from 180 eV upwards. The obtainable detection limits especially of the light elements are mainly influenced by the excitation source, which should provide a large number of photons with an energy near the K-absorption edge of these elements (from 200 eV upwards). Commercially available X-ray tubes do not offer characteristic X-rays in that range. In former experiments a windowless X-ray tube was built to prevent the low energy X-rays from being attenuated in the Be window. Experiments have been performed using Cu as anode material.

Spatial Resolution of X-ray Analysis with Solid and Thin Specimens

1971 ◽  
Vol 29 ◽  
pp. 54-55 ◽  
Author(s):  
John C. Russ
Keyword(s):  
Spatial Resolution ◽  
Elemental Analysis ◽  
Secondary Electron ◽  
Incident Beam ◽  
Image Point ◽  
X Ray ◽  
Resolution Image ◽  
Solid Specimen ◽  
Transmission Electron ◽  
Electron Microscopes

The attachment of xray spectrometers, both wavelength and energy dispersive, to both scanning and transmission electron microscopes has provided the microscopist with the possibility of obtaining elemental analysis of features in the specimen that he can observe in the image. However, the volume of the specimen that emits xrays is in all cases larger than the image point he can observe in the highest resolution image with the microscope, and so he must use judgement to determine just how large a region is being analyzed.With a solid specimen in the SEM the situation is much like the conventional microprobe. Figure 1 shows the typical drop-shaped capture volume many times larger than the incident beam, and much deeper than the secondary electron source.

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