THE MACROSCOPIC BEHAVIOR OF NEMATICS WITH HYDROGEN-BONDED MOLECULES -EXPLANATION THROUGH FAR-IR SPECTROSCOPY

The equilibrium constant for the equilibrium 2(monomer) <----> dimer i s calculated and as a result the energy per linear hydrogen bond is es timated. The hydrogen bond force constants (in the harmonic approximat ion) dependence on the deformation vibration frequencies is found. The activation energy for the dimer and monomer reorientation is calculat ed and compared with that per hydrogen bond. The critical character of the temperature T- (defined as the temperature dividing the nematics with hydrogen-bonded molecules into high-temperature (classical) and low-temperature (smectic-like) subphases) is demonstrated. The anisotr opy of the critical index of the correlation length temperature depend ence is found. The correlation lengths parallel and perpendicular to t he nematic director (xi(parallel to) and xi(perpendicular to)) are cal culated. A theoretical conclusion concerning T- shifting at a set of bulk elastic deformations is confirmed. A value (1.036) for the critic al index mu(1), of NOBA is found. This value coincides with that chara cterizing the susceptibility temperature dependence of He-4 and is int eresting since the corresponding critical index cannot be measured in the superfluid.