Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1673529 | Thin Solid Films | 2008 | 13 Pages |
Abstract
Various deuterium one- and two-dimensional (2D) NMR techniques are used in the present study to characterize molecular self-diffusive processes in some novel mesophases. Both aligned and powder samples of liquid crystals (LC) are chosen to investigate rotational and/or translational jump diffusions. It is demonstrated that rotation of aligned LC samples in a NMR goniometer probe can be helpful in obtaining dynamic and structural information. Both spectral simulations and/or pulse separation (Ï) dependences of the quadrupole echo intensity are successfully employed. Deuteron spin-lattice relaxation times and angle dependent spectra are measured in a columnar phase of a monomeric discotogen to illustrate both the fast and intermediate motion regimes. Jump diffusions of chiral rodlike molecules in various smectic Câ (SmCâ) phases and twist grain boundary Aâ (TGBAâ) phase are studied. In the LC 10B1M7, the jump rate (or diffusion constant) is determined as a function of temperature in the ferro-, ferri- and antiferro-electric chiral Câ phases. 2D deuterium exchange NMR is used to monitor the dynamic processes (self-diffusion) in the ferroelectric SmCâ and TGBAâ phases. Moreover, packing information of the phase can also be obtained in the two ferrielectric subphases and TGBAâ phase, which can be compared with results obtained by X-rays measurements.
Related Topics
Physical Sciences and Engineering
Materials Science
Nanotechnology
Authors
Ronald Y. Dong,