Purchase of a Powder X-Ray Diffractometer

University Of California-Irvine, Irvine CA

Investigators

Abstract

With support from the Chemistry Research Instrumentation and Facilities-Departmental Multiuser Instrument Acquisition (CRIF-MU) Program, the Department of Chemistry at the University of California in Irvine will acquire a powder X-ray diffractometer (powder XRD). This instrument will enable research in the following areas: a) expanding reduction chemistry via the f orbital metals; b) design of new polymeric materials at the interfaces with biology and catalysis; c) characterization of local order in protein nanocrystals and fibers; d) cadmium sulfide-selenide nanowires for fast photoconductive switches and chemical sensing; and e) polymer synthesis: the polyhomologation reaction. The X-ray diffractometer allows accurate and precise measurements of the full three dimensional structure of a molecule, including bond distances and angles, and it provides accurate information about the spatial arrangement of the molecule relative to the neighboring molecules. The synthesis of materials having an extended structure, such as polymers, inorganic solids, or gels, often yields a polycrystalline or phase-impure powder. Powder XRD is the most powerful tool available for the structural characterization of such products. Powder XRD pattern can elucidate the structure and relative abundance of the crystalline phases present, it can expose the existence of preferred crystalline orientation 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. These studies will have an impact in a number of areas, especially synthetic chemistry.