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'Molecular motion' in keywords Facet   Publication Year 1998  [X]
Facet   section ZfN Section A  [X]
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1998[X]
1Author    Maria Zdanowska-Fnjczek, Malgorzata Grottel, Ryszard JakubasRequires cookie*
 Title    C1 NQR and l H NMR Studies of Molecular Motions in Guanidinium Salt of Chloroacetic Acid  
 Abstract    Multinuclear NQR and NMR techniques have been applied in order to study the molecular dynamics in [C(NH 2) 3 ](ClH 2 CCOO). The 35 C1 NQR frequency was measured over a wide range of temperature. The experimental results were described by using the theories of Bayer and Brown which take into account the torsional oscillations of the CClH 2 -group of the anion. A study of the proton NMR second moment as well as relaxation times T, and T Xp performed in a wide temperature range revealed an onset of the guanidinium cation reorientation around its two-fold symmetry axis. Activation parameters for this motion were determined. 
  Reference    Z. Naturforsch. 53a, 484—487 (1998); received March 24 1998 
  Published    1998 
  Keywords    NMR, NQR, Molecular Motion 
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 TEI-XML for    default:Reihe_A/53/ZNA-1998-53a-0484.pdf 
 Identifier    ZNA-1998-53a-0484 
 Volume    53 
2Author    Masao Hashimoto, Yuko Monobe, Hiromitsu Terao, Haruo Niki, Koichi ManoRequires cookie*
 Title    Phase Transition and Crystal Dynamics of 4-Bromobenzyl Alcohol  
 Abstract    For the title compound a phase transition from Phase II to Phase I (low and room temperature phases, respectively) was found at ca. 217 K. The temperature dependence of the 8 'Br NQR frequency and that of the dielectric constant showed anomalies at ca. 195 K that were tentatively attributed to a higher order phase transition. A similar anomaly was found at ca. 218 K for 4-chlorobenzyl alcohol which showed a II-I transition at 236 K. The dielectric dispersion observed for both compounds at low temperatures indicates an excitation of a molecular motion with the dielectric relaxation rate of ca. 1 kHz. The temperature dependence of the sl Br NQR frequencies of 2-and 3-bromobenzyl alcohol, measured at T > 77 K, gave no evidence of phase transition in their crystals. 
  Reference    Z. Naturforsch. 53a, 436—441 (1998); received March 24 1998 
  Published    1998 
  Keywords    NQR, Phase Transition, Molecular Motion, Dielectric Dispersion 
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 TEI-XML for    default:Reihe_A/53/ZNA-1998-53a-0436.pdf 
 Identifier    ZNA-1998-53a-0436 
 Volume    53 
3Author    Hiroyuki IshidaRequires cookie*
 Title    H and 19 F NMR Studies on Molecular Motions in Two Solid Phases of t-Butylammonium Tetrafluoroborate  
 Abstract    Differential thermal analysis (DTA), differential scanning calorimetry (DSC), and the temperature dependence of the spin-lattice relaxation time (T {) and the second moment (M 2) of 1 H and F NMR were studied in (CH3) 3 CNH 3 BF4 and (CH 3) 3 CND 3 BF 4 . DTA and DSC revealed a solid-solid phase transition at 219 K for (CH 3) 3 CNH3BF4 and at 221 K for (CH 3) 3 CND 3 BF 4 . The motions of cations and anions in the two solid phases were studied by T x and M 2 experiments. The motional modes of the ions and their motional parameters were determined. 
  Reference    Z. Naturforsch. 53a, 796—800 (1998); received May 30 1998 
  Published    1998 
  Keywords    Molecular motion, Phase transition, Nuclear magnetic resonance 
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 TEI-XML for    default:Reihe_A/53/ZNA-1998-53a-0796.pdf 
 Identifier    ZNA-1998-53a-0796 
 Volume    53 
4Author    Naohiro Yoshida, Noriko Onoda-Yamamuro, Shin'. Ichi Ishimaru, Keizo Horiuchi, Ryuichi IkedaRequires cookie*
 Title    Temperature Dependence of 2 H Quadrupole Coupling Constants in 2 H 2 0 and Ionic Motions in Crystalline IM( 2 H 2 0) 6 ] ISnCl 6 ] (M: Mg, Ca), Studied by 2 H NMR and Neutron Powder Diffraction  
 Abstract    The temperature dependence of 2 H NMR spectra was measured at 130-430 K on [M(D 2 0) 6 ] [SnCl 6 ] (M : Mg, Ca) (rhombohedral, space group: R3), and neutron powder diffraction on the Mg salt was performed at room temperature. Based on the accurate orientation of D 2 0 molecules in an octahedral cation, spectra with a large asymmetry parameter rj, observed around 200 K, were explained by a model of 180° flip of water molecules. Another motional narrowing observed above room temperature was assigned to a cationic overall reorientation about the C 3 -axis. 
  Reference    Z. Naturforsch. 53a, 473—479 (1998); received October 31 1997 
  Published    1998 
  Keywords    2 H NMR, Neutron Diffraction, Molecular Motion, Quadrupole Coupling Constant, Spectrum Lineshape 
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 TEI-XML for    default:Reihe_A/53/ZNA-1998-53a-0473.pdf 
 Identifier    ZNA-1998-53a-0473 
 Volume    53