POLARISABILITY TENSOR OF CB 5 MOLECULE AND LIGHT WAVELENGTH PrzemysLaw Adamski Institute of Physics Technical University of Lodz, Wolcza ~ nska 219, 93-005 Lodz, Poland Alexej Bubnov Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, 182 21 Prague, Czech Republic The influence of the wavelength of light on the values of polarisability tensor components a k , a ? , polarisability anisotropy ða k a ? Þ and the order parameter S of liquid crystal molecules was verified. The refractive indices are functions of temperature and light wavelength. The values a k and a ? of a liquid crystal molecule can be calculated from refractive indices, density, and coefficient in the Valentova equation. Here, it was found that there is a relation between the wavelengths of the light and values of ða k a ? Þ and a k , a ? of CB 5 molecule. The values of the order parameter S obtained for CB 5 liquid crystal are identical for all wavelengths of light. Keywords: liquid crystals; order parameter; polarisability tensor; polarisability anisotropy of molecule; wavelength of light 1. INTRODUCTION Birefringence properties of liquid crystals are characterised by two polarisability tensors. The first is the polarisability tensor of a liquid crystal sample, described by the components a 1 and a 2 . These components can be calculated from the refractive indices by using the equations proposed re- cently [1–4], or by using Lorenz-Lorentz’, Vuks’ and Neugebauer’s equa- tions [5]. The second polarisability tensor, with components a k and a ? , is connected with the liquid crystal molecule. In 1961, Saupe and Maier used a k and a ? in their theory of orientational order of liquid crystal molecules This work was partly supported by Grant No. 202=00= P044 and No. 202=00=11=98= from the Grant Agency of the Czech Republic. Corresponding author. E-mail: bubnov@fzu.cz 145 Mol. Cryst. Liq. Cryst., Vol. 409, pp. 145–152, 2004 Copyright # Taylor & Francis Inc. ISSN: 1542-1406 print=1563-5287 online DOI: 10.1080=15421400490431075