Abstract

Laplace NMR, consisting of diffusion and relaxation experiments, provides detailed information about dynamics of fluids in porous materials. Recently, we showed that two-dimensional Laplace NMR experiments can be carried out with a single scan based on spatial encoding. The method shortens the experiment time by one to three orders of magnitude, and therefore it is called ultrafast Laplace NMR. Furthermore, the single-scan approach facilitates significantly the use of nuclear spin hyperpolarization for boosting the sensitivity of the experiment, because a laborious hyperpolarization procedure does not need to be repeated. Here, we push the limits of the ultrafast Laplace NMR method by applying it, for the first time, in the investigation of a gas phase substance, namely hyperpolarized xenon gas. We show that, regardless of the fast diffusion of gas, layer-like spatial encoding is feasible, and an ultrafast diffusion — T₂ relaxation correlation experiment reveals significantly different signals of free gas and gas adsorbed in a mesoporous controlled pore glass (CPG). The observed diffusion coefficients are many orders of magnitude larger than those detected earlier from liquid phase substances, emphasizing the extended application range of the method. The challenges in the methodology, caused by the fast diffusion, are also discussed.