DYNAMIC BEHAVIOR OF PYRAMIDIC LIQUID-CRYSTAL FILM AT THE AIR-WATER-INTERFACE

Molecular organization of the different phases of a pyramidic liquid c rystal film spread at the air-water interface has been investigated us ing Langmuir balance and current displacement techniques simultaneousl y. The mesogenic compound exhibits a main transition from an expanded phase to a metastable condensed phase. The results are in agreement wi th previous polarized and fluorescence light microscopy measurements a nd grazing incidence X-ray reflectometry. The study shows that the mol ecules are oriented edge-on in the condensed phase and side-on in the liquid expanded phase. The value of the dipole moment of the pyramidic molecules is given in the liquid expanded phase. Two kinds of displac ement current curves were obtained depending on the kinetic of compres sion.