X-ray elemental mapping and x-ray spectrum imaging are powerful microanalytical tools. However, their scope is limited spatially by the raster area of a scanning electron microscope or microprobe. Limited sampling size becomes a significant issue when large area (>10 cm2), heterogeneous materials such as meteorites, concrete samples, or others must be examined. In such specimens, macro scale structures, inclusions or concentration gradients are often of interest, yet microbeam methods are insufficient or at least inefficient for analyzing them. The inapplicability of defocused, stage scanning microprobe analysis stems largely from the requirement for vacuum and the necessity of charge dissipating coatings. Such requirements largely exclude the samples of interest presented in this paper from electron probe microanalysis. Milli x-ray fluorescence x-ray spectrum imaging (mXRF-XSI) provides a solution to the problem of macro scale x-ray imaging, especially where such difficult samples are considered. Using a mid-sized beam coupled with an x-ray excitation source has a number of advantages, such as the ability to work at atmospheric pressure, and lower limits of detection owing to the absence of the electron Bremsstrahlung. MXRF-XSI also acts as a complement, where applicable, to microbeam x-ray output, highlighting areas of interest for follow-up microanalysis at a finer length scale.
Citation: Microscopy and Microanalysis
Pub Type: Journals
"Imaging", "Mapping", "Analysis", "Concrete", "Meteorites", "Elemental"