Probing molecular dynamics with hyperpolarized ultrafast Laplace NMR using a low-field, single-sided magnet

Abstract

<div lang="en" class="abs"><p class="abs_header">Abstract</p><p>Laplace NMR (LNMR) offers deep insights on diffusional and rotational motion of molecules. The so-called “ultrafast” approach, based on spatial data encoding, enables one to carry out a multidimensional LNMR experiment in a single scan, providing from 10 to 1000-fold acceleration of the experiment. Here, we demonstrate the feasibility of ultrafast diffusion–<em>T</em>₂ relaxation correlation (<em>D</em>–<em>T</em>₂) measurements with a mobile, low-field, relatively low-cost, single-sided NMR magnet. We show that the method can probe a broad range of diffusion coefficients (at least from 10⁻⁸ to 10⁻¹² m² s⁻¹) and reveal multiple components of fluids in heterogeneous materials. The single-scan approach is demonstrably compatible with nuclear spin hyperpolarization techniques because the time-consuming hyperpolarization process does not need to be repeated. Using dynamic nuclear polarization (DNP), we improved the NMR sensitivity of water molecules by a factor of 10⁵ relative to non-hyperpolarized NMR in the 0.3 T field of the single-sided magnet. This enabled us to acquire a <em>D</em>–<em>T</em>₂ map in a single, 22 ms scan, despite the low field and relatively low mole fraction (0.003) of hyperpolarized water. Consequently, low-field, hyperpolarized ultrafast LNMR offers significant prospects for advanced, mobile, low-cost and high-sensitivity chemical and medical analysis.</p></div>