Instrument-model refinement in normalized reciprocal-vector space for X-ray Laue diffraction

Abstract

A simple yet efficient instrument-model refinement method for X-ray diffraction data is presented and discussed. The method is based on least-squares minimization of differences between respective normalized (i.e. unit length) reciprocal vectors computed for adjacent frames. The approach was primarily designed to work with synchrotron X-ray Laue diffraction data collected for small-molecule single-crystal samples. The method has been shown to work well on both simulated and experimental data. Tests performed on simulated data sets for small-molecule and protein crystals confirmed the validity of the proposed instrument-model refinement approach. Finally, examination of data sets collected at both BioCARS 14-ID-B (Advanced Photon Source) and ID09 (European Synchrotron Radiation Facility) beamlines indicated that the approach is capable of retrieving goniometer parameters (e.g. detector distance or primary X-ray beam centre) reliably, even when their initial estimates are rather inaccurate.

Advances in Diffraction Studies of Light-Induced Transient Species in Molecular Crystals and Selected Complementary Techniques

“…Similarly, as it is the case in PRECOGNITION, the experimental setup parameters are of extreme importance to properly obtain the crystal orientation matrix. Originally LAUEUTIL came with no toolkit to refine these parameters, however, recently an instrument-model refinement method has been reported by [71], and successfully applied to the cases where the assumed experimental values were off from their initial estimates. Finally, it should be noted that novel algorithms of this kind still emerge, as for example the new PinkIndexer module developed by Gevorkov et al [72].…”