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Geometric Considerations in EDXRF to Increase Fluorescence Intensities and Reduce Background

Published online by Cambridge University Press:  06 March 2019

Igor Tolokonnikoff
Igor Tolokonnikoff*
Affiliation:
Nuclear Radiometric Methods Moscow Geologic Prospecting Institute 23 MiKlukho-Maclay Str., GSP-7 117373 Moscow, U.S.S.R.
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Abstract

Two methods for improving the sensitivity of EDXRF will be presented. One method is to use a spherical geometry for the measurements. The analyzed specimen is made as a spherical layer (i.e., “orange rind”), with the exciting x-ray source and the detector being located in the inner surface of the specimen at opposite points on the diameter. The source radiation scattered into the detector is minimized by the 90° scattering angle at all points on the specimen. It has been shown that the sensitivity is improved by several times while earring out EDXRF measurements under conditions of spherical geometry as compared to the conventional flat arrangement.

The other method we have investigated makes use of polarized radiation. The source radiation is polarized by scattering from a thin, low atomic number material. Higher energy radiation from the x-ray tube passes through the polarizer, where it impinges on a secondary fluorescer. This secondary radiation is then polarized by the same scatterer as the primary radiation. A quasi-monoenergetic polarized source is produced with maximized intensity by these means. It has been shown experimentally that the use of this polarized source for excitation leads to detection limits which are several times lower in the whole range of moderate energy. It has further been shown that the use of the easily added secondary target to the standard orthogonal polarization geometry increases the polarized beam intensity by 10-15%.

Type
XIII. XRS Techniques and Instrumentation
Information
Advances in X-Ray Analysis , Volume 35 , Issue B: First Pacific-International Congress on X-ray Analytical Methods (PICXAM). Fortieth Annual Conference on Applications of X-ray Analysis, August 7-16, 1991 , 1991 , pp. 1009 - 1017
Copyright
Copyright © International Centre for Diffraction Data 1991

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References

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