Milli X-ray Fluorescence X-ray Spectrum Imaging Technique Development

Significant improvements were made in the area of technique development for Eagle III mXRF since its initial installation in 2007. The diverse applications for mXRF-XSI include thin films, inks, paints and pigments, geological materials, cement and concrete, extraterrestrial meteorites, and the Smithsonian mineral standards. In these applications, mXRF-XSI has provided detailed information on composition, film thickness, trace element distribution, and homogeneity over large (centimeter) areas.

This research is primarily intended to benefit communities that perform X-ray mapping and X-ray spectrum imaging for compositional analysis of various samples. mXRF is capable of complementing and supplementing a host of analytical techniques including EPMA and QXRD. By expanding the user base of the mXRF, the impetus for software development and robust calibration methods will be established, thereby leading to further improvements to the technique.

In this project, our goal was to improve the speed, reliability and measurement accuracy in collecting grayscale and quantified X-ray spectrum images of large sample areas using mXRF. During the early phase of the project, many different types of samples were acquired from diverse groups and analyzed. Each new sample brought a variety of challenges and needs for new technique development. For instance:

• The cement and concrete forensic community is better able to understand the diffusion of ions into concrete. Some ions such as Cl^- and K⁺ have been shown to have detrimental effects on concrete. mXRF has shown the ability to quickly analyze sections of concrete to accurately determine the concentration of various ions.
• The combinatorial thin films community is most interested in a robust, fast method for determining the shape and slope of gradients of concentration in combinatorial libraries. Despite these films being only 10 to 30 nm thick, the mXRF has superior resolution and detection abilities for mapping and imaging these samples.
• The extraterrestrial meteorite community is looking for a way to analyze large sections of meteorites for trace element concentration such as strontium, yttrium and zirconium. In the electron microprobe, these elements are difficult to detect in an energy dispersive system, yet with the mXRF, the detection limits for heavier elements (Z > 30) are at approximately 500 ppm.

• Increased the allowable size of hyperspectral data to over 4 GB (previous limit was less than 800 MB)
• Improved quantification through identification of errors in EDAX computed values
• Successfully completed 4 projects for various collaborators, one of which was turned into a publication