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Resolving Reflections from Large Unit Cells at Short Detector Distances

AppNote PX025: Resolving Reflections from Large Unit Cells at Short Detector Distances

Introduction

Home lab X-ray systems use confocal multilayer optics to produce a small X-ray beam, but often at the expense of higher beam divergence (up to 10 milliradians) that can typically cause reflection overlap when collecting on protein crystals with large unit cells. The Rigaku Oxford Diffraction XtaLAB Synergy systems address this issue by combining two new technologies: the HyPix-6000HE hybrid photon counting (HPC) detector, featuring a small pixel size (100 μm x 100 μm) and a single pixel point-spread function, and a slit mechanism that reduces the beam divergence on demand. Here, we show how reflections along the longest unit cell axis of catalase (~230 Å) can be resolved by using the slit at a short detector distance of 70 mm. Furthermore, we show that a high quality data set to 1.9 Å can be collected overnight and produce an excellent molecular replacement solution.