Polarized Beam X-ray Fluorescence Analysis

Abstract

In this chapter, we explore the sources of spectral background and show how polarization effects can yield improved detection thresholds. In 1963, Champion and Whittem pointed out that the detection of Co traces in aqueous solution can be improved significantly due to polarization of the background in a wavelength-dispersive x-ray fluorescence (WDXRF) setup. We see that the stationary arrangement of components used in energydispersive x-ray fluorescence (EDXRF) is ideally suited for geometrical configurations that exploit polarization phenomena to reduce background and thereby improve signal-tonoise ratios. The ability of simultaneously measure a wide range of elements is one of the greatest advantages of EDXRF. This advantage is strongly reduced when the count-rate limitation of the ED detection electronics is taken into consideration. This is due to simultaneous recording of the entire primary source radiation scattered on the specimen and is especially true for examinations on samples with light matrices. Thus, the main purpose of this chapter is to show that the multiple-element character of EDXRF can be advantageously utilized through the application of polarized x-rays.