scholarly journals Quantitative analysis by energy dispersive X-ray fluorescence by the transmission method applied to geological samples

1994 ◽  
Vol 51 (2) ◽  
pp. 197-206 ◽  
Author(s):  
S.M. Simabuco ◽  
V.F. Nascimento Filho
Keyword(s):  
Atomic Number ◽  
Energy Dispersive ◽  
X Rays ◽  
Geological Samples ◽  
Transmission Method ◽  
Absorption Effect ◽  
X Ray ◽  
Fundamental Parameters ◽  
Absorption Correction

Three certified samples of different matrices (Soil-5, SL-1/IAEA and SARM-4/SABS) were quantitatively analysed by energy dispersive X-ray fluorescence with radioisotopic excitation. The observed errors were about 10-20% for the majority of the elements and less than 10% for Fe and Zn in the Soil-5, Mn in SL-1, and Ti, Fe and Zn in SARM-4 samples. Annular radioactive sources of Fe-55 and Cd-109 were utilized for the excitation of elements while a Si(Li) semiconductor detector coupled to a multichannel emulation card inserted in a microcomputer was used for the detection of the characteristic X-rays. The fundamental parameters method was used for the determination of elemental sensitivities and the irradiator or transmission method for the correction of the absorption effect of characteristic X-rays of elements on the range of atomic number 22 to 42 (Ti to Mo) and excitation with Cd-109. For elements in the range of atomic number 13 to 23 (Al to V) the irradiator method cannot be applied since samples are not transparent for the incident and emergent X-rays. In order to perform the absorption correction for this range of atomic number excited with Fe-55 source, another method was developed based on the experimental value of the absorption coefficients, associated with absorption edges of the elements.

Absorption Correction Curves Obtained from Measurements of the Production of X-Rays as a Function of Depth

1972 ◽  
Vol 16 ◽  
pp. 198-205
Author(s):  
J.D. Brown ◽  
L. Parobek
Keyword(s):  
Electron Probe Microanalysis ◽  
Electron Probe ◽  
X Rays ◽  
Matrix Elements ◽  
X Ray ◽  
Absorption Correction ◽  
Correction Equations

AbstractMeasurements of x-ray production as a function of depth in a sample (ϕ(ρz) curves) are fundamental to the determination of the quantitative equations for relating x-ray intensity to composition in electron probe microanalysis. These ϕ(ρz) curves have been measured for four different voltages and a number of different tracers in aluminum, copper, silver arid gold as matrix elements. From these ϕ(ρz) curves the absorption correction curves (f(x) curves) can be calculated. Such curves have been obtained and comparison is made with the absorption correction equations of Philibert. The effect of a tilted sample on the absorption correction is also discussed.

Oxford HEXameter: Laboratory High Energy X-Ray Diffractometer for Bulk Residual Stress Analysis

2006 ◽  
Vol 524-525 ◽  
pp. 743-748 ◽  
Author(s):  
Alexander M. Korsunsky ◽  
Shu Yan Zhang ◽  
Daniele Dini ◽  
Willem J.J. Vorster ◽  
Jian Liu
Keyword(s):  
Accurate Determination ◽  
High Energy ◽  
Energy Dispersive ◽  
Detector Response ◽  
X Rays ◽  
X Ray Diffraction ◽  
X Ray ◽  
New Instrument ◽  
Synchrotron Beamlines

Diffraction of penetrating radiation such as neutrons or high energy X-rays provides a powerful non-destructive method for the evaluation of residual stresses in engineering components. In particular, strain scanning using synchrotron energy-dispersive X-ray diffraction has been shown to offer a fast and highly spatially resolving measurement technique. Synchrotron beamlines provide best available instruments in terms of flux and low beam divergence, and hence spatial and measurement resolution and data collection rate. However, despite the rapidly growing number of facilities becoming available in Europe and across the world, access to synchrotron beamlines for routine industrial and research use remains regulated, comparatively slow and expensive. A laboratory high energy X-ray diffractometer for bulk residual strain evaluation (HEXameter) has been developed and built at Oxford University. It uses a twin-detector setup first proposed by one of the authors in the energy dispersive X-ray diffraction mode and allows simultaneous determination of macroscopic and microscopic strains in two mutually orthogonal directions that lie approximately within the plane normal to the incident beam. A careful procedure for detector response calibration is used in order to facilitate accurate determination of lattice parameters by pattern refinement. The results of HEXameter measurements are compared with synchrotron X-ray data for several samples e.g. made from a titanium alloy and a particulate composite with an aluminium alloy matrix. Experimental results are found to be consistent with synchrotron measurements and strain resolution close to 2×10-4 is routinely achieved by the new instrument.

Application of Energy Dispersive X-ray Fluorescence Spectrometry to the Determination of Copper, Manganese, Zinc, and Sulfur in Grass (Lolium perenne) in Grazed Agricultural Systems

2018 ◽  
Vol 72 (11) ◽  
pp. 1661-1673 ◽  
Author(s):  
Karen Daly ◽  
Anna Fenelon
Keyword(s):  
Excellent Agreement ◽  
Energy Dispersive ◽  
Emission Spectrometry ◽  
Icp Oes ◽  
X Ray ◽  
Fundamental Parameters ◽  
True Value ◽  
Calibration Methods ◽  
Conventional Methods

Conventional methods for the determination of major nutrients and trace elements in grass rely on acid digestion followed by analysis using inductively coupled plasma optical emission spectrometry (ICP-OES), which can be both time consuming and costly. Energy dispersive X-ray fluorescence (EDXRF) spectrometry offers a rapid alternative that can determine multiple elements in a single scan. Copper, Mn, Zn, and S in grass samples were determined using EDXRF with a number of different calibration approaches using both empirical standards and the theoretical relationships between concentrations and intensities. Using an existing archive of 467 grass samples of known concentrations, a suite of 30 samples was selected as empirical grass standards to build a calibration set between sample concentrations and EDXRF intensities. The theoretical or standardless approach used the fundamental parameters method to determine element concentrations. To validate the two calibration methods, 59 samples were randomly selected from the same archive and database and analyzed by EDXRF. The measurements of Cu, Mn, Zn, and S were compared with the ICP-OES values using agreement statistics. An excellent correlation was observed between the concentrations determined by EDXRF and ICP-OES ( R > 0.90) regardless of the calibration approach. However, agreement and closeness to the true value varied and were assessed using agreement statistics. Across all elements, the empirically calibrated samples were in excellent agreement with the values determined by ICP-OES. The theoretical calibrations provided excellent agreement for Mn and Zn, but a degree of fixed and proportional bias was observed in the Cu and S values. Fixed bias was corrected by subtracting the computed bias from the EDXRF concentrations and improved the overall agreement. Similarly, proportional bias was corrected using the linear regression model to predict the corrected EDXRF values. This improved the overall agreement with the ICP-OES values for both Cu and S using corrected fundamental parameters calibrations. This study provides a practical basis for the use of EDXRF to determine Cu, Mn, Zn, and S in grass samples to monitor forage quality in grazed systems without the need for sample digestion. The observed fixed and proportional bias in the theoretical calibrations can be corrected provided that a good correlation exists between EDXRF and conventional methods.

Energy-Dispersive X-Ray Techniques for Accurate Heavy Element Assay

1986 ◽  
Vol 30 ◽  
pp. 285-292 ◽  
Author(s):  
H. Ottmar ◽  
H. Eberle ◽  
P. Matussek ◽  
I. Michel-Piper
Keyword(s):  
Absorption Edge ◽  
Heavy Element ◽  
Accurate Determination ◽  
Energy Dispersive ◽  
X Rays ◽  
Specific Absorption ◽  
X Ray ◽  
Xrf Analysis ◽  
Analysis Technique

Energy-dispersive X-ray techniques can be employed in two different ways for the accurate determination of element concentrations in specimens: (1) spectrometry of fluoresced characteristic X-rays as widely applied in the various modes of the traditional XRF analysis technique, and (2) spectrometry of the energy-differential transmittance of an X-ray continuum at the element-specific absorption-edge energies.

K shell absorption jump ratios and jump factor measurements for some elements in the range of 40 ≤ Z ≤ 50

2019 ◽  
Vol 97 (7) ◽  
pp. 786-790
Author(s):  
A. Turşucu
Keyword(s):  
Point Source ◽  
Atomic Number ◽  
Semiconductor Detector ◽  
Theoretical Calculations ◽  
Energy Dispersive ◽  
X Rays ◽  
Number Range ◽  
X Ray ◽  
Edxrf Technique ◽  
Experimental Values

In this study, K shell absorption jump ratios (JK) and jump factors (rK) of specimens in the atomic number range of 40 ≤ Z ≤ 50 were measured using the energy dispersive X-ray fluorescence (EDXRF) technique. Related specimens were excited using 59.54 keV γ-photons that were radiated from a 241Am point source. Typical K X-rays emitting from specimens were detected from silicon drifted lithium (Si(Li)) semiconductor detector. Derived JK and rK values of related specimens were compared with calculated theoretical and other experimental values. The agreement of measured values was reasonable with theoretical calculations.

A Secondary-Source, Energy-Dispersive X-Ray Spectrometer and its Application to Quantitative Analytical Chemistry

1973 ◽  
Vol 17 ◽  
pp. 571-583
Author(s):  
R. P. Larsen ◽  
J. O. Karttunen
Keyword(s):  
Background Radiation ◽  
Energy Dispersive ◽  
Excitation Source ◽  
Secondary Source ◽  
X Rays ◽  
X Ray ◽  
Secondary Sources ◽  
The Individual ◽  
Detection Instrument

AbstractAn energy-dispersive X-ray spectrometer that (1) uses as the primary excitation source the power supply and tungsten X-ray tube from a conventional crystal spectrometer (General Electric XRD-6) and (2) uses as the secondary excitation source elemental metal foils that are readily interchangeable has been built and operated. The use of an X-ray tube with a high-voltage capability, 75 kilovolts max, enables the determination of elements with atomic numbers as high as 66 (terbium) to be based on the K series of X-rays; the highpower capability, 3.7 kilowatts max, enables a particularly intense beam of X-rays to be generated by the secondary source and hence, provides a particularly high detection capability for trace elements in a sample. An instrument that uses interchangeable secondary sources to irradiate the samples has several advantages over those instruments in which excitation is accomplished by direct irradiation with an X-ray tube: (1) the background radiation in the energy range where the X-rays of interest are measured is several orders of magnitude lower and is very uniform and (2) the energy of the excitation radiation can be closely matched to the absorption edges of the elements of interest in the sample.In the application of the instrument, particular emphasis has been placed on the development of tectmiques that will enable an energy-dispersive X-ray spectrometer to be used as the detection instrument for quantitative elemental analysis. Methods for the determination of the individual rare earths, plutonium and uranium at the microgram level with an accuracy of ± 1% are outlined and for the determination of plutonium and uranium at the milligram level with an accuracy of ± 0.1% are proposed.

Photoelectron Spectrometry: A New Approach to X-Ray Analysis

1972 ◽  
Vol 16 ◽  
pp. 74-89 ◽  
Author(s):  
Manfred O. Krause
Keyword(s):  
Energy Range ◽  
Emission Spectra ◽  
Atomic Level ◽  
Energy Dispersive ◽  
New Technique ◽  
X Rays ◽  
Electron Spectrometer ◽  
New Approach ◽  
X Ray

AbstractPhotoelectron spectrometry is shown to be an excellent technique for the analysis of x rays in the ultrasoft and soft x-ray regions. X rays are converted into photoelectrons which are ejected from a suitable atomic level, and the photoelectrons are analyzed with an electron spectrometer. The method is energy dispersive, provides a resolution ranging from 0.1 eV at 20 eV to 1.1 eV at 3 keV, and gives well-defined intensity characteristics throughout the range. The energy range can be extended into the 10 keV decade. Properties of the new technique are discussed, compared with conventional techniques, and exemplified by a series of measurements which include determination of the emission spectra of M x rays of yttrium to rhodium, L x rays of zirconium, and the band structures of molybdenum and holmium.

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