Fluctuation X-ray microscopy for measuring medium-range order

Lixin Fan, Ian McNulty, David Paterson, Michael Treacy, J. Murray Gibson

Research output: Chapter in Book/Report/Conference proceedingConference contribution

2 Scopus citations


Many x-ray techniques exist to probe long- and short-range order in matter, in real space by imaging and in reciprocal space by diffraction and scattering. However, measuring medium-range order (MRO) in disordered materials is a long-standing problem. Based on fluctuation electron microscopy, which was applied successfully to the understanding of MRO in amorphous materials, we have developed fluctuation x-ray microscopy (FXM). This novel approach offers quantitative insight into medium-range correlations in materials at nanometer and larger length scales. It examines spatially resolved fluctuations in the intensity of a series of x-ray speckle patterns. The speckle variance depends on higher order correlations that are more sensitive to MRO. Systematically measuring the speckle variance as function of the momentum transfer and x-ray illumination size produces a fluctuation map that contains information about the degree of MRO and the correlation length. This approach can be used for the exploration of MRO and subtle spatial structural changes in a wide range of disordered materials from soft condensed matter to nanowire arrays, semiconductor quantum dot arrays and magnetic materials. It will also help us to understand the mechanisms of order-disorder transitions and may lead to control of ordering, which is important in developing ordered structures tailored for particular applications. A theory for FXM and preliminary experimental results from polystyrene latex spheres are discussed in this paper.

Original languageEnglish (US)
Title of host publicationMaterials Research Society Symposium Proceedings
EditorsS.R. Bhatia, P.G. Khalifah, D.J. Pochan, P.G. Radaelli
Number of pages6
StatePublished - 2005
EventNeutron and X-Ray Scattering as Probes of Multiscale Phenomena - Boston, MA, United States
Duration: Nov 29 2004Dec 1 2004


OtherNeutron and X-Ray Scattering as Probes of Multiscale Phenomena
Country/TerritoryUnited States
CityBoston, MA

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials


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