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Pulse Sequence Development

High-Resolution 1H Solid-State NMR

We have developed, together with the Emsley group in Lyon, France, high-resolution 1H DQ pulse sequences employing DUMBO 1H homonuclear decoupling: in 2004, we presented a 1H-1H DQ-SQ (single-quantum) 2D experiment that was demonstrated to achieve an up to factor of nine resolution enhancement as compared to fast MAS for a dipeptide (Brown 2004); in 2010, we presented a 1H (DQ) -13C (SQ) pulse sequence employing the refocused INEPT pulse sequence element to transfer coherence, which allows the better resolution of 1H DQ peaks via the 13C dimension (Webber 2010).

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spb-pulseq_f3.jpg This work is supported by a collaboration with Paul Hodgkinson, Durham looking at the factors affecting 1H resolution under MAS (Zorin 2006) and homonuclear decoupling (Zorin 2008 & Tatton 2012). spb-pulseq_f2.jpg


Utilising, Detecting and Quantitatively Determining J Couplings

Together with other researchers (including Malcolm Levitt, Southampton & the Emsley (Lyon, France) & Massiot (Orléans, France) groups), we have presented a description that combines analytical theory, experiment and density-matrix simulation for the homonuclear spin-echo (Duma 2004) and refocused INADEQUATE (Fayon 2005 & Cadars 2007) experiments that are used to quantitatively determine J couplings and demonstrate through-bond connectivities, respectively. In 2009, we presented the first-ever 15N-17O experiments, by which 2hJ15N-17O couplings across NH...O hydrogen bonds were quantitatively determined for uracil (Hung 2009).

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We have also shown how the REINE (REfocused INadequate spin-Echo) experiment first presented by Cadars et al (Cadars 2007) can be applied to a phosphate glass to reveal correlations between the 2JPP coupling and the 31P chemical shifts of the coupled nuclei for apparently featureless DQ peaks (Guerry 2009).


Residual Dipolar Couplings

Working together with the Levitt group in Southampton, we have shown how dipolar couplings and hence distances can be determined by recording the spin-echo evolution for sample spinning off the magic angle (Pileio 2007). The use of a doubly-selective cosine-modulated Gaussian pulse enables small dipolar couplings corresponding to longer distances to be determined for fully 13C-labelled molecules (Pileio 2008).
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