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Water Interface

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Zdeněk Samec - One of the best experts on this subject based on the ideXlab platform.

  • charge transfer resistance and differential capacity of the plasticized pvc membrane Water Interface
    Journal of Electroanalytical Chemistry, 2002
    Co-Authors: Jan Langmaier, Květoslava Stejskalová, Zdeněk Samec
    Abstract:

    Abstract Impedance measurements were used to evaluate the differential capacity and the charge transfer resistance of the o-nitrophenyl octyl ether (o-NPOE) plasticized PVC membrane | Water Interface over the range of potential differences from −280 to 180 mV and the range of temperatures from 290 to 305 K. The equilibrium potential difference at the membrane | Water Interface was controlled by the partition of tetramethyl-, tetraethyl-, tetrapropyl- or tetrabutylammonium ion. Soaking of the PVC membrane in Water for up to 8 h does not have an effect on the impedance parameters, which points to an absence of Water sorption into the membrane in the presence of hydrophobic electrolytes. The differential capacity of the membrane | Water Interface is comparable with that of the o-NPOE | Water Interface, and its dependence on temperature throws some light on the role of the surface dipole. Lower apparent rate constants of ion transfer across the membrane | Water Interface (ka0≈10−2 cm s−1) can be linked to the activation barrier associated with a modification of surface layer at the o-NPOE | Water Interface by PVC molecules.

  • Charge transfer resistance and differential capacity of the plasticized PVC membrane | Water Interface
    Journal of Electroanalytical Chemistry, 2002
    Co-Authors: Jan Langmaier, Květoslava Stejskalová, Zdeněk Samec
    Abstract:

    Abstract Impedance measurements were used to evaluate the differential capacity and the charge transfer resistance of the o-nitrophenyl octyl ether (o-NPOE) plasticized PVC membrane | Water Interface over the range of potential differences from −280 to 180 mV and the range of temperatures from 290 to 305 K. The equilibrium potential difference at the membrane | Water Interface was controlled by the partition of tetramethyl-, tetraethyl-, tetrapropyl- or tetrabutylammonium ion. Soaking of the PVC membrane in Water for up to 8 h does not have an effect on the impedance parameters, which points to an absence of Water sorption into the membrane in the presence of hydrophobic electrolytes. The differential capacity of the membrane | Water Interface is comparable with that of the o-NPOE | Water Interface, and its dependence on temperature throws some light on the role of the surface dipole. Lower apparent rate constants of ion transfer across the membrane | Water Interface (ka0≈10−2 cm s−1) can be linked to the activation barrier associated with a modification of surface layer at the o-NPOE | Water Interface by PVC molecules.

Jan Langmaier - One of the best experts on this subject based on the ideXlab platform.

  • charge transfer resistance and differential capacity of the plasticized pvc membrane Water Interface
    Journal of Electroanalytical Chemistry, 2002
    Co-Authors: Jan Langmaier, Květoslava Stejskalová, Zdeněk Samec
    Abstract:

    Abstract Impedance measurements were used to evaluate the differential capacity and the charge transfer resistance of the o-nitrophenyl octyl ether (o-NPOE) plasticized PVC membrane | Water Interface over the range of potential differences from −280 to 180 mV and the range of temperatures from 290 to 305 K. The equilibrium potential difference at the membrane | Water Interface was controlled by the partition of tetramethyl-, tetraethyl-, tetrapropyl- or tetrabutylammonium ion. Soaking of the PVC membrane in Water for up to 8 h does not have an effect on the impedance parameters, which points to an absence of Water sorption into the membrane in the presence of hydrophobic electrolytes. The differential capacity of the membrane | Water Interface is comparable with that of the o-NPOE | Water Interface, and its dependence on temperature throws some light on the role of the surface dipole. Lower apparent rate constants of ion transfer across the membrane | Water Interface (ka0≈10−2 cm s−1) can be linked to the activation barrier associated with a modification of surface layer at the o-NPOE | Water Interface by PVC molecules.

  • Charge transfer resistance and differential capacity of the plasticized PVC membrane | Water Interface
    Journal of Electroanalytical Chemistry, 2002
    Co-Authors: Jan Langmaier, Květoslava Stejskalová, Zdeněk Samec
    Abstract:

    Abstract Impedance measurements were used to evaluate the differential capacity and the charge transfer resistance of the o-nitrophenyl octyl ether (o-NPOE) plasticized PVC membrane | Water Interface over the range of potential differences from −280 to 180 mV and the range of temperatures from 290 to 305 K. The equilibrium potential difference at the membrane | Water Interface was controlled by the partition of tetramethyl-, tetraethyl-, tetrapropyl- or tetrabutylammonium ion. Soaking of the PVC membrane in Water for up to 8 h does not have an effect on the impedance parameters, which points to an absence of Water sorption into the membrane in the presence of hydrophobic electrolytes. The differential capacity of the membrane | Water Interface is comparable with that of the o-NPOE | Water Interface, and its dependence on temperature throws some light on the role of the surface dipole. Lower apparent rate constants of ion transfer across the membrane | Water Interface (ka0≈10−2 cm s−1) can be linked to the activation barrier associated with a modification of surface layer at the o-NPOE | Water Interface by PVC molecules.

Květoslava Stejskalová - One of the best experts on this subject based on the ideXlab platform.

  • charge transfer resistance and differential capacity of the plasticized pvc membrane Water Interface
    Journal of Electroanalytical Chemistry, 2002
    Co-Authors: Jan Langmaier, Květoslava Stejskalová, Zdeněk Samec
    Abstract:

    Abstract Impedance measurements were used to evaluate the differential capacity and the charge transfer resistance of the o-nitrophenyl octyl ether (o-NPOE) plasticized PVC membrane | Water Interface over the range of potential differences from −280 to 180 mV and the range of temperatures from 290 to 305 K. The equilibrium potential difference at the membrane | Water Interface was controlled by the partition of tetramethyl-, tetraethyl-, tetrapropyl- or tetrabutylammonium ion. Soaking of the PVC membrane in Water for up to 8 h does not have an effect on the impedance parameters, which points to an absence of Water sorption into the membrane in the presence of hydrophobic electrolytes. The differential capacity of the membrane | Water Interface is comparable with that of the o-NPOE | Water Interface, and its dependence on temperature throws some light on the role of the surface dipole. Lower apparent rate constants of ion transfer across the membrane | Water Interface (ka0≈10−2 cm s−1) can be linked to the activation barrier associated with a modification of surface layer at the o-NPOE | Water Interface by PVC molecules.

  • Charge transfer resistance and differential capacity of the plasticized PVC membrane | Water Interface
    Journal of Electroanalytical Chemistry, 2002
    Co-Authors: Jan Langmaier, Květoslava Stejskalová, Zdeněk Samec
    Abstract:

    Abstract Impedance measurements were used to evaluate the differential capacity and the charge transfer resistance of the o-nitrophenyl octyl ether (o-NPOE) plasticized PVC membrane | Water Interface over the range of potential differences from −280 to 180 mV and the range of temperatures from 290 to 305 K. The equilibrium potential difference at the membrane | Water Interface was controlled by the partition of tetramethyl-, tetraethyl-, tetrapropyl- or tetrabutylammonium ion. Soaking of the PVC membrane in Water for up to 8 h does not have an effect on the impedance parameters, which points to an absence of Water sorption into the membrane in the presence of hydrophobic electrolytes. The differential capacity of the membrane | Water Interface is comparable with that of the o-NPOE | Water Interface, and its dependence on temperature throws some light on the role of the surface dipole. Lower apparent rate constants of ion transfer across the membrane | Water Interface (ka0≈10−2 cm s−1) can be linked to the activation barrier associated with a modification of surface layer at the o-NPOE | Water Interface by PVC molecules.

Eric Lee - One of the best experts on this subject based on the ideXlab platform.

  • Electrophoresis of a spherical particle normal to an air-Water Interface.
    Electrophoresis, 2010
    Co-Authors: Peter Tsai, James Lou, Eric Lee
    Abstract:

    Electrophoresis of a spherical particle normal to an air-Water Interface is considered theoretically in this study. The presence of the air-Water Interface is found to reduce the particle mobility in general, especially when the double layer is very thick. This boundary effect diminishes as the double layer gets very thin. The higher the surface potential, the more significant the reduction of mobility due to the polarization effect from the double layer deformation when the particle is in motion. Local extrema are observed in the mobility profiles with varying double layer thickness as a result. Comparison with a solid planar boundary is made. It is found that the particle mobility near an air-Water Interface is smaller than that near a solid one when the double layer is thick, and vice versa when the double layer is thin, with a critical threshold value of double layer thickness corresponding roughly to the touch of the Interface. The reason behind it is clearly explained as the buildup of electric potential at the air-Water Interface, which reduces the driving force as a result.

  • Diffusiophoresis of a spherical particle normal to an air-Water Interface.
    Journal of colloid and interface science, 2008
    Co-Authors: James Lou, Chun-yu Shih, Eric Lee
    Abstract:

    The diffusiophoresis of a spherical colloidal particle normal to an air-Water Interface subject to a uniform electrolyte concentration gradient is investigated theoretically. The governing electrokinetic equations are solved numerically with a pseudo-spectral method based on Chebyshev polynomials. Key parameters such as the distance between the particle and the Interface, the double-layer thickness, and the surface potential of the particle are examined to analyze their respective effect on the diffusiophoretic velocity of the particle. Distinctive features pertinent to an air-Water Interface are investigated in particular as compared with a solid metal surface. It is found in this study, among other things, that the diffusiophoretic velocity of a particle moving toward an air-Water Interface is always less than that toward a planar metal surface when the diffusivities of cations and anions are identical. This can be explained nicely by the classic image-charge analogue in electrostatics, where the former (air-Water Interface) stands for an image-charge of the same sign, while the latter (planar metal surface) stands for an image-charge of the opposite sign. In the case of distinct diffusivities of cations and anions, the situation is much more complicated. No such simple and convenient analogue is observed.

James P. Cowin - One of the best experts on this subject based on the ideXlab platform.

  • The oil-Water Interface: mapping the solvation potential.
    Journal of the American Chemical Society, 2009
    Co-Authors: Richard Curtis Bell, Martin J Iedema, Gregory K Schenter, Kai Wu, James P. Cowin
    Abstract:

    An ion moving across an oil−Water Interface experiences strong solvation changes. We have directly measured the solvation potential from 0.4 to 4 nm for Cs+ ions approaching the oil−Water Interface from the oil side (“oil” = 3-methylpentane). The Interfaces were built at 30 K using molecular beam epitaxy. Ions were precisely placed within the film during its growth using a soft-landing ion beam. The ion’s collective electric field was progressively increased (by adding more ions) until it balanced the individual ion’s solvation potential slope. As the samples were slowly warmed, near 90 K the ions began moving, as measured by a Kelvin probe. Their motion precisely determines the local slope of the solvation potential, which was integrated to get the potential. The potential is Born-like for z > 0.4 nm away from the oil−Water Interface. Our method could provide important tests of theoretical estimates of ion motion at biological Interfaces and in atmospheric aerosols.

  • Oil-Water Interface: Mapping Nanoscale Solvation and Fluidity
    2004
    Co-Authors: James P. Cowin, Martin J Iedema
    Abstract:

    Buried liquid-liquid Interfaces, like the oil-Water Interface, can be probed in great detail, by recreating them synthetically via cryogenic molecular beam epitaxy. The structures placed within them persist long enough, once one warms the system to restore true fluidity, to probe many properties. Further, by gently (>1 eV) imbedding tracer ions (like hydronium or cesium) with angstrom precision at, below, and/or above the Interface, it becomes possible to study kinetic processes with high precision. We use it to measure the solvation chemical potential of an ion in the oil versus position near the Water Interface. We also measure the Interface-induced fluidity changes