Before the invention of magnetic resonance imaging (MRI), Mansfield and Grannel proposed a new method for probing the structure of crystalline materials through their nuclear spins. This technique, called NMR diffraction (NMRd), would be a revolutionary tool for studying the structure of materials if realized on the atomic scale. Given the spectroscopic capabilities of NMR, and its non-destructive nature, this would have profound implications as a tool for structural biology, including the study of proteins and virus particles.

Under a high static field, the local polarization of a dipolar-coupled spin ensemble is known to follow diffusive dynamics on length scales much larger than the lattice spacing. This kind of "spin diffusion", is a well-known many-body phenomenon that has been experimentally studied at micron length scales [1]. The combination of large magnetic gradients in our nanoMRI setup and dynamical decoupling sequences allows us to study dipolar spin dynamics at length scales close to the lattice spacing, and examine the exact boundary between coherent microscopic dynamics and spin diffusion.

Achieving nanometer-scale imaging of crucial biomolecules like individual virus particles and protein molecules holds immense promise for advancing both structural biology and targeted drug delivery. Conventional methods for structural determination of the relevant biomolecules rely on indirect measurements through the spectroscopic properties of spin labels like DEER. However, limitations arise when multiple spin labels are used, making the inference of the accurate geometry from DEER challenging. With direct Fourier imaging employing single spin labels at nanometer resolution, a comprehensive image of the molecule can be obtained.