MECHANISM OF MOLECULAR ORDERING IN MONOLAYER LIQUID-CRYSTAL FILMS

Scanning tunneling microscopy and ''molecule corrals'' were used to me asure the temperature dependence of the rate of molecular ordering in monolayer liquid crystal films. Molecule corrals are circular etch pit s, 3.35 Angstrom deep on the basal surface of graphite formed by high- temperature oxidation. A strong negative relationship between temperat ure and nucleation rate was observed, consistent with a nucleation gro wth mechanism of molecular self-assembly. From a fit of classical nucl eation theory the melting temperature of the film was found to be T-me lt = 318 +/- 6 K, the thermodynamic driving force for nucleation Delta F-n(T-melt - T)/T-melt = 1.1 +/- 0.3 kcal mol(-1), and the preexepone ntial factor A = (1.8 +/- 0.8) x 10(8) Angstrom(-2) s(-1).