Field-gradient spin-echo

We finish this section by comparing our results with NMR and incoherent neutron scattering experiments on water dynamics. Self-diffusion constants on the millisecond time scale have been measured by NMR with the pulsed field gradient spin echo (PFGSE) method. Applying this technique to oriented egg phosphatidylcholine bilayers, Wassail [68] demonstrated that the water motion was highly anisotropic, with diffusion in the plane of the bilayers hundreds of times greater than out of the plane. The anisotropy of... 

Meerwall v., E. D. Self-Diffusion in Polymer Systems. Measured with Field-Gradient Spin Echo NMR Methods, Vol. 54, pp. 1—29. 

Pulse Field Gradient Spin Echo-Nuclear Magnetic Spectroscopy Pyridyl... 

Modem NMR diffusion measurements are all based on the Stejskal-Tanner (S-T) pulsed field gradient spin-echo experiment [174] in which a gradient pulse is... 

Proton-driven spin diffusion Pulsed field gradient spin-echo Pleckstrin homology Poly(hydroxyethylmethacrylate)... 

Abbreviations D, self-diffusion coefficient ge, gradient-echo IR, inversion recovery IRFT, inversion recovery fourier transform MRS, magnetic resonance spectroscopy PD, proton density PFGSE, pulsed field gradient spin echo se, spin-echo. 

A(g) is the signal intensity observed with an applied gradient g, A(0) is the intensity in the absence of an applied gradient, y is the nuclear gyromagnetic ratio, and (5 and A are time intervals of the pulsed field gradient spin—echo sequence. 

OPPOSE double pulsed field gradient spin echo... 

Umecky, T, Kanakubo, M., and Ikushima, Y., Self-diffusion coefficients of l-butyl-3-methylimidazolium hexafluorophosphate with pulsed-field gradient spin-echo NMR technique. Fluid Phase Equilib., 228-229, 329, 2005. 

Field gradient spin echo method of measuring self-diffusion, encompasses SGSE and PGSE variants. 

Because field-gradient spin-echo measurements of D depend on no driving force such as a concentration, temperature, or velocity gradient, etc., they reflect Brownian motion of the molecules in the laboratory reference frame, and are usually referred to as self-diffusion. These attributes are further discussed in Sections 2 and 3. 

In polymers, the field-gradient spin-echo methods of measuring self-diffusion have been useful in three more or less distinct areas, the diffusion of polymers in their own melt and in concentrated solutions, in dilute and semidilute solutions, and the diffusion of penetrants and diluents in polymer hosts. A fourth category, the diffusion of bulky or flexible molecules in polymer hosts, is useful for subject matter not closely associated with the first and third category. It should be noted that the work reviewed here represents only a small fraction of the diffusion studies in polymers, including those using other NMR methods. 

The field gradient spin echo methods appear now to have amply proven their validity and usefulness in the study of polymer systems. This early work has been understandably academic in flavor, but there seems to be no impediment to the use of FGSE measurements for routine rheological characterization, e.g., to... 

Self-Diffusion in Polymer Systems, Measured with Field-Gradient Spin-Echo NMR Methods... 

By the pulsed field gradient spin echo method (1) it is possible to measure mean diffusion lengths ( /(l2)) for molecules in a given time interval in systems without a concentration gradient. The application of the method is limited to... 

Diffusion measurement using pulsed-field-gradient spin echoes (PGSE)... 

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