James Keeler

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Organization: University of Cambridge , England
Department: Department of Chemistry
Title: Professor(PhD)
Co-reporter:Michael J. Thrippleton, Richard A.E. Edden, James Keeler
Journal of Magnetic Resonance 2005 Volume 174(Issue 1) pp:97-109
Publication Date(Web):May 2005
DOI:10.1016/j.jmr.2005.01.012
A major problem in J-resolved spectroscopy and many other experiments is the appearance of “artefacts” due to strong coupling. The signals giving rise to these artefacts follow the same coherence transfer pathways as the required signals, making it impossible to suppress them using phase cycling or pulsed field gradients. We present new methods for suppressing these artefacts, applicable to any experiment containing a J-resolved pulse sequence element, as well as to constant-time experiments.
Co-reporter:Michael J. Thrippleton;Nikolaus M. Loening
Magnetic Resonance in Chemistry 2003 Volume 41(Issue 6) pp:441-447
Publication Date(Web):14 APR 2003
DOI:10.1002/mrc.1195

A new experiment for the single-scan measurement of diffusion coefficients is presented. The principle is to introduce a spatial variation in the parameters of a conventional pulse sequence, so that all of the scans required to determine some physical parameter can be recorded simultaneously from different parts of the sample. The spectrum is acquired in the presence of a weak read gradient so that the resulting lineshapes contain the information required. The pulse sequence is described in detail and demonstrated on a sample containing three components; its advantages and limitations are discussed in relation to those of existing techniques. For uncrowded spectra with high signal-to-noise ratio, this experiment provides an order of magnitude reduction in experiment time compared with conventional methods and is likely to be of most benefit where samples are changing rapidly with time or where a long period of polarization, which may be difficult to reproduce accurately, prohibits the use of multiple-scan techniques. Copyright © 2003 John Wiley & Sons, Ltd.

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