NMR diffusion of hyperpolarised He-3 in aerogel: a systematic pressure study

Abstract : Diffusion of hyperpolarised He-3 in a silica aerogel sample with 98% porosity was measured by NMR, and systematically studied as a function of pressure P in the range 20 mbar - I bar. Spin-echo amplitudes, recorded with pulsed gradients in the usual CMPG sequence, follow a monoexponential decay, and the decay rate varies quadratically with the gradient intensity: thus the apparent diffusion coefficient of the gas D can be evaluated. Our results show a power-law (1/D proportional to P-0.55), which could be consistent with a fairly broad mean free path distribution, implying some inhomogeneity in the aerogel structure. We have observed a spatial non-uniformity of D, and some deviation to the quadratic dependence of the decay rate with the gradient intensity, possibly related to sample structure inhomogeneity. (C) 2001 Elsevier Science Inc. All rights reserved.
Document type :
Journal articles
Complete list of metadatas

https://hal.archives-ouvertes.fr/hal-02018521
Contributor : Geneviève Tastevin <>
Submitted on : Wednesday, February 13, 2019 - 9:26:51 PM
Last modification on : Saturday, March 23, 2019 - 1:38:32 AM

Identifiers

  • HAL Id : hal-02018521, version 1

Citation

G. Guillot, P. J. Nacher, G. Tastevin. NMR diffusion of hyperpolarised He-3 in aerogel: a systematic pressure study. Magnetic Resonance Imaging, 2001, 19 (3-4), pp.391--394. ⟨hal-02018521⟩

Share

Metrics

Record views

14