scholarly journals Use of the Disk-of-least-confusion in X-ray Microanalysis

1998 ◽  
Vol 4 (S2) ◽  
pp. 274-275
Author(s):  
E. A. Kenik ◽  
S. X. Ren
Keyword(s):  
Spatial Resolution ◽  
Electron Scattering ◽  
Electron Probe ◽  
X Rays ◽  
High Brightness ◽  
X Ray ◽  
Electron Sources ◽  
Probe Diameter ◽  
Electron Probe Microanalyzer ◽  
Subsequent Emission

Whereas the spatial resolution for standard secondary electron (SEI) imaging in a scanning electron microscope or electron probe microanalyzer is related to the incident probe diameter, the spatial resolution for x-ray microanalysis is related to the convolution of the probe diameter with the spatial extent of the analyzed volume for a point probe. The latter is determined by electron scattering in the specimen and the subsequent emission of excited x-rays from the specimen. As such, it is possible that “What you see is not what you get”. This is especially true for instruments with high brightness electron sources (field emission). This problem is compounded by probe aberrations which at Gaussian image focus can produce significant electron tails extending tens of microns from the center of the probe.

High spatial resolution x-ray microanalysis of interfaces

1995 ◽  
Vol 53 ◽  
pp. 284-285
Author(s):  
J. R. Michael
Keyword(s):  
Spatial Resolution ◽  
Electron Probe ◽  
Solid Angle ◽  
Collection Efficiency ◽  
Spatial Scales ◽  
Energy Dispersive Spectrometer ◽  
X Rays ◽  
X Ray ◽  
Probe Size ◽  
Brightness Field

X-ray microanalysis in the analytical electron microscope (AEM) refers to a technique by which chemical composition can be determined on spatial scales of less than 10 nm. There are many factors that influence the quality of x-ray microanalysis. The minimum probe size with sufficient current for microanalysis that can be generated determines the ultimate spatial resolution of each individual microanalysis. However, it is also necessary to collect efficiently the x-rays generated. Modern high brightness field emission gun equipped AEMs can now generate probes that are less than 1 nm in diameter with high probe currents. Improving the x-ray collection solid angle of the solid state energy dispersive spectrometer (EDS) results in more efficient collection of x-ray generated by the interaction of the electron probe with the specimen, thus reducing the minimum detectability limit. The combination of decreased interaction volume due to smaller electron probe size and the increased collection efficiency due to larger solid angle of x-ray collection should enhance our ability to study interfacial segregation.

Hitachi Model XMA-5 Electron Probe Microanalyzer

1968 ◽  
Vol 26 ◽  
pp. 308-309
Author(s):  
Tomura ◽  
Okano ◽  
Hara
Keyword(s):  
Electron Probe ◽  
High Performance ◽  
List Type ◽  
X Rays ◽  
Type Number ◽  
Fluorescence Excitation ◽  
X Ray ◽  
Electron Probe Microanalyzer ◽  
Scientific Instrumentation ◽  
Made In

The recent advancement in scientific instrumentation has been phenomenal. This is particularity true in the electron probe microanalyzer field. This paper describes the improvements made in the Hitachi Model XMA-5 Electron Probe Microanalyzer to achieve high performance.1.X-ray spectroscopy1-1.It is now possible to analyze a wide variety of elements including ultra light elements in minute concentrations with the advent of an increasing number of dispersing elements and high detectability.1-2.A linear crystal drive and direct wavelength read-out (with respect to the crystal) is employed in the spectrometer to assure simultaneous analyses of up to three elements by using three of the six crystals provided. For correction of absorbed X-rays and fluorescence excitation and with due consideration of the angular distribution of the characteristic X-rays, an X-ray take off angle of 38° (electron probe is incident vertically on the specimen surface) was adopted.

X-Ray Excited Optical Luminescence and Portable Electron Probe Microanalyzer–Cathodoluminescence (EPMA–CL) Analyzers for On-Line and On-Site Analysis of Nonmetallic Inclusions in Steel

2017 ◽  
Vol 23 (6) ◽  
pp. 1143-1149 ◽  
Author(s):  
Susumu Imashuku ◽  
Koichiro Ono ◽  
Kazuaki Wagatsuma
Keyword(s):  
Electron Probe ◽  
Nonmetallic Inclusions ◽  
Beam Current ◽  
X Rays ◽  
X Ray ◽  
Site Analysis ◽  
Electron Probe Microanalyzer ◽  
Optical Luminescence ◽  
On Line ◽  
Inclusions In Steel

AbstractThe potential of the application of an X-ray excited optical luminescence (XEOL) analyzer and portable analyzers, composed of a cathodoluminescence (CL) spectrometer and electron probe microanalyzer (EPMA), to the on-line and on-site analysis of nonmetallic inclusions in steel is investigated as the first step leading to their practical use. MgAl2O4 spinel and Al2O3 particles were identified by capturing the luminescence as a result of irradiating X-rays in air on a model sample containing MgAl2O4 spinel and Al2O3 particles in the size range from 20 to 50 μm. We were able to identify the MgAl2O4 spinel and Al2O3 particles in the same sample using the portable CL spectrometer. In both cases, not all of the particles in the sample were identified because the luminescence intensities of the smaller Al2O3 in particular were too low to detect. These problems could be solved by using an X-ray tube with a higher power and increasing the beam current of the portable CL spectrometer. The portable EPMA distinguished between the MgAl2O4 spinel and Al2O3 particles whose luminescent colors were detected using the portable CL spectrometer. Therefore, XEOL analysis has potential for the on-line analysis of nonmetallic inclusions in steel if we have information on the luminescence colors of the nonmetallic inclusions. In addition, a portable EPMA–CL analyzer would be able to perform on-site analysis of nonmetallic inclusions in steel.

Spatial Resolution and Detectability Limits in Thin-Film X-ay Microanalysis

1990 ◽  
Vol 48 (2) ◽  
pp. 450-451 ◽  
Author(s):  
J. I. Goldstein ◽  
C. E. Lyman ◽  
J. Zhang
Keyword(s):  
Spatial Resolution ◽  
Thick Sample ◽  
High Brightness ◽  
X Ray ◽  
Probe Diameter ◽  
Analytical Electron ◽  
Analytical Electron Microscope ◽  
Brightness Field ◽  
Image Position ◽  
Beam Broadening

The major advantage of performing x-ray microanalysis in the analytical electron microscope (AEM) is the high compositional spatial resolution and the chemical analysis sensitivity. The spatial resolution (R) is dependent on the size of the focused electron probe (d) and the amount of electron beam broadening (b). The spatial resolution across a discrete interface is:The amount of beam broadening is directly proportional to the thickness (t) to the 3/2 power and inversely proportional to the beam voltage (E). Optimizing d and b involve a consideration of the minimum x-ray intensity necessary for analysis since the x-ray intensity is decreased by minimizing d and t. To obtain the optimum spatial resolution one should use the thinnest possible specimen, a high kV AEM and a high brightness field emission gun (FEG). Figure 1 shows a Ni composition profile across a planar lOnm precipitate in the plessite region of the Grant iron meteorite. A spatial resolution of 2.5nm was obtained from a 20nm thick sample analyzed in a VG Microscopes, Ltd. HB 501 FEG AEM (probe diameter 1.8nm (FWTM)).

Quantitative Analysis and High-Resolution X-ray Mapping with a Field Emission Electron Microprobe

2013 ◽  
Vol 21 (3) ◽  
pp. 10-15 ◽  
Author(s):  
C. Hombourger ◽  
M. Outrequin
Keyword(s):  
Quantitative Analysis ◽  
High Resolution ◽  
Field Emission ◽  
Spatial Resolution ◽  
Electron Microprobe ◽  
Electron Probe ◽  
Chemical Elements ◽  
Electron Source ◽  
X Ray ◽  
Electron Probe Microanalyzer

The electron probe microanalyzer (EPMA) provides quantitative analysis for nearly all chemical elements with a spatial resolution of analysis about ~1 μm, which is relevant to microstructures in a wide variety of materials and mineral specimens. Recent implementation of the Schottky emitter field-emission gun (FEG) electron source in the EPMA has significantly improved the spatial resolution and detectability of the EPMA technique.

scholarly journals X-Ray Microprobe for the Microcharacterization of Materials

1988 ◽  
Vol 143 ◽  
Author(s):  
C. J. Sparks ◽  
G. E. Ice
Keyword(s):  
Energy Deposition ◽  
Materials Science ◽  
Charged Particles ◽  
Chemical Characterization ◽  
X Rays ◽  
High Brightness ◽  
X Ray ◽  
Electron Sources ◽  
Detectable Concentration ◽  
Low Levels

AbstractThe unique properties of X rays offer many advantages over those of electrons and other charged particles for the microcharacterization of materials. X rays are more efficient in exciting characteristic X-ray fluorescence and produce higher fluorescent signal-to-background ratios than obtained with electrons. Detectable limits for X rays are a few parts per billion which are 10−3 to 10−5 lower than for electrons. Energy deposition in the sample from X rays is 10–3 to 10–4 less than for electrons for the same detectable concentration. High-brightness storage rings, especially in the 7 GeV class with undulators, will have sources as brilliant as the most advanced electron probes. The highly collimated X-ray beams from undulators simplify the X-ray optics required to produce submicron X-ray probes with fluxes comparable to electron sources. Such X-ray microprobes will also produce unprecedentedly low levels of detection in diffraction, EXAFS, Auger, and photoelectron spectroscopies for structural and chemical characterization and elemental identification. These major improvements in microcharacterization capabilities will have wide-ranging ramifications not only in materials science but also in physics, chemistry, geochemistry, biology, and medicine.

Prediction of X-ray spatial resolution for SEM and STEM specimens using Monte Carlo methods

1978 ◽  
Vol 36 (1) ◽  
pp. 546-547
Author(s):  
R.G. Faulkner
Keyword(s):  
Monte Carlo ◽  
Spatial Resolution ◽  
Electron Scattering ◽  
Experimental Methods ◽  
Source Size ◽  
Computer Method ◽  
Spherical Particles ◽  
X Rays ◽  
X Ray ◽  
Inclined Beam

Determinations of spatial X-ray resolution in conventional microanalysis in electron probe microanalysers where the beam is perpendicular to a smooth surface are now quite straightforward. However, SEM's and STEM'S are becoming increasingly used methods for performing microanalysis. The specimen arrangement for this sort of work often involves both inclined beam and detector geometries. Under these conditions X-ray correction constants have to be altered due to the changed average path length for the emerging X-rays. The spatial resolution and correction constants peculiar to the new geometry can be physically studied using a Monte Carlo computer method which simulates the trajectories of many electrons as they interact with the specimen.Another attempt to predict resolution and effective take-off angle using single electron scattering theory has been made for thin films. This over estimates the X-ray source size at large foil thicknesses and under estimates at small foil thicknesses. Experimental methods have been devised utilising edges and small, spherical particles.

Spatial resolution of X-ray microanalysis in thin foils

1978 ◽  
Vol 36 (1) ◽  
pp. 544-545
Author(s):  
R. Hutchings ◽  
I.P. Jones ◽  
M.H. Loretto ◽  
R.E. Smallman
Keyword(s):  
Spatial Resolution ◽  
Electron Probe ◽  
Beam Divergence ◽  
Inelastic Interaction ◽  
Specimen Thickness ◽  
High Current ◽  
Beam Spreading ◽  
X Ray ◽  
Thin Foils ◽  
Complex Calculation

There is increasing interest in X-ray microanalysis of thin specimens and the present paper attempts to define some of the factors which govern the spatial resolution of this type of microanalysis. One of these factors is the spreading of the electron probe as it is transmitted through the specimen. There will always be some beam-spreading with small electron probes, because of the inevitable beam divergence associated with small, high current probes; a lower limit to the spatial resolution is thus 2αst where 2αs is the beam divergence and t the specimen thickness.In addition there will of course be beam spreading caused by elastic and inelastic interaction between the electron beam and the specimen. The angle through which electrons are scattered by the various scattering processes can vary from zero to 180° and it is clearly a very complex calculation to determine the effective size of the beam as it propagates through the specimen.

X-Ray absorption edge elemental imaging of B. thuringienis

1989 ◽  
Vol 47 ◽  
pp. 212-213
Author(s):  
R. L. Stears
Keyword(s):  
Absorption Edge ◽  
Elemental Distribution ◽  
X Rays ◽  
Differential Absorption ◽  
Synchrotron Source ◽  
High Brightness ◽  
X Ray ◽  
Elemental Imaging ◽  
Cellular Integrity ◽  
X Ray Absorption

Because of the nature of the bacterial endospore, little work has been done on analyzing their elemental distribution and composition in the intact, living, hydrated state. The majority of the qualitative analysis entailed intensive disruption and processing of the endospores, which effects their cellular integrity and composition.Absorption edge imaging permits elemental analysis of hydrated, unstained specimens at high resolution. By taking advantage of differential absorption of x-ray photons in regions of varying elemental composition, and using a high brightness, tuneable synchrotron source to obtain monochromatic x-rays, contact x-ray micrographs can be made of unfixed, intact endospores that reveal sites of elemental localization. This study presents new data demonstrating the application of x-ray absorption edge imaging to produce elemental information about nitrogen (N) and calcium (Ca) localization using Bacillus thuringiensis as the test specimen.

Measurement And Simulation Of X-Ray Emission From Multilayered Structures In Electron Probe Microanalysis.

1999 ◽  
Vol 5 (S2) ◽  
pp. 78-79
Author(s):  
C. Merlet ◽  
X. Llovet ◽  
F. Salvat
Keyword(s):  
Electron Probe ◽  
Numerical Models ◽  
Carbon Layer ◽  
Single Element ◽  
Surface Ionization ◽  
Copper Films ◽  
Multilayered Structures ◽  
X Ray ◽  
Electron Probe Microanalyzer ◽  
Quantitative Epma

Studies of x-ray emission from thin films on substrates using an electron probe microanalyzer (EPMA) provide useful information on the characteristics of x-ray generation by electron beams. In this study, EPMA measurements of multilayered samples were performed in order to test and improve analytical and numerical models used for quantitative EPMA. These models provide relatively accurate results for samples consisting of layers with similar average atomic numbers, because of their similar properties regarding electron transport and x-ray generation. On the contrary, these models find difficulties to describe the process when the various layers have very different atomic numbers. In a previous work, we studied the surface ionization of thin copper films of various thicknesses deposited on substrates with very different atomic numbers. In the present communication, the study is extended to the case of multilayered specimens.The studied specimens consisted of thin copper films deposited on a carbon layer which, in turn, was placed on a variety of single-element substrates, ranging from Be to Bi.

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