INPLANE ORGANIZATION OF LB MONOLAYERS FROM FTIR SPECTROSCOPY

The in-plane organization of monolayers and multilayers of cadmium ara chidate deposited, by the conventional Langmuir-Blodgett technique, on to dielectric substrates has been studied by transmittance FTIR spectr oscopy. Examination of the bending CH2 band associated with the hydroc arbon chains suggests that the first monolayer has a hexagonal subcell packing whether the interaction with the supporting substrate is hydr ophilic or hydrophobic. Conversely, even-numbered multilayer stacks ar e arranged in bilayer structures, and their hydrocarbon chains present an orthorhombic packing with their crystallographic a axis preferenti ally oriented parallel to the withdrawal direction. Odd-numbered multi layer stacks are composed of a first hexagonal monolayer followed by o rthorhombic bilayers.