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'NMR' in keywords Facet   Publication Year 1996  [X]
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1996[X]
1Author    Ho Sung, ChohRequires cookie*
 Title    Magnetic Resonances of 5l V, 209 Bi, Mn 2 + , and Fe 3 + in BiV0 4 Single Crystals  
 Abstract    Nuclear magnetic resonance (NMR) of 51 V and 209 Bi, and electron paramagnetic resonance (EPR) of Mn 2 and Fe 3+ impurities in ferroelastic BiV0 4 single crystals are reviewed. The nuclear quadrupole parameters and principal axes of the two host nuclei, 51 V and 209 Bi, and the second-or-der zero field splitting tensor of the isoelectronic 3d 5 ions, Mn 2 + and Fe 3 + , in Bi V0 4 are determined for the first time. Temperature dependence studies on 51 V NMR and Mn 2+ EPR confirmed that this crystal undergoes a second order phase transition. The substitutional sites of Mn 2+ and Fe 3 + in BiV0 4 are Bi 3 and V 5 + , respectively. 
  Reference    Z. Naturforsch. 51a, 591—602 (1996); received February 3 1996 
  Published    1996 
  Keywords    NMR, EPR, Quadrupole parameters Zero field splittings, Substitutional sites 
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 TEI-XML for    default:Reihe_A/51/ZNA-1996-51a-0591.pdf 
 Identifier    ZNA-1996-51a-0591 
 Volume    51 
2Author    T. A. Babushkina, YuV. Goltyapin, S. I. GushchinRequires cookie*
 Title    I NQR Spectra of Iodobenzoic Acid and Iodophenol Derivatives. H-Bonds and C-I Characteristic Bonds of These Substances  
 Abstract    This is a review of investigations on iodo-benzoic acid, iodohippuric acid, and iodophenol derivatives by NQR, NMR, and emission Mössbauer spectroscopy. The influence of intermolecular, intramolecular, and bifurcated O-H- • I and O-H- • O bonds on the properties of iodine-carbon bonds is demonstrated. Ionized and non-ionized forms of tyrosine differ by the probability of H-bond formation. The simultaneous use of 127 1 NQR and emission Mössbauer 12 T spectroscopy open the possibility to determine the types of tellurium-organic substances formed in the process 
  Reference    Z. Naturforsch. 51a, 651—656 (1996); received October 20 1995 
  Published    1996 
  Keywords    NQR, NMR, iodobenzoic acid, iodohippuric acid, iodophenol 
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 TEI-XML for    default:Reihe_A/51/ZNA-1996-51a-0651.pdf 
 Identifier    ZNA-1996-51a-0651 
 Volume    51 
3Author    Takahiro Ueda, Nobuo NakamuraRequires cookie*
 Title    Sb NMR and SCF-MS-Xa Studies of Quadrupole Interaction and The Electronic Structure of Mixed-Valence Compound, Cs 2 SbCl 6  
 Abstract    Cs 2 SbCl 6 is known as a typical mixed-valence compound. It crystallizes into a tetragonal space group I4 1 /amd and contains two different complex anions, Sb(III)Cl| _ and Sb(V)Clg . The dark blue color of this compound has been considered to originate from a charge transfer between the above two anions. In order to study the electronic structure of these complex anions and the existence of charge transfer between them we measured the 121 Sb NMR spectrum and carried out molecular orbital calculations on the electronic states of these anions. The 121 Sb NMR spectrum consists of two peaks at 0 and 30 kHz which can be assigned to the central transition of l21 Sb in Sb(V)Cl<~ and Sb(III)Cl| _ , respectively. The line shape analyses of the spectra led to nuclear quadrupole coupling constants of nearly zero for Sb(V)Cl7 and 4.9 ±0.5 MHz for Sb(III)Cl| at room temperature. The quadrupole coupling constant of 1 Sb(III) decreases steadily on heating. The calculations of the electronic ground state energies of both anions were calculated by the MS-Xa molecular orbital method. The calculated charge-transfer band from the A lg state of Sb(III)Clg" to the A lg state of Sb(V)Cl6 appears at 610 nm and can account for the experimental electronic spectrum, the calculated quadrupole coupling constant in Sb(III)Clg" however is far larger than the experimental one. The contribution of the charge-transferred state to the ground state is negligible and so the temperature dependence of the quadrupole coupling constant of 121 Sb(III) is attributed to an anisotropic thermal expansion of the compound. 
  Reference    Z. Naturforsch. 51a, 672—676 (1996); received October 10 1995 
  Published    1996 
  Keywords    NMR, Quadrupole interaction, Molecular orbital, Mixed valence 
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 TEI-XML for    default:Reihe_A/51/ZNA-1996-51a-0672.pdf 
 Identifier    ZNA-1996-51a-0672 
 Volume    51 
4Author    K. Ishida, H. Mukuda, Y. Kitaoka, K. Asayama, Y. OnukiRequires cookie*
 Title    Ru NMR and NQR Studies in CeRu 2  
 Abstract    We have carried out Ru NMR and NQR measurements in superconductor CeRu 2 having T c = 6.1 K in the temperature range of 1.3-30 K. From the 9y Ru NMR in 10.2 T above H c2 , T{T-const was found in the measured-T range, and the value of T,TK 2 is almost the same as that in the uncorrelated Korringa relation, suggesting that there does not exist the strong spin fluctuation of Ru d-spins. The property of the superconducting state was investigated by using Ru NQR. We observed the Hebel-Slichter peak just below T c and the exponential decrease in 1 /T,, indicating that this superconductivity has an ordinary s-wave character. The effect of Al substitution for Ru was also studied by NMR and NQR. 
  Reference    Z. Naturforsch. 51a, 793—796 (1996); received February 1 1996 
  Published    1996 
  Keywords    Superconductor CeRu 2, NMR, NQR, T, Knight shift 
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 TEI-XML for    default:Reihe_A/51/ZNA-1996-51a-0793.pdf 
 Identifier    ZNA-1996-51a-0793 
 Volume    51 
5Author    M. Grottel, A. Kozak, Z. PająkRequires cookie*
 Title    *H and 19 F NMR Study of Cation and Anion Motions in Guanidinium Hexafluorozirconate  
 Abstract    Proton and fluorine NMR second moments and spin-lattice relaxation times of polycrystalline guanidinium hexafluorozirconate and its deuterated analogue were studied in laboratory (60 MHz) and rotating (H, = 20 G) frames over a wide range of temperature. An analysis of the experimental results enabled us to reveal a dynamical inequivalence of two crystallographically independent cations and an unexpected high mobility of nonspherical anion dimers. A comparison of the ions dynamics in 2:1 complex studied with the guanidinium 1:1 and 3:1 complexes has shown a significant contribution of the hydrogen bonds to the potential barriers hindering the anion reorien-tations. At low temperatures a proton motion in the hydrogen bond and at 400 K a solid-solid phase transition have been discerned. 
  Reference    Z. Naturforsch. 51a, 991—996 (1996); received May 14 1996 
  Published    1996 
  Keywords    NMR, Ion Motions, Hydrogen Bonds, Phase Transitions 
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 TEI-XML for    default:Reihe_A/51/ZNA-1996-51a-0991.pdf 
 Identifier    ZNA-1996-51a-0991 
 Volume    51 
6Author    Zoran Marković, Stanimir Konstantinović, Ivan GutmanRequires cookie*
 Title    The Dependence of Vicinal Proton-Proton Coupling Constants of Norbomenes on Molecular Structure  
 Abstract    A modification of the Karplus equation, containing four mutually independent structural terms and five adjustable parameters, is put forward. The new structural factor, intro-duced into this modification is sin {6 1 -I-6 2)/2. The new equa-tion reproduces experimental NMR vicinal coupling con-stants of norbornenes with a standard deviation of about 0.45 Hz. 
  Reference    Z. Naturforsch. 51a, 1042—1044 (1996); received April 27 1996 
  Published    1996 
  Keywords    Norbornenes, Coupling Constants, Molecular Mechanics, Karplus Equation, NMR 
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 TEI-XML for    default:Reihe_A/51/ZNA-1996-51a-1042_n.pdf 
 Identifier    ZNA-1996-51a-1042_n 
 Volume    51 
7Author    C. Cruz, J. L. Figueirinhas, P. J. Sebastião, A. C. Ribeiro, F. Noack, H. T. Nguyen, B. Heinrich, D. Guillon, I.P C MRequires cookie*
 Title    Molecular Dynamics in the Columnar and Lamellar Mesophases of a Liquid Crystal of Biforked Molecules  
 Abstract    In this work we present the first study of molecular dynamics in the S c and 4> h mesophases of a liquid crystal of biforked molecules. This study was performed by means of proton NMR relaxation measurements obtained at different temperatures in the studied phases, combining standard and fast field-cycling techniques in order to cover a large domain of Larmor frequencies (100 Hz-300 MHz). The experimental results were analysed considering the potential contributions of different relax-ation mechanisms, namely local molecular rotational reorientations, self-diffusion and collective movements. The description of the contributions of the rotational reorientations and self-diffusion mechanisms are not quite different in the two studied phases. The main distinction in the molecular dynamics is found in the low Larmor frequency range dominated by the collective movements. While in the S c phase this contribution can be described by the law characteristic of smectic layer undulations, the contribution of the collective movements in the </> h phase can be assigned to elastic deformation of the columns. 
  Reference    Z. Naturforsch. 51a, 155—166 (1996); received November 29 1995 
  Published    1996 
  Keywords    NMR, Proton Relaxation, Molecular Dynamics, Biforked Molecules, </> h Mesophase 
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 TEI-XML for    default:Reihe_A/51/ZNA-1996-51a-0155.pdf 
 Identifier    ZNA-1996-51a-0155 
 Volume    51 
8Author    T. Myojin, T. Ohno, K. Mizuno, A. Tsujimura, K. KojimaRequires cookie*
 Title    Spin Reorientation Phenomena in (Rj^R^Co^B Compounds  
 Abstract    The variation of NMR spectra and magnetization with temperature in (Rj _ x R^) 2 Co 14 B (R = Y or Gd. R' = Tb. Dy or Ho 0 < .v < 1) have been measured. These compounds undergo spin reori-entation at a temperature T SR when Y and Gd are substituted by Tb, Dy and Ho, and the temperature T SR increases with the fraction x. Phase diagrams of spin arrangement in these systems have been obtained. The results are discussed from the view point of competition between the crystalline electric field and the Co-R exchange interaction. 
  Reference    Z. Naturforsch. 51a, 726—730 (1996); received November 20 1995 
  Published    1996 
  Keywords    R 2 Co 14 B, Spin reorientation, Magnetic anisotropy, NMR, Magnetization 
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 TEI-XML for    default:Reihe_A/51/ZNA-1996-51a-0726.pdf 
 Identifier    ZNA-1996-51a-0726 
 Volume    51 
9Author    D. BrinkmannRequires cookie*
 Title    Inter-plane Coupling and Spin Gap -an NMR/NQR Look on Typical Properties of High-Temperature Superconductors  
 Abstract    The paper discusses some NQR/NMR studies performed on Y-Ba-Cu-O superconductors at the University of Zürich. In particular, we review studies performed in Y 2 Ba 4 Cu 7 0 15 by measuring various planar Cu NQR/NMR parameters: the spin-lattice relaxation time, the Knight shift and the indirect component of the Gaussian contribution to the spin-spin relaxation time. The temperature dependence of these parameters reveals a coupling between adjacent planes of a double plane. The existence of the inter-plane coupling has independently been confirmed by performing NQR Spin-Echo Double Resonance (SEDOR) experiments. The appearance of a spin gap seems to be the consequence of inter-plane coupling. 
  Reference    Z. Naturforsch. 51a, 786—792 (1996); received November 20 1995 
  Published    1996 
  Keywords    NQR, NMR, High-Temperature Superconductors, Inter-plane Coupling, Spin gap 
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 TEI-XML for    default:Reihe_A/51/ZNA-1996-51a-0786.pdf 
 Identifier    ZNA-1996-51a-0786 
 Volume    51