Spread Oil Measuring Apparatus
Measurement of Oil Film Thickness
Controlling the uniform density of oil molecules
Monolayers are characterized by their surface film pressure. Reducing the surface area will compress the molecules of a monolayer, which will result in a higher density of molecules and a higher surface film pressure.
The relationship between the surface film pressure and the area per molecule is shown in the surface pressure-area curve. By setting the surface film pressure of the SOM-A just before the collapse of the monolayer, the uniform density of oil molecules can be controlled. The maximum surface pressure is usually set to 8 mN/m.
Measuring the surface film pressure
When the measuring probe (glass plate) is immersed in the water subphase, the water is wetting the glass plate and creates a concave meniscus. The oil molecules are arranged on the water surface and build the surface film pressure. This pressure forces the glass plate to move upwards, which can be detected by the precise balancing system.