Development of a New Quantitative X-Ray Microanalysis Method for Electron Microscopy

2010 ◽  
Vol 16 (6) ◽  
pp. 821-830 ◽  
Author(s):  
Paula Horny ◽  
Eric Lifshin ◽  
Helen Campbell ◽  
Raynald Gauvin
Keyword(s):  
Field Emission ◽  
Beam Current ◽  
Physical Parameters ◽  
X Rays ◽  
Experimental Conditions ◽  
X Ray ◽  
Stable Regime ◽  
Transmission Electron ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes

AbstractQuantitative X-ray microanalysis of thick samples is usually performed by measuring the characteristic X-ray intensities of each element in a sample and in corresponding standards. The ratio of the measured intensities from the unknown material to that from the standard is related to the concentration using the ZAF or ϕ(ρz) equations. Under optimal conditions, accuracies approaching 1% are possible. However, all the experimental conditions must remain the same during the sample and standard measurements. This is not possible with cold field emission scanning electron microscopes (FE-SEMs) where beam current can fluctuate around 5% in its stable regime. Very little work has been done on variable beam current conditions (Griffin, B.J. & Nockolds, C.E., Scanning13, 307–312, 1991), and none relating to cold FE-SEM applications. To address this issue, a new method was developed using a single spectral measurement. It is similar in approach to the Cliff-Lorimer method developed for the analytical transmission electron microscope. However, corrections are made for X rays generated from thick specimens using the ratio of the characteristic X-ray intensities of two elements in the same material. The proposed method utilizes the ratio of the intensity of a characteristic X-ray normalized by the sum of X-ray intensities of all the elements measured for the sample, which should also reduce the amplitude of error propagation. Uncertainties in the physical parameters of X-ray generation are corrected using a calibration factor that must be previously acquired or calculated. As an example, when this method was applied to the calculation of the composition of Au-Cu National Institute of Standards and Technology standards measured with a cold field emission source SEM, relative accuracies better than 5% were obtained.

Characterization of small inclusions: SEM vs TEM, or is it even worth considering Sem?

1996 ◽  
Vol 54 ◽  
pp. 498-499
Author(s):  
Carl Blais ◽  
Gilles L’Espérance ◽  
Éric Baril ◽  
Clément Forget
Keyword(s):  
Chemical Composition ◽  
X Rays ◽  
X Ray ◽  
Transmission Electron ◽  
Electron Microscopes ◽  
Diffraction Patterns ◽  
Micro Alloyed Steel ◽  
Steel Welds ◽  
Scanning Electron Microscopes

Inclusions of technological importance are often in the size range from 0.1 to 1 μm, These inclusions are generally too thick for EEL-spectrometry and require the use of EDS to characterize their chemical composition. Recent Monte Carlo simulations indicated that scanning electron microscopes (SEM’s) equiped with a field emission gun (FEG) might challenge transmission electron microscopes (TEM’s) for the charaterization of small inclusions, In the light of these results, we investigated the possibility of using a FEGSEM to characterize inclusions found in micro-alloyed steel welds used for arctic applications. The main setbacks of using EDS for such a task are due to the presence of small phases of unknown thicknesses, non-homogeneity of the X-ray generation volumes, variation in absorption along the path length of the X-rays, etc., Even though these problems are encoutered in both the SEM and the TEM, the relative ease of imaging the very small inclusions in TEM confers a definite advantage to this technique. Furthermore, TEM allows to obtain convergent-bearn electron diffraction patterns (CBED) which complement the chemical composition characterization, thereby allowing the unambiguous identification of the phases present (chemistry and crystal structure).

The Observation of NBC Precipitates In Steels In The Nanometer Range Using A Field Emission Gun Scanning Electron Microscope

1997 ◽  
Vol 3 (S2) ◽  
pp. 1243-1244 ◽  
Author(s):  
Raynald Gauvin ◽  
Steve Yue
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Field Emission ◽  
Incident Electron Energy ◽  
Beam Diameter ◽  
Probe Diameter ◽  
Transmission Electron ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes ◽  
Scanning Electron

The observation of microstructural features smaller than 300 nm is generally performed using Transmission Electron Microscopy (TEM) because conventional Scanning Electron Microscopes (SEM) do not have the resolution to image such small phases. Since the early 1990’s, a new generation of microscopes is now available on the market. These are the Field Emission Gun Scanning Electron Microscope with a virtual secondary electron detector. The field emission gun gives a higher brightness than those obtained using conventional electron filaments allowing enough electrons to be collected to operate the microscope with incident electron energy, E0, below 5 keV with probe diameter smaller than 5 nm. At 1 keV, the electron range is 60 nm in aluminum and 10 nm in iron (computed using the CASINO program). Since the electron beam diameter is smaller than 5 nm at 1 keV, the resolution of these microscopes becomes closer to that of TEM.

High Spatial Resolution Low Energy Electron Beam X-ray Microanalysis

1999 ◽  
Vol 5 (S2) ◽  
pp. 310-311
Author(s):  
I.R. Barkshire ◽  
P. Karduck ◽  
W. Rehbach ◽  
S. Richter
Keyword(s):  
Energy Performance ◽  
Beam Current ◽  
Low Energy ◽  
Advanced Materials ◽  
X Ray ◽  
Routine Basis ◽  
Low Energy Electron ◽  
Electron Microscopes ◽  
Relative Errors ◽  
Scanning Electron Microscopes

Conventionally, x-ray microanalysis on scanning electron microscopes (SEM) with energy dispersive spectrometers (EDS) has been performed with relatively high primary energies (>10 kv). for most samples this results in reasonably good separation of the generated x-ray line series from different elements enabling unambiguous identification and therefore accurate qualitative analysis. Under these circumstances it is widely accepted that quantitative analysis of polished bulk samples is possible on a routine basis with relative errors around 1-5% and detection limits of the order of 0.1%.However, in order to address the analysis requirements of new advanced materials with sub-micron features, there is growing interest in performing x-ray microanalysis at low beam energies(<5kv). this is now a more realistic goal due to the routine availability of field emission sem's which can operate with much improved beam sizes at low beam energies with sufficient beam current to perform practical microanalysis, in conjunction with the improved low energy performance of current, commercially available EDS systems.

scholarly journals Practical Issues for Quantitative X-ray Microanalysis in SEM at Low kV

2006 ◽  
Vol 14 (1) ◽  
pp. 30-33 ◽  
Author(s):  
Peter Statham
Keyword(s):  
Quantitative Analysis ◽  
Atomic Number ◽  
Beam Current ◽  
Research Groups ◽  
X Ray ◽  
Time Scanning ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes ◽  
Scanning Electron

In the three decades following Castaing's seminal thesis [1] x-ray analysis received widespread attention from research groups. By 1980, the methods and correction procedures for quantitative analysis of elements with atomic number 11 and above, using accelerating voltages between 15kV and 25kV, were well established and available in commercial instrumentation. At the time, scanning electron microscopes (SEMs) could rarely deliver high and stable beam current at much lower kV, and x-ray spectrometers had poor efficiency below lkeV so that low kV analysis received comparatively little attention.

scholarly journals New Features in Crystal Orientation and Phase Mapping for Transmission Electron Microscopy

Symmetry ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1675
Author(s):  
Edgar F. Rauch ◽  
Patrick Harrison ◽  
Muriel Véron
Keyword(s):  
Electron Diffraction ◽  
Angular Resolution ◽  
X Ray ◽  
Amorphous Phases ◽  
Transmission Electron ◽  
Tremendous Amount ◽  
Processing Algorithms ◽  
Electron Microscopes ◽  
Diffraction Patterns ◽  
Scanning Electron Microscopes

ACOM/TEM is an automated electron diffraction pattern indexing tool that enables the structure, phase and crystallographic orientation of materials to be routinely determined. The software package, which is part of ACOM/TEM, has substantially evolved over the last fifteen years and has pioneered numerous additional functions with the constant objective of improving its capabilities to make the tremendous amount of information contained in the diffraction patterns easily available to the user. Initially devoted to the analysis of local crystallographic texture, and as an alternative to both X-ray pole figure measurement and EBSD accessories for scanning electron microscopes, it has rapidly proven itself effective to distinguish multiple different phases contained within a given sample, including amorphous phases. Different strategies were developed to bypass the inherent limitations of transmission electron diffraction patterns, such as 180° ambiguities or the complexity of patterns produced from overlapping grains. Post processing algorithms have also been developed to improve the angular resolution and to increase the computing rate. The present paper aims to review some of these facilities. On-going works on 3D reconstruction are also introduced.

An Integrated System for Elemental X-Ray Analysis of Materials

1972 ◽  
Vol 16 ◽  
pp. 284-297
Author(s):  
J.C. Russ ◽  
A.O. Sandborg ◽  
M.W. Barnhart ◽  
C.E. Soderquist ◽  
R.W. Lichtinger ◽  
...  
Keyword(s):  
Low Power ◽  
Integrated System ◽  
X Rays ◽  
Energy Dispersive Analysis ◽  
X Ray ◽  
Field L ◽  
Wavelength Dispersive Spectrometer ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes ◽  
Scanning Electron

The use of energy dispersive analysis of x-rays (EDAX method) is now well entrenched in the electron column field(l), where more scanning electron microscopes have been fitted with EDAX instrumentation than all of the conventional (wavelength-dispersive spectrometer) microprobes ever made. The principle advantage of the EDAX approach for the SEM user is the efficiency of detection, which permits its use at the low power levels of the SEM. In addition, the simultaneous analysis of the entire spectrum and the lack of focusing restrictions that permits analysis of rough samples are important advantages.

An Ultra High Vacuum Modular Electron Beam System

1971 ◽  
Vol 29 ◽  
pp. 20-21
Author(s):  
F. Christiansen
Keyword(s):  
High Vacuum ◽  
Ultra High Vacuum ◽  
Modular Construction ◽  
X Ray ◽  
Beam System ◽  
Transmission Electron ◽  
Common Foundation ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes ◽  
Scanning Electron

Traditionally, x-ray microprobes, scanning electron microscopes and similar electron microbeam instruments have been designed and built in much the same manner as transmission electron microscopes; that is, as single purpose instruments with provisions for a miltiplicity of attachments to increase their scope. Electron optically these instruments are nearly identical, the only differences being in mechanical restrictions necessary to accommodate spectrometers, specimen stages, light optics, etc. Hence, it appears desirable to modularize an electron microbeam system to provide a variety of instruments, each sharing a common foundation. This then allows the user to convert an instrument from one configuration to another at minimum expense without sacrificing performance and also to readily construct specialized instruments from standard parts. Other advantages of modular construction, both from the builders' and users' standpoint have been discussed previously.

scholarly journals Evolution and Comparison of Electron Sources

1993 ◽  
Vol 1 (4) ◽  
pp. 16-17
Author(s):  
Doug Rathkey
Keyword(s):  
Cathode Material ◽  
Field Emission ◽  
Electron Beam Lithography ◽  
Electron Sources ◽  
Thermionic Cathodes ◽  
Transmission Electron ◽  
Electron Microscopes ◽  
Field Emission Cathodes ◽  
Scanning Electron Microscopes ◽  
Scanning Electron

Over the years, we've seen major developments in electron source technologies in response to the demands for better performance. This article presents a brief overview of the cathode technologies in use today.Two types of electron sources are used in commercially available scanning electron microscopes (SEMs), transmission electron microscopes (TEMs), scanning Auger microprobes, and electron beam lithography systems: thermionic and field emission electron cathodes. Thermionic cathodes reiease electrons from the cathode material when they are heated while field emission cathodes rely on a high electric field to draw electrons from the cathode material.

scholarly journals Online Microscopy Lab Training Modules in an Academic Environment

2008 ◽  
Vol 16 (5) ◽  
pp. 44-47
Author(s):  
K. Schierbeek ◽  
A. Mikel ◽  
S. E. Hill ◽  
O. P. Mills
Keyword(s):  
Focused Ion Beam ◽  
Ion Beam ◽  
X Ray ◽  
Transmission Electron ◽  
Analysis Laboratory ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes ◽  
Fluorescence Spectrometer ◽  
Training Modules ◽  
Operation Cost

The Applied Chemical and Morphological Analysis Laboratory (ACMAL) is a multi-user, multi-disciplinary characterization laboratory. ACMAL houses two scanning electron microscopes (SEM and FE-SEM), a transmission electron microscope (TEM), focused ion beam milling system (FIB), four X-ray diffractometers, and an X-ray fluorescence spectrometer. ACMAL operates as a recharge center where users absorb facility operation cost through an hourly use fee. As such, we are keenly interested in encouraging broad access to the facility by lowering obstacles to users. Facility training enhancements provide the best pathway to productive and responsible facility usage.

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