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Journal ArticleDOI

Dielectric Properties of Ice and Solid D2O

01 Aug 1952-Journal of Chemical Physics (American Institute of Physics)-Vol. 20, Iss: 8, pp 1309-1314
TL;DR: In this article, complex dielectric constants have been measured for ice from the melting point to −65°C and for solid D2O to −35°C, by a combination of bridge and transient methods.
Abstract: Complex dielectric constants have been measured for ice from the melting point to −65°C, and for solid D2O to −35°C, by a combination of bridge and transient methods. For both, the dispersion is described by the simple Debye formula, and the relaxation times τ by the simple rate expression τ = A exp(B/RT). For ice, A = 5.3×10−16 sec, B = 13.2 kcal/mole; and for solid D2O, A = 7.7×10−16 sec, B = 13.4 kcal/mole. The equilibrium dielectric constant for ice is 91.5 at 0°C and increases at lower temperatures; the values for solid D2O are only slightly smaller. Measures taken to minimize errors from voids in the sample and direct current conductance are discussed.
Citations
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Journal ArticleDOI
TL;DR: Voltage-gated proton channels represent a specific subset of proton channel that have voltage- and time-dependent gating like other ion channels, but differ from most ion channels in their extraordinarily high selectivity, tiny conductance, strong temperature and deuterium isotope effects on conductance and gating kinetics, and insensitivity to block by steric occlusion.
Abstract: Proton channels exist in a wide variety of membrane proteins where they transport protons rapidly and efficiently. Usually the proton pathway is formed mainly by water molecules present in the protein, but its function is regulated by titratable groups on critical amino acid residues in the pathway. All proton channels conduct protons by a hydrogen-bonded chain mechanism in which the proton hops from one water or titratable group to the next. Voltage-gated proton channels represent a specific subset of proton channels that have voltage- and time-dependent gating like other ion channels. However, they differ from most ion channels in their extraordinarily high selectivity, tiny conductance, strong temperature and deuterium isotope effects on conductance and gating kinetics, and insensitivity to block by steric occlusion. Gating of H+ channels is regulated tightly by pH and voltage, ensuring that they open only when the electrochemical gradient is outward. Thus they function to extrude acid from cells. H+ch...

654 citations


Cites background from "Dielectric Properties of Ice and So..."

  • ...Historically, the question of proton conduction in ice has proven to be difficult and controversial (42, 44, 96, 157, 188, 288, 294, 380, 500, 808)....

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Journal ArticleDOI
TL;DR: In this paper, a consistent treatment of the chemical shift, thermal and dielectric data for water can be given based on a two-state model involving an equilibrium between a hydrogen-bonded ''icelike'' fraction and a ''monomer'' fraction whose interaction with the lattice arises entirely from London dispersion forces.
Abstract: Temperature‐dependence measurements have been made on the chemical shift of the proton of a water molecule in the liquid state and in the gas state at varying pressure. The problem of relating these experimental data to the intermolecular forces leading to cohesion and to hydrogen‐bond formation between water molecules is considered in detail. It is shown that a consistent treatment of the chemical shift, thermal, and dielectric data for water can be given based on a two‐state model involving an equilibrium between a hydrogen‐bonded ``icelike'' fraction and a ``monomer'' fraction whose interaction with the lattice arises entirely from London dispersion forces.Using semiempirically derived values of the chemical shift and energy associated with the condensation of water vapor to ``monomer,'' the magnitude of the shift associated with the transformation to ice is calculated. It is then shown that, on the assumption that the hydrogen bond is electrostatic in character, the ``polar'' contribution to this shif...

636 citations

Journal ArticleDOI
01 Jan 1987
TL;DR: In this article, applications of the interaction of microwaves with the natural snow cover are discussed. But the authors do not consider the effects of microwave technology on the natural vegetation in their work.
Abstract: (1987). Applications of the interaction of microwaves with the natural snow cover. Remote Sensing Reviews: Vol. 2, No. 2, pp. 259-387.

395 citations

Journal ArticleDOI
TL;DR: In this paper, the effect of snow density, impurities, stress, crystal size, and orientation on the permittivity and loss tangent of naturally occurring ice and snow are considered.
Abstract: The permittivity and loss tangent of naturally occurring ice and snow are considered. The direct-current conductivity is considered only when it is of importance to the alternating-current and radio-frequency properties. Laboratory measurements on pure ice, and deliberately contaminated ice, are included to help in explaining and extrapolating the behaviour of natural ice and snow. The lower band of frequencies from 10 c./sec. to 1 Mc./sec. is occupied by a relaxation spectrum in which the relative permittivity falls from approximately 100 to 3. The loss tangent reaches a maximum at a frequency which varies from 50 c./sec. to 50 kc./sec. as the temperature increases from −60°C. to 0°C. We are interested in the effect of snow density, impurities, stress, crystal size, and orientation. For frequencies much greater than 1 Mc./sec., the relative permittivity is 3.17±0.07. The loss tangent reaches a minimum value at approximately 1,000 Mc./sec. beyond which the dominant influence is infrared absorption. The minimum is 10−3 at 0°C or 2×10−5 at −60°C. These values are greatly increased by impurities or free water. Some possible applications to glaciological field measurements are mentioned.

302 citations

Journal ArticleDOI
TL;DR: In this article, a traverse over the ice sheet of north western Greenland in 1964, during which a continuously recorded profile of ice thickness was obtained for the first time, was presented.
Abstract: Experimental results are presented from a traverse over the ice sheet of north western Greenland in 1964, during which a continuously recorded profile of ice thickness was obtained for the first time. Interpretation of data from this traverse is consistent with results of subsequent work to December 1967. The parameters of the apparatus are presented briefly, while the details of electronic circuits are being published separately. Theoretical problems of radio wave propagation in an ice sheet and, in particular, the factors affecting accuracy are discussed. The uncertainty in depth, over a small area, is ±5 m ±1.5% and this is verified by comparison with the seismic results for a range of depths up to 1.5 km. It is found that the only real uncertainty arises in irregular terrain. The effectiveness of the radio echo technique is dependent on the absorption of radio waves in ice. Temperature, and to a lesser extent the impurity content of ice, appear to be the main variables affecting field performance. Earlier laboratory results on the variation of absorption with temperature for ice cores from northwest Greenland, together with theoretically predicted temperature distributions throughout the ice mass, have provided estimates of the total loss by absorption. These estimates are reasonably consistent with the observed echo strengths over most of the traverse. Consequently, it is predicted that echoes can be obtained over considerable areas of the ice sheets of Greenland and Antarctica, as has been verified by subsequent observations. The reflexion coefficient at the ice/rock interface is of the order of —15 dB. It could rise to 0 dB for an ice/water interface and one area was found in Greenland where it appeared to fall to — 30 dB. Results from this traverse have shown that local surface slopes on the ice sheet are largely controlled by variations of longitudinal stress along the line of flow. Regional slopes over several kilometres vary with the velocity of movement of the ice, but appear to be less dependent on basal ice temperatures than laboratory results would suggest. The velocity of ice movement increases in proportion to the square or cube of the basal shear stress, but the stress itself shows no obvious dependence on basal ice temperature. Partially reflecting layers discovered within the ice mass are discussed mainly in terms of small density variations between adjacent layers of ice. One particularly prominent layer is calculated to be about 1000 years old and its variation of depth with position provides evidence in favour of the steady state model of the ice sheet.

272 citations

References
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Book
01 Jan 1949

2,296 citations

Journal ArticleDOI
TL;DR: In this paper, an extension of the Onsager theory of dielectric polarization is presented, which is applied to liquid water under the assumption of tetrahedral coordination and directed bonds between neighboring molecules.
Abstract: An extension of the Onsager theory of dielectric polarization is presented. The local dielectric constant is approximated by the macroscopic dielectric constant of the fluid in a region outside a molecule and its first shell of neighbors rather than in the entire region exterior to the molecule. In addition to the molecular dipole moment, the average value 〈cosγ〉Av of the cosine of the angle between neighbor dipoles is a determining factor. Hindered relative rotation of neighboring molecules produces a correlation between their orientations and prevents 〈cosγ〉Av from vanishing. The theory is applied to liquid water under the assumption of tetrahedral coordination and directed bonds between neighboring molecules.

1,660 citations

Journal ArticleDOI
TL;DR: In this paper, the authors describe a bridge for reasonably accurate measurement by direct balance of capacitance and conductance in the frequency range 50 c/sec. to 5 cm/sec., and over most of this range is essentially direct reading in the two admission components with negligible unbalance from lead effects or guard circuits of the unknown.
Abstract: The bridge described has been developed for reasonably accurate measurement by direct balance of capacitance and conductance in the frequency range 50 c/sec. to 5 mc/sec., and over most of this range is essentially direct reading in the two admittance components with negligible unbalance from lead effects or guard circuits of the unknown. These properties are realized by using two circuits developed from the work of others. The first employs inductively coupled ratio arms to minimize residual impedance effects and unbalance by guard circuits, the second, a conductance shifter wye network with good high frequency properties and an essentially linear conductance reading. Design considerations and limitations of these circuits are discussed, as are suitable test cells and auxiliary equipment.

72 citations

Journal ArticleDOI
TL;DR: In this article, a calculation of the static dielectric constant of ice using only simple molecular data and with well-defined assumptions as to the possibilities of molecular movement in the crystal is presented.
Abstract: A calculation is made of the static dielectric constant of ice using only simple molecular data and with well‐defined assumptions as to the possibilities of molecular movement in the crystal. The paper serves as an illustration of the procedure for calculating static dielectric constants, and it results in a numerical value of this quantity for ice which is in reasonable agreement with experiment.

31 citations