Porträt Dr. habil. Scheinost, Andreas; FWOS

Dr. habil. Andreas Scheinost

Molecular Structures

Phone: +33 476 88 2462
+33 6 340 358 18

Jana Gorzitze
Phone: +49 351 260 3050

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XAFS: fluorescence and transmission detected X-ray Absorption Fine-Structure (XAFS) spectroscopy, including X-ray Absorption Near-Edge Structure (XANES) and Extended X-ray absorption fine-structure (EXAFS) spectroscopies

A large (1 x 10 mm2) beam is obtained by placing the XAFS station far out of focus of the toroidal mirror. A glovebox has been designed, where the samples are exposed to the monochromatic synchrotron beam passing through a back-side extension with Kapton windows, while ionization and fluorescence detectors are at the outside: 

ROBL-II_XAFS-Glovebox ©Copyright: Dr. habil. Scheinost, Andreas

The glovebox contains two automated sample stages, one for room temperature (RT) XAFS measurements (multi-sample RT holder) and one for cryogenic EXAFS measurements (multi-sample cryostat). The RT stage consists of a holder for up to eight samples, which can be moved vertically by a motor to bring each sample into the incident beam. The cryogenic sample stage consists of a custom-made closed-cycle He cryostat (CryoVac). Similar to the RT stage, a motorized vertical translation moves a 6-sample stage inside the cryostat in order to bring the individual samples into the incident beam. Each of the two stages can be moved manually on a tray system between a front position for sample loading, and the back position for the measurement

ROBL-II_XAFS-cryostat ©Copyright: Dr. habil. Scheinost, Andreas

Detectors: two electrically-cooled, Ge or Si multi-element solid state detectors, with individual elements and CMOS-based charge sensitive amplifiers named CUBE (XGLab) for increased count-rate throughput, and Falcon-X read-out spectrometers (XIA). The first one is an electrically cooled (Cryo-Pulse 5 Plus) 18-element Germanium detector (Ultra-LEGe, GUL0055, Mirion Technologies) with 50-µm thick elements providing a spectral resolution of ~150 eV at 100 kcps. The second one is a 7-element Silicon DRIFT detector (SDD) with 500-µm thick Si elements and equipped with a 1.5 Watt pulse tube cooler (PIPS model SXD7X50M-500-CM-CC_01, Mirion Technologies).