Early Career: Upgrade of an X-ray Diffractometer with Capillary & Humidity-Temperature Stages for Suspension & Hydrated Powder Measurements, and Outreach for Geochemistry R

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Clay minerals play an important role in biological, chemical and physical processes in soils and influence the physical and biological availability of contaminants, macromolecules, and organic matter. This award funds equipment that will enable the researchers to examine the interactions of organic molecules with certain clay minerals. The research enabled by this equipment has important relevance to the formation of porous soil aggregates, the dynamics of water movement through soils, sequestration and biogeochemical cycling of soil organic matter, and the fate and transport of contaminants in soils. Thus, it is expected that the research findings will be of interest to scientists across various disciplines. The principal investigator is also developing new curricula to engage undergraduates in using nanoscale techniques in aqueous geochemistry research and is active in recruiting undergraduates from underrepresented groups as active participants in her research team. This award will provide funding for additional undergraduate researchers to gain hands-on experience in state-of-the-art techniques provided by the instrumentation to be purchased.Specifically, this award funds the purchase of two accessories to upgrade an X-ray diffraction system with the capabilities to conduct liquid-state suspension and temperature- and humidity-dependentX-ray diffraction measurements. Additional support will be provided for outreach activities to engage underrepresented undergraduates in this research. The response of the structural dynamics within clay minerals to interactions with organic guest molecules can be probed by monitoring changes in the clay structures via X-ray diffraction techniques. Traditional powder X-ray diffraction measurements provide no information about the organic-clay mineral interaction in suspension or as a function of moisture content and temperature. The accessory stages to be purchased will enable the researchers to conduct such experiments to obtain such information. Using a combination of computational techniques and these experimental X-ray diffraction and other spectroscopic techniques, the researchers will investigate the structural dynamics responsible for the binding interactions and mechanisms of sequestration of organic contaminants and natural organic molecules within hydrated smectite-type clay particles at different temperatures. These structural insights will contribute to elucidating the influence of clay minerals on the storage and stability of organic carbon in soils, which have important implications for understanding how the global carbon cycle will respond to projected climate change.