Relationship between the capacitive characteristics of a flat capacitor and the amount of surfactant in a Langmuir monolayer formed between its plates.

Abstract

The paper proposes a research method based on the registration of changes in the electrical characteristics and parameters of a flat capacitor in which a dielectric represents a complex system «air gap–Langmuir monolayer–water subphase». Certain relationships have been obtained between the amount of arachidic acid present on the water surface and the frequency-capacitive characteristics.
The relationship between the change in capacitance and the value of the introduced volume was ambiguous for the investigated frequency range. In the range of 1-100 kHz, the capacitance decreased in proportion to the percentage of surfactants. In this case, the change was about 5% of the maximum capacity (when the water surface was clean). At high frequencies, the capacitance changes were up to 80%.
Thus, the electrical properties of such a capacitor depend very noticeably on the phase state of the Langmuir monomolecular layer. This allows us to expect the development of the technique will significantly expand the range of data obtained on the monolayer (including frequency dependencies in a wide frequency range) and will allow us to obtain data on the effects associated with changes in the packaging of molecules.
The reported study was funded by RFBR according to the research project №19-07-00086

Speaker

Mironyuk V. N.
Education and Research Institute of Nanostructures and Biosystems, Saratov State University.
Russia

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