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.

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.

Monte Carlo Simulation of Characteristic Secondary Fluorescence in Electron Probe Microanalysis of Homogeneous Samples Using the Splitting Technique

2015 ◽  
Vol 21 (3) ◽  
pp. 753-758 ◽  
Author(s):  
Mauricio Petaccia ◽  
Silvina Segui ◽  
Gustavo Castellano
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Electron Probe Microanalysis ◽  
Electron Probe ◽  
Variance Reduction ◽  
Fluorescence Enhancement ◽  
Radiation Transport ◽  
X Rays ◽  
X Ray ◽  
Secondary Fluorescence

AbstractElectron probe microanalysis (EPMA) is based on the comparison of characteristic intensities induced by monoenergetic electrons. When the electron beam ionizes inner atomic shells and these ionizations cause the emission of characteristic X-rays, secondary fluorescence can occur, originating from ionizations induced by X-ray photons produced by the primary electron interactions. As detectors are unable to distinguish the origin of these characteristic X-rays, Monte Carlo simulation of radiation transport becomes a determinant tool in the study of this fluorescence enhancement. In this work, characteristic secondary fluorescence enhancement in EPMA has been studied by using the splitting routines offered by PENELOPE 2008 as a variance reduction alternative. This approach is controlled by a single parameter NSPLIT, which represents the desired number of X-ray photon replicas. The dependence of the uncertainties associated with secondary intensities on NSPLIT was studied as a function of the accelerating voltage and the sample composition in a simple binary alloy in which this effect becomes relevant. The achieved efficiencies for the simulated secondary intensities bear a remarkable improvement when increasing the NSPLIT parameter; although in most cases an NSPLIT value of 100 is sufficient, some less likely enhancements may require stronger splitting in order to increase the efficiency associated with the simulation of secondary intensities.

Measurement and parameterization of ϕ(ρz) curves for quantitative electron probe microanalysis

1990 ◽  
Vol 48 (2) ◽  
pp. 190-191
Author(s):  
J. D. Brown
Keyword(s):  
Electron Probe Microanalysis ◽  
Electron Probe ◽  
Absorption Coefficients ◽  
Computing Power ◽  
X Ray ◽  
Practical Applications ◽  
Absorption Correction ◽  
Exponential Decrease ◽  
Quantitative Electron Probe Microanalysis ◽  
Z Curve

The goal of correction methods for quantitative electron probe microanalysis is to convert k-ratios for any type of specimen, any x-ray line and all electron beam energies into accurate concentrations. Early attempts to approach this goal were hindered by sparse data on electron interactions with solids, limited knowledge of x-ray parameters such as mass absorption coefficients and limited computing power which made necessary mathematical simplifications in practical applications.In developing the early models for quantitative analysis, the argument was made that the absorption correction was insensitive to the shape of the ϕ(ρz) curve. For that reason, a number of very crude models which ranged from constant x-ray generation as a function of depth(l) to an exponential decrease from the surface(2) were used. In fact, these models worked quite well for the restricted conditions for which they were designed but of course lack accuracy when applied to more general situations. ϕ(ρz) measurements

scholarly journals A Model for Characteristic X-Ray Emission in Electron Probe Microanalysis based on the Spherical Harmonic (PN) Method for Electron Transport

2021 ◽  
Author(s):  
Jonas Buenger ◽  
Silvia Richter ◽  
Manuel Torrilhon
Keyword(s):  
Monte Carlo ◽  
Electron Transport ◽  
Electron Probe Microanalysis ◽  
Spherical Harmonic ◽  
Electron Probe ◽  
Material Structure ◽  
X Rays ◽  
Minimum Entropy ◽  
Promising Alternative ◽  
X Ray

Classical k-ratio models, e.g. ZAF and phi(rho z), used in electron probe microanalysis (EPMA) assume a homogeneous or multi-layered material structure, which essentially limits the spatial resolution of EPMA to the size of the interaction volume where characteristic x-rays are produced. We present a new model for characteristic x-ray emission that avoids assumptions on the material structure to not restrict the resolution of EPMA a-priori. Our model bases on the spherical harmonic (PN) approximation of the Boltzmann equation for electron transport in continuous slowing down approximation. PN models have a simple structure, are hierarchical in accuracy and well-suited for efficient adjoint-based gradient computation, which makes our model a promising alternative to classical models in terms of improving the resolution of EPMA in the future. We present results of various test cases including a comparison of the PN model to a minimum entropy moment model as well as Monte-Carlo (MC) trajectory sampling, a comparison of PN-based k-ratios to k-ratios obtained with MC, a comparison with experimental data of electron backscattering yields as well as a comparison of PN and Monte-Carlo based on characteristic X-ray generation in a three-dimensional material probe with fine structures.

Low-Voltage Electron-Probe Microanalysis of Fe–Si Compounds Using Soft X-Rays

2013 ◽  
Vol 19 (6) ◽  
pp. 1698-1708 ◽  
Author(s):  
Phillip Gopon ◽  
John Fournelle ◽  
Peter E. Sobol ◽  
Xavier Llovet
Keyword(s):  
Electron Probe Microanalysis ◽  
Electron Probe ◽  
Low Voltage ◽  
Mass Attenuation Coefficient ◽  
X Rays ◽  
X Ray ◽  
Voltage Electron ◽  
Increased Sensitivity ◽  
Quantitative Analyses ◽  
Areas Of Interest

AbstractConventional electron-probe microanalysis has an X-ray analytical spatial resolution on the order of 1–4 μm width/depth. Many of the naturally occurring Fe–Si compounds analyzed in this study are smaller than 1 μm in size, requiring the use of lower accelerating potentials and nonstandard X-ray lines for analysis. Problems with the use of low-energy X-ray lines (soft X-rays) of iron for quantitative analyses are discussed and a review is given of the alternative X-ray lines that may be used for iron at or below 5 keV (i.e., accelerating voltage that allows analysis of areas of interest <1 μm). Problems include increased sensitivity to surface effects for soft X-rays, peak shifts (induced by chemical bonding, differential self-absorption, and/or buildup of carbon contamination), uncertainties in the mass attenuation coefficient for X-ray lines near absorption edges, and issues with spectral resolution and count rates from the available Bragg diffractors. In addition to the results from the traditionally used Fe Lα line, alternative approaches, utilizing Fe Lβ, and Fe Ll-η lines, are discussed.

Characteristic and Continuum Fluorescence in Electron Beam X-ray Microanalysis

1999 ◽  
Vol 5 (S2) ◽  
pp. 562-563
Author(s):  
C.E. Nockolds
Keyword(s):  
Electron Beam ◽  
Electron Probe Microanalysis ◽  
Electron Probe ◽  
Mathematical Framework ◽  
X Rays ◽  
Correction Procedure ◽  
X Ray ◽  
Exponential Term ◽  
Accurate Expression ◽  
Original Formula

Of the different aspects of electron probe microanalysis(EPMA)which were studied by Castaing during his doctorate the work on characteristic x-ray fluorescence was the most definitive. In his thesis, which was completed in 1951, Castaing established the physical and mathematical framework for a correction procedure for fluorescence which is essentially still used in EPMA today. Much of the effort since then has been in refining and improving the accuracy of the correction and extending the scope of the correction to a wider range of specimen types. The Castaing formula was developed for the case of a K x-ray from element A being excited by a K xray from element B (K-K fluorescence) and in 1965 Reed extended the range of the correction by including the K-L, L-L and L-K interactions. In the same paper Reed also introduced the expression from Green and Cosslett for the calculation of K intensities, which was believed to be more accurate than the expression used by Castaing. The original formula included a somewhat unrealistic exponential term to allow for the depth of the production of the primary x-rays and a number of workers have tried replacing this term with a more accurate expression, however, in general this has led to only small changes in the final correction. Reed also simplified the formula in order to make the calculation easier in the days before fast computers; in particular he replaced the jump ratio variable by two constants, one for the K-shell and one for the L-shell. Much later Heinrich showed that this simplification was no longer necessary and that the jump ratio could in fact be calculated directly.

scholarly journals X-ray spectral analysis development in Novosibirsk city (Electron probe microanalysis and X-ray fluorescence analysis using the synchrotron radiation)

2021 ◽  
Vol 25 (2) ◽  
pp. 155-173
Author(s):  
A. G. Revenko ◽  
Keyword(s):  
Spectral Analysis ◽  
Synchrotron Radiation ◽  
Electron Probe Microanalysis ◽  
Electron Probe ◽  
Ussr Academy ◽  
Chemical Elements ◽  
Fluorescence Analysis ◽  
X Ray ◽  
Academy Of Sciences

Current article considers the contribution of X-ray physicists from the city of Novosibirsk to the formation and development of the two X-ray spectral analysis directions: electron probe microanalysis and X-ray fluorescence analysis using the synchrotron radiation. The research on geological topics at the Institute of Geology and Geophysics of the Siberian Branch of the USSR Academy of Sciences using the MS-46 electron probe microanalyzer of the French company CAMECA (since 1967) served as the basis for the development of methods for the quantitative X-ray microanalysis of rock-forming minerals as the methods for quantitative determination of the contents of elements with low atomic numbers in the long-wavelength X-ray region were still in their infancy. With the development and the improvement of the method’s technical base (microprobes JXA-5A, JEOL, 1975; Kamebaks Micro, CAMECA, 1981; JXA-8100, JEOL, 2003; JXA-8230, JEOL, 2016; electronic computing), the software for controlling the operation of devices and converting the measured intensities of the analytical lines into the concentration of elements continued to changed and improve. The first results of elemental analysis, obtained using the synchrotron radiation to excite X-ray fluorescence at the VEPP-3 accelerating ring at the Institute of Nuclear Physics of the Siberian Branch of the USSR Academy of Sciences, were published in1977. Inthe following years, at the station of elemental SRXRF, samples of various nature were studied — biological (bio tissues of the heart, liver, lungs, hairs, bones, plants), geological, environmental objects (soils, sediments, aerosols, etc.), archaeological sites as well as new technological materials. The procedures for the determination of chemical elements in low-mass samples (milligrams) in unique samples of lunar soil samples, biopsy material of human myocardial tissues, etc. have been developed. The scanning device at the elemental SRXRF station made it possible to obtain the information for reconstructing the climate change for different periods of time – from 100 to 1000 years. A new non-destructive method of confocal X-ray microscopy for studying micro-objects and visualizing the distribution of chemical elements in extended objects on this station are currently being developed.

ϕ(ρz)-Determination for Advanced Applications of Electron Probe Microanalysis

1990 ◽  
Vol 48 (2) ◽  
pp. 14-15
Author(s):  
Peter Karduck ◽  
Norbert Ammann
Keyword(s):  
Electron Probe Microanalysis ◽  
Electron Probe ◽  
Analytical Description ◽  
Experimental Procedure ◽  
General Application ◽  
X Ray ◽  
Theoretical Approaches ◽  
Absorption Correction ◽  
Sample Technique ◽  
Versatile Technique

In the last 35 years electron probe microanalysis (EPMA) has developed to a versatile technique for the quantitative analysis of materials on a microscopic scale. This development has been initiated by the pioneering work of Castaing in 1951 (1). Already in 1955 Castaing and Descamps have introduced a basic formulation for the absorption correction to quantify characteristic x-ray data (2). This correction already presumed the knowledge of the distribution ϕ(ρz) of the generated x-ray intensity as a function of the depth ρz inside the target. The authors presented the first experimental procedure to determine this distribution for pure elements by the so called sandwich sample technique. The results of this early work, obtained for several pure elements, became a standard in the field and many authors have examined their theoretical approaches or their Monte-Carlo simulations of ϕ(ρz) by means of these ϕ(ρz) data. In the following time further attempts of ϕ(ρz) determinations by experiments or by theoretical approaches, e.g. Philibert (3), became necessary because a general application of a matrix correction to the whole elemental range, detectable by EPMA, required a generalized analytical description of ϕ(ρz).

Celebrating 40 Years of Energy Dispersive X-Ray Spectrometry in Electron Probe Microanalysis: A Historic and Nostalgic Look Back into the Beginnings

2009 ◽  
Vol 15 (6) ◽  
pp. 476-483 ◽  
Author(s):  
Klaus Keil ◽  
Ray Fitzgerald ◽  
Kurt F.J. Heinrich
Keyword(s):  
Electron Microscopy ◽  
Solid State ◽  
Electron Probe Microanalysis ◽  
Electron Probe ◽  
Energy Dispersive Spectrometer ◽  
Fluorescence Analysis ◽  
Energy Dispersive ◽  
X Rays ◽  
New Era ◽  
X Ray

AbstractOn February 2, 1968, R. Fitzgerald, K. Keil, and K.F.J. Heinrich published a seminal paper in Science (159, 528–530) in which they described a solid-state Si(Li) energy dispersive spectrometer (EDS) for electron probe microanalysis (EPMA) with, initially, a resolution of 600 eV. This resolution was much improved over previous attempts to use either gas-filled proportional counters or solid-state devices for EDS to detect X-rays and was sufficient, for the first time, to make EDS a practically useful technique. It ushered in a new era not only in EPMA, but also in scanning electron microscopy, analytical transmission electron microscopy, X-ray fluorescence analysis, and X-ray diffraction. EDS offers many advantages over wavelength-dispersive crystal spectrometers, e.g., it has no moving parts, covers the entire X-ray energy range of interest to EPMA, there is no defocusing over relatively large distances across the sample, and, of particular interest to those who analyze complex minerals consisting of many elements, all X-ray lines are detected quickly and simultaneously.

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