A new view of the spin echo diffusive diffraction on porous structures

TL;DR

This paper presents a novel analysis of spin echo diffusive diffraction in porous structures, revealing how boundary interactions influence diffraction patterns and providing insights into the media's morphology and transport properties.

Contribution

It introduces a new theoretical framework using the characteristic functional of stochastic motion to interpret spin echo measurements in restricted environments.

Findings

Diffraction patterns relate to boundary-induced spin phase shifts.

Diffraction depends on gradient pulse timing and width.

Method clarifies transport analysis in restricted systems.

Abstract

Analysis with the characteristic functional of stochastic motion is used for the gradient spin echo measurement of restricted motion to clarify details of the diffraction-like effect in a porous structure. It gives the diffusive diffraction as an interference of spin phase shifts due to the back-flow of spins bouncing at the boundaries, when mean displacement of scattered spins is equal to the spin phase grating prepared by applied magnetic field gradients. The diffraction patterns convey information about morphology of the surrounding media at times long enough that opposite boundaries are restricting displacements. The method explains the dependence of diffraction on the time and width of gradient pulses, as observed at the experiments and the simulations. It also enlightens the analysis of transport properties by the spin echo, particularly in systems, where the motion is restricted by structure or configuration.