Two‐ and three‐dimensional multinuclear stray‐field imaging of rotating samples with magic‐angle spinning (STRAFI‐MAS): From bio to inorganic materials

Abstract

To revisit and illustrate the potential of a simple and effective multidimensional stray-field imaging technique with magic-angle spinning, known as STRAFI-MAS. STRAFI-MAS images are acquired with a standard NMR magnet and a traditional magic-angle sample spinning (MAS) probe. The stray-field gradients are achieved by placing the MAS probe, along the z-direction, at a distance from the center of the magnet. No pulsed-field gradients are applied. The multidimensional spatial encoding is carried out by synchronizing the radiofrequency pulses with the sample MAS rotation. Two-dimensional (2D) and 3D multinuclear images of various phantoms, including a tibia bone and silicon carbide, are recorded. Images of inorganic solids containing quadrupolar nuclei, (23)Na and (27)Al, are also explored for the first time by STRAFI-MAS. We have demonstrated that STRAFI-MAS is a simple and user-friendly technique for multidimensional imaging without the need of imaging equipment. With the current advancements in NMR and MRI methodologies, STRAFI-MAS is expected to be further developed and improved. We anticipate that STRAFI-MAS can spark a wide spectrum of interest, from material to bio science, where can benefit from high-resolution images.