Technical details to beamline and endstations

Source: The beamline is utilizing the outboard tangent point (5.29 Tesla) of a 6 Tesla super conducting bending magnet in sector 12 of the Advanced Light Source. The critical energy is 12.7 keV delivering a quasi continuous spectrum usable between ~ 6 keV and 35 keV.

Optics: The beamline design follows the tried ALS two-stage focusing design (MacDowell et al., 2004). A vertically deflecting plane parabolic collimating mirror (M1) provides parallel light onto two sets of double-crystal monochromators (Si(111) and multilayer). A toroidal focusing mirror (M2) in the 2:1 position focuses the monochromatic X-ray beam onto a first focus spot in the hutch. This first focus spot is equipped with vertical and horizontal slits to create a virtual source. It also serves as the first experimental station (ES-1, high-pressure single crystal diffraction). Alternatively the virtual source can be re-imaged with a set of KB mirrors (demag 2.4(h) x 6.7 (v) onto the sample position of the second end-station (ES-2, high-pressure powder diffraction).

More details can be found in beamline paper Kunz et al. (2005) (attached below)

End-Station 1:

End-station 1 sits at the primary focus spot of the toroidal M2 mirror inside the X-ray hutch. It has been equipped with Stoe StadiVari 4-circle diffractometer, which is situated on a set of Aerotech heavy duty high-precision stages to align the center of rotation (combined sphere of confusion ~ 10 um) of the goniometer onto the ~ 30 x 30 um sized X-ray beam. This goniometer is designed to carry larger diamond anvil cells (BX-90, symmetric cells) within the specified small sphere of confusion. A RDI 1-M CMOS detector serves as the area detector.

The beamline is operational and open to users.

End-Station 2:

End-station 2 is situated at the secondary focus spot created by a set of Kirkpatrick-Baez mirrors on the experimental table. The X-ray focus spot can be adjusted between 5 x 5 um to ~ 15 x 15 um (source size limited). The primary purpose of end-station 2 is to perform X-ray powder diffraction on samples under non-ambient condition. The end-station currently focuses on 2 main techniques: The first one is in-situ high-pressure diffraction on samples in diamond anvil cells (DACs) in axial or radial geometry. Both geometries can be combined with double-sided in-situ laser heating. The second set of experiments combines ambient-pressure X-ray powder diffraction with high temperature and controlled atmospheric composition. The end station can also collect single crystal diffraction data sets by means of a single rotation axis.

As detectors this end-station currently employs a Mar345 image plate reader (cycle-time ca 90 secs) as well as a Dectris Pilatus3 S 1M Hybrid Photon Counting detector

End station 2 is equipped with a double sided laser-heating system applicable to both axial and radial DAC diffraction geometry. Two 100 W SPI fiber lasers serve as the source. The optical path for laser delivery, signal extraction as well as visual viewing is mounted on a 1 x 1 m breadboard assuring short mechanical lever arms and thus low susceptibility to vibration. Pyrometric temperature measurement is based on peak-scaling temperature mapping as introduced by Kavner and co-workers (Rainey and Kavner, 2014; https://doi.org/10.1002/2014JB011267 ). More details on the 12.2.2 laser heating system can be found in Kunz et al. 2018 (https://doi.org/10.1063/1.5028276).

In an Approved Program (AP) collaboration with the Gurlo research group (TU Berlin), we developed a lamp heater interfaced with a gas flow mixer which allows to combine X-ray powder diffractionm (at ambient pressure) with high temperature and controlled atmosphere. This answers a growing demand from the catalysis and energy research community to monitor solid gas reactions in-situ as a function of temperature and atmospheric composition. More details on this capability can be found in Doran et al. (2017) and Schlicker et al (2018).