title: Determination of crystallographic intensities from sparse data.
abstract: X-ray serial microcrystallography involves the collection and merging of frames of diffraction data from randomly oriented protein microcrystals. The number of diffracted X-rays in each frame is limited by radiation damage, and this number decreases with crystal size. The data in the frame are said to be sparse if too few X-rays are collected to determine the orientation of the microcrystal. It is commonly assumed that sparse crystal diffraction frames cannot be merged, thereby setting a lower limit to the size of microcrystals that may be merged with a given source fluence. The EMC algorithm [Loh & Elser (2009 ▶), Phys. Rev. E, 80, 026705] has previously been applied to reconstruct structures from sparse noncrystalline data of objects with unknown orientations [Philipp et al. (2012 ▶), Opt. Express, 20, 13129-13137; Ayyer et al. (2014 ▶), Opt. Express, 22, 2403-2413]. Here, it is shown that sparse data which cannot be oriented on a per-frame basis can be used effectively as crystallographic data. As a proof-of-principle, reconstruction of the three-dimensional diffraction intensity using sparse data frames from a 1.35 kDa molecule crystal is demonstrated. The results suggest that serial microcrystallography is, in principle, not limited by the fluence of the X-ray source, and collection of complete data sets should be feasible at, for instance, storage-ring X-ray sources.
authors.affiliation: Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, NY 14853, USA.
authors.forename: Kartik
authors.initials: K
authors.lastname: Ayyer
authors.affiliation: Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, NY 14853, USA.
authors.forename: Hugh T
authors.initials: HT
authors.lastname: Philipp
authors.affiliation: Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, NY 14853, USA.
authors.forename: Mark W
authors.initials: MW
authors.lastname: Tate
authors.affiliation: Field of Biophysics, Cornell University, Ithaca, NY 14853, USA ; Cornell High Energy Synchrotron Source (CHESS), Cornell University, Ithaca, NY 14853, USA.
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Wierman
authors.affiliation: Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, NY 14853, USA.
authors.forename: Veit
authors.initials: V
authors.lastname: Elser
authors.affiliation: Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, NY 14853, USA ; Cornell High Energy Synchrotron Source (CHESS), Cornell University, Ithaca, NY 14853, USA ; Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, NY 14853, USA.
authors.forename: Sol M
authors.initials: SM
authors.lastname: Gruner
keywords: EMC algorithm; X-ray serial microcrystallography; reconstruction of diffraction intensity; sparse data