INPLANE ORGANIZATION OF LB MONOLAYERS FROM FTIR SPECTROSCOPY

The in-plane organization of monolayers and multilayers of cadmium arachidate deposited, by the conventional Langmuir-Blodgett technique, onto dielectric substrates has been studied by transmittance FTIR spectroscopy. Examination of the bending CH2 band associated with the hydrocarbon chains suggests that the first monolayer has a hexagonal subcell packing whether the interaction with the supporting substrate is hydrophilic or hydrophobic. Conversely, even-numbered multilayer stacks are arranged in bilayer structures, and their hydrocarbon chains present an orthorhombic packing with their crystallographic a axis preferentially oriented parallel to the withdrawal direction. Odd-numbered multilayer stacks are composed of a first hexagonal monolayer followed by orthorhombic bilayers.