NMR diffusion measurements of time-dependent samples

![CDATA[In addition to increasing throughput, increasing the speed of NMR diffusion measurements extends the practical lower limit of detection that can be used as well as increasing the feasibility of applying the technique to the study of reacting systems [1, 2]. Most methods for increasing the measurement efficiency have ‘fatal’ flaws such as no longer having a defined diffusion measurement timescale Δ or losing chemical shift information. We have previously shown that measurement efficiency can be increased by running the experiment in a steady state mode [3] whilst retaining full information content. More recently, we have explored a seemingly unutilised approach in which the number of scans (NS) is varied through the (i.e., normally corresponding to iterations of the gradient amplitude g) that constitute the diffusion measurement and the signal is normalised by NS used at each iteration [4]. In contrast to conventionally performed measurements where the same NS is used at each iteration this new normalisation approach requires far fewer total scans. Both approaches can shorten the experimental time by more than 70% without any loss in accuracy and, unlike previous approaches, are totally general in their application. We have also been exploring the optimal use of window functions in the analysis to maximise the experimental efficiency and sophisticated multi-suppression techniques [5]. We discuss and illustrate these approaches in this presentation.]]