Positron annihilation studies of 4-n-butyl-4'-isothiocyanato-1,1'-biphenyl.

Positron annihilation lifetime spectroscopy (PALS) measurements were performed between 93 and 293 K in order to study the supercooled smectic-E (Sm-E) phase of 4-n-butyl-4'-isothiocyanato-1,1'-biphenyl (4TCB), the ordered molecular crystal of 4TCB, and the phase transition between the Sm-E phase and the ordered molecular crystal of 4TCB. The phase transition was well reflected in the abrupt increase of the ortho-positronium (o-Ps) lifetime and intensity. The value of the o-Ps lifetime in the Sm-E liquid crystalline phase of 4TCB, i.

Isothermal high-pressure studies of 4-cyano-3-fluorophenyl 4-butylbenzoate dynamics near room temperature.

For 4-cyano-3-fluorophenyl 4-butylbenzoate, a glass former giving glass of nematic phase at ambient pressure and after rapid pressurizing, isothermal studies of complex dielectric permittivity vs pressure were performed near room temperature. In the previous isobaric experiment, on cooling the nematic phase two super-Arrhenius α relaxations, ascribed to the reorientations of molecules around short axes (main process) and precession of long molecular axes, and β relaxation related to intramolecular motions were found. In the present isothermal experiments nematic-smectic phase transition was induced by increasing pressure.

Infrared spectroscopic and X-ray studies of the 4-propyl-4'-isothiocyanatobiphenyl (3TCB).

The results of mid-infrared spectroscopy and X-ray studies of the third member of the 4-n-alkyl-4'-isothiocyanatobiphenyl (nTCB) homologous series are presented. Correspondence between the phase transitions observed by means of the IR spectroscopy and those given by the adiabatic calorimetry was found. The structure of five solid phases was obtained by X-ray measurements.