From the Scanning Electron Microscope to the Scanning Electron Macroscope with X-Ray Microanalysis in the ESEM

2000 ◽  
Vol 6 (S2) ◽  
pp. 792-793 ◽  
Author(s):  
Raynald Gauvin
Keyword(s):  
Monte Carlo ◽  
Electron Beam ◽  
Electron Microscope ◽  
Incident Beam ◽  
Correction Procedure ◽  
Measured Intensity ◽  
X Ray ◽  
Image Position ◽  
Corrected Intensity ◽  
Scanning Electron

Recently, a new correction procedure has been proposed in order to perform X-Ray microanalysis in the ESEM or in the VP-SEM1. This new correction procedure is based on this equation:where I is the measured intensity at a given pressure P, Ip is the intensity that would be generated without any gas in the microscope (the corrected intensity) and Im is the intensity with complete scattering of the electron beam. Im is therefore the contribution of the skirt on I. In equation (1), fp is the fraction of the incident beam, which is not scattered by the gas above the specimen, and it can be obtained from Monte Carlo simulations or from an analytical equation.

Extracting Low Energy X-Ray Peaks From EDS and WDS Spectra

1998 ◽  
Vol 4 (S2) ◽  
pp. 218-219
Author(s):  
Robert L. Myklebust ◽  
Dale E. Newbury
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
High Resolution ◽  
High Performance ◽  
Incident Beam ◽  
Low Energy ◽  
Nanometer Scale ◽  
X Ray ◽  
Chemical Effects ◽  
Scanning Electron

Interest in electron beam x-ray microanalysis with low incident beam energies, defined arbitrarily as 5 keV and below, has been greatly stimulated in recent years by the development of the high performance field emission gun scanning electron microscope (FEG-SEM), which can produce a nanometer-scale probe with sufficient current to operate with both energy dispersive (EDS) and wavelength dispersive (WDS) spectrometers. Microanalysis in this regime requires the analyst to confront new spectrometry problems that are not typically encountered, or that can be safely ignored, when operating with conventional beam energies, 10 keV or greater. With low energy operation, the choice of atomic shells that can be accessed is restricted, forcing the analyst to make use of shells that have low fluorescence yields for intermediate and high atomic number elements, and possibly strong chemical effects, which are evident with high resolution x-ray spectrometry.

X-ray micro tomography in the scanning electron microscope

1978 ◽  
Vol 36 (1) ◽  
pp. 106-107 ◽  
Author(s):  
W. Brünger
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Target Surface ◽  
The Body ◽  
X Rays ◽  
Cross Sectional ◽  
X Ray ◽  
Micro Tomography ◽  
Scanning Electron

Reconstructive tomography is a new technique in diagnostic radiology for imaging cross-sectional planes of the human body /1/. A collimated beam of X-rays is scanned through a thin slice of the body and the transmitted intensity is recorded by a detector giving a linear shadow graph or projection (see fig. 1). Many of these projections at different angles are used to reconstruct the body-layer, usually with the aid of a computer. The picture element size of present tomographic scanners is approximately 1.1 mm2.Micro tomography can be realized using the very fine X-ray source generated by the focused electron beam of a scanning electron microscope (see fig. 2). The translation of the X-ray source is done by a line scan of the electron beam on a polished target surface /2/. Projections at different angles are produced by rotating the object.During the registration of a single scan the electron beam is deflected in one direction only, while both deflections are operating in the display tube.

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.

scholarly journals Win X-ray, The Monte Carlo Program for X-ray Microanalysis in the Scanning Electron Microscope

2003 ◽  
Vol 9 (S02) ◽  
pp. 32-33 ◽  
Author(s):  
Raynald Gauvin ◽  
Eric Lifshin ◽  
Hendrix Demers ◽  
Paula Horny ◽  
Helen Campbell
Keyword(s):  
Monte Carlo ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Monte Carlo Program ◽  
X Ray ◽  
Scanning Electron

Energy Filtered Electron Backscattering Images of 10-nm NbC and AIN Precipitates in Steels Computed by Monte Carlo Simulations

1996 ◽  
Vol 54 ◽  
pp. 150-151
Author(s):  
Raynald Gauvin ◽  
Dominique Drouin ◽  
Pierre Hovington
Keyword(s):  
Monte Carlo ◽  
Electron Beam ◽  
Electron Microscope ◽  
Materials Science ◽  
Specimen Preparation ◽  
Backscattered Electrons ◽  
Electron Backscattering ◽  
Transmission Electron ◽  
Properties Of Materials ◽  
Scanning Electron

In modern materials science, it is important to improve the resolution of the Scanning Electron Microscope (SEM) because small phases play a crutial role in the properties of materials. The Transmission Electron Microscope (TEM) is the tool of choice for imaging small phases embedded in a given matrix. However, this technique is expensive and also is slow owing to specimen preparation. In this context, it is important to improve spatial resolution of the SEM.In electron backscattering images, it is well know that the backscattered electrons have an energetic distribution when they escape the specimen.The electrons having loss less energy are those which have travelled less in the specimen and thus escape closer to the electron beam. So, in filtering the energy of the backscattering electron and keeping those which have loss only a small amount of energy to create the image, a significant improvement of the resolution of such images is expected. New detectors are now under development to take advantage of this technique of imaging.

scholarly journals A new methodology for determination of water of crystallization for uranyl nitrate samples using scanning electron microscope, energy dispersive X-ray, and MCPN-5

2019 ◽  
Vol 34 (4) ◽  
pp. 368-374
Author(s):  
Sameh Shaban ◽  
Mohamed Hazzaa ◽  
Rasha El-Tayebany
Keyword(s):  
Monte Carlo ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Uranyl Nitrate ◽  
Nuclear Material ◽  
Energy Dispersive ◽  
Monte Carlo Code ◽  
Suggested Approach ◽  
X Ray ◽  
Scanning Electron

The scanning electron microscope and its attached X-ray unit are valid tools for conducting surveys to determine whether or not the studied samples contain nuclear material. To verify their structure, ten solid uranyl nitrate specimens with various enrichment values (0.1 % to 1 %) were analyzed. The used samples have different numbers of hydrated water molecules; consequently, the properties of these materials in analytical chemistry and computational methods are not the same. Scanning electron microscope and energy dispersive X-ray are used in this work to visualize and analyze the sample of hexahydrate uranyl nitrate (natural 0.72 %). The specimen has been screened under optimal microscopy circumstances. In spite of the reliability of these tools, they are not accurate, particularly when carrying out complete qualitative and quantitative analysis. With the aid of the Monte Carlo code (MCNP-5), the approach presented here can resolve the limitations that tackle the microscope and X-ray testing. The suggested approach relates to the Monte Carlo calculations and X-ray elemental analysis. This relationship depends on the chemical composition of the material and was developed like software. The concentration and count rate calculation software has been established to determine the water of crystallization for uranyl nitrate samples.

Combined Electron Excitation and X-Ray Excitation for Spectrometry in the SEM

2013 ◽  
Vol 21 (4) ◽  
pp. 24-28 ◽  
Author(s):  
Kenny C. Witherspoon ◽  
Brian J. Cross ◽  
Mandi D. Hellested
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Electron Excitation ◽  
X Rays ◽  
X Ray ◽  
Analytical Technique ◽  
Atomic Electrons ◽  
Non Destructive ◽  
Scanning Electron

Energy-dispersive X-ray spectrometry (EDS) is an analytical technique used to determine elemental composition. It is a powerful, easy-to-use, non-destructive technique that can be employed for a wide variety of materials. In this technique the electron beam of the scanning electron microscope (SEM) impinges on the sample and excites atomic electrons causing the production of characteristic X rays. These characteristic X rays have energies specific to elements in the sample. The EDS detector collects these X rays as a signal and produces a spectrum. Samples also can be excited by X rays. Collimated and focused X rays from an X-ray source produce characteristic X rays that can be detected by the same EDS detector. When X rays are used as the source of excitation, the method is then called X-ray fluorescence (XRF) or micro-XRF.

X-Ray Emission of Porous Materials In The Scanning Electron Microscope Computed Using Monte Carlo Simulations

1997 ◽  
Vol 3 (S2) ◽  
pp. 883-884 ◽  
Author(s):  
Raynald Gauvin
Keyword(s):  
Monte Carlo ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Monte Carlo Simulations ◽  
Porous Materials ◽  
Cross Sections ◽  
Quantitative Methods ◽  
Electron Trajectories ◽  
X Ray ◽  
Scanning Electron

Conventional quantitative X-ray microanalysis in the scanning electron microscope or in the electron microprobe is valid for specimens of bulk homogeneous composition and with flat and polished surfaces. Quantitative methods, using X-ray microanalysis and Monte Carlo simulations of electron trajectories in solids, have been developed for the chemical analysis of spherical inclusions embedded in a matrix and for multilayered specimens. In this paper, the effect of porosity and of the size of the pores are investigated concerning their effect on X-ray emission using Monte Carlo simulation of electron trajectories in solids since porous materials are of great technological importance.This new Monte Carlo program uses elastic Mott cross-sections to compute electron trajectories and the Joy & Luo modification of the continuous Bethe law of energy loss and the details are given elsewhere. This program assumes that all the pores are spherical and have the same size.

X-Ray Microanalysis of Materials in the ESEM or VP-SEM

2001 ◽  
Vol 7 (S2) ◽  
pp. 778-779
Author(s):  
Raynald Gauvin
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Incident Beam ◽  
Operating Conditions ◽  
Variable Pressure ◽  
Environmental Scanning ◽  
Copper Strip ◽  
X Ray ◽  
Gas Molecules ◽  
Scanning Electron

When performing X-Ray microanalysis in the ESEM (Environmental Scanning Electron Microscope) or in the VP-SEM (Variable Pressure Scanning Electron Microscope), the operating conditions of the microscope must be optimized. This is to reduce the beam broadening of the incident electrons when they scatter with the gas molecules before entering into the specimen. As a result of this scattering, the incident beam is composed of two parts. The first part of the beam is the unscattered beam and the second part is the scattered beam, named the skirt. in high pressure and long working distances conditions, the diameter of the skirt may extend to several millimeters. in order to show the effect of the skirt on X-Ray generation, a copper strip was placed .5 mm away of the electron beam on a flat Al specimen. The peak to background ratio of the copper line was measured at different pressure (from 25 to 200 Pa) for Air as gas.

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