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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.

Selenium-rich Ge-Te-Se glasses have been synthesized along the GeSe4-GeTe4 pseudo-composition line and acquired by (77)Se Hahn echo magic-angle spinning NMR. The comparison with the GeSe4 spectrum shows a drastic modification of the typical double-resonance lineshape even at low Te concentrations (<10%). In order to rationalize this feature and to understand the effect of Te on the structure of our glasses, first-principles molecular dynamics simulations and gauge including projector augmented wave NMR parameter calculations have been performed. The distribution of the tellurium atoms in the selenium phase was shown to be mainly responsible for the (77)Se lineshape changes. Another possible factor related to the perturbation of the δiso value due to Te proximity appears to be much more limited in the bulk, while the results obtained using molecular models suggest shifts of several hundreds of ppm.

Solid-state (77)Se NMR measurements, first-principles molecular dynamics and DFT calculations of NMR parameters were performed to gain insight into the structure of selenium-rich GexSe(1-x) glasses. We recorded the fully-relaxed NMR spectra on natural abundance and 100% isotopically enriched GeSe4 samples, which led us to reconsider the level of structural heterogeneity in this material. In this paper, we propose an alternative procedure to initialise molecular dynamics runs for the chalcogenide glasses. The (77)Se NMR spectra calculated on the basis of the structural models deduced from these simulations are consistent with the experimental spectrum.

Lithium self-diffusion coefficients are measured for the first time using (7)Li Pulsed-Field Gradient Nuclear Magnetic Resonance (PFG-NMR) in a crystalline inorganic powder of α-Li(3)N between 534 K and 774 K. The diffusion of lithium cations is anisotropic, and the activation energy for the diffusion within the Li(2)N layers was found to be 0.150 ± 0.009 eV.

Measuring internuclear distances through dipolar interaction is a major challenge for solid-state nuclear magnetic resonance (NMR) spectroscopy. Obtaining reliable interatomic distances provides an access to the local structure in ordered or disordered solids. We show that at magic angle spinning (MAS) frequencies larger than ca. 50 kHz, some of the three-spin terms of the homogeneous homonuclear dipolar Hamiltonian can be used to promote the creation of double-quantum coherences between neighbouring (1)H or (19)F spins without using dipolar recoupling pulse sequences in the Dipolar Homonuclear Homogeneous Hamiltonian (DH(3)) double-quantum/single-quantum correlation experiment. This makes it possible to probe inter-nuclear spatial proximity with limited risk of probe or sample damage from radio-frequency (RF) irradiation, and is fully appropriate for fast repetition rate offering sensitivity gains in favourable cases. Experimental demonstrations are supported by multi-spin numerical simulations, which points to new possibilities for the characterization of spin-system geometries., (This journal is © the Owner Societies 2011)

Chemical disorder can be characterized in silicate glasses using spectral editing in (29)Si solid-state NMR. Resonances of the Q(n)(mX) (i.e. Si(OX)(m)(OSi)(n-m)) molecular motifs, which strongly overlap in the (29)Si solid-state NMR spectra of silicate glasses, can be separated and quantified using 2 to n-quantum filters in INADEQUATE-like experiments, without prior knowledge of assigned chemical shifts, offering a new probe for the microscopic origins of residual entropy in glassy materials.

Scalar couplings, recoupled or full dipolar interactions can be used to characterize multinuclear structural molecular motifs in solids, by counting the neighbouring spins in solid-state NMR, opening new ways for the differentiation of overlapping spectral responses which is a limiting factor in many high resolution experiments carried out on disordered systems.