Solvent relaxation NMR
Pulsed nuclear magnetic resonance (NMR) experiments are commonly used for sensitive and accurate structural identification of unknown compounds and for investigating the physical properties of mixtures. We have developed a miniaturised bench-top NMR as part of an on-going project of creating small, cheap, low-power NMR instrumentation for deployment in both laboratory settings and field-work.
The physical basis for the instrument is the measurement of the relaxation rates of the solvent molecules following excitation of the nuclei by a radiofrequency pulse. The NMR solvent relaxation times are sensitive to the available surface area in a dispersion of particles in a ﬂuid. The basic idea is that a molecule adsorbed at an interface has a much shorter relaxation time than one in the bulk. Typically for a silica in water dispersion the bulk spin relaxation times will be of the order of 2 s, whereas the surface ones will be ~1 ms. In the fast exchange limit we measure a dynamic average of these times.
Our approach was discussed in presentations at the 24th European Colloids and Interface Society Meeting  and the UK Colloids 2011 meeting . Other publications relating to this work have appeared in Langmuir [3, 4]. Our commercial partner in this venture is XiGo Nanotools and an overview of our work with them can be found in Spectroscopy Europe .
- Molecules at the solid-liquid interface: a miniature NMR to characterise colloidal systems. CL Cooper, B Cattoz, SW Prescott and T Cosgrove. 24th Conference of the European Colloids and Interfaces Society, Prague, Czech Republic, September 2010.
- NMR as an analytical tool to characterise dispersions. CL Cooper, P Wiroonpochit, T Cosgrove, SW Prescott and D Fairhurst. UK Colloids 2011, July 2011.
- Surfactant-mediated desorption of polymer from the nanoparticle interface. B Cattoz, T Cosgrove, M Crossman and SW Prescott. Langmuir, 28(5), 2485–2492, 2012.
- Manipulating interfacial polymer structures through mixed surfactant adsorption and complexation. B Cattoz, WM de Vos, T Cosgrove, M Crossman and SW Prescott. Langmuir, 28(15), 6282–6290, 2012.
- The use of nuclear magnetic resonance as an analytical tool in the characterisation of dispersion behaviour. D Fairhurst and SW Prescott. Spectroscopy Europe, 23 2011.
Last edited: Wednesday November 28, 2012
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