Tortuosity Measurement and the Effects of Finite Pulse Widths on Xenon Gas Diffusion NMR Studies of Porous Media

Details Tortuosity Measurement and the Effects of Finite Pulse Widths on Xenon Gas Diffusion NMR Studies of Porous Media Tortuosity Measurement and the Effects of Finite Pulse Widths on Xenon Gas Diffusion NMR Studies of Porous Media

2002-11-10

arxiv.org/abs/cond-mat/0211184v1

Magnetic Resonance Imaging 19, 345 (2001)

Physics

Condensed Matter

Soft Condensed Matter

single pdf file containing all figures

Scientific paper

We have extended the utility of NMR as a technique to probe porous media structure over length scales of ~ 100 - 2000 micron by using the spin 1/2 noble gas 129Xe imbibed into the system's pore space. Such length scales are much greater than can be probed with NMR diffusion studies of water-saturated porous media. We utilized Pulsed Gradient Spin Echo NMR measurements of the time-dependent diffusion coefficient, D(t) of the xenon gas filling the pore space to study further the measurements of both the surface area-pore volume ratio, S/Vp, and the tortuosity (pore connectivity) of the medium. In uniform-size glass bead packs, we observed D(t) decreasing with increasing t, reaching an observed asymptote of ~ 0.62 - 0.65D0, that could be measured over diffusion distances extending over multiple bead diameters. Measurements of D(t)/D0 at differing gas pressures showed this tortuosity limit was not affected by changing the characteristic diffusion length of the spins during the diffusion encoding gradient pulse. This was not the case at the short time limit, where D(t)/D0 was noticeably affected by the gas pressure in the sample. Increasing the gas pressure, and hence reducing D0 and the diffusion during the gradient pulse served to reduce the previously observed deviation of D(t)/D0 from the S/Vp relation. The Pade approximation is used to interpolate between the long and short time limits in D(t). While the short time D(t) point lay above the interpolation line in the case of small beads, due to diffusion during the gradient pulse on the order of the pore size, it was also noted that the experimental D(t) data fell below the Pade line in the case of large beads, most likely due to finite size effects.

Affiliated with

Also associated with

No associations

Rating

Tortuosity Measurement and the Effects of Finite Pulse Widths on Xenon Gas Diffusion NMR Studies of Porous Media does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Tortuosity Measurement and the Effects of Finite Pulse Widths on Xenon Gas Diffusion NMR Studies of Porous Media, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Tortuosity Measurement and the Effects of Finite Pulse Widths on Xenon Gas Diffusion NMR Studies of Porous Media will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-69727