Hole-Burning Diffusion Measurements in High Magnetic Field Gradients

TL;DR

This paper introduces novel NMR techniques using hole-burning sequences to measure translational diffusion in large magnetic field gradients, enabling submicron spatial resolution and efficient diffusion measurement modes.

Contribution

The paper presents new NMR methods, including the hole-comb technique, for high-resolution diffusion imaging in large static magnetic field gradients.

Findings

Achieved submicron diffusion imaging with fringe field gradients of 42 T/m.

Demonstrated the efficiency of the hole-comb method for measuring multiple diffusion times.

Discussed potential applications in non-Fickian and restricted diffusion environments.

Abstract

We describe methods for the measurement of translational diffusion in very large static magnetic field gradients by NMR. The techniques use a "hole-burning" sequence that, with the use of fringe field gradients of 42 T/m, can image diffusion along one dimension on a submicron scale. Two varieties of this method are demonstrated, including a particularly efficient mode called the "hole-comb," in which multiple diffusion times comprising an entire diffusive evolution can be measured within the span of a single detected slice. The advantages and disadvantages of these methods are discussed, as well as their potential for addressing non-Fickian diffusion, diffusion in restricted media, and spatially inhomogeneous diffusion.