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On the measurement of intermolecular heteronuclear cross relaxation rates in ionic liquids

journal contribution
posted on 21.05.2018, 00:00 authored by Pierre-Alexandre Martin, Elodie Salager, Maria ForsythMaria Forsyth, Luke O'DellLuke O'Dell, Michaël Deschamps
The HOESY (Heteronuclear Overhauser Effect SpectroscopY) NMR experiment is commonly used to study interactions and structuring in ionic liquids (ILs) via the measurement of the cross relaxation rate σ between two spins. In the intermolecular case, σ is proportional to r-n, where r is the internuclear distance and n can vary between 1 and 6 depending on the frequency of the nuclei and their dynamics, thus σ can potentially provide detailed information on the liquid phase structure. However, in HOESY studies of ILs only relative values for σ are typically reported, making comparisons between different samples difficult. Herein we discuss the quantitative measurement of intermolecular cross relaxation rates based on the normalisation of HOESY signal intensities to the nuclear Boltzmann polarisation, demonstrated for 7Li-1H spin pairs in a lithium-containing pyrrolidinum-based ionic liquid electrolyte. We also use a simple model based on diffusing hard spheres for interpreting these quantities in terms of a distance of closest approach.

History

Journal

Physical chemistry chemical physics

Volume

20

Issue

19

Pagination

13357 - 13364

Publisher

Royal Society of Chemistry

Location

Cambridge, Eng.

eISSN

1463-9084

Language

eng

Publication classification

C1 Refereed article in a scholarly journal

Copyright notice

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