Time-resolved structure determinations are at the forefront of attempts to understand the mechanisms of protein reactions. We have demonstrated a system for collecting high quality x-ray absorption spectroscopy data on microsecond timescales. The method can be used for both full spectra accumulation and kinetic spectro-photometry. These experiments have vast potential, not only for examining metalloproteins, but also for observing the dynamic behavior of a wide range of chemical elements in conjunction with photochemical, rapid mixing, and temperature jump techniques. The following accomplishments have been made in the preceeding 12-month period: 1) We have successfully increased the effective X-ray flux more than 10 fold by implementing the sagittal dynamic focusing monochromator. 2) We have increased the signal-to-noise ratio by nearly 3 times, with the design, construction and reliable operation of time-resolved 14 channel window discriminator copuled to a computer controlled data acquisition system. 3) We have permanently installed a 20 Hz Nd-YAG laser system with 532 and 355 nm pump beams on beamline X-9B for initiating time-resolved photo-reactions. 4) We have published two papers detailing these improvements, along with several published abstracts and meeting presentations and have another manuscript in preparation.
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