The Experts below are selected from a list of 21153 Experts worldwide ranked by ideXlab platform

Wolfgang M. Sigmund - One of the best experts on this subject based on the ideXlab platform.

Hiroshi Tateyama - One of the best experts on this subject based on the ideXlab platform.

  • direct Surface Force Measurement for synthetic smectites using the atomic Force microscope
    Langmuir, 2002
    Co-Authors: Satoshi Nishimura, Masaya Kodama, Yusuke Imai, Hiroshi Tateyama
    Abstract:

    An atomic Force microscope with a colloid probe technique was used to measure Forces interacting between smectites, that is, saponite and hectorite. The measured Forces fit well to the Forces calculated by the Derjaguin-Landau -Verwey-Overbeek (DLVO) theory at separations larger than 4 nm over concentrations of 10 - 5 -10 - 2 M NaCl and the pH range of 4-10. There is also a good agreement between zeta potential and the electrical double-layer (EDL) potential extracted from the best fit to the DLVO Force curve. According to the analysis on the pH dependence of the EDL potential using the Gouy-Chapman-Stern-Graham model, the inner Helmholtz layer capacitance for the good fit of the outer Helmholtz plane potential to the EDL potential required a much lower value for hectorite (∼5 μF/cm 2 ) than that for saponite (∼500 μF/cm 2 ), reflecting the difference in the location of the lattice charge between saponite and hectorite. This provided evidence for the fact that the EDL Force for smectites is dominated by the location of the charges as well as the density of the charges. Extra short-range repulsion was observed at separations below ∼3 nm with increasing NaCl concentration and pH and then disappeared with decreasing pH or the NaCl concentration. The short-range repulsion was extracted as a double-exponential function, that is, F/R = A 1 exp(-D/D 1 ) + A 2 exp(-D/D 2 ), by subtracting the DLVO Forces from the measured Forces in the same way as the study with a Surface Force apparatus (Pashley, R. M. J. Colloid Interface Sci. 1981, 83, 531). The values of two decay lengths (D 1 and D 2 ) for smectites showed a very similar result to those for muscovite mica rather than silica. It was also found that the sum of the Force constants (A 1 + A 2 ) was closely related to the density and structure of the lattice charge.

Satoshi Nishimura - One of the best experts on this subject based on the ideXlab platform.

  • direct Surface Force Measurement for synthetic smectites using the atomic Force microscope
    Langmuir, 2002
    Co-Authors: Satoshi Nishimura, Masaya Kodama, Yusuke Imai, Hiroshi Tateyama
    Abstract:

    An atomic Force microscope with a colloid probe technique was used to measure Forces interacting between smectites, that is, saponite and hectorite. The measured Forces fit well to the Forces calculated by the Derjaguin-Landau -Verwey-Overbeek (DLVO) theory at separations larger than 4 nm over concentrations of 10 - 5 -10 - 2 M NaCl and the pH range of 4-10. There is also a good agreement between zeta potential and the electrical double-layer (EDL) potential extracted from the best fit to the DLVO Force curve. According to the analysis on the pH dependence of the EDL potential using the Gouy-Chapman-Stern-Graham model, the inner Helmholtz layer capacitance for the good fit of the outer Helmholtz plane potential to the EDL potential required a much lower value for hectorite (∼5 μF/cm 2 ) than that for saponite (∼500 μF/cm 2 ), reflecting the difference in the location of the lattice charge between saponite and hectorite. This provided evidence for the fact that the EDL Force for smectites is dominated by the location of the charges as well as the density of the charges. Extra short-range repulsion was observed at separations below ∼3 nm with increasing NaCl concentration and pH and then disappeared with decreasing pH or the NaCl concentration. The short-range repulsion was extracted as a double-exponential function, that is, F/R = A 1 exp(-D/D 1 ) + A 2 exp(-D/D 2 ), by subtracting the DLVO Forces from the measured Forces in the same way as the study with a Surface Force apparatus (Pashley, R. M. J. Colloid Interface Sci. 1981, 83, 531). The values of two decay lengths (D 1 and D 2 ) for smectites showed a very similar result to those for muscovite mica rather than silica. It was also found that the sum of the Force constants (A 1 + A 2 ) was closely related to the density and structure of the lattice charge.

William A Ducker - One of the best experts on this subject based on the ideXlab platform.

  • atomic Force microscopy colloid probe Measurements with explicit Measurement of particle solid separation
    Langmuir, 2004
    Co-Authors: Spencer C Clark, John Y Walz, William A Ducker
    Abstract:

    We describe the use of evanescent wave scattering to measure the separation between the Surface of a solid and a particle that is attached to an atomic Force microscope (AFM) cantilever. Termed evanescent wave atomic Force microscopy, our approach involves measuring the intensity of the light scattered from an evanescent field formed by the total internal reflection of a laser beam at a solid/fluid interface. In a conventional AFM "colloid probe" Measurement, this separation must be inferred from an examination of the Surface Forces. Direct Measurement of this separation with an evanescent wave atomic Force microscope (EW-AFM) removes some ambiguity in the Surface Force Measurement and, in addition, allows new types of Measurements. For example, the Force can be monitored at a constant separation. Our evanescent scattering apparatus is essentially identical to that used in total internal reflection microscopy (TIRM), except that we collect the light that scatters back into the incident medium, because the AFM partly obscures the forward scattered light (i.e., light scattered into the transmitted region). Compared to a conventional TIRM Measurement, where the particle moves freely, attaching the particle to the cantilever in an EW-AFM gives much greater control of the particle position.

Masaya Kodama - One of the best experts on this subject based on the ideXlab platform.

  • direct Surface Force Measurement for synthetic smectites using the atomic Force microscope
    Langmuir, 2002
    Co-Authors: Satoshi Nishimura, Masaya Kodama, Yusuke Imai, Hiroshi Tateyama
    Abstract:

    An atomic Force microscope with a colloid probe technique was used to measure Forces interacting between smectites, that is, saponite and hectorite. The measured Forces fit well to the Forces calculated by the Derjaguin-Landau -Verwey-Overbeek (DLVO) theory at separations larger than 4 nm over concentrations of 10 - 5 -10 - 2 M NaCl and the pH range of 4-10. There is also a good agreement between zeta potential and the electrical double-layer (EDL) potential extracted from the best fit to the DLVO Force curve. According to the analysis on the pH dependence of the EDL potential using the Gouy-Chapman-Stern-Graham model, the inner Helmholtz layer capacitance for the good fit of the outer Helmholtz plane potential to the EDL potential required a much lower value for hectorite (∼5 μF/cm 2 ) than that for saponite (∼500 μF/cm 2 ), reflecting the difference in the location of the lattice charge between saponite and hectorite. This provided evidence for the fact that the EDL Force for smectites is dominated by the location of the charges as well as the density of the charges. Extra short-range repulsion was observed at separations below ∼3 nm with increasing NaCl concentration and pH and then disappeared with decreasing pH or the NaCl concentration. The short-range repulsion was extracted as a double-exponential function, that is, F/R = A 1 exp(-D/D 1 ) + A 2 exp(-D/D 2 ), by subtracting the DLVO Forces from the measured Forces in the same way as the study with a Surface Force apparatus (Pashley, R. M. J. Colloid Interface Sci. 1981, 83, 531). The values of two decay lengths (D 1 and D 2 ) for smectites showed a very similar result to those for muscovite mica rather than silica. It was also found that the sum of the Force constants (A 1 + A 2 ) was closely related to the density and structure of the lattice charge.