Quantitative Composition and Thickness Mapping With High Spatial Resolution By XEDS In a 300kv FEG-AEM

1998 ◽  
Vol 4 (S2) ◽  
pp. 136-137
Author(s):  
M. Watanabe ◽  
D. B. Williams
Keyword(s):  
Spatial Resolution ◽  
Collection Efficiency ◽  
Bulk Sample ◽  
Beam Current ◽  
Vacuum System ◽  
Beam Current Density ◽  
Quantitative Composition ◽  
X Ray ◽  
Electron Probe Microanalyzer ◽  
Major Disadvantage

Since the first demonstration by Cosslett and Duncumb, X-ray mapping by an electron probe microanalyzer (EPMA) has become a most popular approach in microanalysis because elemental distributions of constituents in a bulk sample can be displayed visually. The major disadvantage of EPMA mapping is poor spatial resolution (∼ 1 μm). The spatial resolution of X-ray microanalysis can be improved to a few nanometers using electron transparent thin-specimens in the analytical electron microscope (AEM). However, X-ray count rates from thin specimens are strictly limited because of the improved spatial resolution (i.e. smaller interaction volume) and the poor collection efficiency of X-ray. To obtain reasonable counts for accurate quantification in the AEM, extraordinarily long mapping times are required. Therefore, quantitative X-ray mapping is rarely attempted in the AEM. However, these limitations can be overcome by use of intermediate-volt age instruments combined with field-emission guns to increase the beam current-density, careful stage design to maximize the X-ray collection efficiency and the peak-to-background ratio, and ultrahigh vacuum system to reduce contamination.

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.

Practical Importance of Spatial Resolution and Analytical Sensitivity in AEM X-ray Microanalysis

1990 ◽  
Vol 48 (2) ◽  
pp. 432-433
Author(s):  
J. Zhang ◽  
D.B. Williams ◽  
J.I. Goldstein
Keyword(s):  
Spatial Resolution ◽  
Practical Importance ◽  
Beam Current ◽  
Specimen Thickness ◽  
Analytical Sensitivity ◽  
Related Factors ◽  
X Ray ◽  
Probe Size ◽  
Excitation Volume ◽  
Two Parameters

Analytical sensitivity and spatial resolution are important and closely related factors in x-ray microanalysis using the AEM. Analytical sensitivity is the ability to distinguish, for a given element under given conditions, between two concentrations that are nearly equal. The analytical sensitivity is directly related to the number of x-ray counts collected and, therefore, to the probe current, specimen thickness and counting time. The spatial resolution in AEM analysis is determined by the probe size and beam broadening in the specimen. A finer probe and a thinner specimen give a higher spatial resolution. However, the resulting lower beam current and smaller X-ray excitation volume degrade analytical sensitivity. A compromise must be made between high spatial resolution and an acceptable analytical sensitivity. In this paper, we show the necessity of evaluating these two parameters in order to determine the low temperature Fe-Ni phase diagram.A Phillips EM400T AEM with an EDAX/TN2000 EDS/MCA system and a VG HB501 FEG STEM with a LINK AN10 EDS/MCA system were used.

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.

Digital x-ray mapping of catalyst particles

1984 ◽  
Vol 42 ◽  
pp. 654-655
Author(s):  
C. E. Lyman
Keyword(s):  
Spatial Resolution ◽  
Energy Dispersive Spectrometer ◽  
Scanning Transmission Electron Microscope ◽  
Polished Section ◽  
Early Application ◽  
X Ray ◽  
Electron Probe Microanalyzer ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Early Maps

Formation of 2-dimensional dot maps of x-ray intensity from various elements in a flat polished section was an early application of the scanning beam electron probe microanalyzer. The spatial resolution of those early maps was the same as the microprobe itself, about lpm. These maps were usually scanned in an analogue fashion, and there was generally enough x-ray signal to produce maps with good peak-to-background ratios. For analysis of individual catalyst particles, a scanning transmission electron microscope (STEM) must be used to obtain the required spatial resolution. However, the x-ray signal level is usually low and is collected with an energy-dispersive spectrometer which has a lower peak-to-background ratio than the wavelength-dispersive spectrometer used in the microprobe. To produce suitable high magnification x-ray maps of catalyst particles digital beam techniques were employed.

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.

Dendritic Growth During Phase Transformation in Ni-Mo System Induced by Ion Beam

1986 ◽  
Vol 74 ◽  
Author(s):  
B. X. Liu ◽  
L. J. Huang ◽  
C. H. Shang
Keyword(s):  
Dendritic Growth ◽  
Room Temperature ◽  
Ion Beam ◽  
Cluster Formation ◽  
Beam Current ◽  
Beam Current Density ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Amorphous Phase Formation

AbstractMultilayered Ni-Mo films were irradiated by 200keV Xe ions at room temperature to various doses. The beam current density was confined to be less than lμA/cm2 to avoid overheating. The experimental evidences from X-ray diffraction, electrical resistivity, as well 4 as Rutherford Backscattering, indicate that a dose of 7 × 1014/cm2 was the critical one for uniform mixing of the layers and amorphous phase formation in Ni65 Mo35 films. Under this critical dose, various dendritic patterns were formed as revealed by bright field transmission electron microscopy. The microscopic mechanisms of the ion induced dendritic growth are attributed to the cluster formation and the aggregation of the formed clusters.

scholarly journals Создание пористых слоев германия имплантацией ионами серебра

2018 ◽  
Vol 44 (8) ◽  
pp. 84
Author(s):  
А.Л. Степанов ◽  
В.В. Воробьев ◽  
В.И. Нуждин ◽  
В.Ф. Валеев ◽  
Ю.Н. Осин
Keyword(s):  
Ion Beam ◽  
Silver Ions ◽  
Average Diameter ◽  
Beam Current ◽  
High Energy ◽  
Beam Current Density ◽  
High Dose ◽  
X Ray ◽  
Force Microscopy ◽  
20 Nm

AbstractWe propose a method for the formation of porous germanium ( P -Ge) layers containing silver nanoparticles by means of high-dose implantation of low-energy Ag^+ ions into single-crystalline germanium ( c -Ge). This is demonstrated by implantation of 30-keV Ag^+ ions into a polished c -Ge plate to a dose of 1.5 × 10^17 ion/cm^2 at an ion beam-current density of 5 μA/cm^2. Examination by high-resolution scanning electron microscopy (SEM), atomic-force microscopy (AFM), X-ray diffraction (XRD), energy-dispersive X-ray (EDX) microanalysis, and reflection high-energy electron diffraction (RHEED) showed that the implantation of silver ions into c -Ge surface led to the formation of a P -Ge layer with spongy structure comprising a network of interwoven nanofibers with an average diameter of ∼10–20 nm Ag nanoparticles on the ends of fibers. It is also established that the formation of pores during Ag^+ ion implantation is accompanied by effective sputtering of the Ge surface.

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.

Improved sensitivity, accuracy and spatial resolution of light-element analysis in the SEM at low beam voltages

1992 ◽  
Vol 50 (2) ◽  
pp. 1630-1631
Author(s):  
E D Boyes ◽  
I R Hartmann ◽  
D L Smith ◽  
F W Gooding ◽  
L Hanna ◽  
...  
Keyword(s):  
Spatial Resolution ◽  
Light Element ◽  
Thin Foil ◽  
Bulk Sample ◽  
Element Analysis ◽  
Strong Function ◽  
Physical Separation ◽  
X Ray ◽  
Epma Analysis ◽  
Foil Specimen

We have found that at low beam voltages, and especially at or below 5kV, the sensitivity, accuracy and spatial resolution for light element EDX analysis of bulk specimens in the SEM are all improved, compared to the conventional 30kV, by more than a factor of 10x. The reduced range (R) of the electron beam into a bulk sample is a strong function of beam voltage (R ∝ E05/3). This translates directly into much better spatial resolution of analysis which can be well into the sub-micron range and often <0. 1μm, compared with the 1-10<m typical of conventional EPMA analysis at 30kV. The greatly reduced electron penetration, and therefore much shorter x-ray escape range, substantially reduces, and in many cases entirely eliminates absorption (A) and fluorescence (F) effects on the (ZAF) x-ray signal. The situation is similar to that with a detached thin foil specimen prepared for STEM/AEM by physical separation, where the A and F effects are also generally very small and quantitation is also simplified.

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