Electron Diffraction and Imaging of Uncompressed Monolayers of Amphiphilic Molecules on Vitreous and Hexagonal Ice

Abstract

A new approach is described for probing domains of ordered self-assemblies of amphiphilic monolayers at the aqueous solution interface. The method has potential importance for the study of membrane structure, Langmuir-Blodgett films, and nucleation processes of two-and three-dimensional crystals. Electron diffraction (ED) patterns indicative of two-dimensional crystalline self-assembly were obtained from samples, which were examined by cryo-electron microscopy, of monolayers of water-insoluble amphiphiles on vitrified aqueour substrates. The apparent hexagonal symmetry of an ED pattern from a C₁₆H₃₃OH monolayer was interpreted in terms of multiple twinning. Monolayers of the CL₃₁H₆₃OH and cadmium salt of C₁₉H₃₉CO₂H that were studied by dark-field techniques displayed faceted two-dimensional crystallites with a maximal size of 1 to 2 micrometers. Epitaxial nucleation of hexagonal ice by the C₃₁H₆₃OH monolayer has also been demonstrated by ED.