scholarly journals Nanoscale Automated Quantitative Mineralogy: A 200-nm Quantitative Mineralogy Assessment of Fault Gouge Using Mineralogic

Minerals ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 665 ◽  
Author(s):  
Shaun Graham ◽  
Nynke Keulen
Keyword(s):  
Primary Electron ◽  
Fault Gouge ◽  
Spectroscopy Analysis ◽  
Primary Electron Beam ◽  
X Ray ◽  
Fine Grained ◽  
Quantitative Mineralogy ◽  
Fine Grained Material ◽  
Individual Grains ◽  
Acceleration Voltage

Effective energy-dispersive X-ray spectroscopy analysis (EDX) with a scanning electron microscope of fine-grained materials (submicrometer scale) is hampered by the interaction volume of the primary electron beam, whose diameter usually is larger than the size of the grains to be analyzed. Therefore, mixed signals of the chemistry of individual grains are expected, and EDX is commonly not applied to such fine-grained material. However, by applying a low primary beam acceleration voltage, combined with a large aperture, and a dedicated mineral classification in the mineral library employed by the Zeiss Mineralogic software platform, mixed signals could be deconvoluted down to a size of 200 nm. In this way, EDX and automated quantitative mineralogy can be applied to investigations of submicrometer-sized grains. It is shown here that reliable quantitative mineralogy and grain size distribution assessment can be made based on an example of fault gouge with a heterogenous mineralogy collected from Ikkattup nunaa Island, southern West Greenland.

X-Ray Energy Dispersive Spectroscopy in the Environmental Scanning Electron Microscope

1998 ◽  
Vol 4 (S2) ◽  
pp. 182-183
Author(s):  
John F. Mansfield ◽  
Brett L. Pennington
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Energy Dispersive Spectroscopy ◽  
Primary Electron ◽  
Environmental Scanning ◽  
Primary Electron Beam ◽  
X Ray ◽  
Environmental Sem ◽  
Scanning Electron

The environmental scanning electron microscope (Environmental SEM) has proved to be a powerful tool in both materials science and the life sciences. Full characterization of materials in the environmental SEM often requires chemical analysis by X-ray energy dispersive spectroscopy (XEDS). However, the spatial resolution of the XEDS signal can be severely degraded by the gaseous environment in the sample chamber. At an operating pressure of 5Torr a significant fraction of the primary electron beam is scattered after it passes through the final pressure limiting aperture and before it strikes the sample. Bolon and Griffin have both published data that illustrates this effect very well. Bolon revealed that 45% of the primary electron beam was scattered by more than 25 μm in an Environmental SEM operating at an accelerating voltage of 30kV, with a water vapor pressure of 3Torr and a working distance of 15mm.

Effects of chamber pressure and accelerating voltage on X-RAY resolution in the ESEM

1992 ◽  
Vol 50 (2) ◽  
pp. 1324-1325 ◽  
Author(s):  
Brendon J. Griffin
Keyword(s):  
Electron Beam ◽  
Primary Electron ◽  
Chamber Pressure ◽  
X Rays ◽  
Viewing Angle ◽  
Primary Electron Beam ◽  
Specific Data ◽  
X Ray ◽  
Working Distance ◽  
Eds Microanalysis

Chamber pressure, accelerating voltage and working distance have been shown to control the relative diameter of the scattered skirt of the primary electron beam at the specimen surface in the ESEM. Inital x-ray studies indicate that at 3 torr, 30 kV and a WD=15mm, 45% of the beam comes from beyond 25 μm of the incidence point and 4% from beyond 1.5mm. At 5 torr 66% of the beam is scattered beyond 25 μm2. No specific data was available on the spatial resolution of x rays and this study aimed to improve that situation. The results also form the basis for establishing a mechanism for and defining the potential limits of quantitative EDS microanalysis in the ESEM.The negative viewing angle of the EDS x-ray detector in the current ESEM (model E-3) requires at least a 15 degree tilt on a flat sample for microanalysis. This geometry places a narrow limit on the working distance range that can be used, due to the collimation of the detector, thereby effectively eliminating working distance as a variable in x-ray microanalysis.

Quantitative EDS analysis in the environmental ESEM using a bremstrahlung intensity-based correction for primary electron beam variation and scatter

1996 ◽  
Vol 54 ◽  
pp. 842-843 ◽  
Author(s):  
B.J. Griffin ◽  
C.E. Nockolds
Keyword(s):  
Electron Beam ◽  
Beam Current ◽  
Primary Electron ◽  
Primary Beam ◽  
Minimum Condition ◽  
Chamber Pressure ◽  
Primary Electron Beam ◽  
Faraday Cage ◽  
X Ray ◽  
Eds Analysis

Quantitative EDS analysis of bulk samples in the scanning electron microscope (SEM) or electron microprobe requires, as a fundamental parameter, a stable and reproducible primary electron beam current Beam current is usually measured with a Faraday cage positioned in the electron column below the objective aperture or in the specimen holder. Reproducibility and stability within 1%/hour is a minimum condition.Primary beam current measurement in the ESEM or any high pressure SEM is difficult to measure. Electron-gas interaction in the biased chamber generates a positive ion flow highly amplified relative to the primary beam (Danilatos, 1990) and generates an x-ray signal from the gas. The latter signal amplitude is dependent on primary beam current, chamber pressure and backscatter electron signal from the specimen (Griffin et al. 1993). These interactions prevent quantification of EDS data standardised to Faraday cage primary beam current measurements or x-ray counts from a reference standard.

The measurement of the fluorescence of Si K x-rays by Au M x-rays

1990 ◽  
Vol 48 (2) ◽  
pp. 198-199
Author(s):  
John A. Small ◽  
Scott A. Wight ◽  
Robert L. Myklebust ◽  
Dale E. Newbury
Keyword(s):  
Electron Beam ◽  
Electron Probe ◽  
Primary Electron ◽  
Characteristic Line ◽  
X Rays ◽  
Limited Information ◽  
Primary Electron Beam ◽  
X Ray ◽  
Image Position ◽  
Critical Excitation

The characteristic fluorescence correction is used in electron probe microanalysis to account for the x-ray intensity excited in element “a” by the x-rays from the characteristic line of another element, “b”, in the sample. Since the excited intensity is not generated by the primary electron beam, it is necessary to apply the fluorescence correction for quantitative elemental analysis. This correction can be significant particularly when element “b” is a major component of the sample and the characteristic line for element “b” is slightly higher in energy than the critical excitation energy for the excited line of element “a”.The fluorescence correction, which is used in the various analytical programs, is described in equation 1.where I'*fa/I'*pa is the ratio of the emitted “a” intensity excited by “b” x-rays to the emitted intensity excited by the primary electron beam. The various parameters in this equation are accurately known for the K x-ray lines, but only very limited information is available for the M x-ray lines.

Part I-Description and Application of Diffraction Method

1958 ◽  
Vol 2 ◽  
pp. 23-37
Author(s):  
Sigmund Weissmann
Keyword(s):  
Optical Microscopy ◽  
Diffraction Method ◽  
Special Technique ◽  
Double Crystal ◽  
X Ray ◽  
Fine Grained ◽  
Structural Details ◽  
The Individual ◽  
Individual Grains ◽  
Relationship Of

AbstractA method is described which combines optical microscopy with x-ray microscopy and diffraction analysis. The topographical relationship of the grains of a fine-grained material and the fine-structural details of their surface texture are disclosed by a special technique of reflection x-ray microscopy. The experimental observations made by this technique are being correlated to those made by optical microscopy. The individual grains are subsequently analyzed for their substructure characteristics by a photographic tracer technique and a method based on the principle of the double-crystal diffractometer. Quantitaive information is obtained concerning the lattice misalignment of the grains, the size of subgrains, disorientation angle between subgrains, lattice misalignment existing within the subgrains and the nature of low-angle boundaries. Application of the method to the analysis of inclusions and precipitates dispersed in a polycrystalline matrix is discussed.

Chemical Composition of an Unusual Xenolith of the Allende Meteorite

1989 ◽  
Vol 44 (10) ◽  
pp. 1005-1014 ◽  
Author(s):  
H. Palme ◽  
G. Kurat ◽  
B. Spettel ◽  
A. Burghele
Keyword(s):  
Chemical Composition ◽  
Bulk Composition ◽  
Forming Process ◽  
Volatile Elements ◽  
X Ray ◽  
Fine Grained ◽  
Oxygen Isotopic ◽  
Fine Grained Material ◽  
Chondrule Formation ◽  
Type 3

Abstract The chemical composition of an unusual xenolith (All-AF) from the Allende meteorite was determined by neutron activation and x-ray fluorescence analyses. The xenolith is similar in bulk composition to Allende, but has large excesses in some moderately volatile trace elements, such as Na, K, Au, Sb etc. Some of these elements show considerable variations in other components of Allende, suggesting inhomogeneous distribution in Allende. However, elements of higher volatility, such as Zn and Se have concentrations typical of bulk Allende and other type 3 carbonaceous chondrites. Therefore, All-AF must have formed from the same reservoir as bulk Allende.All-AF has uniform grain size and does not, and did never, contain chondrules. The low content of volatile elements, therefore cannot be ascribed to loss of volatiles during the chondrule forming process. It is a characteristic of the Allende reservoir. The chemical composition of related dark inclusions (DIs) in Allende is different from All-AF. Dark inclusions may have formed by separation of fine grained material in the early solar nebula while All-AF resembles bulk Allende material that was never subject to chondrule formation. Both, dark inclusions and All-AF have oxygen isotopic compositions which plot at the upper end of the δ18O vs. δ17O correlation, suggesting extensive oxygen exchange with ambient gas.

Low Acceleration Voltage EBIC Using FESEM and Application to Cross-Sectional Junction Evaluation

1996 ◽  
Author(s):  
Y. Kadota ◽  
K. Mori
Keyword(s):  
Electron Beam ◽  
Current Method ◽  
Beam Current ◽  
Primary Electron ◽  
Electron Beam Current ◽  
Junction Depth ◽  
Primary Electron Beam ◽  
Cross Sectional ◽  
Electron Beam Induced Current ◽  
Acceleration Voltage

Abstract EBIC (Electron beam induced current) method has been applied to the evaluation of half micron MOSFET junctions. We have been able to clearly measure the junction depth profile and the impurities density, using FESEM/EBIC which provides the highest SEM resolution currently available. We have found that it is necessary to understand the relation of the acceleration voltage and the primary electron beam current, in order to take full advantage of the FESEM/EBIC technique for junction evaluation. We have been able to experimentally demonstrate the accurate measurement of junction position.

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