A NEW DISPLACEMENT CURRENT MEASURING SYSTEM COUPLED WITH THE LANGMUIR-FILM TECHNIQUE

The new displacement current measuring system used for detecting the dynamic behavior of monolayers at the air-water interface is described. It basically consists of a film balance, a light source and a pair of electrodes connected to each other through a sensitive ammeter. Here, one electrode is suspended in air and the other electrode is placed in the water. Using the system, displacement current generated from a single monolayer by either the application of surface pressures or the photoirradiation can be detected. Since the displacement current flows due to the dynamic behavior of polar molecules at the air-water interface, the physicochemical properties of monolayers, e.g., dipole moment of the constituent molecules and the molecular structural change due to the photoisomerization, can be investigated without destroying the monolayers themselves.