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1997[X]
1Author    Roman GocRequires cookie*
 Title    Calculation of the NMR Second Moment for Solid Benzene with Rotation and Diffusion of Molecules -Numerical Approach  
 Abstract    Numerical calculations of the NMR second moment in case of rotation and diffusion of molecules were performed. As an example computer simulations of molecular reorientation and self-diffusion in solid benzene have been performed. For each model and rate of motion the Van Vleck's second moment of the proton NMR absorption spectrum was calculated, and these values were compared with experimental data. It is concluded that restricted self-diffusion must be implied in order to obtain better agreement between calculated and experimental NMR second moments. The temperature at which self-diffusion was detected through NMR line-width narrowing was found to be about 120 K, nearly 80 K less than the temperature at which the self-diffusion was detected by T lp relaxation measurements. 
  Reference    Z. Naturforsch. 52a, 477—184 (1997); received March 29 1997 
  Published    1997 
  Keywords    NMR, molecular rotation, self-diffusion, numerical approach 
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 TEI-XML for    default:Reihe_A/52/ZNA-1997-52a-0477.pdf 
 Identifier    ZNA-1997-52a-0477 
 Volume    52 
2Author    Hiroyuki Ishida, Masakazu Kato, Hiroshi Ono, Ryuichi IkedaRequires cookie*
 Title    Cationic Self-diffusion in Solid Choline Perchlorate Studied by NMR  
 Abstract    The 1 H spin-lattice and spin-spin relaxation times, and the second moment of the 1 H NMR linewidth of choline Perchlorate, [(Cff^NCfFCHiOHJClC^, were measured in its highest-temperature solid phase, i. e. above 275 K. X-ray powder patterns taken at ca. 380 K revealed that in this phase the crystal has a CsCl-type cubic structure (a = 6.326(4) A and Z = 1). From *H NMR experiments it was found that the cations in this phase undergo isotropic rotation and translational self-diffusion. From the 1 H T, measurements, the activation energies of the cationic rotation and self-diffusion were evaluated to be 21.4 ± 0.4 and 62 ± 3 kJ mol -1 , respectively. 
  Reference    Z. Naturforsch. 52a, 637—639 (1997); received May 28 1997 
  Published    1997 
  Keywords    Ionic plastic phase, Self-diffusion, Crystal structure, Nuclear magnetic resonance 
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 TEI-XML for    default:Reihe_A/52/ZNA-1997-52a-0637.pdf 
 Identifier    ZNA-1997-52a-0637 
 Volume    52