Development of High Energy Resolution Anomalous X-ray Scattering Instrumentation for High-Brilliance Synchrotron Beamlines

化学研究仪器和设施(CRIF)计划和综合活动办公室的重大研究仪器(MRI)计划颁发的这一奖项将支持开发一种准确可靠的异常X射线衍射(AXD)光谱仪，该光谱仪由高能分辨率窄带通晶体光学单色仪和晶体分析仪组成。这是北伊利诺伊大学物理系的苏珊·米尼和芝加哥大学高级放射源联盟(CARS)的科学家蒂莫西·格雷伯和P·詹姆斯·维卡罗共同参与的团队工作。该光谱仪将允许在吸收边附近原子的散射截面中利用全部能量色散。该仪器将安装在高级光子源(APS)的光束线15上，主要用于特定价态的静态和时间分辨化学结晶学实验。应用领域包括研究大磁阻氧化物、软材料的表面和界面性质，以及聚合物的时间相关性研究。AXD技术将帮助解决含有混价原子的未知晶体结构，以补充中子衍射和局部探测器，如X射线吸收光谱。AXD还将提供一种有用的方法来研究具有不同配位几何类型的元素在单一氧化态的行为。目前，AXD研究是在几个eV的能量分辨率下进行的，这防止了对一个特定价态的原子的结构因子进行选择性修改。该仪器具有更高的分辨率，再加上APS的高光谱亮度，将对固态和材料科学产生重大影响。

This award from the Chemistry Research Instrumentation and Facilities (CRIF) Program and the Major Research Instrumentation (MRI) Program of the Office of Integrative Activities will support the development of an accurate and reliable anomalous x-ray diffraction (AXD) spectrometer consisting of a high-energy-resolution narrow-band-pass crystal-optics monochromator and crystal analyzer. This is a team effort involving Susan Mini of the Physics Department at Northern Illinois University and Timothy Graber and P. James Viccaro, both scientists at The Consortium for Advanced Radiation Sources (CARS) of The University of Chicago. The spectrometer will allow utilization of full energy dispersion in scattering cross-section of atoms near the absorption edge. The instrumentation, which will be installed on beamline 15 at the Advanced Photon Source (APS), will be used primarily for valence-specific static and time-resolved chemical crystallography experiments. Applications include studies on large magnetoresistive oxides, surfaces and interfacial properties of soft materials and time-dependent studies of polymers. The AXD technique will help solve unknown crystal structures containing mixed-valent atoms in a way complementary to neutron diffraction and local probes such as x-ray absorption spectroscopy. AXD will also provide a useful method to study the behavior of an element in a single oxidation state with different types of coordination geometry. Currently, AXD studies are carried out with energy resolution of a few eV, which prevents selective modification of the structure factor of atoms of one particular valence over another. This instrument, with its significantly higher resolution, combined with the high spectral brilliance of the APS, will have significant impact in solid-state and materials science.