Determination of the Defining Boundary in Nuclear Magnetic Resonance Diffusion Experiments

TL;DR

This paper demonstrates that modified NMR diffusion experiments can precisely identify the boundaries of confining structures like pores, overcoming previous limitations by preserving phase information and enhancing signal-to-noise ratio.

Contribution

It introduces a novel method using modified Stejskal-Tanner gradients to detect pore boundaries in NMR diffusion experiments, enabling accurate imaging of confining structures.

Findings

Boundaries of pores can be detected with phase-preserving gradients.

Enhanced signal-to-noise ratio improves boundary detection accuracy.

The method relates to classical problems like 'hear the drum' in mathematical physics.

Abstract

While nuclear magnetic resonance diffusion experiments are widely used to resolve structures confining the diffusion process, it has been elusive whether they can exactly reveal these structures. This question is closely related to X-ray scattering and to Kac's "hear the drum" problem. Although the shape of the drum is not "hearable", we show that the confining boundary of closed pores can indeed be detected using modified Stejskal-Tanner magnetic field gradients that preserve the phase information and enable imaging of the average pore in a porous medium with a largely increased signal-to-noise ratio.