The utility of phase alternated pulses for the measurement of dipolar couplings in 2D-SLF experiments

Das, Bibhuti B and Sinha, N and Ramanathan, KV (2008) The utility of phase alternated pulses for the measurement of dipolar couplings in 2D-SLF experiments. In: Journal of Magnetic Resonance, 194 (2). pp. 237-244.

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Abstract

The measurement of hetero-nuclear dipolar coupling using two-dimensional separated local field (SLF-2D) NMR experiments is a powerful technique for the determination of the structure and dynamics of molecules in the solid state and in liquid crystals. However, the experiment is sensitive to a number of factors such as the Hartmann-Hahn match condition, proton frequency off-set and rf heating. It is shown here that by the use of phase alternated pulses during spin-exchange the effect of rf mismatch on the dipolar coupling measurement can be compensated over a wide range of off-sets. Phase alternation together with time and amplitude modulation has also been considered and incorporated into a pulse scheme that combines spin exchange with homonuclear spin decoupling based on magic sandwich sequence and named as SAMPI4. Such time and amplitude averaged nutation experiments use relatively low rf power and generate less sample heating. One of these schemes has been applied on liquid crystal samples and is observed to perform well and yield spectra with high resolution.

Item Type:	Journal Article
Publication:	Journal of Magnetic Resonance
Publisher:	Academic Press INC Elsevier Science
Additional Information:	Copyright for this article belongs to Academic Press INC Elsevier Science
Keywords:	Solid State NMR; CP; SLF; Magic-sandwich; Amplitude time averaged nutation
Department/Centre:	Division of Chemical Sciences > NMR Research Centre (Formerly Sophisticated Instruments Facility)
Date Deposited:	26 Dec 2008 11:05
Last Modified:	19 Sep 2010 04:51
URI:	http://eprints.iisc.ac.in/id/eprint/16405

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