Novel angular encoder for a quick-extended x-ray absorption fine structure monochromator

Abstract

New concepts for time-resolved x-ray absorption spectroscopy using the quick-extended x-ray absorption fine structure (QEXAFS) method are presented. QEXAFS is a powerful tool to gain structural information about, e.g., fast chemical reactions or phase transitions on a subsecond scale. This can be achieved with a monochromator design that employs a channel-cut crystal on a cam driven tilt table for rapid angular oscillations of the Bragg angle. A new angular encoder system and a new data acquisition were described and characterized that were applied to a QEXAFS monochromator to get spectra with a directly measured accurate energy scale. New electronics were designed to allow a fast acquisition of the Bragg angle values and the absorption data during the measurements simultaneously.

Applying Dynamic and Synchronous DRIFTS/EXAFS to the Structural Reactive Behaviour of Dilute (≤1 wt%) Supported Rh/Al2O3 Catalysts using Quick and Energy Dispersive EXAFS

“…The author is given to understand (and sincerely hopes) that other resources of this nature are planned elsewhere, and will pass into the realm of accessible user facilities in the relatively near future. Further information regarding this new type of QUEXAFS resource can be found in [58,59] or (http://sls.web.psi.ch/view.php/beamlines/superxas/). processes, and materials research in general.…”

Study of the Chemical Mechanism Involved in the Formation of Tungstite in Benzyl Alcohol by the Advanced QEXAFS Technique

“…The other energy values were calculated relative to this value through the signal of an angular encoder installed inside the QEXAFS monochromator. [28] A high voltage of 1500 V was applied to the two plates of each chamber, which were mounted with a gap of 10 mm. In all experiments, a time resolution of one spectrum every 500 ms was chosen to follow the dynamics of the reaction.…”

Reduction and re-oxidation of Cu/Al2O3catalysts investigated with quick-scanning XANES and EXAFS

“…With an excenter disk of 0.30° an energy range between about 8960 eV and 9440 eV was covered providing the possibility to study the EXAFS region at the Cu K-edge. The Bragg angle was acquired simultaneously to the signal of the three air-filled ionisation chambers using a recently installed angular encoder [16]. A copper metal foil placed between the second and third chamber was used for accurate energy calibration.…”