Center for Functional Nanomaterials Seminar

"Fluctuation Electron Microscopy â€" probing higher order structural correlations in disordered materials by coherent diffraction Soft Matter Enhanced Electrochemical Energy Storage and 3D Photonic Crystals"

Presented by J. Murray Gibson, Department of Physics, Northeastern University, Boston

Thursday, September 10, 2015, 11:00 am — CFN, Building 735, 2nd floor - Seminar Conf. Rm.

Center for Functional Nanomaterials J. Murray Gibson Department of Physics, Northeastern University, Boston Fluctuation Electron Microscopy â€" probing higher order structural correlations in disordered materials by coherent diffraction Soft Matter Enhanced Electrochemical Energy Storage and 3D Photonic Crystals Thursday, September 10, 2015 11:00 a.m. Seminar Room, 2nd Fl. The conventional pair-correlation function, measured directly from diffraction, is a powerful tool to measure short-range order on the scale of chemical bonds and next neighbors. With sufficiently well-defined long range order, the 2-body function clearly reveals symmetry and periodicity. Diffraction techniques have thus been incredibly successful at the short-range in teaching us about the structure of liquids and amorphous solids, and at the other scale most of what we know about the crystalline structure of matter. However the 2-body function has a potential "blind spot" for ordering at intermediate length scales, typically up to of order ten bond lengths. Studies of amorphous materials by other techniques suggest that there can be pronounced medium-range ordering on the nanoscale and that it can significantly affect physical properties. It is now recognized that higher-order correlation functions (3 and 4 body) are far more sensitive to medium-range order and that that they can be accessed experimentally from coherent diffraction experiments. One of the earliest techniques to examine this was fluctuation microscopy (FM), developed by Treacy and Gibson1 for electron microscopy (FEM) and applied early to demonstrate medium-range order and the effect of annealing in amorphous germanium2. In more recent years, with the freer access to coherent sources of electrons and x-rays, more people are using FEM and developing related techniq

Hosted by: Eric Stach

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