Rapid Quantitative Analysis by X-Ray Spectrometry

1971 ◽  
Vol 15 ◽  
pp. 164-175 ◽  
Author(s):  
Robert D. Giauque ◽  
Joseph M. Jaklevic
Keyword(s):  
Cross Sections ◽  
Fluorescence Analysis ◽  
Selective Excitation ◽  
Single Element ◽  
X Rays ◽  
Analysis Method ◽  
Yield Data ◽  
X Ray ◽  
Minimum Number ◽  
Sample Dilution

An x-ray fluorescence analysis method applicable to the case of fluorescent spectra excited with monoenergetic x-rays has been developed. The technique employs a minimum number of calibration steps using single element thin film standards and depends upon theoretical cross sections and fluorescent yield data to interpolate from element to element. The samples are treated as thin films and corrections for absorption effects are easily determined- Enhancement effects, if not negligible, are minimized by sample dilution techniques or by selective excitation.

Multielement Analysis of Rubber Samples by X-Ray Fluorescence

1996 ◽  
Vol 50 (11) ◽  
pp. 1373-1377 ◽  
Author(s):  
Peter Kump ◽  
Marijan Nečemer ◽  
Borut Smodiš ◽  
Radojko Jač'Imović
Keyword(s):  
Reference Materials ◽  
Fluorescence Analysis ◽  
Standard Reference Materials ◽  
Single Element ◽  
Rubber Industry ◽  
X Ray ◽  
Minimum Number ◽  
Cheap Alternative ◽  
Rapid Tool ◽  
Absorption Measurements

Destructive elemental analysis of rubber samples for major and trace element constituents is a rather demanding task, mainly because of the need for sophisticated and time-consuming sample preparation procedures. X-ray analysis has so far been used in the rubber industry primarily as a rapid tool for qualitative analysis, but a more realistic estimate of the accuracy of this, in many aspects, advantageous technique indicates that it could qualify as a quantitative method. In this work rubber samples were analyzed by the X-ray fluorescence analysis (XRFA) technique, utilizing Cd-109 and Fe-55 for excitation radioactive sources. The quantification procedure used employed a minimum number of calibration steps, utilizing only single-element-thick standards and stable compounds, or standard reference materials. Matrix correction calculations employed known fundamental constants and absorption measurements on a particular sample. In order to validate the results, and to establish the accuracy of analysis, some samples were also analyzed by neutron activation analysis (NAA). For the same purpose, the analysis of some standard reference materials of biological and inorganic matrices were performed. The accuracy of 5 to 6% achieved by XRFA means that it should be considered in the rubber industry as a rapid, simple, and cheap alternative to the analytical methods usually adopted.

scholarly journals Novel Zeff imaging method for deep internal areas using back-scattered X-rays

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Akio Yoneyama ◽  
Masahide Kawamoto ◽  
Rika Baba
Keyword(s):  
Atomic Number ◽  
Effective Atomic Number ◽  
Chemical Properties ◽  
Fluorescence Analysis ◽  
High Energy ◽  
Single Element ◽  
Imaging Method ◽  
X Rays ◽  
Front Side ◽  
X Ray

AbstractElemental kinds, composition ratios, effective atomic number (Zeff), and spatial distributions are the most basic information on materials and determine the physical and chemical properties of materials. X-ray fluorescence analysis have conventionally been used for elemental mapping, however maps on deep internal areas cannot be obtained because the escape depth of fluorescence X-rays is limited to a few mm from the surface of samples. Herein, we present a novel Zeff imaging method that uses back-scattered X-rays. The intensity ratio of elastic and inelastic back-scattered X-rays depends on the atomic number (Z) of a single-element sample (Zeff for a plural-element sample), and so Zeff maps in deep areas can be obtained by spectrum analysis of the scattered high-energy incident X-rays. We demonstrated the feasibility of observing a phantom covered by an aluminum plate by using synchrotron radiation X-ray. A fine Zeff map that can be used to identify materials was obtained from only front-side observation. The novel method opens up a new way for Zeff mapping of deep areas of thick samples from front-side observation.

Proton Induced X-Ray Fluorescence Analysis Using a Cockcroft-Walton Accelerator

1974 ◽  
Vol 18 ◽  
pp. 299-308
Author(s):  
D. I. Bales ◽  
R. R. Landolt ◽  
W. E. Toll
Keyword(s):  
High Resolution ◽  
Sample Preparation ◽  
Water Sample ◽  
Cross Sections ◽  
Proton Energy ◽  
Fluorescence Analysis ◽  
X Rays ◽  
X Ray ◽  
Beam Currents ◽  
Better Than

AbstractThe production of characteristic x rays by 100-keV protons has been studied to determine the feasibility of using a Cockcroft- Walton accelerator as an excitation source for x ray fluorescence analysis. Because of the low cross sections at this proton energy, it was necessary to concentrate on characteristic x rays below 6 keV and to use beam currents of 10 to 100 μA. The x rays were measured by a high resolution Si(Li) detector.The preparation of various types of samples and the problems that arise when working at low proton energies and high beam currents are discussed.It was found that the technique is useful for low atomic number elements down to less than 1 ppm in a water sample when there are no other significant impurities. When other elements are present, however, proton absorption becomes an important factor and quantitative determinations become very difficult. Proton absorption and its effect upon the usefulness of the technique are discussed.The precision for the technique was determined and found to be better than 20% for most measurements. This includes errors in sample preparation which was considered to be a significant portion of the uncertainty.

Digital x-ray mapping of nanometer-size supported bimetallic catalysts

1988 ◽  
Vol 46 ◽  
pp. 530-531
Author(s):  
L. T. Germinario
Keyword(s):  
Background Radiation ◽  
Metal Cluster ◽  
Single Element ◽  
Beam Diameter ◽  
X Rays ◽  
X Ray ◽  
Major Interest ◽  
Induced Changes

Understanding the role of metal cluster composition in determining catalytic selectivity and activity is of major interest in heterogeneous catalysis. The electron microscope is well established as a powerful tool for ultrastructural and compositional characterization of support and catalyst. Because the spatial resolution of x-ray microanalysis is defined by the smallest beam diameter into which the required number of electrons can be focused, the dedicated STEM with FEG is the instrument of choice. The main sources of errors in energy dispersive x-ray analysis (EDS) are: (1) beam-induced changes in specimen composition, (2) specimen drift, (3) instrumental factors which produce background radiation, and (4) basic statistical limitations which result in the detection of a finite number of x-ray photons. Digital beam techniques have been described for supported single-element metal clusters with spatial resolutions of about 10 nm. However, the detection of spurious characteristic x-rays away from catalyst particles produced images requiring several image processing steps.

An x-ray microprobe based upon a close-coupled focal-spot / glass capillary arrangement

1992 ◽  
Vol 50 (2) ◽  
pp. 1758-1759
Author(s):  
D. A. Carpenter ◽  
M. A. Taylor
Keyword(s):  
Imaging Techniques ◽  
Fluorescence Analysis ◽  
High Sensitivity ◽  
Specimen Preparation ◽  
X Rays ◽  
Glass Capillary ◽  
Close Coupling ◽  
X Ray ◽  
Point To Point ◽  
Beam Damage

The development of intense sources of x rays has led to renewed interest in the use of microbeams of x rays in x-ray fluorescence analysis. Sparks pointed out that the use of x rays as a probe offered the advantages of high sensitivity, low detection limits, low beam damage, and large penetration depths with minimal specimen preparation or perturbation. In addition, the option of air operation provided special advantages for examination of hydrated systems or for nondestructive microanalysis of large specimens.The disadvantages of synchrotron sources prompted the development of laboratory-based instrumentation with various schemes to maximize the beam flux while maintaining small point-to-point resolution. Nichols and Ryon developed a microprobe using a rotating anode source and a modified microdiffractometer. Cross and Wherry showed that by close-coupling the x-ray source, specimen, and detector, good intensities could be obtained for beam sizes between 30 and 100μm. More importantly, both groups combined specimen scanning with modern imaging techniques for rapid element mapping.

XRMF applications of a monolithic, polycapillary, focusing x-ray optic

1996 ◽  
Vol 54 ◽  
pp. 240-241
Author(s):  
D. A. Carpenter ◽  
Ning Gao ◽  
G. J. Havrilla
Keyword(s):  
Trace Elements ◽  
Point Source ◽  
Focal Spot ◽  
Fluorescence Analysis ◽  
X Rays ◽  
Focal Distance ◽  
Spot Diameter ◽  
X Ray ◽  
Focal Spot Diameter

A monolithic, polycapillary, x-ray optic was adapted to a laboratory-based x-ray microprobe to evaluate the potential of the optic for x-ray micro fluorescence analysis. The polycapillary was capable of collecting x-rays over a 6 degree angle from a point source and focusing them to a spot approximately 40 µm diameter. The high intensities expected from this capillary should be useful for determining and mapping minor to trace elements in materials. Fig. 1 shows a sketch of the capillary with important dimensions.The microprobe had previously been used with straight and with tapered monocapillaries. Alignment of the monocapillaries with the focal spot was accomplished by electromagnetically scanning the focal spot over the beveled anode. With the polycapillary it was also necessary to manually adjust the distance between the focal spot and the polycapillary.The focal distance and focal spot diameter of the polycapillary were determined from a series of edge scans.

How to Use the Features of Total Reflection of X-Rays for Energy Dispersive XRF

1988 ◽  
Vol 32 ◽  
pp. 105-114 ◽  
Author(s):  
H. Schwenke ◽  
W. Berneike ◽  
J. Knoth ◽  
U. Weisbrod
Keyword(s):  
Thin Films ◽  
Penetration Depth ◽  
Fluorescence Analysis ◽  
Total Reflection ◽  
X Rays ◽  
X Ray ◽  
Characteristic Features ◽  
Respective Characteristic ◽  
Nanometer Regime ◽  
Sensitive Method

AbstractThe total reflection of X-rays is mainly determined by three parameters , that is the orltical angle, the reflectivity and the penetration depth. For X-ray fluorescence analysis the respective characteristic features can be exploited in two rather different fields of application. In the analysis of trace elements in samples placed as thin films on optical flats, detection limits as low as 2 pg or 0.05 ppb, respectively, have been obtained. In addition, a penetration depth in the nanometer regime renders Total Reflection XRF an inherently sensitive method for the elemental analysis of surfaces. This paper outlines the main physical and constructional parameters for instrumental design and quantitation in both branches of TXRF.

ASSESSMENT OF OSTEOARTHRITIS INITIATIVE–KELLGREN AND LAWRENCE SCORING PROJECTS QUALITY USING COMPUTER ANALYSIS

2010 ◽  
Vol 13 (04) ◽  
pp. 197-201 ◽  
Author(s):  
Lior Shamir ◽  
David T. Felson ◽  
Luigi Ferrucci ◽  
Ilya G. Goldberg
Keyword(s):  
Image Analysis ◽  
Gold Standard ◽  
Population Studies ◽  
Detection Accuracy ◽  
X Rays ◽  
Analysis Method ◽  
Image Analysis Method ◽  
X Ray ◽  
Osteoarthritis Initiative ◽  
Kellgren And Lawrence

The detection of knee osteoarthritis (OA) is a subjective task, and even two highly experienced and well-trained readers might not always agree on a specific case. This problem is noticeable in OA population studies, in which different scoring projects provide significantly different scores for the same knee X-rays. Here we propose a method for quantitative assessment and comparison of knee X-ray scoring projects in OA population studies. The method works by applying an image analysis method that automatically detects OA in knee X-ray images, and comparing the consistency of the scores when using each of the scoring projects as "gold standard." The method was applied to compare the osteoarthritis initiative (OAI) clinic reading derived Kellgren and Lawrence (K&L) scores to central reading, and showed that when using the derived K&L scores the automatic image analysis method was able to accurately differentiate between healthy joints and moderate OA joints in ~70% of the cases. When the OAI central reading scores were used as gold standard, the detection accuracy was elevated to ~77%. These results show that the OAI central readings scores are more consistent with the X-rays, indicating that the central reading better reflects the radiographic features associated with OA, compared to the OAI K&L scores derived from clinic readings.

scholarly journals Photoproduction of H3+ from gaseous methanol inside dense molecular clouds

2008 ◽  
Vol 4 (S251) ◽  
pp. 369-370
Author(s):  
S. Pilling ◽  
D. P. P. Andrade ◽  
A. C. F. Santos ◽  
H. M. Boechat-Roberty
Keyword(s):  
Cross Sections ◽  
Molecular Clouds ◽  
Mass Spectra ◽  
Column Density ◽  
X Rays ◽  
Alternative Source ◽  
X Ray ◽  
Flight Mass Spectrometry ◽  
Dense Molecular Cloud ◽  
Synchrotron Light

AbstractWe present experimental results obtained from photoionization and photodissociation processes of abundant interstellar methanol (CH3OH) as an alternative route for the production of H3+ in dense clouds. The measurements were taken at the Brazilian Synchrotron Light Laboratory (LNLS) employing soft X-ray and time-of-flight mass spectrometry. Mass spectra were obtained using the photoelectron-photoion coincidence techniques. Absolute averaged cross sections for the production of H3+ due to molecular dissociation of methanol by soft X-rays (C1s edge) were determined. The H3+'s photoproduction rate and column density were been estimated adopting a typical soft X-ray luminosity inside dense molecular and the observed column density of methanol. Assuming a steady state scenario, the highest column density value for the photoproduced H3+ was about 1011 cm2, which gives the ratio photoproduced/observed of about 0.05%, as in the case of dense molecular cloud AFGL 2591. Despite the small value, this represent a new and alternative source of H3+ into dense molecular clouds and it is not been considered as yet in interstellar chemistry models.

Destruction of C2H4O2 isomers in ice-phase by X-rays: Implication on the abundance of acetic acid and methyl formate in the interstellar medium

2017 ◽  
Vol 13 (S332) ◽  
pp. 418-424
Author(s):  
Marina G. Rachid ◽  
K. Faquine ◽  
S. Pilling
Keyword(s):  
Acetic Acid ◽  
Cross Sections ◽  
Methyl Formate ◽  
X Rays ◽  
Formation Cross Section ◽  
X Ray ◽  
Synchrotron Light ◽  
The Difference ◽  
Astrophysical Ices

AbstractC2H4O2 isomers, methyl formate (HCOOCH3), acetic acid (CH3COOH) and glycoaldehyde (HOCH2CHO), have been detected in a lot of sources in ISM. However, their abundances are very different, with methyl formate much more abundant than the other two isomers. This fact may be related to the different destruction by ionizing radiation of these molecules. The goal of this work is experimentally study the photodissociation processes of methyl formate and acetic acid ices when exposed to broadband soft X-ray from 6 up to 2000 eV. The experiments were performed coupled to the SGM beamline in the Brazilian Synchrotron Light Source (LNLS/CNPEM) at Campinas, Brazil. The simulated astrophysical ices (12K) were monitored throughout the experiment using infrared vibrational spectroscopy. The analysis of processed ices allowed the determination of the effective destruction cross sections of the parent molecules as well as the effective formation cross section of daughter molecular species. The relative abundance between acetic acid and methyl formate (NCH3COOH/NHCOOCH3) in different astronomical scenarios and their column density evolution in the presence of X-rays were calculated and our results suggests that such radiation field can be one of the factors that explain the difference in the isomers C2H4O2 abundances. We also quantified the daugther species after the establishment of a chemical equilibrium in the samples.

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