title: Angular correlations of photons from solution diffraction at a free-electron laser encode molecular structure.
abstract: During X-ray exposure of a molecular solution, photons scattered from the same molecule are correlated. If molecular motion is insignificant during exposure, then differences in momentum transfer between correlated photons are direct measurements of the molecular structure. In conventional small- and wide-angle solution scattering, photon correlations are ignored. This report presents advances in a new biomolecular structural analysis technique, correlated X-ray scattering (CXS), which uses angular intensity correlations to recover hidden structural details from molecules in solution. Due to its intense rapid pulses, an X-ray free electron laser (XFEL) is an excellent tool for CXS experiments. A protocol is outlined for analysis of a CXS data set comprising a total of half a million X-ray exposures of solutions of small gold nanoparticles recorded at the Spring-8 Ångström Compact XFEL facility (SACLA). From the scattered intensities and their correlations, two populations of nanoparticle domains within the solution are distinguished: small twinned, and large probably non-twinned domains. It is shown analytically how, in a solution measurement, twinning information is only accessibleviaintensity correlations, demonstrating how CXS reveals atomic-level information from a disordered solution of like molecules.
authors.affiliation: Department of Applied Physics, Stanford University, Stanford, CA 94305, USA.
authors.forename: Derek
authors.initials: D
authors.lastname: Mendez
authors.affiliation: Department of Applied Physics, Stanford University, Stanford, CA 94305, USA.
authors.forename: Herschel
authors.initials: H
authors.lastname: Watkins
authors.affiliation: Department of Physics, Stanford University, Stanford, CA 94305, USA.
authors.forename: Shenglan
authors.initials: S
authors.lastname: Qiao
authors.affiliation: Department of Applied Physics, Stanford University, Stanford, CA 94305, USA.
authors.forename: Kevin S
authors.initials: KS
authors.lastname: Raines
authors.affiliation: SLAC National Accelerator Laboratory, Menlo Park, CA 94025 USA.
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Lane
authors.affiliation: Department of Applied Physics, Stanford University, Stanford, CA 94305, USA.
authors.forename: Gundolf
authors.initials: G
authors.lastname: Schenk
authors.affiliation: Department of Physics, Arizona State University, Tempe, AZ 85287, USA.
authors.forename: Garrett
authors.initials: G
authors.lastname: Nelson
authors.affiliation: Department of Physics, Arizona State University, Tempe, AZ 85287, USA.
authors.forename: Ganesh
authors.initials: G
authors.lastname: Subramanian
authors.affiliation: Japan Synchrotron Radiation Research Institute (JASRI), Kouto 1-1-1, Sayo, Hyogo 679-5198, Japan.
authors.forename: Kensuke
authors.initials: K
authors.lastname: Tono
authors.affiliation: Japan Synchrotron Radiation Research Institute (JASRI), Kouto 1-1-1, Sayo, Hyogo 679-5198, Japan.
authors.forename: Yasumasa
authors.initials: Y
authors.lastname: Joti
authors.affiliation: RIKEN SPring-8 Center, Kouto 1-1-1, Sayo, Hyogo 679-5148, Japan.
authors.forename: Makina
authors.initials: M
authors.lastname: Yabashi
authors.affiliation: SLAC National Accelerator Laboratory, Menlo Park, CA 94025 USA.
authors.forename: Daniel
authors.initials: D
authors.lastname: Ratner
authors.affiliation: Department of Applied Physics, Stanford University, Stanford, CA 94305, USA; SLAC National Accelerator Laboratory, Menlo Park, CA 94025 USA.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Doniach
keywords: XFELs; angular photon correlations; correlated X-ray scattering; gold nanoparticles; solution diffraction