Suppressing X-ray Fluorescence – Energy Selective Detectors vs. Exchanging X-ray Sources

This study compares fluorescence reduction in XRDynamic 500 using the new energy filtering feature available since XRDdrive v1.4.0 and a cobalt (Co) X-ray source versus the conventional copper (Cu) source. Energy filtering offers a fast, software-based approach but reduces signal-to-peak ratio and intensity. In contrast, using a Co source stops fluorescence at its origin, improving signal-to-noise ratio but requiring hardware changes. The choice between these methods depends on the user’s need for speed versus data quality.

Introduction

X-ray diffraction (XRD) is a fundamental analytical technique widely employed in both research and industry to determine the crystallographic structure and phase composition of solids and powders. However, when samples contain elements that exhibit fluorescence under X-ray irradiation, usually those with atomic numbers close to that of the X-ray source target, X-ray fluorescence can significantly interfere with the measurement. This fluorescence generates an elevated background signal, which is especially problematic when using a copper (Cu) X-ray tube for samples containing iron (Fe) or cobalt (Co).

Various strategies have been developed to mitigate this effect. Energy-selective detectors enable discrimination between diffracted and fluorescent radiation by adjusting the energy detection window, thereby suppressing the fluorescence background. Another even more promising approach involves selecting an alternative X-ray source with an emission line that does not induce fluorescence in the sample. For instance, Co radiation is often employed instead of Cu when analyzing Fe-containing materials. This method was previously evaluated for a XRDynamic 500 diffractometer by Anton Paar in an earlier application report (1). The choice of the optimal method depends on sample composition, desired resolution, and specific application requirements, with the overarching goal of enhancing the signal-to-noise (S/N) ratio and ensuring a more accurate structural characterization. This report presents a comparative analysis of the newly implemented energy discrimination (filtering) functionality introduced in XRDdrive v1.4.0, focusing on its effectiveness in mitigating fluorescence background. Additionally, the study evaluates fluorescence suppression at its origin through the use of a Co X-ray source, providing an alternative approach at the excitation stage.

 

References:

  1. Anton Paar GmbH. Treating Fluorescence at its Roots: Choice of the X-ray Tube for X-ray Diffraction on Iron-containing Samples. 2024. E29IA006EN-A.

Get the document

To receive this document please enter your email below.

Loading...

Error