L. Calucci et al., A H-2 NMR-STUDY OF ORIENTATIONAL ORDER AND SPIN RELAXATION IN THE MESOGEN P-HEXYLOXYBENZYLIDENE-P'-FLUOROANILINE, Molecular crystals and liquid crystals science and technology. Section A, Molecular crystals and liquid crystals, 303, 1997, pp. 415-429
H-2 NMR measurements of orientational order and spectral densities in
the nematic, smectic A and smectic B phases of p-hexyloxybenzylidene-p
'-fluoroaniline (FAB-OC6) deuterated in the benzylidene methine group
and in the aniline ring are reported. The orientational order paramete
rs obtained indicate a high order of the aromatic core in the smectic
phases. The Wimperis pulse sequence was used to measure the Zeeman and
quadrupolar spin-lattice relaxation times at the frequency of 46.04 M
Hz. The spectral densities are discussed within rotational diffusion m
odels for the reorientational motions, taking also into account intern
al rotations and collective fluctuations.