Wednesday 7 November 2012, 4.00PM
Speaker(s): Dr. Sharon Ashbrook (St. Andrews)
Determining the structure of well-ordered, periodic crystalline solids can often be straightforward using methods exploiting Bragg diffraction. However, it is often the deviations from periodicity, e.g., compositional, positional or temporal disorder, that produce the interesting physical properties that may be of commercial interest. As NMR is sensitive to the atomic-scale environment, it provides a potentially useful tool for studying disordered materials. However, much of the information available from solid-state NMR spectra remains unexploited owing to the difficulty of obtaining high-resolution spectra, and the challenges associated with their assignment. Recent advances enabling accurate and efficient determination of NMR parameters in periodic systems have revolutionized the application of DFT calculations in solid-state NMR spectroscopy, particularly among experimentalists. The use of first-principles calculations aids both in the interpretation and assignment of the complex spectral lineshapes observed for solid-state NMR. Furthermore, for materials with poorly characterized structures calculations provide a method for evaluating potential structural models against experimental measurements. After a brief introduction to the experimental and theoretical approaches used, the application of this combined approach for studying structure, disorder and dynamics will be illustrated with examples from recent work studying high-pressure silicates important in the inner Earth.
Originally from Liverpool, Sharon Ashbrook graduated with an MChem from Hertford College, Oxford, in 1997, before studying for her DPhil (2001) in the Physical and Theoretical Chemistry Laboratory, Oxford in the group of Professor Stephen Wimperis. After two year postdoctoral work at the University of Exeter, in 2003 she was awarded a Royal Society Dorothy Hodgkin Fellowship, which she held at the Department of Earth Sciences, University of Cambridge and, subsequently, in St Andrews. She also held the Charles and Katherine Darwin Research Fellowship at Darwin College. From October 2005, she was appointed as an RCUK Academic Fellow in the School of Chemistry at the University of St Andrews, and was promoted to Reader in 2009. Her research focuses on the application of multinuclear solid-state NMR techniques, and their combination with first-principles DFT calculations, to investigate structure, disorder and dynamics in inorganic solids, and she has published 98 papers in this area. She was awarded the RSC Harrison Prize in 2004, the RSC Marlow Award for Physical Chemistry in 2011, and the RSE Makdougall Brisbane Medal for Early Career Research in Physical Science in 2012.