Quantitative Bulk and Trace Element X-Ray Mapping Using Multiple Detectors

X-ray mapping using energy dispersive spectroscopy or wavelength dispersive spectroscopy is a very popular characterisation tool for determining the elemental distribution in materials. Furthermore, quantitative X-ray mapping has become a very powerful technique enabling reliable quantitative results that can be an order of magnitude better than traditional analysis. Quantitative X-ray mapping is also far superior to regions of interest X-ray maps where low levels of an element or elemental overlaps are present. The one major drawback with X-ray mapping is the time required to obtain a high resolution X-ray map with good statistics at low levels of concentration. The use of multi-detectors, and just developed dual turret detectors for X-ray mapping, allows improvement in performance at low levels without compromising quantification quality and precision of traces, even in the presence of overlaps. However, for quantitative X-ray mapping to work properly, the characteristics of each detector must be accurately determined so that the final quantification of the individual detectors can be summed. To accomplish this effectively, the full spectrum at each pixel for each energy dispersive detector should be saved. As a final check for consistency between detectors, a technique was developed that involves assigning a different red-green-blue colour for each detector for the same element. By doing this, when we combine the three maps of the same element, we should obtain a grey scale map that indicates total correlation between the three detectors at the most critical final stage of quantification. To reduce contrast noise and further improve the quality of quantitative X-ray mapping images, a filter referred to as a “speckle filter” has been developed that allows the eye to see a more correct elemental concentration relationship.