Orientation of Surface-Active Azodye in Langmuir-Blodgett Films as Determined by IR and UV-Visible Spectroscopies

Abstract

Infrared (IR) transmission and reflection-absorption spectra were measured for Langmuir-Blodgett (LB) films of surface-active azodye prepared at surface pressures of 5 and 30mNm^-1. The IR spectra showed that the molecules are preferentially arranged in the LB films with the molecular orientation dependent on the transfer pressure. The absorption peak of the trans isomer of the azodye in the ultraviolet-visible absorption spectra blue-shifted for the LB film prepared at 5mNm^-1 and red-shifted for that at 30mNm^-1. The formation of H and J aggregates of the azodye, respectively, would thus appear to occur. The orientation of the azodye molecules in the LB films is discussed.