Diffusion de l'helium dans la glace monocristalline

Haas, J. F.; Bullemer, B.; Kahane, Ahuvia

doi:10.1016/0038-1098(71)90354-1

Cited by 28 publications

(33 citation statements)

References 4 publications

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“…Since the qualitative dependence of the diffusive motion is dominated by the local ice structure, we chose a periodic representation of ice I h as a suitable model for ASW in the TST analysis. The close agreement between the higher temperature ice I h He diffusion kinetic parameters [12] and those determined here indicates that He is likely hopping through cages similar to ice I h although distorted and nonuniform. The model system consisted of a hexagonal lattice comprised of 16 rigid water molecules with periodic boundary conditions interacting with a single He atom.…”

supporting

confidence: 79%

“…4 displays the ratio of the D 2 O to H 2 O diffusion rates versus temperature. The ratio shows that the isotope effect will decrease rapidly with increasing temperature and would be unobservable above 150 K. Extrapolation of the experimental ASW and TST calculated Arrhenius parameters for He diffusion in H 2<=m:mn> O are in good agreement with higher temperature experimental (170 -250 K) measurements [12] and recent molecular dynamics simulations (200 -273 K) [18] of He diffusion in ice I h . The magnitude of the diffusion coefficients determined in our study (10 ÿ15 < D < 10 ÿ9 cm 2 =s) are many orders of magnitude too small to be calculated using direct molecular dynamics simulation.…”

supporting

confidence: 77%

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Helium Diffusion throughH2OandD2OAmorphous Ice: Observation of a Lattice Inverse Isotope Effect

et al. 2004

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The diffusion of He through both H2O and D2O amorphous solid water (ASW) has been measured between 55 and 110 K. We find the diffusion rate is dependent on the isotopic composition of the ASW lattice. This lattice isotope effect is the "inverse" of a normal isotope effect in that diffusion is faster in the heavier (D2O) isotope. Transition state theory calculations show that the inverse isotope effect is due to a tight transition state and predominantly arises from the zero-point vibrational energy associated with the frustrated rotational modes of water in the lattice.

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supporting

confidence: 79%

supporting

confidence: 77%

Helium Diffusion throughH2OandD2OAmorphous Ice: Observation of a Lattice Inverse Isotope Effect

et al. 2004

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“…Available experimental data are presented in [33][34][35][36][37], whereas numerical data are summarized in Tab The solubility appears to be 20-30 % higher in comparison with the solubility of helium in liquid water at the same pressures. The helium content in S2 samples was calculated as described in Section 2.…”

Section: Resultsmentioning

confidence: 99%

Gas Hydrate Formation by Methane‐Helium Mixtures

et al. 2011

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Equilibrium conditions for gas hydrates formed by methane-helium mixtures with helium concentrations of 31.9, 63.9, and 74.6 mol.-% have been studied at pressures up to 160 bar. The data obtained indicate that in the studied range of helium concentrations and pressures helium hardly contributes to the stability of the gas hydrate formed. The shift of equilibrium conditions to lower temperatures and higher pressures is caused by dilution of methane in the gas phase and, consequently, the decrease in the chemical potential of methane in the gas phase. IntroductionGas hydrates are inclusion compounds in which the host framework is composed of hydrogen-bonded water molecules. Guest molecules occupy cavities of this framework. Under normal conditions the guest species are gases or volatile liquids [1]. At comparatively low pressures three structural types of gas hydrates are most abundant, namely, the cubic structures I and II, and structure H (or hexagonal structure III) [1][2][3][4]. Gas hydrate studies are highly topical due to the following reasons: (i) substantial deposits of natural gas hydrates in the earth's crust; (ii) necessity of prevention of hydrate formation in the course of gas and oil production; (iii) possibility of storage and transportation of natural gas in the form of gas hydrates, and (iv) separation of gas mixtures through hydrate formation [1,[3][4][5][6][7][8][9].The gas hydrate method of gas mixture separation is based on the differences in the stability of gas hydrates formed by different hydrate formers. The hydrate phase is enriched with the component forming a more stable hydrate [10][11][12][13][14][15]. It is known that helium, hydrogen, and neon do not form gas hydrates at relatively low pressure (several hundreds of bar). Due to this reason, the usage of gas hydrates appears to be promising for separating the above light gases from gas mixtures, in particular for concentrating helium when obtaining it from natural gas. The development of gas hydrate methods for separation of gas mixtures requires data of the phase diagrams of the systems gas mixture/water. For the hydrate-forming systems involving hydrogen, a relatively large amount of information has been accumulated, e.g., in [10,[16][17][18][19][20][21][22][23][24]. At the same time, only few papers have been published concerning the systems with helium [25][26][27][28][29]. In [26,27], helium hydrates were studied at very high pressures, and [29] deals with calculations. Insufficient experimental information concerning the role of helium in gas hydrate formation in the practically interesting range of pressures stimulated our interest for this subject. In the present communication, the results on the equilibrium conditions for gas hydrates formed by a mixture of methane and helium as well as informations concerning helium concentration in the hydrates formed are described. Materials and MethodsThe curves of hydrate decomposition were studied with the apparatus and experimental procedure described in [30]. The maximum possible err...

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“…For comparison, we also measured the relaxation of 3 He in pure water (H 2 O) in the range of 0 to 80°C and derived the same activation energy. Close values of activation energies were found for the diffusion of helium atoms in water [35] and ice [36]. These values show that the relaxation of 3 He nuclei in Mn 2ϩ solutions is determined by translational motion of helium atoms.…”

Section: Solutions Of Mn 2+ Ionsmentioning

confidence: 87%

Magnetic Resonance of 3He and 129Xe in Aqueous Solutions Containing Paramagnetic Mn2+ and Co2+ Ions. A Comparisonwith Isoelectronic 7Li+ and 133Cs+ Ions

Mazitov¹,

Seydoux²,

Diehl³

et al. 2000

Zeitschrift Für Physikalische Chemie

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Noble Gas / 3 He / 129 Xe / Paramagnetic Ions / Aqueous SolutionsThe chemical shifts and relaxation times T1 and T2 of 3 He and 129 Xe nuclei of noble gas atoms as well as those of 7 Li and 133 Cs nuclei of isoelectronic Li ϩ and Cs ϩ ions have been measured in aqueous solutions, which contain paramagnetic Mn 2ϩ and Co 2ϩ ions. The magnetic relaxation of all studied nuclei in Co 2ϩ solutions proceeds via an electronic spin relaxation of these ions. The relaxation in Mn 2ϩ solutions is determined by the translational diffusion of the solute particles. The closest approach distances for collisions of paramagnetic ions with atoms of noble gases and alkali ions were estimated from relaxation data.

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Diffusion de l'helium dans la glace monocristalline

Cited by 28 publications

References 4 publications

Helium Diffusion throughH2OandD2OAmorphous Ice: Observation of a Lattice Inverse Isotope Effect

Helium Diffusion throughH2OandD2OAmorphous Ice: Observation of a Lattice Inverse Isotope Effect

Gas Hydrate Formation by Methane‐Helium Mixtures

Magnetic Resonance of 3He and 129Xe in Aqueous Solutions Containing Paramagnetic Mn2+ and Co2+ Ions. A Comparisonwith Isoelectronic 7Li+ and 133Cs+ Ions

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