Pulsed field-gradient nuclear magnetic resonance

Key words Nuclear magnetic resonance - pulsed field gradients -diffusion - emulsions - droplet size -concentrated emulsions... 

Some of the most successful methods of nuclear magnetic resonance used in the study of disordered porous media have been reviewed and their applications to the measurement of pore size distribution, diffusion coefficients and permeability have been presented. This is the case of nuclear relaxation and pulsed field gradient method of a specific imbibed solvent in various fully or partially saturated organic or inorganic porous media. The cases of narrow and large distributions of pores have been... 

Lead, J.R., Wilkinson, K.J., Balnois, E., Cutak, B.J., Larive, C.A., Assemi, S., and Beckett, R., (2000). Diffusion coefficients and polydispersities of the Suwannee River ful-vic acid Comparison of fluorescence correlation spectroscopy, pulsed field gradient nuclear magnetic resonance, and field-flow fractionation. Environ. Sci. TechnoL, 34, 3508-3513. 

W. Brown, R. Johnsen, P. Stilbs, B. Lindman. Size and shape of nonionic amphiphile (Ci2Eg) micelles in dilute aqueous solutions as derived from quasielastic and intensity of light scattering, sedimentation and pulsed-field-gradient nuclear magnetic resonance self-diffusion data. J Phys Chem 87 4548-4553, 1983. 

Hadden, DA, Master of Science Thesis, Florida State University, Tallahassee, FL, 1999. Hadden, D Rill, RL McFadden, L Locke, BR, Oligonucleotide and Water Self-Diffusion in Pluronic Triblock Copolymer Gels and Solutions by Pulsed Field Gradient Nuclear Magnetic Resonance, Macromolecules 33, 4235, 2000. 

While the nuclear magnetic resonance (NMR) technique has widely been used to study diffusion processes of normal liquids, solids, or colloidal systems, there are only a few applications to molten salts. The spin echo self-diffusion method with pulsed field gradients was applied to molten salts by Herdlicka et al. "" There is no need to set up or maintain a concentration gradient. 

W. S. Price 1997, (Pulsed-field gradient nuclear magnetic resonance as a tool for studying translational diffusion Part 1. Basic theory), Concepts Magn. Reson. 9, 299-336. 

U.Tallarek, E. Bayer, G. Guiochon 1998, (Study of dispersion in packed chromatographic columns by pulsed field gradient nuclear magnetic resonance), J. Am. Chem. Soc. 120, 1494. 

P. T. Callaghan, K. W. Jolley, R. S. J. Humphrey 1983, (Diffusion of fat and water in cheese as studied by pulsed field gradient nuclear magnetic-resonance), Colloid Interface Sci. 93, 521. 

Price, W.S. 1998a. Pulsed-field gradient nuclear magnetic resonance as a tool for studying translational diffusion. II. Experimental aspects. Basic theory. Concepts in Magn. Reson. 10, 197-237. Price, W.S. 1998b. NMR imaging. In Annual Reports on NMR Spectroscopy (G.A. Webb, ed.), Vol. 34, pp. 140-216. Academic Press, New York. 

The pulsed field gradient nuclear magnetic resonance (PFG NMR) technique is experimentally distinct from the radiotracer technique but the principle is very similar. A fraction of the nuclei of each constituent is labelled by flipping their spins and monitoring the diffusion of these species. Both techniques are influenced by the presence of neutral associates unlike the Hittorf/Tubandt method. 

Abbreviations MD, molecular dynamics TST, transition state theory EM, energy minimization MSD, mean square displacement PFG-NMR, pulsed field gradient nuclear magnetic resonance VAF, velocity autocorrelation function RDF, radial distribution function MEP, minimum energy path MC, Monte Carlo GC-MC, grand canonical Monte Carlo CB-MC, configurational-bias Monte Carlo MM, molecular mechanics QM, quantum mechanics FLF, Hartree-Fock DFT, density functional theory BSSE, basis set superposition error DME, dimethyl ether MTG, methanol to gasoline. 

A more sophisticated method which has found wide application in the study of intracrystalline diffusion in zeolites is the nuclear magnetic resonance (NMR) pulsed field gradient self-diffusion method. The method, which is limited to hydrocarbons and other sorbates with a sufficient density of unpaired nuclear spins, depends on measuring directly the mean square distance traveled by molecules,... 

CW = continuous-wave CW-NQR = continuous wave NQR DFT = density fiuictional theory EFG = electric field gradient IR = infrared NMR = nuclear magnetic resonance NQR = nuclear quadmpole resonance OSSE = octahedral site stabilization energy PAC = perturbed angular correlation pulse-FT = pulse-fourier transform TMED = tetramethylethylenediamine. 

Sattler M, Schleucher J, Griesinger C. Heteronuclear multidimensional NMR experiments for the structure determination of proteins in solution employing pulsed field gradients. Progress Nuclear Magnet. Reson. Spectros. 1999 34 93-158. 

Jost S, Bar NK, Fritzsche S, Haberlandt R, and Karger J. Diffusion of a mixture of methane and xenon in silicalite A molecular dynamics study and pulsed field gradient nuclear magnetic resonance experiments. J Phys Chem B 1998 102 6375-6381. 

Various new techniques suitable for estimating D are now available fluorescence correlation spectroscopy (FCS) [5], fluorescence recovery after photobleaching (FRAP) [6], pulsed field gradient nuclear magnetic resonance (PFG-NMR) [7], diffusion ordered NMR spectroscopy (DOSY) [8], and others. Among these, FCS and FRAP are popular in biological studies because they are often installed on a commercial LSM system and conveniently coupled with it. 

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