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'NMR' 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    N. Velikite, N. Sinyavsky, M. MaćkowiakRequires cookie*
 Title    Lineshape Analysis of 2D NMR and NQR Nutation Spectra of Integer and Half-Integer Quadrupolar Nuclei  
 Abstract    A lineshape analysis of the NMR and NQR powder nutation spectra of integer and half-integer quadrupolar nuclei is presented. Simulated NMR nutation spectra of spin I = 1 and 3 nuclei are reported. For / = 1 the formulas for the singularities of the NMR nutation powder patterns as a functions of rj, e 2 Qq and 7B x are given. The NQR nutation powder patterns for spin / = 3/2, 5/2, 7/2, and 9/2 for different induced transitions are calculated, and some experimental aspects of the method are discussed. A universal empirical formula to facilitate the determination of the asymmetry parameter from the NQR nutation frequency singularities for any arbitrary spin or transition is found. The NQR nutation spectra for half-integer and integer spins are compared. For integer spins the two-frequency excitation of the nutation spectrum is analysed. Application of the 2D-nutation lineshape analysis for the determination of the quadrupole interaction parameters is emphasised. 
  Reference    Z. Naturforsch. 54a, 351—357 (1999); received April 9 1999 
  Published    1999 
  Keywords    2D Nutation Spectroscopy, NQR, NMR, Electric Field Gradient Tensor 
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 TEI-XML for    default:Reihe_A/54/ZNA-1999-54a-0351.pdf 
 Identifier    ZNA-1999-54a-0351 
 Volume    54 
3Author    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 
4Author    Shin'. Ichi Ishimaru, Ryuichi IkedaRequires cookie*
 Title    NMR Studies on Dynamics of Water Intercalated in Clay Minerals  
 Abstract    The dynamics of water molecules intercalated in D2O saturated synthetic and natural smectites, and a synthetic Na-fluormica were studied by measurements of solid state 2 H NMR spectra and spin-lattice relaxation times at 150 — 370 K. The obtained results could be explained by the 2-site flip, the C2 rotation and the isotropic rotation of the D2O molecules in smectites. In fluormica, the isotropic motion was undetectable, but the axial rotation of the hydration sphere as a whole was observed. The activation energies and correlation times of the C2 rotation were almost independent of the interlayer cations but depended on the character of clay-layers. 
  Reference    Z. Naturforsch. 54a, 431—36 (1999); received April 12 1999 
  Published    1999 
  Keywords    Clay Minerals, NMR, Intercalated Water, T\ 
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 TEI-XML for    default:Reihe_A/54/ZNA-1999-54a-0431.pdf 
 Identifier    ZNA-1999-54a-0431 
 Volume    54 
5Author    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 
6Author    Halil Oturak, Adnan Sağlam, Semiha BahçeliRequires cookie*
 Title    /-Modulation in ID NMR l H Spectrum of Taurine and Aspartate Using Spin-Echo Technique  
 Abstract    This study reports on a theoretical calculation of Hahn's spin-echo experiment in case of a model A 2 Bt spin system with a strongly coupling character and gives the experimental results of one-dimen-sion n H high-resolution NMR spectra of taurine and aspartate. The calculated amplitudes of the spin-echoes for two different proton groups of taurine are given. Using results of our calculations for tau-rine, the computer simulations of /-modulation are implemented. It is shown that the agreement be-tween the experimental and simulated spectra is good. 
  Reference    Z. Naturforsch. 54a, 305—310 (1999); received February 24 1999 
  Published    1999 
  Keywords    NMR, Amino Acids, A 2 B 2 System, /-modulation 
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 TEI-XML for    default:Reihe_A/54/ZNA-1999-54a-0305.pdf 
 Identifier    ZNA-1999-54a-0305 
 Volume    54