Determination of the Dipole Moment of a Monolayer at the Air/Water Interface Using a Current-Measuring Technique

Abstract

A new technique for determining the dipole moment of the constituent molecules of a monolayer at the air/water interface has been developed. In this technique, two electrodes parallel to the water surface are used. One electrode (Electrode 2) is placed in the water and the other electrode (Electrode 1) is suspended in the air. Both electrodes are grounded. The displacement current due to the induced change on Electrode 1 is measured with the surface pressure-aria isotherm. Since the induced change is caused by the dipoles of the constituent molecules, the dipole moments of the molecules are determined. In this study, fatty acids are used as examples. A theoretical analysis for determining dipole moments by the present technique is also described.