Purchase of an X-ray Powder Diffractometer

在化学研究仪器和设施部门多用户仪器采购（CRIF-MU）计划的支持下，埃默里大学化学系将获得粉末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）金属氧化物簇和由其组成的功能材料; B）螺旋肽基序自组装衍生的纳米结构的合理设计; c）低温合成纳米晶体的单一来源前体; d）纳米颗粒的分子动力学：电子转移和拯救; e）从水环境中选择性汞补救的聚合材料;和f）开发定义明确的负载型氧化物催化剂。 X射线衍射仪可以精确测量分子的完整三维结构，包括键距和角度，并提供有关分子相对于相邻分子的空间排列的准确信息。具有延伸结构的材料（例如聚合物、无机固体或凝胶）的合成通常产生多晶或相不纯的粉末。粉末XRD是可用于此类产品结构表征的最强大工具。粉末XRD图案可以阐明存在的结晶相的结构和相对丰度，它可以暴露材料膜相对于结晶基底表面的优选结晶取向的存在，并且XRD线宽可以提供平均微晶直径的估计。此外，可以通过粉末XRD研究材料的极薄膜（100 nm）的结构，而这种膜不能通过单晶XRD探测。这些研究将在许多领域产生影响，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.