Abstract
The dynamic behavior of fatty acid monolayers at the air–water interface was investigated using a displacement current-measuring technique coupled with the so-called Langmuir-film technique and also the dipole moment of the acids was determined. The displacement current flowing though a short circuit was generated only when induced charges on an electrode suspended in air was changed by monolayer compression. The displacement current measurement was found to be a very sensitive method used for a better understanding of the relationship between the structure and function of the monolayers placed on the water surface and it was also found to be a very useful method for detecting the dynamic motion of molecules in the entire range from the so-called gaseous state to the solid state at the same time. Finally, the generalized displacement current was theoretically analyzed.