Microstructural Geometry Revealed by NMR Lineshape Analysis

In this talk, I introduce a technique for extracting microstructural geometry from NMR lineshape analysis in porous materials at angstrom-scale resolution using weak magnetic field gradients. I demonstrate that a detailed analysis of the line shape can unravel structural geometry on much smaller scales than previously thought. This is achieved by solving the generalized Langevin equations for the non-Markovian dynamics of diffusion, while the memory effects are extracted from the Green-Kubo correlation function evaluated using Molecular Dynamics simulations.

As a model system, we simulated diffusion of xenon particles confined within carbon nanotubes over a range of temperatures and nanotube diameters in order to uncover the effects of confinement on diffusion behavior. Our results highlight how NMR methodologies can be adapted as effective tools towards structural investigation at very small scales, even in the presence of complicated geometries. While traditional PFG NMR relies on strong magnetic field gradients in order to achieve high spatial resolution, our current approach reaches comparable or higher resolution using much weaker gradients. This method is expected to find applications in materials science, catalysis, biomedicine and other areas.