Properties of monolayers of long-chained aliphatic compounds adsorbed at an amalgamated platinum electrode

Electrochemical impedance spectra are obtained in a wide potential range for electrodes covered by monolayers of cetyl alcohol and stearic acid. The conditions for the determination of true values of the monolayer's capacitance and ohmic resistance are found. It is shown that the restructuring of the stearic acid monolayer in alkaline solutions slightly increases its true resistance and consequently does not involve an increase in its dielectric constant. This validates the assumption on the thinning of the monolayer, which follows from the increase of its capacitance. The short-term adsorption of the above aliphatic compounds results in the formation of a monolayer whose chains are orientated parallel to the electrode surface while during the long-term adsorption, the chains are normal to the surface.