Purchase of a Powder X-Ray Diffractometer

在化学研究仪器和设备部门多用户仪器获取（CRIF-MU）计划的支持下，加州大学欧文分校化学系将获得一台粉末x射线衍射仪（粉末XRD）。该仪器将使以下领域的研究成为可能：a)通过f轨道金属扩展还原化学；B)在生物学和催化界面设计新的高分子材料；C)蛋白质纳米晶体和纤维中局部秩序的表征；D)用于快速光导开关和化学传感的硫化硒化镉纳米线；e)聚合物合成：多同化反应。x射线衍射仪可以精确测量分子的完整三维结构，包括键的距离和角度，并提供分子相对于邻近分子的空间排列的准确信息。具有延伸结构的材料的合成，如聚合物、无机固体或凝胶，通常会产生多晶或相不纯的粉末。粉末XRD是这类产品结构表征最有力的工具。粉末XRD图谱可以阐明所存在的晶相的结构和相对丰度，它可以揭示材料薄膜相对于晶体基底表面的优选晶向的存在，并且XRD线宽可以提供平均晶（或晶粒）直径的估计。此外，粉末XRD可以研究材料的极薄薄膜（100 nm）的结构，而单晶XRD不能探测这种薄膜。这些研究将对许多领域产生影响，特别是合成化学。

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.