Issue 97, 2016

Convection in liquid-state NMR: expect the unexpected

Abstract

Temperature gradients in liquid-state NMR samples are unavoidable, but undesirable: they lead to sample convection, and consequently to signal attenuation in experiments that use field gradients. This paper illustrates how widely the dependence of sample convection velocity on the temperature at which the sample is maintained can differ between different probes and different spectrometers, including the first such results for cryoprobe systems, and highlights the importance of understanding this dependence if the effects of sample convection are to be kept to an acceptable minimum. It is sometimes thought that efficient sample temperature control should suffice to avoid convection: alas, this is not true, and rapid sample convection can occur even with the best hardware. Previous experiments have shown that the effects of convection can sometimes be avoided by setting the sample temperature regulation to one particular temperature; here it is shown that no such temperature exists in some probes. The issue of convection is all too often swept under the carpet; these results confirm that it is a more general problem than is commonly realized.

Graphical abstract: Convection in liquid-state NMR: expect the unexpected

Supplementary files

Article information

Article type
Paper
Submitted
20 Sept. 2016
Accepted
26 Sept. 2016
First published
26 Sept. 2016
This article is Open Access
Creative Commons BY license

RSC Adv., 2016,6, 95173-95176

Convection in liquid-state NMR: expect the unexpected

T. M. Barbosa, R. Rittner, C. F. Tormena, G. A. Morris and M. Nilsson, RSC Adv., 2016, 6, 95173 DOI: 10.1039/C6RA23427E

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

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