STRUCTURAL CHARACTERIZATION OF PHTHALOCYANINE LANGMUIR-BLODGETT MULTILAYER ASSEMBLIES BY FT-IR SPECTROSCOPY

Structural characterization of tetrakis (dimethyldioctadecylammonium)nickel phthalocyanine tetrasulfonate (Pc4) Y-type Langmuir-Blodgett (LB) films with 1-, 2-, 3-, 4- and 10-monolayers has been made by Fourier-transform infrared (FT-IR) transmission, reflection-absorption (RA), and polarized transmission spectroscopy. The following conclusions can be obtained from the above measurements: (i) The hydrocarbon chains of Pc4 in the LB films are in a hexagonal or analogous (pseudohexagonal) subcell packing and take an uniaxial orientation with respect to the surface normal. (ii) The hydrocarbon chains are inclined to a considerable extent with respect to the surface normal while the Pc plane is oriented nearly perpendicular to the surface in the LB films. (iii) The structure and molecular orientation of the Y-type LB films with the first layer in the "head-on" configuration and those with the first layer in the "tail-on" configuration are very similar to each other.