Permittivity of liquid crystals of the alkylcyanobiphenyl group in a decimeter wavelength range

The high-frequency dielectric spectra of liquid crystals of the alkylcyanob iphenyl group with various length of the mobile alkyl chain CnH2n+1 (n = 5- 8) are experimentally studied. It is established that a resonance feature i s observed in the frequency range of 300 MHz for all the crystals on the hi gh-frequency branch of the orientational part of dielectric spectra. It is shown that the position of the dielectric resonance is virtually independen t of the temperature and the degree of crystal dilution by benzene, but its intensity essentially depends on both factors. The nature of the dielectri c resonance found is probably caused by the intramolecular motion of methyl ene fragments, which are strongly bound with a rigid core of molecules. (C) 2000 MAIK "Nauka/Interperiodica".