Abstract
Carbon-13 NMR spectra have been obtained for -methoxy benzylidene -butylaniline (MBBA) in the isotropic, nematic, and solid phases. Sharp, resolved spectra were obtained in the nematic phase with high-power proton-spin decoupling. The isotropic-nematic transition is accompanied by a discontinuous change in absorption frequencies due to the molecular ordering and anisotropic chemical shielding. It is concluded that the benzene rings reorient rapidly about the para axes. Employing average values from studies of chemical shielding tensors in model aromatic solids, absolute values of the order parameter are estimated and normalized values are compared with previous results. The nematic-solid transition is accompanied by sudden and severe line broadening due to anisotropic chemical shielding.
- Received 3 April 1974
DOI:https://doi.org/10.1103/PhysRevA.10.946
©1974 American Physical Society