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'Quadrupole interaction' in keywords Facet   Publication Year 2000  [X]
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2000[X]
1Author    H. Nishihara, N. Kijima, S. NagataRequires cookie*
 Title    NMR of 93 Nb perturbed by Quadrupole Interaction in Quasi-One-Dimensional BaNbS 3+d  
 Abstract    Field-swept NMR spectra of y3 Nb are examined for a sample of BaNbS 2 . 96 which has a semicon-ductive temperature dependence of the resistivity at low temperature, and a sample of BaNbS 3 0 3 which has a metallic temperature dependence at low temperature. Both spectra are so-called NMR powder patterns perturbed by a quadrupole interaction with a quadrupole frequency u Q = 3e 7 qQ/2I(2I — l)/i of 2.5 [MHz]. No appreciable difference in the spectra has been observed between the two samples, suggesting that the amplitude of the conduction electron density is too small to perturb the electronic environments around the niobium atoms. The general behavior of the nuclear spin-lattice relaxation of 93 Nb in both compounds is consistent with an interpretation that the relaxation at low temperature is dominated by a Korringa mechanism and at higher temperature by a quadrupole interaction. 
  Reference    Z. Naturforsch. 55a, 359—361 (2000); received August 23 1999 
  Published    2000 
  Keywords    NMR, 93 Nb, BaNbS 3, Quadrupole Interaction 
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 TEI-XML for    default:Reihe_A/55/ZNA-2000-55a-0359.pdf 
 Identifier    ZNA-2000-55a-0359 
 Volume    55 
2Author    A. C. Junqueira, A. W. Carbonari, J.Mestnik Filho, R. N. SaxenaRequires cookie*
 Title    Electric Field Gradient at Nb Site in the Intermetallic Compounds Nb 3 X (X = AI, In, Si, Ge, Sn) Measured by PAC  
 Abstract    The electric field gradient (efg) at the Nb site in the intermetallic compounds Nb 3 X (X = Al, In, Si, Ge, Sn) was measured by the Perturbed Angular Correlation (PAC) method using the well-known gamma-gamma cascade of 133 -482 keV in lxl Ta from the ß~ decay of 1K1 Hf, substituting approximately 0.1 atom percent of Nb. The PAC results show that V zz drops by nearly 40% when X changes from Al to In, and by about 25% when X changes from Si to Ge and Sn. This behavior is most probably related to the change in the degree of sp hybridization in these compounds. The V zz values of the studied compounds do not follow the well known universal correlation for the efg's in non-cubic metals but the observed trend is well reproduced by results of ab-initio electronic structure calculations. In the case of Nb 3 Al a linear temperature dependence of the quadrupole frequencies was observed in the temperature range of 6.5 to 1210 K. 
  Reference    Z. Naturforsch. 55a, 41—14 (2000); received August 25 1999 
  Published    2000 
  Keywords    Electric Field Gradient, PAC Measurements, Nb-based Alloys, Quadrupole Interactions 
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 TEI-XML for    default:Reihe_A/55/ZNA-2000-55a-0041.pdf 
 Identifier    ZNA-2000-55a-0041 
 Volume    55 
3Author    K. Królas, M. Rams, J. WojtkowskaRequires cookie*
 Title    Quadrupole Interaction of 172 Yb and 168 Er Nuclei in the First Excited 2 + State  
 Abstract    We have measured the hyperfine interactions in YbVC>4 and YbPC>4 using 172 Yb perturbed angular correlation spectroscopy for 90 -1094 keV and 1094 -79 keV 7-7 cascades. The quadrupole interaction frequency varied with temperature from 0 to 2 GHz. Precise information was obtained from both cascades independently even using the cascade with the intermediate state of the half life as short as 1.6 ns. 
  Reference    Z. Naturforsch. 55a, 45—18 (2000); received September 11 1999 
  Published    2000 
  Keywords    Quadrupole Interaction, Perturbed Angular Correlations, 172 Yb, 16X Er, YbVCV 
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 TEI-XML for    default:Reihe_A/55/ZNA-2000-55a-0045.pdf 
 Identifier    ZNA-2000-55a-0045 
 Volume    55 
4Author    M. Dietrich, A. Burchard, D. Degering, M. Deicher, J. Kortus, R. Magerle, A. Möller, V. Samokhvalov, S. Unterricker, R. ViandenRequires cookie*
 Title    Quadrupole Interaction in Ternary Chalcopyrite Semiconductors: Experiments and Theory  
 Abstract    Electric field gradients have been measured at substitutional lattice sites in ternary semiconduc-tors using Perturbed 7-7 Angular Correlation spectroscopy (PAC). The experimental results for A I B III C 2 chalcopyrite structure compounds and • A 1I B2 C4 1 defect chalcopyrites are compared with ab-initio calculations. The latter were carried out with the WIEN code that uses the Full Poten-tial Linearized Augmented Plane Wave method within a density functional theory. The agreement between experiment and theory is in most cases very good. Furthermore, the anion displacements in AgGaX 2 -compounds (X: S, Se, Te) have been determined theoretically by determining the minimum of the total energy of the electrons in an elementary cell. 
  Reference    Z. Naturforsch. 55a, 256—260 (2000); received September 11 1999 
  Published    2000 
  Keywords    Quadrupole Interaction, Chalcopyrite Semiconductors, First Principles Calculations, Perturbed Angular Correlations, Structure Parameters 
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 TEI-XML for    default:Reihe_A/55/ZNA-2000-55a-0256.pdf 
 Identifier    ZNA-2000-55a-0256 
 Volume    55 
5Author    Takahiro Ueda, Nobuo NakamuraRequires cookie*
 Title    Nature of Hydration Water in (±)-Tris(ethylenediamine)cobalt(III) Chloride Hydrate, (±)-[Co(en) 3 ]Cl 3 -/iH 2 0, as Studied by *H, 2 H, and 17 O Solid State NMR  
 Abstract    The static and dynamics properties of hydration water molecules in (±)-[Co(en) 3 ]Cl 3 were studied by means of 'H, 2 H, and ,7 0 solid state NMR. By 'H pulsed field gradient (PFG) NMR the apparent diffusion coefficient of mobile water through a micropore along the crystalline unique c-axis was found to be 1.0 x 10~ 9 m 2 s -1 . The 2 H NMR spectrum at 141 K consists of two components, one being a Pake doublet corresponding to a quadrupole coupling constant (QCC) of (226 ± 2) kHz and an asymmetry parameter of the electric field gradient 77 of 0.08 ± 0.01, and another being a Gaussian line with a linewidth of 3.5 kHz. The 17 0 NMR spectrum at 300 K also consists of a narrow Gaussian peak and a broad powder pattern with a second order quadrupole effect corresponding to QCC = (6.3 ± 0.5) MHz and 77 = 0.55±0.02. The broad and narrow components are assigned to water molecules accommodated at general 12g positions and special 2a and 2b positions in the trigonal lattice with space group Plcl. From the ratio of the populations at these positions their potential energy difference was estimated to be between (2.7 ±0.1) and (3.5 ± 0.1) kJmol -1 . The 2 H NMR spectrum at room temperature indicates a finite quadrupole interaction which is attributable to the rapid rotation of water molecule about the molecular C 2 -axis. When the water content exceeds 2.7, the QCC is reduced sharply to (5.0 ±0.1) kHz at 285 K, suggesting that there occurs rapid rotation of water and rapid exchange of 2 H between nonequivalent positions. 
  Reference    Z. Naturforsch. 55a, 362—368 (2000); received August 23 1999 
  Published    2000 
  Keywords    (±)-[Co(en) 3 ]Cl 3, Absorbed Water, Molecular Motion, Hydrogen Bond, Quadrupole Interaction 
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 TEI-XML for    default:Reihe_A/55/ZNA-2000-55a-0362.pdf 
 Identifier    ZNA-2000-55a-0362 
 Volume    55