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A Method for Trace Analysis with an Electron Microprobe

  • L. A. Fergason
Conference paper

Abstract

A “chopped beam” system of analysis has been devised for a scanning electron microprobe equipped with a 400-channel analyzer. The system has been programed with circuitry which places a signal onto the X or Y scanning coils of the probe, so that the beam jumps back and forth between two analytical areas. The same signal is used to activate alternate halves or quadrants on the 400-channel analyzer in a synchronous manner. The analyzer accumulates X-ray intensity data in the appropriate halves and quadrants as the electron beam oscillates between sample and standard or, in the case of trace analysis, between the unknown and the pure major constituent for background correction. The probe may be left unattended while it is gathering information in this manner. The dwell time of the probe on a given analytical area is 6 sec “live” time.

Errors due to instrumental drift and sample contamination are nullified or minimized by this technique. Consequently, theoretical precision is closely approached for extended counting times. 100 ppm levels of aluminum, silicon, nickel, and iron in uranium have been determined to precisions as good as ± 10 ppm at the 95% confidence level.

Keywords

Trace Analysis Live Time Carbon Contamination Instrumental Drift Digital Printer 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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References

  1. 1.
    R. Theisen, “Detection Limits of Electron Microprobe Analysis,” presented at E.C.S.—A.I.M.E. Meeting, Toronto, May 1964.Google Scholar
  2. 2.
    T. O. Ziebold, “Trace Determinations in Microanalysis,” presented as a lecture at M.I.T. Special Summer Program on the Electron Microanalyzer and its Application, August 3–4, 1964.Google Scholar
  3. 3.
    L. S. Birks, Electron Probe Microanalysis, Interscience Publishers, Inc., New York, 1963, p. 136.Google Scholar
  4. 4.
    A. Jarret, Statistical Methods Used in the Measurement of Radioactivity, Technical Information Service Extension, U.S. Atomic Energy Commission, AECU-262, June 1946.Google Scholar
  5. 5.
    L. A. Fergason and N. F. Neumann, “An Energy Dispersion System for Light Element Analysis with the Microprobe,” to be published.Google Scholar
  6. 6.
    T. O. Ziebold and R. E. Ogilvie, “Quantitative Analysis with the Electron Microanalyzer,” Anal. Chem. 35: 621, 1963.CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media New York 1966

Authors and Affiliations

  • L. A. Fergason
    • 1
  1. 1.Mallinckrodt Chemical WorksSaint CharlesUSA

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