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Evaluation of the Variable Pressure Correction Technique for X-ray Microanalysis in the ESEM

Published online by Cambridge University Press:  02 July 2020

R. A. Carlton ,
C. E. Lyman  and
J. E. Roberts
R. A. Carlton
Affiliation:
Pharmaceutical Research and Development, Rhone-Poulenc Rorer, Collegeville, PA19438
C. E. Lyman
Affiliation:
Department of Materials Science and Engineering, Lehigh University, Bethlehem, PA18015
J. E. Roberts
Affiliation:
Department of Chemistry, Lehigh University, Bethlehem, PA18015
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Extract

The purpose of this study is to evaluate the variable pressure correction technique (VPCT) as a solution to the problem of extraneous x-ray peaks due to electron beam broadening in the chamber gas of the ESEM. The basis of VPCT is the observation that target x-ray counts decrease with increasing chamber pressure; whereas, x-ray counts due to beam broadening increase. If data are collected at two or more chamber pressures, the number of x-ray counts for an element can be corrected to that expected at zero gas pressure (high vacuum). Tests of NIST SRM 482 have shown EDS x-ray analysis in the ESEM (within the chamber pressure range of 1 to 8 torr) to have comparable accuracy and precision values to those of EDS in the traditional SEM. The samples used in the these studies, however, were quite large (ca. 500 μm in diameter) and so extraneous EDS peaks, due to the electron beam broadening effect of the chamber gas, were minimized.

The 60% Au / 40% Cu wire of SRM 482 was pressed into a hole in the surface of an Al specimen stub so as to produce a flat surface with a sharp interface between the wire and the stub. Spectra were collected at 5 and 150 μm from the junction of the wire and the Al stub at chamber pressures of 2, 4, and 8 torr.

Type
Environmental Scanning Electron Microscopy and Other Wet Work
Information
Microscopy and Microanalysis , Volume 5 , Issue S2: Proceedings: Microscopy & Microanalysis '99, Microscopy Society of America 57th Annual Meeting, Microbeam Analysis Society 33rd Annual Meeting, Portland, Oregon August 1-5, 1999 , August 1999 , pp. 292 - 293
Copyright
Copyright © Microscopy Society of America

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References

references

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