Ian R. Peterson

The lamellar-columnar transition in Langmuir-Blodgett multilayers of cadmium soaps

Abstract At temperatures in the vicinity of 100 °C, multilayer Langmuir-Blodgett films of cadmium octadecanoate deposited under typical literature conditions undergo a slow phase transition to a columnar phase, in which the molecules are organized into long, laterally dense-packed rods. On the molecular scale, the order in the new phase is identical to that in the stable bulk phase at that temperature, while macroscopically, the substrate is still covered with a uniform film and shows long-range order. The columnar phase is quite stable at room temperature and at temperatures up to at least 140 °C.

Surface plasmon observation of striations in Langmuir-Blodgett films

Langmuir-Blodgett films are commonly subject to specific defects called striations which are associated with meniscus instability during deposition. In the present paper these have been characterized by observing their effect on the coupling of evanescent optical modes into the surface modes associated with metallic silver. The reflectivity as a function of incidence angle has been measured and fitted to a theoretical model and the spatial distribution of the defects has been directly imaged. The striations are shown to be exactly a bilayer thicker than the rest of the film.