NMR Studies of Fluid Diffusion in Confining Geometries

1992 ◽  
Vol 290 ◽  
Author(s):  
Michael Jerosch-Herold ◽  
Hans Thomann ◽  
A. H. Thompson
Keyword(s):  
Internal Field ◽  
Restricted Diffusion ◽  
Length Scale ◽  
Nmr Studies ◽  
Longitudinal Magnetization ◽  
Complementary Method ◽  
Field Gradients ◽  
Diffusion Dynamics ◽  
Pfg Nmr ◽  
Fluid Diffusion

AbstractDiffusion dynamics for fluids in sandstone rocks were studied by CPMG and pulsed field gradient (PFG) NMR measurements. Stretched exponential decays of the transverse magnetization were observed while varying the interpulse spacing, τ, in the CPMG experiment which sets the time for diffusion. A crossover from free to restricted diffusion is evident in the dependence of both T2 and the stretch exponent, β2, on the diffusion time τ. The T2(τ) data is fit to a model which interpolates between free and restricted diffusion and has only one free adjustable length scale despite the fact that the sandstone rocks are characterized by a pore size distribution. This NMR derived length scale correlates with a characteristic length derived from Hg injection experiments at the percolation threshold. We compare these results from the CPMG experiment with stimulated echo PFG-NMR diffusion measurements. This provides a complementary method of probing the diffusion dynamics since the longitudinal magnetization is insensitive to the dephasing effects of diffusion in internal field gradients.

Interpretation of restricted diffusion in sandstones with internal field gradients

2001 ◽  
Vol 19 (3-4) ◽  
pp. 535-537 ◽  
Author(s):  
Matthias Appel ◽  
J.Justin Freeman ◽  
John S. Gardner ◽  
George H. Hirasaki ◽  
Q.Gigi Zhang ◽  
...  
Keyword(s):  
Internal Field ◽  
Restricted Diffusion ◽  
Field Gradients ◽  
Internal Field Gradients

PFG NMR and internal magnetic field gradients in plant-based materials

2002 ◽  
Vol 20 (7) ◽  
pp. 567-573 ◽  
Author(s):  
Nikolaus Nestle ◽  
Asal Qadan ◽  
Petrik Galvosas ◽  
Wolfgang Süss ◽  
Jörg Kärger
Keyword(s):  
Magnetic Field ◽  
Internal Magnetic Field ◽  
Field Gradients ◽  
Magnetic Field Gradients ◽  
Pfg Nmr

A PFG-NMR Study of Restricted Diffusion in Heterogeneous Polymer Particles

2001 ◽  
Vol 239 (1) ◽  
pp. 168-177 ◽  
Author(s):  
John Georg Seland ◽  
Matteo Ottaviani ◽  
Bjørn Hafskjold
Keyword(s):  
Restricted Diffusion ◽  
Polymer Particles ◽  
Nmr Study ◽  
Heterogeneous Polymer ◽  
Pfg Nmr

Diffusion NMR and bicelle morphology

2011 ◽  
Vol 89 (9) ◽  
pp. 1021-1035 ◽  
Author(s):  
Peter M. Macdonald ◽  
Ronald Soong
Keyword(s):  
Lateral Diffusion ◽  
Diffusion Method ◽  
Nmr Studies ◽  
Diffusion Nmr ◽  
Magnetically Aligned Bicelles ◽  
Diffusion Studies ◽  
Membrane Bound ◽  
Nmr Diffusion ◽  
Pfg Nmr ◽  
Magnetically Aligned

This minireview focuses on diffusion NMR studies in bicelles. Following a discourse on diffusion fundamentals, and a comparative overview of fluorescence and NMR-based techniques for measuring diffusion, the pulsed field gradient (PFG) NMR diffusion method is introduced, emphasizing its specific advantages and limitations when applied to diffusion measurements in macroscopically oriented lamellar systems such as magnetically aligned bicelles. The utility of PFG NMR diffusion measurements in bicellar model membrane systems for examining lateral diffusion of membrane-bound molecular species is demonstrated, along with certain features of lateral diffusion that such studies illuminate. Further, those aspects of bicelle morphology that have been resolved using PFG NMR diffusion studies of various molecular weight soluble polymeric species are reviewed. The discussion concludes with an outline of future prospects for diffusion NMR studies in bicelles.

scholarly journals Bicellar Mixtures Containing Pluronic F68: Morphology and Lateral Diffusion from Combined SANS and PFG NMR Studies

Langmuir ◽  
2010 ◽  
Vol 26 (4) ◽  
pp. 2630-2638 ◽  
Author(s):  
Ronald Soong ◽  
Mu-Ping Nieh ◽  
Eric Nicholson ◽  
John Katsaras ◽  
Peter M. Macdonald
Keyword(s):  
Lateral Diffusion ◽  
Nmr Studies ◽  
Pluronic F68 ◽  
Pfg Nmr

On the Use of Pulsed Field Gradients in a High-Field NMR Spectrometer to Study Restricted Diffusion in Zeolites

1995 ◽  
Vol 50 (2-3) ◽  
pp. 186-190 ◽  
Author(s):  
J. Kärger ◽  
N.-K. Bär ◽  
W. Heink ◽  
H. Pfeifer ◽  
G. Seiffert
Keyword(s):  
High Field ◽  
Spin Echo ◽  
Magnetic Field Gradient ◽  
High Sensitivity ◽  
Superconducting Magnet ◽  
Self Diffusion ◽  
Field Gradients ◽  
Large Gradient ◽  
Pfg Nmr ◽  
First Time

Abstract A probe system is described which allows the application of magnetic field gradient pulses with amplitudes up to 24 T/m for self-diffusion measurements by means of a PFG NMR spectrometer operating at a proton resonance frequency of 400 MHz. It is demonstrated that PFG NMR measurements in the high field of a superconducting magnet necessitate precautions which are of minor relevance for measurements with iron magnets. Taking advantage of the large gradient intensity and the high sensitivity in signal detection of the described system, attenuation patterns of the NMR spin echo are observed for the first time that represent the PFG NMR analogue of the diffraction pattern of a sphere.

Solid-State NMR Study on Actinide Dioxides

2012 ◽  
Vol 1444 ◽  
Author(s):  
Yo Tokunaga ◽  
Hironori Sakai ◽  
Shinsaku Kambe ◽  
Hiroyuki Chudo ◽  
Masahiko Osaka ◽  
...  
Keyword(s):  
Low Temperatures ◽  
Internal Field ◽  
Bulk Property ◽  
Line Broadening ◽  
Temperature Dependent ◽  
Nmr Studies ◽  
System A ◽  
Nmr Study ◽  
First Time ◽  
Ordered State

ABSTRACTBesides the importance of the actinide dioxide series as a nuclear fuel, the magnetic properties of these compounds at low temperatures are particularly interesting. Their surprisingly varied physical properties at low temperatures stimulate continuing interest for both theory and experiment. Recently, we have performed 17O-NMR studies for the first time on Pu and Amcontaining dioxide systems, (Pu1-xAmx)O2. For the x=0.09 sample, a temperature-dependent NMR line broadening has been observed at low temperatures. By comparing the experimental data with the results of NMR line simulations, we have estimated the effective moment of Am ions to be Peff=1.38 μB. The value suggests the 5f5 (Am4+) state of the Am ion in PuO2. For the x=1 (=AmO2) sample, on the other hand, our 17O-NMR data provide the first microscopic evidence for a phase transition at 8.5 K as a bulk property in this system. A spectrum with a triangular line shape indicates that the internal field is distributed very nearly randomly in the ordered state.

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