Accuracy of Quantitative EPMA Models at Low Voltages

2011 ◽  
Vol 17 (S2) ◽  
pp. 548-549
Author(s):  
C Merlet ◽  
X Llovet
Keyword(s):  
Quantitative Epma

Extended abstract of a paper presented at Microscopy and Microanalysis 2011 in Nashville, Tennessee, USA, August 7–August 11, 2011.

Quantitative EPMA of nitrogen : A tricky element in the electron-probe microanalyzer

1992 ◽  
Vol 50 (2) ◽  
pp. 1622-1623
Author(s):  
G.F. Bastin ◽  
H.J.M. Heijligers
Keyword(s):  
Background Subtraction ◽  
Electron Probe ◽  
Detection System ◽  
Higher Order ◽  
Light Elements ◽  
Strong Suppression ◽  
Electron Probe Microanalyzer ◽  
Quantitative Epma ◽  
Peak Count ◽  
Lead Stearate

Among the ultra-light elements B, C, N, and O nitrogen is the most difficult element to deal with in the electron probe microanalyzer. This is mainly caused by the severe absorption that N-Kα radiation suffers in carbon which is abundantly present in the detection system (lead-stearate crystal, carbonaceous counter window). As a result the peak-to-background ratios for N-Kα measured with a conventional lead-stearate crystal can attain values well below unity in many binary nitrides . An additional complication can be caused by the presence of interfering higher-order reflections from the metal partner in the nitride specimen; notorious examples are elements such as Zr and Nb. In nitrides containing these elements is is virtually impossible to carry out an accurate background subtraction which becomes increasingly important with lower and lower peak-to-background ratios. The use of a synthetic multilayer crystal such as W/Si (2d-spacing 59.8 Å) can bring significant improvements in terms of both higher peak count rates as well as a strong suppression of higher-order reflections.

Measurement And Simulation Of X-Ray Emission From Multilayered Structures In Electron Probe Microanalysis.

1999 ◽  
Vol 5 (S2) ◽  
pp. 78-79
Author(s):  
C. Merlet ◽  
X. Llovet ◽  
F. Salvat
Keyword(s):  
Electron Probe ◽  
Numerical Models ◽  
Carbon Layer ◽  
Single Element ◽  
Surface Ionization ◽  
Copper Films ◽  
Multilayered Structures ◽  
X Ray ◽  
Electron Probe Microanalyzer ◽  
Quantitative Epma

Studies of x-ray emission from thin films on substrates using an electron probe microanalyzer (EPMA) provide useful information on the characteristics of x-ray generation by electron beams. In this study, EPMA measurements of multilayered samples were performed in order to test and improve analytical and numerical models used for quantitative EPMA. These models provide relatively accurate results for samples consisting of layers with similar average atomic numbers, because of their similar properties regarding electron transport and x-ray generation. On the contrary, these models find difficulties to describe the process when the various layers have very different atomic numbers. In a previous work, we studied the surface ionization of thin copper films of various thicknesses deposited on substrates with very different atomic numbers. In the present communication, the study is extended to the case of multilayered specimens.The studied specimens consisted of thin copper films deposited on a carbon layer which, in turn, was placed on a variety of single-element substrates, ranging from Be to Bi.

scholarly journals Report from the NIST-MAS Workshop on “The Accuracy Barrier in Quantitative EPMA and the Role of Standards”

2003 ◽  
Vol 9 (S02) ◽  
pp. 528-529 ◽  
Author(s):  
Dale Newbury ◽  
Ryna Marinenko ◽  
John Armstrong ◽  
John Small ◽  
Eric Steel
Keyword(s):  
Quantitative Epma

Equilibrium tie-line in PrOy–BaO–CuO ternary phase diagram around peritectic temperature of Pr1+xBa2−xCu3O7−δ

1998 ◽  
Vol 13 (1) ◽  
pp. 118-125 ◽  
Author(s):  
Minoru Tagami ◽  
Makoto Kambara ◽  
Takateru Umeda ◽  
Yuh Shiohara
Keyword(s):  
Phase Diagram ◽  
Ternary Phase ◽  
Ternary Phase Diagram ◽  
Peritectic Temperature ◽  
Air Atmosphere ◽  
Epma Analysis ◽  
Tie Lines ◽  
Growth Method ◽  
Quantitative Epma ◽  
Tie Line

This paper presents tie-lines between Pr1+xBa2−xCu3O7−δ and liquid on a PrOy –BaO–CuO ternary phase diagram at 965, 970, 975, 980, and 990 °C in air atmosphere, for which knowledge is necessary to fabricate composition controlled Pr1+xBa2−xCu3O7−δ single crystals by the solution growth method. Liquidus faces have been investigated by dipping MgO single crystal rods into the thermal equilibrium melt at various temperatures and analyzing the composition of the adhering melt by ICP. The compositions of Pr1+xBa2−xCu3O7−δ solid solution coexisting with various compositions of liquids were obtained by quantitative EPMA analysis of quenched melts. Tie-lines were calculated by applying the lever rule to these experimental data for solid compositions and liquidus faces. Furthermore, the relationships between solid solubilities and peritectic temperatures of Pr1+xBa2−xCu3O7−δ are reported.

Quantitative EPMA of element depth distribution

1994 ◽  
Vol 114-115 (1) ◽  
pp. 195-203 ◽  
Author(s):  
Alexander Berner ◽  
Guy Proaktor
Keyword(s):  
Depth Distribution ◽  
Quantitative Epma

scholarly journals Quantitative EPMA of Nitrogen in Silicate Glasses

2016 ◽  
Vol 22 (S3) ◽  
pp. 1810-1811 ◽  
Author(s):  
Anette von der Handt ◽  
Celia Dalou
Keyword(s):  
Silicate Glasses ◽  
Quantitative Epma

Ionization Cross Sections for Quantitative Electron Probe Microanalysis

2001 ◽  
Vol 7 (S2) ◽  
pp. 672-673
Author(s):  
C. Merlet ◽  
X. Llovet ◽  
S. Segui ◽  
J.M. Fernández-Varea ◽  
F. Salvat
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Electron Probe Microanalysis ◽  
Electron Probe ◽  
Ionization Cross Section ◽  
Ionization Cross ◽  
Quantitative Electron Probe Microanalysis ◽  
Ionization Cross Sections ◽  
Semi Empirical ◽  
Quantitative Epma

Quantitative procedures in electron probe microanalysis (EPMA) require the knowledge of various atomic parameters, the most fundamental of which is the ionization cross section. A number of semi-empirical, approximate analytical formulas have been proposed to calculate the ionization cross section. The simplicity of these formulas makes them suitable for quantitative EPMA procedures. However, it is difficult to assess their reliability because of the lack of accurate experimental data. Indeed, inspection of currently available data reveals that they are still scarce for many elements and, when they are available, one usually finds significant discrepancies between data from different authors. Fortunately, the inaccuracies in the semi-empirical cross section formulas used in EPMA have only a small effect on the analytical results when standards are used. Nonetheless, in quantitative EPMA studies at low overvoltages or using standardless methods, the evaluated compositions largely depend on the adopted ionization cross sections and, therefore, knowledge of accurate ionization cross sections is a requisite for the development of improved quantification methods.

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