In situ monitoring of metal surfaces exposed to milk using total internal reflection ellipsometry

A technique combining ellipsometry with total internal reflection is presented. The method is called total internal reflection ellipsometry (TIRE) and is suitable for monitoring of internal surfaces which opens new possibilities for measuring adsorption on metal surfaces in opaque liquids. Results from measurements of adsorption of milk and subsequent cleaning with sodium hydroxide on metal surfaces are given. These include studies on gold, iron, and chromium surfaces. A schematic design of the instrument used in TIRE is included. The main advantages of the system are non-invasive probing, fast response, and high sensitivity. The method has potential for applications in monitoring of internal surfaces of pipelines in industrial processes.