MRI: Acquisition of a Direct Detection Electron Energy Loss Spectrometer for Fast, Low-Dose, and High Resolution Spectroscopic Imaging of Hard and Soft Materials

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This Major Research Instrumentation (MRI) award supports the acquisition of a high-speed electron energy loss spectrometer (EELS) equipped with a direct electron detection (DED) camera. This instrument is integrated with an aberration-corrected transmission electron microscope at the Facility for Electron Microscopy of Materials at the University of Colorado Boulder, vastly expanding the utility and regional impact of this already powerful microscope. The science enabled by this advanced electron spectrometer system spans many fields and includes collaborations across diverse departments, institutes, universities, national labs, and industry. The instrument is readily accessible to graduate students, postdocs, and researchers from the broader region (including academic, industry, and national laboratory personnel), and because of unique capabilities, is of interest to scientists around the country. Required training and support are provided to all internal and external users. Through connections with various campus programs, faculty using the new system enrich educational experiences of hundreds of students by sharing their cutting-edge research. The instrument is integrated into graduate and undergraduate courses, initiatives and outreach programs for students from underrepresented groups, K-12 students, and teachers to cultivate their interest in science and engineering.The new EELS system probes optical and electronic properties of materials in ultraviolet, visible, and infrared regions down to energies of 80 meV with high spatial resolution. Researchers measure elemental composition, chemical bonding, and oxidation state information contained in the electron energy loss near edge structures with atomic resolution, providing new insights into the relationship between materials structure and chemistry. The instrumentation is also designed to enable high resolution electron imaging and spectroscopy on beam-sensitive and low-contrast materials, such as polymers and organic thin films, while minimizing electron dose. The high-speed DED camera allows scientists to further develop the technique of electron ptychography. The combination of DED camera and electron biprism enables phase and spectroscopic imaging of beam-sensitive materials. Nanomaterials designed for renewable and sustainable energy applications are analyzed to facilitate the analysis of performance for thermo-, photo-, and electro-catalytic reactions in terms of atomistic-level electronic structure. The new system is also employed for several applications in biominerals and natural materials, such as for mapping the chemical composition of beam-sensitive nanomaterials generated by biological organisms. Beyond these specific examples, users from a wide variety of disciplines interrogate atomic and electronic structures of diverse types of materials.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.