In situ Processing of Langmuir Monolayers

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The purpose of this research is to actively control factors affecting the quality of the Langmuir fils, which we call "processing". It is essential to have in situ characterization techniques in order to know the effect of a particular processing. We used the following techniques : (1) Capillary wave probe : The effect of the film heterogeneity has been studied. In liquid/gas coexisting films, the liquid phase is practically invisible to the capillary wave. In solid/gas coexisting films, the continuity of the solid phase (islands) determins the propagation characteristics. (2) Reflection spectroscopy : The formation of polyion complex with a spread monolayer has been studied. The charge nutrality was found to be the deciding factor of the amount of the polymer on the monolayer and hence the adsorbed layer is monomolecular. The kinetics is completely governed by the diffusion of the polyymer in the solution and can be fitted to a universal curve. (3) Nonlinear optics : The 2nd and 3rd harmonic generations have been used to elucidate the nonlinear effects particular to the ultra thin films. Further refinement of the LB related techniques has been attempted as follows : (4) Single layer LB films have been used as an anisotropic substrate for the subsequent vacuum deposition. We demonstrated that the orientational order in the LB film can be transferred semi-quantitatively to the evaporated film. (5) An automated moving-wall trough with the capillary wave probe has been constructed and thick LB films have been succesfully fabricated in which the order in the L-film has been preserved in the LB-film.