This movie highlights recent experiments which measure the re-distribution of a contaminant (insoluble surfactant) by waves at the surface of a fluid. The apparatus is designed to simultaneously measure both the shape of the surface wave and the location of the fluorescent surfactant molecules as each evolves through many oscillations of a thin container of water. We observed that for standing waves, known as Faraday waves, the surfactant molecules accumulate at the troughs between waves. For traveling waves generated at the sides of the container, the surfactant molecules accumulate at the leading edge of the waves. This research sheds light on surface transport phenomena such as oil slicks or the coating of medical treatments on mucus membranes. Our success of these experiments suggests new means for characterizing interfacial properties such as the viscosity and compressibility of molecular monolayers.
This work is licensed under the Creative Commons Attribution-NonCommercial 4.0 International License. Any reuse must credit the author(s) and provide a link back to this page.