MRI: Acquisition of a Laboratory-Based X-ray Absorption and Emission Spectroscopy Instrument

This Major Research Instrumentation (MRI) program award supports the purchase of an X-ray absorption and emission spectrometer that will be hosted by Washington University in St. Louis. The new instrument will be available for use by researchers at the university, in the surrounding region, and further afield.

It will be the first of its kind at a university in the United States that is optimized for research in the field of Earth and environmental science. Scientists will use this new tool to study a wide array of questions, such as how life forms minerals, how soils and treatment methods remove contaminants from water, and how gases and water in molten rock affect volcanic eruptions.

In addition, this instrument will be used to train the next generation of scientists and as part of research internships for college and high school students, including those from the City of St. Louis. The instrument laboratory will accept samples by mail in addition to in-person usage.

This mail-in service opens up access to this unique research capability to students at undergraduate-serving institutions that lack their own major instrumentation and to persons with disabilities who would otherwise need to travel to one of the four major national facilities where these X-ray techniques have traditionally been available.

The proposed instrument will enable two types of measurements in a laboratory setting that until recently were only accessible at a synchrotron lightsource: transmission X-ray absorption spectroscopy (XAS) and high-resolution X-ray emission spectroscopy (XES). The XAS capability will allow quantification of oxidation state, coordination environment, and local structure of elements occurring at >1 wt.%.

The XES capability extends sensitivity to elements occurring at concentrations as low as 10 to 100 μg/g, providing information on oxidation state, transition metal spin state, and coordination. Diverse solid, liquid, or biological samples can be studied using both methods. The instrument will facilitate research on a diverse array of topics, including biogeochemical mineral formation and transformation, biosignatures and prebiotic chemistry on the early Earth, bacterial and fungal metabolisms and products, metal contaminant fate and remediation, volatiles that drive volcanic eruptions, conditions during the formation and evolution of the Solar System, signatures of sedimentary and diagenetic processes in the rock record, drinking water treatment and supply, and recovery of nutrient and energy resources from wastewaters.

The instrument enables migration of a subset of XAS measurements from a synchrotron to a laboratory setting, freeing time at beamlines for the many experiments that uniquely require a lightsource facility. In addition, the proposed instrument facilitates the development of XES for Earth and environmental sciences applications, where this technique has seen little usage to date, and will serve as a testbed for wider migration of X-ray spectroscopic methods into a laboratory setting over the coming decade.

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.