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Transport properties in ionic liquids and ionic liquid mixtures : the challenges of NMR pulsed field gradient diffusion measurements

journal contribution
posted on 04.07.2007, 00:00 authored by G Annat, D MacFarlane, Maria ForsythMaria Forsyth
Pulsed field gradient NMR is a powerful method for the measurement of diffusion coefficients in liquids and solids and has begun to attract much attention in the ionic liquids field. However, aspects of the methodology as traditionally applied to solutions may not be uniformly applicable in these more viscous and chemically complex systems. In this paper we present data which shows that the Pulsed Gradient Spin Echo (PGSE) method in particular suffers from intrinsic internal gradients and can produce apparent diffusion coefficients which vary by as much as 20% for different 1H nuclei within a given moleculean obvious anomaly. In contrast, we show that the Pulsed Gradient Stimulated Echo method does not suffer from this problem to the same extent and produces self-consistent data to a high degree of accuracy (better than 1%). This level of significance has allowed the detection, in this work, of subtle mixing effects in [C3mpyr][NTf2] and [C4mpyr][NTf2] mixtures.

History

Journal

Journal of physical chemistry B : condensed matter, materials, surfaces, interfaces and biophysical

Volume

111

Issue

30

Pagination

9018 - 9024

Publisher

American Chemical Society

Location

Washington, D.C.

ISSN

1520-6106

eISSN

1520-5207

Language

eng

Publication classification

C1.1 Refereed article in a scholarly journal

Copyright notice

2007, American Chemical Society