The Piezo-QEXAFS technique is a novel tool for time-resolved X-ray absorption spectroscopy in the hard X-ray range. Monochromator components consisting of specialized tilt stages to perform fast energy scans, lightweight crystal holders, bending mechanics, and control electronics are being installed and commissioned. It is planned to perform fast EXAFS scans with time resolution in the millisecond range. With Piezo-QEXAFS all typical X-ray absorption experiments will be possible as it retains the standard linear geometry. The achieved time resolution opens interesting insights into the dynamics of phase transitions and chemical reactions.

The Piezo-QEXAFS technique is a novel tool for time-resolved X-ray absorption spectroscopy in the hard X-ray range. It makes use of piezo tilt tables mounted below the crystals in a double crystal or channel cut crystal monochromator. Repetitive energy scans are performed by applying an oscillatory high voltage to the piezo translators of the tilt tables. This year, new components consisting of specialized tilt stages, lightweight crystal holders and control electronics have been commissioned to improve the performance. It is now possible to perform fast scans over a larger energy range with a time resolution in the ms range. With Piezo-XAFS all typical X-ray absorption experiments are possible. All detection modes can be used, especially fluorescence detection, which is suitable even for highly diluted systems. The achieved time resolution opens interesting insights into the dynamics of chemical reactions and phase transitions. The method will be described in detail and latest results from performance tests and scientific applications will be discussed.

A new bending mechanism for an indirectly water cooled monochromator crystal has been developed. The main design goals were a lightweight construction, ease of manufacture, and control. The construction consists of a U-shaped first Si(111) crystal, which can be bent by compressed air to compensate the bowing induced by the heat load from the impinging white synchrotron radiation. The performance of the system was tested at the x-ray undulator beamline BW1 at HASYLAB (Hamburg, Germany). For heat loads between ∼100 and 400 W, rebending of the crystal significantly increases the intensity of the monochromatic beam while the rocking curve is narrowed accordingly, typical widths obtained at 8.9 keV photon energy amount to about 10 arc sec.

No abstract