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Time-resolved X-ray absorption spectroscopy are combined with UV-vis and Raman spectroscopies to study the in situ reduction of Ce(super 4+) to Ce(super 3+) in ethanolic solution with a time resolution of ca.4-5 s. It is observed that high quality results can be obtained simultaneously, thus giving a detailed insight into the mechanisms of the investigated chemical reaction.

The article focuses on the first beam experimental test of a superconductive undulator (SCU14) at the Institute for Synchrotron Radiation storage ring at the Karlsruhe Research Center in Karlsruhe, Germany. SCU14 has been designed by ACCEL Instruments GmbH for nanometer beamline. The experiment has been aimed at demonstrating that the device can be operated under conventional user considerations, which will pave way towards advancement in spectroscopy.

Hard x-ray absorption spectroscopy is combined with scanning microtomography to reconstruct full near-edge spectra of an elemental species at each location on an arbitrary virtual section through a sample. These spectra reveal the local concentrations of different chemical compounds of the absorbing element inside the sample and give insight into the oxidation state, the local atomic structure, and the local projected free density of states. The method is implemented by combining a quick scanning monochromator and data acquisition system with a scanning microprobe setup based on refractive x-ray lenses. [ABSTRACT FROM AUTHOR]

The growth of an opal-like polymer photonic crystal (PhC) on deeply etched silicon wafers is reported. It is shown that 10 μm deep trenches, as narrow as 10 μm can be uniformly filled by self-assembly of microspheres, in a close-packed face-centered-cubic lattice. These observations are confirmed by optical reflectance measurements in the visible range, in agreement with theoretical calculations of the photonic band gap. A slight fluctuation of the lattice parameter is noticed in the case of the narrowest channels. The possibility to detach the PhC from the substrate is also demonstrated. The potential of this approach for building complex PhC-based complex architectures is discussed. [ABSTRACT FROM AUTHOR]

The dynamics of the ignition and extinction of the catalytic partial oxidation (CPO) of methane to hydrogen and carbon monoxide over Pt-Rh/Al(2)O(3) and Pt/Al(2)O(3) were studied in the subsecond timescale using quick-EXAFS with a novel cam-driven X-ray monochromator employing Si(111) and Si(311) crystals. The experiments were performed under reaction conditions in a small fixed-bed capillary reactor. For the first time XAS data were taken with this QEXAFS technique with a Si(311) crystal that opens the energy range up to 35 keV. In addition, both XANES and EXAFS data are shown at the Pt L(3)-edge, allowing to discuss the potential and limitation of this technique in catalysis and related areas. With respect to the noble metal catalysed partial oxidation of methane, several interesting observations were made: structural changes during ignition were-independent of the chosen reaction conditions-significantly faster than during the extinction of the reaction. The dynamic behavior of the catalysts was dependent on the flow conditions and the respective noble metal component(s). Higher reaction gas flow led to a faster ignition process. While the ignition over Pt-Rh/Al(2)O(3) occurred at lower temperature than over Pt/Al(2)O(3), the structural changes during ignition were significantly faster in the latter case. The rate of reduction of the catalyst during ignition was also dependent on the axial position in the fixed-bed. The spectroscopic results provide important insight into the ignition and extinction behavior of the CPO of methane and are complementing results from time-resolved infrared thermography and full field X-ray microscopy studies.