NMR diffusometry applied to liquids

Gradient based nuclear magnetic resonance spectroscopy provides a convenient method to determine self-diffusion coefficients especially in liquid samples. The method has many advantages including short experiment time, sensitivity, molecular resolution, and accuracy — all without the need for adding perturbing probes or chemically introducing isotopes. In this contribution we introduce the method and discuss through several examples its uses. We discuss how the method provides diffusion coefficients in supercooled water and alcohol–water mixtures. In ionic liquids the method conveys information about single ion mobilities and cluster formation. In self-assembling systems possible aggregate growth can be conveniently investigated. We demonstrate, based on self-diffusion coefficients, that there is little evidence for aggregation in aqueous solutions of cyclodextrins. Finally, we demonstrate how NMR diffusometry can be used to determine the diffusion of water inside a biological cell. It goes without saying that such data are very important in the understanding of transport properties in cells, where diffusion plays a major role.