Orientational ordering in polymorphic terepthal-bis-4-butylaniline (TBBA)

Individual molecular tilt angle behavior in the smectic C region is represented upon application of a molecular statistical model to the polymorphic terepthal-bis-butylaniline (TBBA) in conjunction with the experimental layer spacings from SAXS measurements using the synchrotron X-ray beam. In the smectic A and smectic H phases of the mesogen, the order parameter fluctuations and pre-transitional effects responsible for sharp changes in the layer spacing and scattered intensities near the phase transition temperature are corroborated with varying positron annihilation lineshapes as a result of electron density fluctuations. © 2002 Published by Elsevier Science Ltd.