Research Fellows Directory
Professor Sharon Ashbrook
University of St Andrews
Exploiting NMR spectroscopy: Local structure and disorder in solids
Nuclear Magnetic Resonance (NMR) spectroscopy is one of the most widely-used analytical tools in chemistry and certainly one of the most powerful. As practically all elements in the periodic table can be studied using NMR, the technique has been used in wide-ranging areas such as materials science, geochemistry, biology and medicine. The ability of NMR to obtain detailed local structural information, without relying on any long-range order, has resulted in the relatively recent development of NMR as an important method for the study of solids. However, NMR spectra of solids contain much broader lines than in solution, making it difficult to see separate signals and extract the information required. This is a particular problem for disordered materials, where variations in exact atomic positions, or the type of atom on a particular site, lead to additional broadening. However, it is often these differences from a regular arrangement of atoms that produce interesting physical and chemical properties that can be exploited commercially.
To obtain information from solid-state NMR spectra we use multinuclear and multidimensional high-resolution experimental methods that resolve the different species present, and we combine these with theoretical prediction of NMR parameters using first-principles computational methods, to understand the complicated and overlapping lineshapes observed. The combination of experiment and calculation offers an exciting new approach for studying solids, and can be applied to solve a wide range of challenges. Rather than focus on simple model systems, we are interested in tackling complex, real systems, exploiting the power of calculation rather than its routine study. While in the short term our work enables new structural insight for the specific systems considered, the ultimate long-term aim is to change the way in which solid-state chemists characterise materials; so that solid-state NMR is viewed as a vital and straightforward step in the development of meaningful structural models.
Areas of current interest include (i) understanding how water is stored in the high-pressure minerals that are found in the inner Earth, (ii) investigating how microporous materials interact with small molecules adsorbed within them, and (iii) considering the prospects for using ceramic oxides to incorporate radioactive cations from nuclear waste streams for long-term containment.
Interests and expertise (Subject groups)