scholarly journals Periodic Multilayer for X-ray Spectroscopy in the Li K Range

2021 ◽  
Vol 11 (14) ◽  
pp. 6385
Author(s):  
Vladimir Polkonikov ◽  
Nikolai Chkhalo ◽  
Roman Pleshkov ◽  
Angelo Giglia ◽  
Nicolas Rividi ◽  
...  
Keyword(s):  
Magnetron Sputtering ◽  
Spectral Range ◽  
Electron Microprobe ◽  
Incident Energy ◽  
High Order ◽  
X Ray ◽  
Glancing Angle ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes ◽  
Scanning Electron

X-ray spectroscopy of lithium is very difficult, even impossible, with wavelength dispersive spectrometers commonly deployed on scanning electron microscopes or electron microprobe analyzers. This is due to the absence of crystals and lack of efficient periodic multilayer for this spectral range, around 50 eV. To address this issue, we propose using a Be/Si/Al multilayer having a period of about 29 nm. The multilayer was deposited by magnetron sputtering and its reflectivity measured as a function of the glancing angle in the spectral range of the Li K emission and as a function of the incident energy up to ~200 eV. This characterization demonstrates that the designed multilayer is suitable to efficiently perform spectroscopy in the range of the Li K emission in terms of reflectance (0.32 at 51.5 eV), bandwidth (around 3.5 eV) and rejection of high order diffracted radiation.

Standardless quantitative x-ray analysis

1992 ◽  
Vol 50 (2) ◽  
pp. 1650-1651
Author(s):  
Jean-Louis pouchou ◽  
Françoise Pichoir
Keyword(s):  
Electron Microprobe ◽  
Basic Data ◽  
Light Elements ◽  
X Ray ◽  
Quantitative Results ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes ◽  
Scanning Electron

The ϕ(ρz) models developed during the recent years (Gaussian, PAP, XPP) have been shown by several authors to improve significantly the capability of quantitative x-ray microanalysis, mainly in the field of light elements, tilted specimens, and layered specimens. An increasing number of users is now able to take advantage of these models, since some of them have been implemented in EPMA or EDS commercial softwares.However, most of the reported successful applications are the result of analyses with standards, where the basic data are the relative x-ray intensities (also called k-ratios). Indeed, analyses with standards are well adapted to the electron microprobes, and permit to obtain very accurate results. But in the scanning electron microscopes (SEM), the operations of acquiring, processing and handling the EDS spectra of all the required standards are really time consuming. It is why an EDS standardless mode giving satisfactory quantitative results would be so useful, even for those laboratories which can also operate an electron microprobe for the applications requiring the highest degree of accuracy.

scholarly journals Creep Failure of Reformer Tubes in a Petrochemical Plant

Metals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 1026 ◽  
Author(s):  
Abbas Bahrami ◽  
Peyman Taheri
Keyword(s):  
High Temperature ◽  
Void Coalescence ◽  
Petrochemical Plant ◽  
Creep Failure ◽  
X Ray ◽  
Carbide Phases ◽  
Electron Microscopes ◽  
Reformer Tubes ◽  
Scanning Electron Microscopes ◽  
Scanning Electron

This paper investigates a failure in HP-Mod radiant tubes in a petrochemical plant. Tubes fail after 90,000 h of working at 950 °C. Observed failure is in the form of excessive bulging and longitudinal cracking in reformer tubes. Cracks are also largely branched. The microstructure of service-exposed tubes was evaluated using optical and scanning electron microscopes (SEM). Energy-dispersive X-ray spectroscopy (EDS) was used to analyze and characterize different phases in the microstructure. The results of this study showed that carbides are coarsened at both the inner and the outer surface due to the long exposure to a carburizing environment. Metallography examinations also revealed that there are many creep voids that are nucleated on carbide phases and scattered in between dendrites. Cracks appeared to form as a result of creep void coalescence. Failure is therefore attributed to creep due to a long exposure to a high temperature.

Mini-Scanning Electron Miscroscope Concept

1974 ◽  
Vol 32 ◽  
pp. 406-407
Author(s):  
Donald J. Evins ◽  
Robert J. Engle
Keyword(s):  
Electron Microscope ◽  
Depth Of Field ◽  
X Ray ◽  
Rapid Scan ◽  
Operational Characteristics ◽  
Electron Microscopes ◽  
The Cost ◽  
Scanning Electron Microscopes ◽  
Large Research ◽  
Scanning Electron

The scanning electron microscope has already established itself as one of the most useful instrument developments in recent years. The SEM provides 20 times greater useful magnifications and up to 500 times greater depth of-field than the best optical microscopes. Until the introduction of the Mini-SEM concept, the cost and complexity of SEM's has limited their use primarily to large research oriented laboratories.Design features, specifications, and operational characteristics will be reviewed. The Mini-Rapid Scan with resolution of 750Å will be described, along with the Mini-SEM with resolution of 150 to 200Å. Both of these are table top scanning electron microscopes. Various specimen stage options will be illustrated. Other accessories extending the SEM's versatility will be described, such as the energy dispersive x-ray system

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.

Take-off Angle Imaging: A New Image Mode for Scanning Electron Microscopy

2013 ◽  
Vol 21 (3) ◽  
pp. 22-25
Author(s):  
Nicholas C. Barbi ◽  
Richard B. Mott
Keyword(s):  
Electrical Current ◽  
Avalanche Photodiode ◽  
Si Substrate ◽  
Silicon Photomultiplier ◽  
Silicon Photomultipliers ◽  
X Ray ◽  
Backscattered Electron ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes ◽  
Scanning Electron

Traditional electron detectors for scanning electron microscopes (SEMs) are the Everhart-Thornley detector located on one side of the specimen and the overhead backscattered electron detector (BSED), usually mounted under the final lens. In 2011 PulseTor introduced an efficient BSED based on scintillator/silicon photomultipler technology that is small enough to be mounted on the tip of an X-ray detector. The scintillator converts the electron signal to light, which is in turn converted to an electrical current in the silicon photomultiplier (SiPM). Silicon photomultipliers were initially developed in Russia in the 1990s. The review article by Dolgoshein et al. cites much of the historical development. Following the recent work of Piemonte and others, the SiPM consists of an array of many identical and independent detecting elements (microcells) connected in parallel on a common Si substrate. Each microcell is an avalanche photodiode only tens of micrometers in size.

scholarly journals Sensitivity Analysis of X-ray Spectra from Scanning Electron Microscopes

2014 ◽  
Author(s):  
Thomas Martin Miller ◽  
Bruce W. Patton ◽  
Charles F. Weber ◽  
Kursat B. Bekar
Keyword(s):  
Sensitivity Analysis ◽  
X Ray ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes ◽  
Scanning Electron

Importance of the relative x-ray line intensities

1992 ◽  
Vol 50 (2) ◽  
pp. 1636-1637
Author(s):  
János L. Lábár ◽  
Charles E. Fiori ◽  
Robert L. Myklebust
Keyword(s):  
Rare Earth ◽  
Energy Dispersive Spectrometry ◽  
X Ray ◽  
Line Intensities ◽  
Elemental Concentrations ◽  
Wavelength Dispersive Spectrometry ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes ◽  
Standardless Analysis ◽  
Scanning Electron

Relative intensities of the non-analytical lines of an element (as compared to the analytical X-ray line of the same element) directly affect the accuracy of quantitative X-ray microanalysis. Correct spectral deconvolution can only be based on the knowledge of these relative intensities. Not even wavelength dispersive spectrometry (WDS) is free from spectral overlaps, making deconvolution of the X-ray lines necessary. A typical example for such a serious overlap can be the L line series of different rare-earth elements simultaneously present in the same sample. Energy dispersive spectrometry (EDS) is even more affected. Many EDS systems are equipped on scanning electron microscopes (SEM). Quick standardless analysis is frequently in use in these systems. Starting approximation of the elemental concentrations are based on computed "standard intensities" in contrast to measured ones in full quantitative analysis. Computation of the generated standard intensities directly contain the relative intensities of other lines too.

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.

Electron microprobe analysis under conditions of non-normal Electron beam incidence

2000 ◽  
Vol 6 (S2) ◽  
pp. 922-923
Author(s):  
E. Lifshin ◽  
R. Gauvin
Keyword(s):  
Electron Microprobe ◽  
Microprobe Analysis ◽  
Electron Microprobe Analysis ◽  
Normal Incidence ◽  
Radial Symmetry ◽  
X Ray ◽  
Detection Systems ◽  
Electron Microscopes ◽  
Normal Electron ◽  
Scanning Electron Microscopes

From its inception, electron microprobe analysis was almost exclusively done under conditions of normal electron probe incidence. The radial symmetry of this geometry greatly simplified the development of quantitative equations, and these equations where further refined based on large amounts of data also collected at normal incidence. However, as x-ray detection systems where added to scanning electron microscopes (SEMs), samples were often viewed under conditions of non-normal incidence and attempts were made to modify the various correction procedures to give acceptable quantitative results. Little justification for these methods has ever been published and so the current study was undertaken to compare theoretically calculated x-ray emission from a well characterized sample, in this case NiAl (.685 wt. % Ni, .315 wt. %A1) with experimentally measured results collected as a function of tilt angle. The theoretical calculation where done using a Monte Carlo (MC) program developed by Gauvin and Lifshin.

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.

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