NEXAFS Crystallography: A novel approach to refinement of proton positions in organic crystal structures

Product design in many industrial sectors requires accurate information on the positions of hydrogen atoms in organic crystalline structures. While crystallography has been the gold standard for crystal structure determination, many of the materials of interest cannot be produced as single crystals, and powder diffraction methods are limited in their ability to locate hydrogen atoms.

Our research group has shown how X-ray absorption spectroscopy (XAS) can be combined with Density Functional Theory (DFT) calculations to determine the positions of protons in crystal structures with very high accuracy, comparable to high-resolution X-ray diffraction and neutron diffraction methods. Such XAS refinement of proton and hydrogen positions is a radically novel way of analysing crystal structures formed by small organic molecules.

The proposed PhD project will use the Near-Edge X-ray Absorption Fine Structure (NEXAFS) facilities at Diamond Light Source. The PhD student will perform these studies by choosing libraries of representative crystal structures from the Cambridge Crystallography database. The student will be embedded in the Diamond-Leeds collaboration and in the Continuous Manufacturing and Crystallisation (CMAC) Group in the Research Complex at Harwell. Close collaboration with the Industrial Liaison Office (ILO) at Diamond will ensure both academic and industrial impact.