dorsal/arxiv
View SchemaEffect of Subphase Ca++ Ions on the Viscoelastic Properties of Langmuir Monolayers
| Authors | R. S. Ghaskadvi, Sharon Carr, Michael Dennin |
|---|---|
| Categories | |
| ArXiv ID | physics/9912016 |
| URL | https://arxiv.org/abs/physics/9912016 |
| DOI | 10.1063/1.479648 |
| Journal | J. Chem. Phys. 111, 3675 (1999) |
Abstract
It is known that the presence of cations like Ca++ or Pb++ in the water subphase alters the pressure-area isotherms for fatty acid monolayers. The corresponding lattice constant changes have been studied using x-ray diffraction. Reflection-absorption spectroscopy has been used to probe the chemical composition of the film. We report on the first measurements of the time evolution of the shear viscosity of arachidic acid monolayers in the presence of Ca++ ions in the subphase. We find that the introduction of Ca++ ions to the water subphase results in an increase of the film's viscosity by at least three orders of magnitude. This increase occurs in three distinct stages. First, there is a rapid change in the viscosity of up to one order of magnitude. This is followed by two periods, with very different time constants, of a relatively slow increase in the viscosity over the next 10 or more hours. The corresponding time constants for this rise decrease as either the subphase pH or Ca++ concentration is increased.
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"abstract": "It is known that the presence of cations like Ca++ or Pb++ in the water\nsubphase alters the pressure-area isotherms for fatty acid monolayers. The\ncorresponding lattice constant changes have been studied using x-ray\ndiffraction. Reflection-absorption spectroscopy has been used to probe the\nchemical composition of the film. We report on the first measurements of the\ntime evolution of the shear viscosity of arachidic acid monolayers in the\npresence of Ca++ ions in the subphase. We find that the introduction of Ca++\nions to the water subphase results in an increase of the film\u0027s viscosity by at\nleast three orders of magnitude. This increase occurs in three distinct stages.\nFirst, there is a rapid change in the viscosity of up to one order of\nmagnitude. This is followed by two periods, with very different time constants,\nof a relatively slow increase in the viscosity over the next 10 or more hours.\nThe corresponding time constants for this rise decrease as either the subphase\npH or Ca++ concentration is increased.",
"arxiv_id": "physics/9912016",
"authors": [
"R. S. Ghaskadvi",
"Sharon Carr",
"Michael Dennin"
],
"categories": [
"physics.chem-ph",
"cond-mat"
],
"doi": "10.1063/1.479648",
"journal_ref": "J. Chem. Phys. 111, 3675 (1999)",
"title": "Effect of Subphase Ca++ Ions on the Viscoelastic Properties of Langmuir Monolayers",
"url": "https://arxiv.org/abs/physics/9912016"
},
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