title: Structure beyond pair correlations: X-ray cross-correlation from colloidal crystals.
abstract: The results of an X-ray cross-correlation analysis (XCCA) study on hard-sphere colloidal crystals and glasses are presented. The article shows that cross-correlation functions can be used to extract structural information beyond the static structure factor in such systems. In particular, the powder average can be overcome by accessing the crystals' unit-cell structure. In this case, the results suggest that the crystal is of face-centered cubic type. It is demonstrated that XCCA is a valuable tool for X-ray crystallography, in particular for studies on colloidal systems. These are typically characterized by a rather poor crystalline quality due to size polydispersity and limitations in experimental resolution because of the smallqvalues probed. Furthermore, nontrivial correlations are observed that allow a more detailed insight into crystal structures beyond conventional crystallography, especially to extend knowledge in structure formation processes and phase transitions.
authors.affiliation: Deutsches Elektronen-Synchrotron (DESY), Notkestrasse 85, 22607 Hamburg, Germany; The Hamburg Centre for Ultrafast Imaging, Luruper Chaussee 149, 22761 Hamburg, Germany.
authors.forename: Felix
authors.initials: F
authors.lastname: Lehmkühler
authors.affiliation: Deutsches Elektronen-Synchrotron (DESY), Notkestrasse 85, 22607 Hamburg, Germany; The Hamburg Centre for Ultrafast Imaging, Luruper Chaussee 149, 22761 Hamburg, Germany.
authors.forename: Birgit
authors.initials: B
authors.lastname: Fischer
authors.affiliation: Deutsches Elektronen-Synchrotron (DESY), Notkestrasse 85, 22607 Hamburg, Germany.
authors.forename: Leonard
authors.initials: L
authors.lastname: Müller
authors.affiliation: ESRF - The European Synchrotron, 71 avenue des Martyrs, CS 40220, 38043 Grenoble Cedex 9, France.
authors.forename: Beatrice
authors.initials: B
authors.lastname: Ruta
authors.affiliation: Deutsches Elektronen-Synchrotron (DESY), Notkestrasse 85, 22607 Hamburg, Germany; The Hamburg Centre for Ultrafast Imaging, Luruper Chaussee 149, 22761 Hamburg, Germany.
authors.forename: Gerhard
authors.initials: G
authors.lastname: Grübel
keywords: X-ray cross-correlation analysis; coherent X-ray scattering; colloidal crystals; small-angle X-ray scattering