Ž . Thin Solid Films 385 2001 246251 Raman polarization study of the film orientation of liquid crystalline NiPc T.V. Basova a,  , B.A. Kolesov a , A.G. Gurek b , V. Ahsen b,c ¨ a Institute of Inorganic Chemistry, La rentie  A enue 3, No osibirsk 630090, Russia b Tubitak-Marmara Research Center, Department of Chemistry, P.O. Box 21, Gebze-Kocaeli 41470, Turkey c Gebze Institute of Technology, Department of Chemistry, P.O. Box 141, Gebze-Kocaeli 41400, Turkey Received 5 June 2000; received in revised form 12 December 2000; accepted 12 December 2000 Abstract In this work, we determine, using Raman spectroscopy, the orientation of molecules relative to the substrate surface in films of Ž . Ž . octa 13,17-dioxanonacosane-15-sulfanyl -substituted nickel II phthalocyanine, showing a liquid crystalline phase at room temper- ature. 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  and  angles, respectively. We study the dependence of film orientation on temperature in the range from 0 to Ž . 30°C. The  angle is decreased from 30 to 10° with increasing temperature, whereas, the  angle is held constant 65° . The phase transition from liquid crystalline to isotropic phase in the NiPc film is observed at approximately 10°C.  2001 Elsevier Science B.V. All rights reserved. Keywords: Raman spectra; Thin-films; Phthalocyanine; Liquid crystal 1. Introduction Phthalocyanines films have been widely used as pho- toconductors, gas sensors and molecular electronic de- vices. The structure of phthalocyanine films must be characterised in order to study the relevant mechanism of photoconductivity and to realize its potential appli- cation. Recently, a number of reports have appeared on fabrication and structure characterisation of Lang- muir  Blodgett phthalocyanine films. Usually for char- acterisation of phthalocyanine films with long alkyl substituents the methods of polarized UV-visible and     i.r. absorption 1  4 , ESR spectroscopy 2,4 and low  angle X-ray diffraction 5 are used. Recently, we have suggested the general approach to the analysis of the orientation of thin molecular films  Corresponding author. Tel.: 7-3832-343957; fax: 7-3832- 344489. Ž . E-mail address: basova@che.nsk.su T.V. Basova . based on the polarization Raman studies of internal molecule vibrations, using the films of - and -copper phthalocyanines as an example. It has been shown that the orientation of thin organic films may be determined  using the analysis of external crystal modes 6 as well   as internal molecular vibrations 7,8 . The application of the proposed technique to determine film orienta- tion is not limited to the analysis of non-substituted phthalocyanines. This approach can be used success- fully to analyse various molecular films irrespective of the substrate used. It may be especially important in determining the orientation of polymers in Langmuir  Blodgett and liquid crystalline films, which are extensively studied today. In this work, we demonstrate the application of the given approach to the analysis of the orientation of molecules relative to the substrate surface in the films Ž . of octa 13,17-dioxanonacosane-15-sulfanyl -substituted Ž . Ž . nickel II phthalocyanine ods-NiPc Fig. 1 showing a liquid crystalline phase at room temperature. We study 0040-609001$ - see front matter  2001 Elsevier Science B.V. All rights reserved. Ž . PII: S 0 0 4 0 - 6 0 9 0 01 00779-9