Innovative Resources: A Pilot Program Facilitating Access to Unpublished XAS Data for Earth Sciences

X-ray absorption spectroscopy (XAS), measured at national Synchrotron user-facilities, is a valuable tool for non-destructively characterizing the chemistry of an element within a geologic or environmental sample, as well as on bulk or in micro- or nano-scale samples. The methods has a broad range of applications including ore mineralogy for critical materials, geochronology and tectonics, geologic carbon cycling, nutrient and contaminant cycling in Earth’s Critical Zone, climate change and paleoclimate research. XAS studies rely heavily on matching resulting spectra from individual sample analyses with those of reference samples, or with systematic studies of spectral features in a suite of materials. However, there is limited availability of reference data and individual experimenters often have to repeat others’ measurements. This project will assemble a large quantity of previously measured XAS analysis results, most of which are unpublished and would otherwise remain inaccessible. Making this library available in an online database will greatly improve efficiency and productivity of future research, particularly given the limited capacity of synchrotron facilities. Broader impacts will be realized by making this database open and available based on FAIR (findable, accessible, interoperable and reusable) principles. Database spectra for training and for data mining efforts -- without requiring travel to a synchrotron facility -- will benefit underrepresented and/or disadvantaged communities, as off-line training on XAS techniques and data analysis broadens participation and lowers entry barriers. Remote researchers will also be able to systematically explore new dimensions of XAS data and conduct integrative experimental-theoretical research including approaches utilizing Artificial Intelligence and/or Machine Learning methods. This project will include the curation, calibration and ability to quality-check spectral data (and associated metadata) for a particularly important subset of XAS covering lighter elements Silicon, Phosphorous, Sulfur, Chlorine, Potassium and Calcium. These elements are measured using the “tender” energy range, X-rays of 1.8 to 5 keV delivered by only a few specialized synchrotron facilities worldwide. The team has specific expertise in this area, coupled with direct access to unpublished measurements made during commissioning and operation of some of these facilities. Much of this data would be lost to the community without intervention. The project will also lead to the creation of an open online database of spectra of these elements in order to make them available to the full Earth and Environmental sciences research and education community. Spectral data format and well-defined metadata parameters are ideally suited for machine-searchable databases. Additionally, the project will make possible the development and publishing of systematic and comparative studies that are enabled by the database. Finally, this project will allow for the long-term continuation and potential expansion of this resource beyond the term and scope of the pilot project, through partnership with larger organizations such as SEES (Synchrotron Earth and Environmental Sciences), EarthChem (hosted at the Lamont-Doherty Earth Observatory) and MSA (Mineralogical Society of America, whose Mineral Structure Database is an extremely successful online resource). 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.