Detection of a monolayer at the nitrobenzene/water interface by a quasielastic laser scattering method

In oil/water system there are various kinds of reactions which take place at the interface. One of the most interesting such reactions is a self oscillation of the electrical potential in a water/nitrobenzene/water three-layer system. However, there are few effective techniques for an in-situ investigation of such interface reactions. In the present study a quasielastic laser scattering was applied to the remote detection of a monolayer at the nitrobenzene/water interface. Dipalmitoylphosphatidylcholine molecules with various molecular densities were spread at nitrobenzene/water interface and the dependence of the frequency of capillary wave (ripplon) at the interface was determined by the quasielastic laser scattering with optical heterodyne. The interfacial tension was estimated and compared with the conventional Dunoüy's method.