ELECTRON-DIFFRACTION AND IMAGING OF UNCOMPRESSED MONOLAYERS OF AMPHIPHILIC MOLECULES ON VITREOUS AND HEXAGONAL ICE

A new approach is described for probing domains of ordered self-assemb lies of amphiphilic monolayers at the aqueous solution interface. The method has potential importance for the study of membrane structure, L angmuir-Blodgett films, and nucleation processes of two- and three-dim ensional crystals. Electron diffraction (ED) patterns indicative of tw o-dimensional crystalline self-assembly were obtained from samples, wh ich were examined by cryo-electron microscopy, of monolayers of water- insoluble amphiphiles on vitrified aqueous substrates. The apparent he xagonal symmetry of an ED pattern from a C16H33OH monolayer was interp reted in terms of multiple twinning. Monolayers of the C31H63OH and ca dmium salt of C19H39CO2H that were studied by dark-field techniques di splayed faceted two-dimensional crystallites with a maximal size of 1 to 2 micrometers. Epitaxial nucleation of hexagonal ice by the C31H63O H monolayer has also been demonstrated by ED.