Quantitative Measurement of Iron-Silicides by EPMA Using the Fe L α and L β X-ray Lines

A New Twist to an Old Approach

Aurélien Moy, John Fournelle, Anette von der Handt

Research output: Contribution to journalArticle

Abstract

The recent availability of Schottky-type field emission electron microprobes provides incentive to consider analyzing micrometer-sized features. Yet, to quantify sub-micrometer-sized features, the electron interaction volume must be reduced by decreasing accelerating voltage. However, the K lines of the transition elements (e.g., Fe) then cannot be excited, and the L lines must be used. The Fe Lα 1,2 line is the most intense of the L series but bonding effects change its atomic parameters because it involves a valence band electron transition. For successful traditional electron probe microanalysis, the mass absorption coefficient (MAC) must be accurately known, but the MAC of Fe Lα 1,2 radiation by Fe atoms varies from one Fe-compound to another and is not well known. We show that the conventional method of measuring the MAC by an electron probe cannot be used in close proximity to absorption edges, making its accurate determination impossible. Fortunately, we demonstrate, using a set of Fe-silicide compounds, that it is possible to derive an accurate calibration curve, for a given accelerating voltage and takeoff angle, which can be used to quantify Fe in Fe-silicide compounds. The calibration curve can be applied to any spectrometer without calibration and gives accurate quantification results.

Original languageEnglish (US)
JournalMicroscopy and Microanalysis
DOIs
StatePublished - Jan 1 2019

Fingerprint

Silicides
silicides
Electron probe microanalysis
absorptivity
Calibration
electron probes
Iron
iron
X rays
Electrons
micrometers
incentives
K lines
takeoff
x rays
electron transitions
Takeoff
Electric potential
electric potential
curves

Keywords

  • EPMA
  • MAC
  • iron silicide
  • low kV
  • soft X-ray

Cite this

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title = "Quantitative Measurement of Iron-Silicides by EPMA Using the Fe L α and L β X-ray Lines: A New Twist to an Old Approach",
abstract = "The recent availability of Schottky-type field emission electron microprobes provides incentive to consider analyzing micrometer-sized features. Yet, to quantify sub-micrometer-sized features, the electron interaction volume must be reduced by decreasing accelerating voltage. However, the K lines of the transition elements (e.g., Fe) then cannot be excited, and the L lines must be used. The Fe Lα 1,2 line is the most intense of the L series but bonding effects change its atomic parameters because it involves a valence band electron transition. For successful traditional electron probe microanalysis, the mass absorption coefficient (MAC) must be accurately known, but the MAC of Fe Lα 1,2 radiation by Fe atoms varies from one Fe-compound to another and is not well known. We show that the conventional method of measuring the MAC by an electron probe cannot be used in close proximity to absorption edges, making its accurate determination impossible. Fortunately, we demonstrate, using a set of Fe-silicide compounds, that it is possible to derive an accurate calibration curve, for a given accelerating voltage and takeoff angle, which can be used to quantify Fe in Fe-silicide compounds. The calibration curve can be applied to any spectrometer without calibration and gives accurate quantification results.",
keywords = "EPMA, MAC, iron silicide, low kV, soft X-ray",
author = "Aur{\'e}lien Moy and John Fournelle and {von der Handt}, Anette",
year = "2019",
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language = "English (US)",
journal = "Microscopy and Microanalysis",
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AU - Moy, Aurélien

AU - Fournelle, John

AU - von der Handt, Anette

PY - 2019/1/1

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N2 - The recent availability of Schottky-type field emission electron microprobes provides incentive to consider analyzing micrometer-sized features. Yet, to quantify sub-micrometer-sized features, the electron interaction volume must be reduced by decreasing accelerating voltage. However, the K lines of the transition elements (e.g., Fe) then cannot be excited, and the L lines must be used. The Fe Lα 1,2 line is the most intense of the L series but bonding effects change its atomic parameters because it involves a valence band electron transition. For successful traditional electron probe microanalysis, the mass absorption coefficient (MAC) must be accurately known, but the MAC of Fe Lα 1,2 radiation by Fe atoms varies from one Fe-compound to another and is not well known. We show that the conventional method of measuring the MAC by an electron probe cannot be used in close proximity to absorption edges, making its accurate determination impossible. Fortunately, we demonstrate, using a set of Fe-silicide compounds, that it is possible to derive an accurate calibration curve, for a given accelerating voltage and takeoff angle, which can be used to quantify Fe in Fe-silicide compounds. The calibration curve can be applied to any spectrometer without calibration and gives accurate quantification results.

AB - The recent availability of Schottky-type field emission electron microprobes provides incentive to consider analyzing micrometer-sized features. Yet, to quantify sub-micrometer-sized features, the electron interaction volume must be reduced by decreasing accelerating voltage. However, the K lines of the transition elements (e.g., Fe) then cannot be excited, and the L lines must be used. The Fe Lα 1,2 line is the most intense of the L series but bonding effects change its atomic parameters because it involves a valence band electron transition. For successful traditional electron probe microanalysis, the mass absorption coefficient (MAC) must be accurately known, but the MAC of Fe Lα 1,2 radiation by Fe atoms varies from one Fe-compound to another and is not well known. We show that the conventional method of measuring the MAC by an electron probe cannot be used in close proximity to absorption edges, making its accurate determination impossible. Fortunately, we demonstrate, using a set of Fe-silicide compounds, that it is possible to derive an accurate calibration curve, for a given accelerating voltage and takeoff angle, which can be used to quantify Fe in Fe-silicide compounds. The calibration curve can be applied to any spectrometer without calibration and gives accurate quantification results.

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