MRI: Acquisition of an Energy-tunable X-ray Analytical Characterization Tool (EXACT) for Measuring Local Structure and Chemistry in Materials

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This Major Research Instrumentation (MRI) Program grant supports the acquisition of a lab-based energy-tunable x-ray analytical characterization tool (EXACT), which will provide element-specific chemical-state and local atomic environment information for bulk materials. Such an instrument will also provide a platform for hands-on training of nascent and future users of synchrotron-enabled materials characterization methods by allowing them to gather initial data in preparation for more advanced measurements at synchrotron facilities. The project will also have significant broader impact by providing leadership opportunities to a highly diverse team in terms of rank, gender, race and academic disciplines. The EXACT project will bring together a coalition of users from diverse regional institutions, including research universities, predominantly undergraduate institutions, and historically black colleges and universities. The instrument will serve as a platform for in-depth scholar training on radiation-matter interactions and will merge well into existing laboratory modules of the graduate and the undergraduate curriculum at the Georgia Institute of Technology (GT). The instrument will feature in a regional training hub for new and proficient users of world-class synchrotron facilities.Energy-tunability and high energy resolution detection will enhance in-house research capability at GT. Measurements using two types of spectroscopies, previously unavailable at GT, will now be possible with EXACT: x-ray absorption fine structure (XAFS) and high-resolution x-ray emission spectroscopy (XES). Collectively, XAFS and XES can be used to elucidate local atomic structural information, such as, bond distance, coordination, order/disorder parameter, local symmetry, and local chemical information, such as oxidation state, ligand type, etc. The EXACT facility will provide an x-ray energy range of 2-12 keV with an average energy resolution of about 1 eV, comparable to those at standard synchrotron beamlines. While there is a compromise on the source flux relative to a synchrotron, EXACT measurements can deliver useful XAFS/XES data over a reasonable timescale (within about an hour or even less for concentrated samples). The science space to be explored includes: reaction mechanisms of active materials in batteries and fuel cells under in-situ/operando conditions; role of coordination chemistry and electronic structure on bulk material properties and separations processes of f-element materials; metal-ligand bond covalency in transition metal, lanthanide, and actinide complexes; detailed characterization and structural screening of candidate spin-liquid materials for quantum computing; elucidating reaction mechanisms related to microbially impacted mineral formation/transformation (e.g. biomineralization and bioweathering); mechanistic processes of embedding catalyst nanoparticles in metal organic frameworks and investigating photo and electrocatalytic nitrogen fixation (reduction and oxidation) on iron and titanium based oxides with transition metal based co-catalyst.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.