Structure beyond pair correlations: X-ray cross-correlation from colloidal crystals

Journal of applied crystallography 49(6), 2046 - 2052(2016). doi:10.1107/S1600576716017313
The results of an X-ray cross-correlation analysis (XCCA) study on hard-spherecolloidal crystals and glasses are presented. The article shows that cross-correlation functions can be used to extract structural information beyond thestatic structure factor in such systems. In particular, the powder average can beovercome by accessing the crystals’ unit-cell structure. In this case, the resultssuggest that the crystal is of face-centered cubic type. It is demonstrated thatXCCA is a valuable tool for X-ray crystallography, in particular for studies oncolloidal systems. These are typically characterized by a rather poor crystallinequality due to size polydispersity and limitations in experimental resolutionbecause of the small $q$ values probed. Furthermore, nontrivial correlations areobserved that allow a more detailed insight into crystal structures beyondconventional crystallography, especially to extend knowledge in structureformation processes and phase transitions.
Published by Munksgaard, Copenhagen