Acquisition of a Four-Circle Single-Crystal Diffractometer with CCD Detector

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9725354 Finger This grant provides partial support of the costs of acquiring a new four-circle single-crystal X-ray diffractometer with a CCD detector. This area detector has much higher sensitivity than previous models, and collects two-dimensional sections of the diffracted intensity that can be combined to construct a full three-dimensional view of reciprocal space. With such information, it is possible to study very small or twinned crystals, and to study diffuse scattering arising from various sources of disorder. The X-ray group at the Geophysical Laboratory, consisting of Larry Finger, Charles Prewitt, Robert Hazen, and Hexiong Yang, will develop the necessary techniques to use the CCD detector system with the diamond-anvil cell. With the new instrument, it will be possible to measure lattice constants and perform a crystal- structure refinement in less time than currently used for a lattice-constant determination. High-pressure crystallography is an essential component in understanding phase relations in the deep earth. Once this instrument is installed, 25% of the operating time will be available as a regional resource, with emphasis on the earth science community. It will also be used as a resource in the Laboratory's summer intern program, which is funded a by a REU grant. ***