Open AccessImproved crystal orientation and physical properties from single‐shot XFEL stills
Author(s) -
Sauter Nicholas K.,
Hattne Johan,
Brewster Aaron S.,
Echols Nathaniel,
Zwart Petrus H.,
Adams Paul D.
Publication year - 2014
Publication title -
acta crystallographica section d
Language(s) - English
Resource type - Journals
ISSN - 1399-0047
DOI - 10.1107/s1399004714024134
Subject(s) - diffraction , bragg's law , optics , orientation (vector space) , femtosecond , physics , laser , rotation (mathematics) , crystal (programming language) , reciprocal lattice , bragg peak , shot noise , detector , computer science , geometry , mathematics , beam (structure) , programming language
X‐ray diffraction patterns from still crystals are inherently difficult to process because the crystal orientation is not uniquely determined by measuring the Bragg spot positions. Only one of the three rotational degrees of freedom is directly coupled to spot positions; the other two rotations move Bragg spots in and out of the reflecting condition but do not change the direction of the diffracted rays. This hinders the ability to recover accurate structure factors from experiments that are dependent on single‐shot exposures, such as femtosecond diffract‐and‐destroy protocols at X‐ray free‐electron lasers (XFELs). Here, additional methods are introduced to optimally model the diffraction. The best orientation is obtained by requiring, for the brightest observed spots, that each reciprocal‐lattice point be placed into the exact reflecting condition implied by Bragg's law with a minimal rotation. This approach reduces the experimental uncertainties in noisy XFEL data, improving the crystallographic R factors and sharpening anomalous differences that are near the level of the noise.