TEMPERATURE-DEPENDENCE OF ORIENTATIONAL ORDERING IN THE SMECTIC-H AND SMECTIC-VI PHASES OF TBBA

The temperature dependence of the bipolar orientational order parameter 〈cos 2φ〉 at the 14N sites has been determined for the smectic H and smectic VI phases of TBBA via a measurement of the 14N-proton double resonance spectra. In the smectic H phase 〈cos 2φ〉 increases from 0.08 to 0.15 on cooling, whereas in the smectic VI phase 〈cos 2φ〉 varies between 0.85 at the high temperature end and 1 at the low temperature end of this phase. The results are interpreted in terms of a six-well potential for the jump motion of the TBBA molecules around the long molecular axis. © 1979 American Institute of Physics.