Translational diffusion of liquids at surface of microporous materials: new theoretical analysis of field cycling magnetic relaxation measurements

Korb, Jean-Pierre; Hodges, Maria; Bryant, Robert G.

doi:10.1016/s0730-725x(98)00051-4

Cited by 11 publications

(14 citation statements)

References 9 publications

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“…Especially for the Merzenhausen soil, a predicted bilinear dependence of 1/ T 1 vs. log ν is most probably present, as indicated by the two lines in Fig. 6 (Korb et al, 1998). The fast mode found in the sandy loam Kaldenkirchen soil behaved quite similarly to the main mode of the silt loam Merzenhausen soil.…”

Section: Resultsmentioning

confidence: 88%

“…Consequently, for even more restricted motion, 1/ T 1 increases more strongly on log ν in terms of a power law. Furthermore, the theory states that if translational diffusion in the neighborhood of the surfaces controls relaxation mediated by dipole–dipole interactions at the surfaces, a bilinear behavior of 1/ T 1 vs. log ν is expected (Korb et al, 1998). In view of this theory, the three systems represent the dynamics of water molecules in confined geometries ranging from nearly unrestricted diffusion (FH31 sand), to slight two‐dimensional diffusion (Kaldenkirchen slow mode), to more pronounced two‐dimensional diffusion in confined spaces (Merzenhausen main mode and Kaldenkirchen fast mode).…”

Section: Resultsmentioning

confidence: 99%

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A Fast Field Cycling Nuclear Magnetic Resonance Relaxometry Study of Natural Soils

Pohlmeier

Haber‐Pohlmeier

Stapf

2009

Vadose Zone Journal

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735W and solute transport in soils are controlled by the water dynamics in the porous system. Classical techniques for the investigation of pore space are the determination of pore size distributions from analysis of water retention curves or gas and Hg adsorption isotherms. As an extension of these methods, NMR relaxometry is particularly convenient since it probes pore spaces by direct investigation of the dynamics of included water. Th e physical basis is the nuclear magnetic resonance of 1 H 2 O. In a magnetic fi eld with a fl ux density B, proton spins (here, 1 H 2 O) possess two states: precession parallel and antiparallel around the direction of B. For an ensemble of spins in thermal equilibrium, the parallel state is more highly populated than the antiparallel one. Th is ensemble can be excited by absorption of electromagnetic radiation of the Larmor frequency ν = Bγ H /2π, where γ H is the gyromagnetic ratio of 1 H (γ H = 267.5 × 10 6 rad s −1 ), and B is the absolute value of the magnetic fl ux density B, i.e., B = |B| (units of T). After excitation, two kinds of relaxation processes take place: spin-spin or T 2 relaxation and spin-lattice or T 1 relaxation, which restores thermal equilibrium. In water molecules, both are mainly controlled by dipole-dipole interactions between the water molecules and the matrix, i.e., by translational and rotational motion. Th e exact physics of these processes are well derived in, e.g., Callaghan (1991) and Blümich (2000).Since the relaxation properties of water in porous media are also strongly infl uenced by pore sizes and geometries, NMR relaxometry methods are very convenient for probing the pore space of natural porous media like rocks or soils (Kleinberg et al., 1994;Hall et al., 1997;Votrubová et al., 2000). Th us, numerous studies have used the T 2 relaxation time distribution for such purposes. Th is approach has been investigated intensively and is routinely used for purposes like oil well logging (Dunn et al., 2002), but it has also been applied successfully on natural and model soils (e.g., Hall et al., 1997;Todoruk et al., 2003;Mikutta et al., 2004;Jaeger et al., 2006;Keating and Knight, 2007). Measured T 2 data are apparent quantities, however, since they are aff ected additionally by diff usion of the water molecules in magnetic fi eld gradients (Barrie, 2000). Th is can be demonstrated by variation of the echo time T E , which is an experimental parameter. With shorter T E , the measured T 2 relaxation times increase due to the decreasing infl uence of water motion in inhomogeneous magnetic fi elds and local magnetic fi eld gradients, which are present at phase boundaries in porous systems (Dunn et al., 2002). Th erefore, if optimization of measurement time is not an issue, as in well logging, the determination of the spin-lattice relaxation time T 1 is A : BET, Brunauer-Emmett-Teller; CT, computed tomography; NMR, nuclear magnetic resonance. S S : A IThis study used nuclear magne c resonance (NMR) relaxometry at diff erent Larmor frequencies to inves g...

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Section: Resultsmentioning

confidence: 88%

Section: Resultsmentioning

confidence: 99%

A Fast Field Cycling Nuclear Magnetic Resonance Relaxometry Study of Natural Soils

Pohlmeier

Haber‐Pohlmeier

Stapf

2009

Vadose Zone Journal

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“…7,8 DNA approximates a charged rod in solution, and one might assume that relaxation events induced by the rod would reflect one-dimensional diffusion along the rod to sites of high relaxation rate, perhaps associated with transient binding. If relaxation were limited by diffusion to rare relaxation sinks such as a paramagnetic metal ion site, then the dominant relaxation pathway may become diffusive exploration along the rod until a relaxation site is encountered.…”

Section: Resultsmentioning

confidence: 99%

“…This situation is in contrast to proton relaxation dispersion measurements of liquids in microporous systems in which relaxation is limited by diffusive motions to rare relaxation sites and the relaxation rate follows a power law in the Larmor frequency. 8 …”

Section: Discussionmentioning

confidence: 99%

“…1 This diffusive constraint by itself, or in combination with specific ion binding, may affect the magnetic field dependence of the spin-lattice relaxation rate of the diffusing spin in ways that report the characteristics of the ion motion. 7,8 In favorable cases, analysis of the MRD profiles may also provide a quantitative characterization of the local translational diffusion constant. Here, we investigated the magnetic field dependence of the spin-lattice relaxation rate constants for lithium ion, 7 Li I D 3/2 , and tetramethylammonium ion, 1 H I D 1/2 , and found a similar magnetic field dependence in the spin-lattice relaxation rates in spite of the different relaxation mechanisms.…”

Section: Introductionmentioning

confidence: 99%

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Magnetic relaxation dispersion of lithium ion in solutions of DNA

Victor

Teng

Dinesen

et al. 2004

Magnetic Reson in Chemistry

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The magnetic field dependence of the nuclear spin-lattice relaxation rate constant defines the magnetic relaxation dispersion (MRD) and provides a direct characterization of the molecular dynamics that cause fluctuations in the magnetic couplings in the system and may also indicate the dimensional constraints on the motion. The counterion cloud surrounding a linear polyelectrolyte ion, such as DNA in solution, provides an interesting opportunity for ion confinement that helps in understanding the thermodynamics and the dynamics of the interactions between the polyion and other solutes. The MRD profiles of lithium ion and tetramethylammonium ion were recorded in dilute aqueous solutions of native calf thymus DNA, which provides a long, charged rod that reorients slowly. The 7Li ion relaxes through the nuclear electric quadrupole coupling and the proton-lithium dipole-dipole coupling; the protons of the tetramethylammonium ion relax by dipole-dipole coupling. MRD profiles of the 7Li+ ion are dominated by transient interactions with the DNA that yield a linear dependence of the spin-lattice relaxation rate constant on the logarithm of the Larmor frequency. This magnetic field dependence is consistent with diffusive ion motions that modulate two spatial coordinates that characterize the relaxation couplings in the vicinity of the polyion. Motions around the rod and fluctuations in the ion distance from the rod are consistent with these constraints for lithium. The magnetic field dependence of the tetramethylammonium ion proton relaxation rate constant is weak, but also approximately a linear function of the logarithm of the Larmor frequency, which implies that the field dependence is caused in part by local order in the DNA solution.

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Boron nitride nanotubes as magnetic resonance imaging contrast agents

Calucci

Forte

2016

Boron Nitride Nanotubes in Nanomedicine

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Translational diffusion of liquids at surface of microporous materials: new theoretical analysis of field cycling magnetic relaxation measurements

Cited by 11 publications

References 9 publications

A Fast Field Cycling Nuclear Magnetic Resonance Relaxometry Study of Natural Soils

A Fast Field Cycling Nuclear Magnetic Resonance Relaxometry Study of Natural Soils

Magnetic relaxation dispersion of lithium ion in solutions of DNA

Boron nitride nanotubes as magnetic resonance imaging contrast agents

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