Mosaic Mapping: A Means of Tiling Images to Shorten Acquisition Speed for Lower - Magnification SEM Images and Wavelength Dispersive Spectrometers (WDS) X-Ray Maps

1996 ◽  
Vol 54 ◽  
pp. 438-439
Author(s):  
J.D. Geller ◽  
C.R. Herrington
Keyword(s):  
Limiting Factors ◽  
X Rays ◽  
Angular Range ◽  
Acceptance Angle ◽  
Sem Images ◽  
Worst Case ◽  
X Ray ◽  
Focusing Distance ◽  
Layered Crystals ◽  
Working Distance

The minimum magnification for which an image can be acquired is determined by the design and implementation of the electron optical column and the scanning and display electronics. It is also a function of the working distance and, possibly, the accelerating voltage. For secondary and backscattered electron images there are usually no other limiting factors. However, for x-ray maps there are further considerations. The energy-dispersive x-ray spectrometers (EDS) have a much larger solid angle of detection that for WDS. They also do not suffer from Bragg’s Law focusing effects which limit the angular range and focusing distance from the diffracting crystal. In practical terms EDS maps can be acquired at the lowest magnification of the SEM, assuming the collimator does not cutoff the x-ray signal. For WDS the focusing properties of the crystal limits the angular range of acceptance of the incident x-radiation. The range is dependent upon the 2d spacing of the crystal, with the acceptance angle increasing with 2d spacing. The natural line width of the x-ray also plays a role. For the metal layered crystals used to diffract soft x-rays, such as Be - O, the minimum magnification is approximately 100X. In the worst case, for the LEF crystal which diffracts Ti - Zn, ˜1000X is the minimum.

scholarly journals X-ray Analysis in the Low Vacuum SEM (Part 3 of 3)

1998 ◽  
Vol 6 (10) ◽  
pp. 10-13
Author(s):  
Don Chernoff
Keyword(s):  
Electron Beam ◽  
Path Length ◽  
Experimental Methods ◽  
Gas Pressure ◽  
Operating Conditions ◽  
X Rays ◽  
X Ray ◽  
Software Models ◽  
Working Distance ◽  
Low Vacuum Sem

In this third and final installment on x-ray analysis in the environmental and low vacuum SEM, I will present experimental methods for measuring beam scatter. In my previous two articles I discussed how operating conditions detemine beam scatter. It was shown that the type of gas used, the gas pressure in the chamber, the working distance or beam gas path length, and the accelerating voltage all have an effect on how much the electron beam scatters. I also discussed how the beam scatter influences x-ray results by producing x-rays beyond the area of the primary beam. Furthermore, I showed how software models could be used to determine the amount of beam scatter based on different combinations of the four variables (pressure, gas, working distance, and kV).

Investigation of Elemental Analysis of Water Samples by Radioalpha Induced X-Ray Emission Spectroscopy*

1974 ◽  
Vol 18 ◽  
pp. 333-342
Author(s):  
R. Hight ◽  
C. C. Foster
Keyword(s):  
Water Samples ◽  
Background Radiation ◽  
Trace Element Analysis ◽  
Alpha Particles ◽  
Particle Accelerators ◽  
X Rays ◽  
Element Analysis ◽  
Worst Case ◽  
Helium Atmosphere ◽  
X Ray

AbstractAlpha particles and protons from charged particle accelerators and photons from both x-ray tubes and radioactive sources have been shown to be useful for the excitation of characteristic x-rays for multi-element energy dispersive trace analysis of environmental samples to the few ppm range. We have investigated the use of 4.5 MeV alpha particles from a thin window Po-210 source of 5 mCi effective strength to directly excite x-rays from trace elements in 1 cc water samples evaporated on 1.75 mg/cm2 thick mylar backings in a helium atmosphere in a lucite enclosure. Minimum detectable amounts (MDA's) were established for 19 elements (22 ≤ Z ≤ 82) using K-, L- and M- radiation and 50 minute counting times. The smallest MDA determined was 0.11 μg for vanadium. Other representative MDA's, in μg, are Fe-0.54, Mo-0.31 and Pb-0.43. MDA's lower by an average factor of about 10 over an eight month source life would result from the use of 1 Ci of Po-210 for 50 minutes per sample. Thinner sample backings and improved source encapsulation will reduce background radiation and further improve sensitivity. Comparison of our MDA's (5 mCi-Po-210) with those of Blasius et al., who used radiophoton sources and 40,000 sec. counting times to determine trace metal pollutants in water samples, shows radioalpha excitation to have comparable sensitivity in the worst case, arsenic and better, by more than two orders of magnitude, sensitivity in the best case, vanadium.Radioalpha induced x-ray trace element analysis offers the same advantages of portability, ease of operation, low maintenance and cost, and "in house" availability as radiophoton induced analysis. Because of the availability of more intense sources (up to 10 Ci), the fact that the detected radiation (x-rays) differs from the excitation radiation (a-particles) and that K, L, and M x-ray emission cross-sections depend essentially only on the emitted x-ray energy, lower MDA's are obtainable for many elements in thin samples for comparable counting times, as well.

scholarly journals Implementation of a crossed-slit system for fast alignment of sealed polycapillary X-ray optics

2020 ◽  
Vol 27 (6) ◽  
pp. 1730-1733
Author(s):  
Anna Zymaková ◽  
Krishna Khakurel ◽  
Alessandra Picchiotti ◽  
Wojciech Błachucki ◽  
Jakub Szlachetko ◽  
...  
Keyword(s):  
X Rays ◽  
Acceptance Angle ◽  
Ray Optics ◽  
X Ray ◽  
Starting Point ◽  
User Facility ◽  
3D Printed ◽  
Good Starting Point ◽  
Slit System ◽  
Jet Plasma

A new modification of a table-top laser-driven water-jet plasma X-ray source has been successfully implemented and commissioned at the Extreme Light Infrastructure (ELI) Beamlines user facility. In order to preserve the broadband nature of the source for spectroscopic experiments, a polycapillary lens was initially chosen as the focusing element. Generally, polycapillary X-ray optics have a narrow photon acceptance angle and small field of view, making alignment complicated and time-consuming. This contribution demonstrates a straightforward, reliable and reproducible procedure for aligning polycapillary focusing optics with broadband X-rays. The method involves a pre-alignment step where two X-ray slits are mounted orthogonally on opposite sides of a 3D-printed cylindrical polycapillary holder. This helps to precisely determine the optical axis of the X-ray beam. Subsequent mounting of the polycapillary in the pre-aligned holder with the slits removed allowed for immediate transmission of the X-ray photons through the optics and has provided a good starting point for fine alignment.

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.

scholarly journals Focusing X-Rays with Curved Multiplate Crystal Cavity

2010 ◽  
Vol 2010 ◽  
pp. 1-7 ◽  
Author(s):  
Ying-Yi Chang ◽  
Sung-Yu Chen ◽  
Shih-Chang Weng ◽  
Chia-Hung Chu ◽  
Mau-Tsu Tang ◽  
...  
Keyword(s):  
Focal Length ◽  
Silicon Crystal ◽  
Incident Beam ◽  
Cavity Resonance ◽  
X Rays ◽  
Ultrahigh Energy ◽  
Acceptance Angle ◽  
Transmitted Beam ◽  
X Ray ◽  
Focusing Effect

An overview is given of the study on X-ray focusing using the Fabry-Perot type multi-plate silicon crystal cavities consisting of compound refractive lenses. Silicon (12 4 0) is used as the back reflection for cavity resonance at the photon energy of 14.4388 keV. Measurements of focal length of the transmitted beam through the crystal cavities show enhanced focusing effect due to the presence of back diffraction. Also, an incident beam with ultrahigh energy resolution can improve the focusing owing to the wider acceptance angle of the back diffraction. Considerations based on the excitation of dispersion surface within the framework of X-ray dynamical diffraction theory are also presented to reveal the origin of this enhanced focusing.

Optimization of multilayer Laue lenses for a scanning X-ray microscope

2012 ◽  
Vol 20 (1) ◽  
pp. 89-97 ◽  
Author(s):  
Hanfei Yan ◽  
Yong S. Chu
Keyword(s):  
Light Source ◽  
Careful Consideration ◽  
Nanometer Scale ◽  
X Rays ◽  
National Synchrotron Light Source ◽  
X Ray ◽  
Synchrotron Light ◽  
Working Distance

Multilayer Laue lenses (MLLs) have demonstrated great capabilities for efficiently focusing hard X-rays down to the nanometer scale. Optimized use of MLLs in a scanning X-ray microscope requires careful consideration of a number of practical parameters other than resolution and efficiency in order to optimize the microscope's performance and scientific throughput. Here, relationships among the apodization effect owing to the presence of a beamstop, the monochromaticity requirement and the allowable working distance are discussed, as well as their impacts on the performance of the optics. Based on these discussions, optimal MLL schemes aiming at 10 nm resolution for a scanning X-ray microscope for the Hard X-ray Nanoprobe (HXN) beamline at National Synchrotron Light Source II are presented.

scholarly journals The Effect of Gas Type on Beam Scatter

1998 ◽  
Vol 6 (7) ◽  
pp. 12-13
Author(s):  
Don Chernoff
Keyword(s):  
Primary Beam ◽  
Chamber Pressure ◽  
X Rays ◽  
X Ray ◽  
Working Distance ◽  
Low Vacuum Sem

Last month I addressed the phenomena of beam scatter in the environmental and low vacuum SEM. In that article I covered how beam scatter is affected by chamber pressure, working distance, and accelerating voltage. To briefly summarize, beam scatter becomes worse at higher chamber pressure, longer working distance, and lower accelerating voltages. As the beam scatters, electrons strike the sample some distance away from the primary beam and as a result, generate X-rays from unwanted areas of the sample. It is advantageous for the analyst to keep beam scatter to a minimum to reduce the generation of these X-ray signals. Under conditions of high chamber pressure, long working distance, and low accelerating voltage, it is possible for electrons from the beam to strike the sample on the order of a millimeter or more from the primary beam.

One-Dimensional, Curved, Position-Sensitive Detector for X-Ray Diffractometry

1982 ◽  
Vol 26 ◽  
pp. 269-274 ◽  
Author(s):  
B. Sleaford ◽  
V. Perez-Mendez ◽  
C.N.J. Wagner
Keyword(s):  
Delay Line ◽  
Position Sensitive Detector ◽  
Gas Mixture ◽  
X Rays ◽  
Angular Range ◽  
Sensitive Detector ◽  
Crystalline Materials ◽  
One Dimensional ◽  
X Ray ◽  
Position Sensitive

AbstractA curved, one-dimensional position-sensitive detector has been designed and constructed for the measurement of the scattering patterns from non-crystalline materials. The chamber is a one-dimensional, pressurized, gas-filled detector with delay line readout for position encoding. It covers an angular range of 45° in 2θ, and its quantum efficiency is 80% and 50% for 17.5 and 60 KeV x-rays, respectively, when using a Xe-20%CO2 gas mixture at 7 atm.

Examination of CoNiCu thin films by using XRF and XRD

2014 ◽  
Vol 92 (5) ◽  
pp. 435-439 ◽  
Author(s):  
Ö. Söğüt ◽  
Ç. Dönük ◽  
G. Apaydın ◽  
Ö.F. Bakkaloğlu
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
X Rays ◽  
X Ray Diffraction ◽  
Sem Images ◽  
X Ray ◽  
Radioisotope Source ◽  
Surface Morphologies ◽  
Xrf Spectroscopy ◽  
Fcc Structure

A series of thin films of CoNiCu and NiCu produced using the electrodeposition method have been examined using X-ray fluorescence (XRF), X-ray diffraction (XRD), and scanning electron microscopy (SEM). Energy dispersive XRF spectroscopy was used to determine the concentrations of the atomic percentage in these films. CoNiCu and NiCu thin film samples were excited by gamma rays with 59.5 keV energy photons from 100 mCi 241Am radioisotope source. K X-rays emitted by samples were counted by an Ultra-LEGe detector having a resolution of 150 eV at 5.9 keV. Structural analyses of these films have been done using the XRD technique and thin films were found to have a face-centred cubic (fcc) structure. In addition, surface morphologies of the films have been analysed by SEM. If one examines the SEM images of thin film samples, it can be seen that these elements have been homogeneously distributed in the samples of the thin films.

White-Light Coronal Structures: Streamers and CMEs

1994 ◽  
Vol 144 ◽  
pp. 82
Author(s):  
E. Hildner
Keyword(s):  
Emission Line ◽  
Electron Density ◽  
White Light ◽  
Coronal Mass Ejections ◽  
X Rays ◽  
Solar Cycles ◽  
Temperature Function ◽  
X Ray ◽  
Eclipse Observations ◽  
Coronal Structures

AbstractOver the last twenty years, orbiting coronagraphs have vastly increased the amount of observational material for the whitelight corona. Spanning almost two solar cycles, and augmented by ground-based K-coronameter, emission-line, and eclipse observations, these data allow us to assess,inter alia: the typical and atypical behavior of the corona; how the corona evolves on time scales from minutes to a decade; and (in some respects) the relation between photospheric, coronal, and interplanetary features. This talk will review recent results on these three topics. A remark or two will attempt to relate the whitelight corona between 1.5 and 6 R⊙to the corona seen at lower altitudes in soft X-rays (e.g., with Yohkoh). The whitelight emission depends only on integrated electron density independent of temperature, whereas the soft X-ray emission depends upon the integral of electron density squared times a temperature function. The properties of coronal mass ejections (CMEs) will be reviewed briefly and their relationships to other solar and interplanetary phenomena will be noted.

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