Separated local field spectroscopy of columnar and nematic liquid crystals.
نویسندگان
چکیده
We are in this work comparing the efficiencies of various 1H-13C separated local field (SLF) experiments when applied to columnar and nematic liquid crystals. In particular, the performances of the conventional SLF, proton-detected local field (PDLF), and polarization inversion spin exchange at the magic angle (PISEMA) methods in terms of spectral resolution, robustness, and ability to measure long-range couplings are investigated. The PDLF sequence provides in most cases the best dipolar resolution. This is especially obvious for weakly coupled 1H-13C spin pairs.
منابع مشابه
A phase-field-crystal model for liquid crystals.
On the basis of static and dynamical density functional theory, a phase-field-crystal model is derived which involves both the translational density and the orientational degree of ordering as well as a local director field. The model exhibits stable isotropic, nematic, smectic A, columnar, plastic-crystalline and orientationally ordered crystalline phases. As far as the dynamics is concerned, ...
متن کاملInvestigation into the temperature dependence of isotropic- nematic phase transition of Gay- Berne liquid crystals
Density functional approach was used to study the isotropic- nematic (I-N) transition and calculate the values of freezing parameters of the Gay- Berne liquid crystal model. New direct and pair correlation functions of a molecular fluid with Gay- Berne pair potential were used. These new functions were used in density functional theory as input to calculate the isotropic- nematic transition den...
متن کاملStability of liquid crystalline phases in the phase-field-crystal model.
The phase-field-crystal model for liquid crystals is solved numerically in two spatial dimensions. This model is formulated with three position-dependent order parameters, namely the reduced translational density, the local nematic order parameter, and the mean local direction of the orientations. The equilibrium free-energy functional involves local powers of the order parameters up to fourth ...
متن کاملReentrant nematic and columnar phases in disc-like liquid crystals at atmospheric pressure
2014 We describe the first example of reentrant ND nematic and Dr columnar mesophases at atmospheric pressure in a pure disc-like compound. J. Physique LETTRES 42 (1981 ) L-417 L-419 15 SEPTEMBRE 1981, Classification Physics Abstracts 61.30 64.70E
متن کاملتغییرات ساختاری بلورمایع نماتیک آمیخته به نانوکلوئیدهای مغناطیسی
The stable colloidal dispersions of magnetic nano-particles in nematic liquid crystals are called ferronematics. Their behaviour in magnetic fields depends on various parameters such as anchoring energy, magnetic anisotropy, and shape and volume fraction of the particles. In the present paper, the threshold field is obtained for these colloidal nematics. Then, the influence of magnetic anisotr...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
- Journal of magnetic resonance
دوره 163 1 شماره
صفحات -
تاریخ انتشار 2003