M. Iwahashi, K. Itoh, K. Ohshima
Sep 1, 1988
Citations
0
Influential Citations
5
Citations
Journal
Bulletin of the Chemical Society of Japan
Abstract
The desorption of [1-14C]octadecanoic acid molecules in vacuo from a Langmuir-Blodgett film, which is regarded as an extremely thin crystal, was studied by using three kinds of radioactive samples containing ten molecular layers: The first sample was labeled at the tenth (the outermost) layer; the second one, at the ninth layer and the third one, at both the ninth and tenth layers. From the initial slopes in the desorption curves for these samples it is suggested that most of the acid molecules desorb from the tenth layer and some acid molecules desorb as a dimer consisting of a pair of molecules from the ninth and tenth layers. The scanning electron micrographic observations were carried out for nonradioactive samples stored for a week at 298.2 or 278.2 K under atmospheric pressure; it was concluded that the fatty acid molecules jump back and forth between a boundary (stagnant) layer and the surface of the LB multilayer and coagulate into micron-size crystals.