Deuterium NMR study of molecular order and reorientation in the nematic phase of p-methoxy-d3-benzylidene-d1-p-n-butyl-d9-aniline
- 15 December 1978
- journal article
- research article
- Published by AIP Publishing in The Journal of Chemical Physics
- Vol. 69 (12), 5314-5318
- https://doi.org/10.1063/1.436558
Abstract
The deuterium quadrupole doublet splittings and spin–lattice relaxation times (T1) are measured as a function of temperature in the nematic phase of p‐methoxy‐d3‐benzylidene‐d1‐p‐n‐butyl‐d9‐aniline (MBBA‐d13). It is shown that a single order parameter tensor is sufficient to fully describe the orientational order of the molecule even though the molecule is nonrigid. The molecular conformational averages, which are different for various C–D bonds, result in resolved deuterium NMR spectra from which the T1 for each deuteron site can be measured. While the simplest approach in treating order director fluctuations, in which molecular reorientations and collective fluctuation modes are assumed to be uncoupled, fails to explain our T1 data for all deuterons, Freed’s treatment of spin relaxation in liquid crystals does give a qualitative explanation. Using this theory, molecular reorientation times for different deuteron sites are estimated.Keywords
This publication has 14 references indexed in Scilit:
- Molecular Order versus Conformation Changes in the Liquid-Crystal PhasesPhysical Review Letters, 1978
- High resolution carbon-13 spin–lattice relaxation study of the nematogen p-methoxybenzylidene–p-?-butylanilineThe Journal of Chemical Physics, 1978
- Stochastic-molecular theory of spin–relaxation for liquid crystalsThe Journal of Chemical Physics, 1977
- A proton and deuteron spin–lattice relaxation study of the partially deuterated nematogens PAA and MBBAThe Journal of Chemical Physics, 1977
- Molecular Orientational Order and NMR in the Uniaxial and Biaxial PhasesMolecular Crystals and Liquid Crystals, 1977
- Molecular rotation in liquid crystals selective deuterium spin-lattice relaxation times in the nematic mesophase of 4-cyano-4′-d17-n-octylbiphenylMolecular Physics, 1976
- Deuteron magnetic resonance comparison of mesogen molecules with octyl and octyloxy end-chainsJournal de Physique, 1976
- Chain ordering in the nematic mesophase of 4-cyano-4′-n-pentylbiphenylMolecular Physics, 1975
- Proton decoupling in deuteron magnetic resonance spectra of oriented moleculesJournal of Magnetic Resonance (1969), 1974
- Nuclear relaxation in a nematic liquid crystalSolid State Communications, 1969