XRD-1: A heavy-duty, Eulerian cradle, 6-circle goniometer for (high-resolution) powder X-ray diffraction (PXRD), surface-sensitive crystal truncation rod (CTR) and resonant anomalous X-ray reflectivity (RAXR) measurements

The XRD-1 station is a 6-circle diffractometer (Huber Diffraktionstechnik GmbH) equipped to analyze well-defined single reflexes with high resolution, and is hence suited for high-resolution powder diffraction as well as for surface diffraction. The diffractometer is equipped with a Pilatus 100k detector mounted on a rigid detector arm, which can freely rotate in relation to the sample mount. The diffractometer construction is based on the classical Eulerian cradle geometry. The detector arm can be moved in the horizontal and in the vertical scattering plane, as well as in any direction combing the horizontal and vertical movements.

The incoming X-ray beam is shaped and monitored with the beam conditioning unit, which is placed in front of the diffractometer. Its components are modular and easily exchangeable. The intensity of the incoming X-ray beam is counted by a monitor, which consists of a 45°-tilted, 20-µm Kapton scattering foil and a LaCl3 scintillation counter (FMB Oxford /Cyberstar). The second module allows to reduce the primary intensity by remote-controlled pneumatic insertion of different metal foils. A third module suppresses parasitic scattering with a vacuum-tight slit (IB-C22-HV, JJ-X-ray). The fourth module is a fast shutter (RI Research Instruments GmbH) to protect the final detector from too intense reflections during goniometer and detector movements. Module 5 is an ionization chamber (IC Plus 50, FMB Oxford) to monitor the true incoming X-ray intensity for normalization. Module 6 is a pinhole, which cuts off the remaining parasitic beam scattering off the tungsten blades of the slit. The unit is under vacuum except for the last two components.

Two detection modules are available, one for surface diffraction and one for high-resolution powder diffraction. Both modules use a Pilatus 100K detector with a 450-µm Si sensor (Dectris Ltd.).

The diffractometer is operated with SPEC.