VISUALIZATION OF 1ST-ORDER AND 2ND-ORDER PHASE-TRANSITIONS IN EICOSANOL MONOLAYERS USING BREWSTER-ANGLE MICROSCOPY

In the intermediate temperature and the upper pressure regions, the phase diagram of an eicosanol monolayer consists of four phases: (1) one normal condensed high-pressure phase, A', (2) and (3) two high-pressure superliquids, Rot I and Rot II, and (4) one low-pressure phase, C. The phase transitions A'/C and Rot II/C are of second order and correlated with a collective tilting of the molecules. The phase transition C/Rot I, however, is of first order and correlated with formation and growth of nuclei consisting of tilted or normally oriented molecules, depending on the direction of the transition. The kinetics of the phase transitions between the tilted and untilted phases were visualized with a Brewster angle microscope (BAM). After C --> A' --> C compression/decompression cycles a memory effect for the shape of the domains in the C phase was observed.