Nuclear spin relaxation in a hexagonal lyotropic liquid crystal J. Chem. Phys. 95, 6945 (1991); 10.1063/1.461506Nuclear magnetic resonance determination of the CF2 order parameter tensor in a lyotropic liquid crystal
Constant gradient and pulsed gradient NMR spin echo methods have been used to measure the diffusion constant of potassium oleate in the lamellar phase. Oriented samples were employed and yielded a mean value of ?1×10−6 cm2/sec at 29 °C for the diffusion constant parallel to the lamellar surface.
Rotating frame nuclear magnetic relaxation times have been measured as a function of temperature from 117 to 290°K for perfluorocyclohexane, cyclohexane, 2,2-dichloropropane, neopentane, and tetramethylammonium iodide. The data are interpreted in terms of molecular rotation and diffusion in the solid state.
A magnet configuration has been devised, consisting of two nested coaxial coils with the current in the inner coil circulating in an opposite sense from that in the outer coil. The magnetic field generated by such an opposed pair exhibits a small region of homogeneity outside of the magnet itself, creating the possibility of constructing a unilateral nuclear-magnetic-resonance device capable of examining an object from only one side. Calculations on one special case, the inside-out Helmholtz configuration, indicate a volume of 10 cm3 with homogeneity of ±1% for a coil of outer radius 10 cm, and 0.1 cm3 with 100-ppm homogeneity. A second special case, consisting of two sets of opposed solenoids arranged in a quasi-Helmholtz manner, offers homogeneity comparable to a conventional Helmholtz pair of similar diameter but with an increase in separation of as much as a factor of 2.
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