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'Relaxation' in keywords Facet   Publication Year 1999  [X]
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1999[X]
1Author    A. Pajzderska, J. Wąsicki, S. LewickiRequires cookie*
 Title    Molecular Motion in Tetraphenyltin Studied by NMR  
 Abstract    NMR second moment and spin-lattice relaxation times in the laboratory (60 and 25 MHz) and in the rotating frame (B { = 2.1 mT) were studied for polycrystalline tetraphenyltin Sn(C 6 H 5) 4 in a wide tem-perature range. Two kinds of motions were detected: isotropic rotation of whole molecules and reorien-tations/oscillations of phenyl rings. A dependence of the potential energy of the molecule in the crystal on the angle of the phenyl ring rotation about the Sn-C bond was obtained on the basis of atom-atom calculations. The amplitude of the ring-oscillations at 133 K was estimated as ± 7°. Below room tem-perature the magnetisation recovery is significantly non-exponential, which may be interpreted as due to the correlated motion of phenyl rings. 
  Reference    Z. Naturforsch. 54a, 488—494 (1999); received June 7 1999 
  Published    1999 
  Keywords    NMR, Relaxation, Potential Energy 
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 TEI-XML for    default:Reihe_A/54/ZNA-1999-54a-0488.pdf 
 Identifier    ZNA-1999-54a-0488 
 Volume    54 
2Author    Roman GocRequires cookie*
 Title    Monte Carlo Calculation of the Correlation Functions for Molecular Rotation -Application to NMR  
 Abstract    The Monte Carlo method for calculating correlation functions for the rotational motion of atoms is presented. This method applies to crystalline solids and allows the determination of the correlation functions for any model of rotating atoms, molecules or ions constituting the material of interest, if only its crystal structure is known. The presented method permits the calculation of the correlation functions for a whole block of unit cells, not only for a single group of particles. The described method can be employed to calculate correlation functions used in the theoretical description of NMR, dielectric or neutron diffraction experiments. As an example the correlation functions and NMR relaxation time T\ of solid benzene are calculated by the Monte Carlo method for the. 
  Reference    Z. Naturforsch. 54a, 358—364 (1999); received March 9 1999 
  Published    1999 
  Keywords    Correlation Function, Monte Carlo, NMR, Relaxation 
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 TEI-XML for    default:Reihe_A/54/ZNA-1999-54a-0358.pdf 
 Identifier    ZNA-1999-54a-0358 
 Volume    54 
3Author    R. Goc, J. Wąsicki, S. LewickiRequires cookie*
 Title    Ammonium Ions Dynamics in NH 4 Br -Proton NMR T 1 Measurements and Simulations  
 Abstract    Monte Carlo simulation of correlation functions for ammonium bromide have been carried out and the NMR relaxation times T { resulting from these functions were calculated. Results of simulations are compared to experimental values of T x measured in the temperature range 92 K to 292 K. 
  Reference    Z. Naturforsch. 54a, 689—694 (1999); received October 29 1999 
  Published    1999 
  Keywords    NMR, NH 4 Br, Relaxation, Monte Carlo, Simulation 
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 TEI-XML for    default:Reihe_A/54/ZNA-1999-54a-0689.pdf 
 Identifier    ZNA-1999-54a-0689 
 Volume    54