Purchase of an X-ray Powder 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，埃默里大学化学系将获得一台粉末x射线衍射仪（粉末XRD）。该仪器将促进以下领域的研究：a)金属氧化物团簇及其组成的功能材料；B)合理设计螺旋肽基序自组装的纳米结构；C)低温合成纳米晶体的单源前驱体；D)纳米粒子的分子动力学：电子传递与救赎；E)用于水环境中选择性汞修复的聚合物材料；f)发展明确的负载氧化物催化剂。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谱图可以说明所存在的晶相的结构和相对丰度，可以揭示材料薄膜相对于晶体衬底表面的择优结晶取向的存在，XRD线宽可以提供平均晶粒直径的估计。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，特别是材料化学和纳米科学。

With support from the Chemistry Research Instrumentation and Facilities-Departmental Multiuser Instrument Acquisition (CRIF-MU) Program, the Department of Chemistry at Emory University will acquire a powder X-ray diffractometer (powder XRD). This instrument will enable research in the following areas: a) metal oxide clusters and functional materials comprised thereof; b) rational design of nanostructures derived from self-assembly of helical peptide motifs; c) single source precursors for low temperature synthesis of nanocrystals; d) molecular dynamics on nanoparticles: electron transfer and salvation; e) polymeric materials for selective mercury remediation from aqueous environments; and f) development of well-defined supported oxide catalysts. 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 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, in particular materials chemistry and the nanosciences.