Preparation and Characterization of Asymmetric Soap Films on Vertical Si/SiO ₂ -Interfaces

Stable water films covered by arachidic-acid monolayers are deposited on vertically arranged Si/SiO2 substrates which are partially pulled out of a film balance. The applicability of such asymmetric soap films to study the process of monolayer deposition on solid substrates and the fluid-solid interface interaction as a function of lateral pressure, π, is demonstrated. Equilibrium thicknesses of h01 = 17 nm and h02 = 4 nm and a decrease of h01 by 1.5 nm at decreasing π from 25 to 15 mN m-1 is observed. Light scattering experiments provide first evidence for large thickness fluctuations during thinning.