NEW SOFT-ENERGY X-RAY ABSORPTION SPECTROSCOPY BEAM LINE

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. A new beam line side station for XAS measurements in the 2-5 keV, BL4-3, range was commissioned in 2008-2009 and brought to general user access in the spring of 2009. In this energy range, x-rays have a very short path length in air and thus the entire beam path is enclosed in a helium atmosphere to enable data collection. The instrumentation developed for this beam line incorporate several features to improve efficiency and ease of use. This includes computer-controlled motorized x-ray slits, a motorized linear motion feed-through, and a computer-controlled shutter to close off the beam between data points (to reduce x-ray induced damage to samples). Oxygen sensors and flowmeters are utilized for monitoring the purity of the helium atmosphere. A LHe cryostream is used for cooling samples to ~50 K. Valuable experience in user mode is being used to further improve the beam line and instrumentation.