With this award from the Chemistry Research Instrumentation and Facilities: Multi-user (CRIF:MU) program, Professor David Giedroc and colleagues Lyudmila Bronstein, Daniel Mindiola, Maren Pink and Sara Skrabalak from Indiana University will acquire an X-ray powder diffractometer equipped with a variable temperature system. The award will enhance research training and education at all levels, especially in areas of study such as (a) magnetic nanoparticles as building blocks in advanced materials, (b) characterization of inorganic solids for photocatalytic applications by powder X-ray diffraction, (c) self-assembly of chiral discotic molecules: powder XRD for structure analysis of nanofibers and organogels, (d) study of phase transitions with variable temperature X-ray powder diffraction, (e) in-situ investigations of solid state reactions,
An X-ray diffractometer allows accurate and precise measurements of the full three dimensional structure of a molecule, including bond distances and angles, and provides accurate information about the spatial arrangement of a molecule relative to neighboring molecules in single crystals or in crystalline powdered samples. Powder X-ray diffraction (XRD) patterns can also be used to elucidate the structure and relative abundance of the crystalline phases in a sample, it can expose the existence of preferred crystalline orientation (called texture) of a film of a material relative to a crystalline substrate surface, and the XRD linewidth can provide an estimate of the mean crystallite (or grain) diameter. In addition, the structure of extremely thin films (<100 nm) of materials can be investigated by powder-XRD whereas such films cannot be probed by single-crystal XRD. The studies described here will impact a number of areas, including organic and inorganic chemistry, as well as materials chemistry. This instrument will be an integral part of teaching as well as research and will also be available to collaborators and students via cyber-enabling.
The objective of this project was to acquire a multi-purpose X-ray diffractometer to enhance Indiana University (IU) research and teaching in the areas of chemistry, material sciences, and physics by providing the capability for a variety of X-ray diffraction experiments. The instrument has been installed at the Indiana University Molecular Structure Center (IUMSC), a facility serving researchers and students of the Indiana University (IU) system. Intellectual Merit. The diffractometer enhances research by providing high quality diffraction data to the researchers of the IU system. Data obtained with the instrument support interdisciplinary research including the design and properties of magnetic nanoparticles, electro- and photocatalytic solids, chiroptical molecular devices, small-molecule activating catalysts, gas storage applications, and environmentally (atmospherically) relevant bulk and surface studies. The highly modular instrument allows for experiment optimization, and the interfacing with modern data processing software and databases greatly improves sample characterization including identification and accurate quantification of samples. Results have been published in peer-reviewed professional journals and M.S. and Ph.D. theses. Since the diffractometer’s final acceptance in March 2013, over 900 unique datasets have been collected on the instrument including experiments such as routine powder X-ray diffraction (PXRD), non-ambient powder X-ray diffraction, reflectivity, and texture analysis. As one example from the NSF-funded project DMR 0955028, the Skrabalak Laboratory has prepared NaSbO3 nanoplates by salt-assisted aerosol combustion. These nanoplates were used as topotactic templates to synthesize AgSbO3 visible-light photocatalysts by ion exchange, which were analyzed by scanning electron microscopy and transmission electron microscopy. PXRD data helped to determine that full conversion to AgSbO3 was achieved in one day using NaSbO3 nanoplates as the template, whereas the reflection contributed by residual NaSbO3 was still evident in the PXRD pattern of AgSbO3 prepared by traditional solid state methods. This observation implies that the ion exchange process is more facile on the thinner nanoplates than the sub-micrometer sized crystals. This characterization is central to ensuring that the appropriate phase for photocatalytic evaluation is obtained by our various synthetic methods. In this example, the AgSbO3 nanoplates and the sample prepared by traditional solid state methods displayed different photocatalytic properties, emphasizing the importance of reaction-specific tailoring of the particles’ structural parameters. The results are reported in Chem. Mater., 2015, 27 (1), 174–180. Broader Impacts. The goal was to integrate the diffractometer into research and teaching endeavors at IU. Topical research in areas such as energy storage materials, catalytic solids and environmentally relevant surface reactions may transform directly into industrial applications and/or influence policymaking for the common good of the public. For example, PXRD data from the instrument are supporting environmental chemistry research in the Raff Laboratory and contribute to a more accurate description of air pollution chemistry that is implemented in airshed models. Data help elucidate how reactive oxides of nitrogen are formed on aerosols, dust, and soil. This will ultimately help the scientific community to fully understand the oxidative capacity of the atmosphere and improve how accurately one can predict and explain air pollution events. This research has clear human health, policy, and economic consequences since airshed models are the primary tools used to inform policymakers, who can put science-based and more effective pollution control measures into service. These data also have the potential to impact other areas of environmental chemistry, especially with respect to the photochemistry that occurs on liquid/solid interfaces, an area we know very little about. Educational use of the diffractometer enriches a broad range of courses in chemistry, physics, and materials science and trains next generation scientists by improving their research and learning experience. Hands-on experimentation on the diffractometer has been implemented in two graduate-level classes, and demonstrations and tours on the diffractometer augment undergraduate-level classes in chemistry. Undergraduate students, graduate students, postdoctoral researchers and faculty have been trained on the instrument and have become semi-independent or proficient users, who design and perform their own experiments and analyze the obtained data. The new instrument has significantly contributed M.S. and Ph.D. thesis research at IU. The experiments on the instrument are also an integral part for annual 6-week summer research projects for students of the IU STEM initiate of the Office for Diversity, Equity, and Multicultural Affairs, supporting minorities, first-generation college and economically disadvantaged students. In the summers of 2013 and 2014, IUMSC staff hosted two incoming freshmen for these summer research projects. A substantial part of their research included PXRD experiments and data analysis; it culminated in a final paper and a poster presentation at a campus-wide research conference. Demonstrations to laypeople and the Bloomington community during departmental or college-wide open houses were carried out as an important part of our mission to increase science literacy.
