The Ocean Optics Spectrometer uses the interference of light of different colors reflected from a thin liquid film to measure it’s thickness with nano-meter accuracy.
In the Thin Film Balance we can determine the properties of thin liquid films in a controlled atmosphere. The film is generated in a porous frit in a sealed champer whose pressure can be controlled. During an experiment, one determines how the thickness of the film depends on the pressure drop applied between the liquid in the film and the gas around the film. The thickness of the film is determined by measuring the intensity of light reflected off the film.
With this method one obtains very accurate measurements of dependence of the Disjoining pressure of two interfaces as a function of the distance between them.
|Schema of a film in the thin film balance||Image of a film in the Thin Film balance|
We use a fully automated, home-made device to pull vertical liquid films from a solution at a controlled velocity. The device allows us to relate the film thickness and stability to the pulling velocity and size of the films. Additionally we measure the force on the frame of the film, which provides a measure of the surface tension.