GARFIELD, a toolkit for interpreting ultrafast electron diffraction data of imperfect quasi-single crystals

Abstract: The analysis of ultrafast electron diffraction (UED) data from low-symmetry single crystals of small molecules is often challenged by the difficulty of assigning unique Laue indices to the observed Bragg reflections. For a variety of technical and physical reasons, UED diffraction images are typically of lower quality when viewed from the perspective of structure determination by single-crystal X-ray or electron diffraction. Nevertheless, time series of UED images can provide valuable insight into structural dynamics, provided that an adequate interpretation of the diffraction patterns can be achieved. GARFIELD is a collection of tools with a graphical user interface designed to facilitate the interpretation of diffraction patterns and to index Bragg reflections in challenging cases where other indexing tools are ineffective. To this end, GARFIELD enables the user to interactively create, explore, and optimize sets of parameters that define the diffraction geometry and characteristic properties of the sample.