Raman polarization study of the film orientation of liquid crystalline NiPc

In this work, we determine, using Raman spectroscopy, the orientation of molecules relative to the substrate surface in films of octa(13,17-dioxanonacosane-15-sulfanyl)-substituted nickel(II) phthalocyanine, showing a liquid crystalline phase at room temperature. It was stated that the phthalocyanine molecules in the film are disordered relative to the z-axis and rotated around x and Y-axis on fixed alpha and beta angles, respectively. We study the dependence of film orientation on temperature in the range from 0 to 30 degreesC. The alpha angle is decreased from 30 to 10 degrees with increasing temperature, whereas, the beta angle is held constant (65 degrees). The phase transition from liquid crystalline to isotropic phase in the NiPc film is observed at approximately 10 degreesC. (C) 2001 Elsevier Science B.V. All rights reserved.