High-Resolution Crystallographic Studies Using Synchrotron Radiation

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Professor Coppens is supported by a grant from the Experimental Physical Chemistry Program to use synchrotron radiation to determine the locations of atoms in solids which are superconductors and organic substances which are conductors. These studies will help us understand why some materials behave as superconductors at high temperatures and why the organic materials are superconductors at very low temperatures. The project involves the use of synchrotron radiation to study the following: Anomalous scattering of X-rays is used to selectively identify site occupancy, and in combination with high-accuracy charge density techniques, to site-selectively determine the oxidation states of atoms in solids. The response of organic and inorganic crystals to an external electric field is measured and analysed in terms of the piezoelectric effect and molecular and ionic displacements. Very low temperature single crystal techniques are used in the analysis of charge densities in crystals, and in the investigation of the dependence of the structure of low-dimensional conducting solids on temperature.