A procedure for studying the sorption of ethanol vapor on a monomolecular Langmuir-Blodgett arachic acid film

The paper presents the results of studies of the sorption of ethanol from the gas phase by a monomolecular arachic acid layer deposited by the Langmuir-Blodgett method onto the surface of a nickel substrate. Studies were performed using a working model based on a field-effect transistor. Sorption was accompanied by changes in the potential of the nickel substrate. The dependence of transistor current I _D on time t was related to the conditions of Langmuir-Blodgett film deposition. The value and characteristic time of signal variations as the atmosphere changed depended on the pressure of monolayer deposition and, therefore, monolayer phase state on the surface of water when it was transferred to the solid substrate. The experimental I _D (t) dependence was compared with the time dependence of arachic monolayer surface coverage with sorbent molecules calculated by the Langmuir model. The conclusion was drawn that the model was capable of describing the sorption of ethanol vapor by the Langmuir-Blodgett arachic acid monolayer at low partial pressures p ≤ 0.05p ₀, where p ₀ is the saturated vapor pressure.