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Secondary Fluorescence in WDS: The Role of Spectrometer Positioning

Published online by Cambridge University Press:  03 December 2018

Ben Buse ,
Jon Wade ,
Xavier Llovet ,
Stuart Kearns  and
John J. Donovan
Ben Buse*
Affiliation:
School of Earth Sciences, University of Bristol, Wills Memorial Building, Queen’s Road, Bristol BS81RJ, UK
Jon Wade
Affiliation:
Department of Earth Sciences, University of Oxford, South Parks Road, Oxford OX1 3AN, UK
Xavier Llovet
Affiliation:
Scientific and Technological Centres, Universitat de Barcelona, Lluís Solé i Sabarís, 1-3/ES-08028, Barcelona
Stuart Kearns
Affiliation:
School of Earth Sciences, University of Bristol, Wills Memorial Building, Queen’s Road, Bristol BS81RJ, UK
John J. Donovan
Affiliation:
CAMCOR, Department of Chemistry, University of Oregon, Eugene, OR, 97403, USA
*
Author for correspondence: Ben Buse, E-mail: ben.buse@bristol.ac.uk
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Abstract

Secondary fluorescence (SF), typically a minor error in routine electron probe microanalysis (EPMA), may not be negligible when performing high precision trace element analyses in multiphase samples. Other factors, notably wavelength dispersive spectrometer defocusing, may introduce analytical artifacts. To explore these issues, we measured EPMA transects across two material couples chosen for their high fluorescence yield. We measured transects away from the fluorescent phase, and at various orientations with respect to the spectrometer focal line. Compared to calculations using both the Monte Carlo simulation code PENEPMA and the semi-analytical model FANAL, both codes estimate the magnitude of SF, but accurate correction requires knowledge of the position of the spectrometer with respect to the couple interface. Positioned over the fluorescent phase or otherwise results in a factor of 1.2–1.8 of apparent change in SF yield. SF and spectrometer defocusing may introduce systematic errors into trace element analyses, both may be adequately accounted for by modeling. Of the two, however, SF is the dominant error, resulting in 0.1 wt% Zn apparently present in Al at 100 μm away from the Zn boundary in an Al/Zn couple. Of this, around 200 ppm Zn can be attributed to spectrometer defocusing.

Keywords

secondary fluorescencewavelength dispersive spectrometerdefocusingelectron microprobespectrometer positioning
Type
Materials Science Applications
Information
Microscopy and Microanalysis , Volume 24 , Issue 6 , December 2018 , pp. 604 - 611
Copyright
© Microscopy Society of America 2018 

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Footnotes

Cite this article: Buse B, Wade J, Llovet X, Kearns S and Donovan JJ (2008) Secondary Fluorescence in WDS: The Role of Spectrometer Positioning. Microsc Microanal. 24(6), 604–611. doi: 10.1017/S1431927618015416

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