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1Author    W. Tröger, C. Lippert, P. Schmidt, U. Schmidt, T. Butz, R. Hoffmann, M. ZeppezauerRequires cookie*
 Title    Hg-Coordination Studies of Cysteine Containing Oligopeptides * and the ISOLDE Collaboration 0  
 Abstract    In order to study the interaction of cysteine containing peptide chains with Hg(II) the nuclear quadrupole interaction (NQI) of 199m Hg in the Hg complex of the oligopeptide Alanine-Alanine-Cysteine-Alanine-Alanine (AACAA) was determined by time differential perturbed angular correla-tion. Different 199m Hg-NQI's for free and resin-bound AACAA were obtained. Furthermore, the 199m Hg-NQI's are influenced by the Hg:AACAA stoichiometry. 
  Reference    Z. Naturforsch. 51a, 427—430 (1996); received October 20 1995 
  Published    1996 
  Keywords    TDPAC, Nuclear quadrupole interaction, Oligopeptides, Hg-Coordination 
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 TEI-XML for    default:Reihe_A/51/ZNA-1996-51a-0427.pdf 
 Identifier    ZNA-1996-51a-0427 
 Volume    51 
2Author    W. Tröger, C. Lippert, T. Butz, K. Sigfridsson, Ö. Hansson, E. Mclaughlin, R. Bauer, E. Danielsen, L. Hemmingsen, M. J. BjerrumRequires cookie*
 Title    Small Scale Intramolecular Flexibility in lllm Cd-Plastocyanin  
 Abstract    The effect of mutations in the vicinity of the putative electron transfer path on the metal center of the electron transfer protein plastocyanin (spinacea) is investigated by monitoring the nuclear quadrupole interaction of 1Um Cd in Cd-derivatives of the protein via time differential perturbed angular correlation. The spectra for the wild type protein and the mutants were rather similar. All spectra exhibit a peculiar line profile which points towards a small scale intramolecular flexibility of the metal center. 
  Reference    Z. Naturforsch. 51a, 431—436 (1996); received October 20 1995 
  Published    1996 
  Keywords    TDPAC, Nuclear quadrupole interaction, lllm Cd-Plastocyanin, flexibility 
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 TEI-XML for    default:Reihe_A/51/ZNA-1996-51a-0431.pdf 
 Identifier    ZNA-1996-51a-0431 
 Volume    51 
3Author    Nobuo Nakamura, Hirotsugo Masui, Takahiro UedaRequires cookie*
 Title    Effect of Intermolecular Hydrogen Bonding on the Nuclear Quadrupole Interaction in Imidazole and its Derivatives as Studied by ab initio Molecular Orbital Calculations  
 Abstract    Ab initio Hartree-Fock molecular orbital calculations were applied to the crystalline imidazole and its derivatives in order to examine systematically the effect of possible N-H---N type hydrogen bond-ing on the nuclear quadrupole interaction parameters in these materials. The nitrogen quadrupole coupling constant (QCC) and the asymmetry parameter (r?) of the electric field gradient (EFG) were found to depend strongly on the size of the molecular clusters, from single molecule, to dimer, trimer and to the infinite molecular chain, i.e., crystalline state, implying that the intermolecular N-H -N hydrogen bond affects significantly the electronic structure of imidazole molecule. A certain correla-tion between the QCC of l4 N and the N-H bond distance R was also found and interpreted on the basis of the molecular orbital theory. However, we found that the value of the calculated EFG at the hy-drogen position of the N-H group, or the corresponding QCC value of 2 H, increases drastically as /C* when R is shorter than about 0.1 nm, due probably to the inapplicability of the Gaussian basis sets to the very short chemical bond as revealed in the actual imidazole derivatives. We suggested that the ob-served N-H distances in imidazole derivatives should be re-examined. 
  Reference    Z. Naturforsch. 55a, 315—322 (2000); received August 26 1999 
  Published    2000 
  Keywords    Hydrogen Bond, Nuclear Quadrupole Interaction, Molecular Orbital, Imidazole 
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 TEI-XML for    default:Reihe_A/55/ZNA-2000-55a-0315.pdf 
 Identifier    ZNA-2000-55a-0315 
 Volume    55 
4Author    Karlheinz Schwarz, Peter BlahaRequires cookie*
 Title    Ab initio Calculations of the Electric Field Gradients in Solids in Relation to the Charge Distribution  
 Abstract    A first principles method for the computation of electric field gradients (EFGs) is illustrated for various solids. This scheme is based on self-consistent energy band-structure calculations by the full potential linearized augmented plan wave (FLAPW) method which provides the electronic charge density including all polarization effects. By numerically solving Poisson's equation we obtain the Coulomb potential in a form which allows to compute the EFG directly. Our method is demon-strated for insulators (Cu20), metals (hcp-Zn), supercondutors (YBa2Cu3Ö7) and molecular crystals (Cl2, Br2, I2). 
  Reference    Z. Naturforsch. 47a, 197—202 (1992); received August 3 1991 
  Published    1992 
  Keywords    Band-structure calculation, Electric field gradient, Nuclear quadrupole interaction, Molecular crystals, High-Tc superconductors 
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 TEI-XML for    default:Reihe_A/47/ZNA-1992-47a-0197.pdf 
 Identifier    ZNA-1992-47a-0197 
 Volume    47 
5Author    T. J. BastowRequires cookie*
 Title    Materials Characterisation by Nuclear Quadrupole Interaction  
 Abstract    The power of solid state N M R to characterise solids by determining the nuclear quadrupole coupling of the constituent nuclei is demonstrated for a number of com pounds o f current interest in a materials science laboratory. Recent results are presented for the nuclei 170 , 23Na, 27A1, 39K, 71Ga, 91Zr, 93Nb, and 139La. These were derived using a variety of FT N M R techniques including static, magic angle spinning and frequency stepped spin echo N M R spectroscopy. 
  Reference    Z. Naturforsch. 49a, 320 (1994); received August 31 1993 
  Published    1994 
  Keywords    Materials, Nuclear quadrupole interaction, M ultinuclear NM R, N Q R , Materials char­ acterisation 
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 TEI-XML for    default:Reihe_A/49/ZNA-1994-49a-0320.pdf 
 Identifier    ZNA-1994-49a-0320 
 Volume    49 
6Author    T. ButzRequires cookie*
 Title    Nuclear Quadrupole Interactions Studied by Time Differential Perturbed Angular Correlations of y-Rays  
 Abstract    This paper gives an elementary introduction to time differential perturbed angular correlation of y-rays emitted from excited nuclei with particular reference to nuclear quadrupole interactions. We start with a comparison to other techniques such as nuclear quadrupole resonance and the Mössbauer effect, quote all necessary formulae, describe a typical spectrometer, list suitable iso-topes, and finally give some examples for modern applications. 
  Reference    Z. Naturforsch. 51a, 396—410 (1996); received December 12 1995 
  Published    1996 
  Keywords    Nuclear quadrupole interactions, Time differential perturbed angular correlations (TDPAC), TDPAC: theory, spectrometers, isotopes, Mercury compounds, Tungsten compounds 
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 TEI-XML for    default:Reihe_A/51/ZNA-1996-51a-0396.pdf 
 Identifier    ZNA-1996-51a-0396 
 Volume    51 
7Author    H. M. Petrilli, M. Marszalek, H. SaitovitchRequires cookie*
 Title    Study of the EFG Trends in Zr 2 T (T = Fe, Co, Ni) Intermetallic Compounds  
 Abstract    We use the linear muffin-tin orbital formalism, in the atomic sphere approximation, to investigate the trends of the electric field gradient (EFG) at the nucleus for the non-equivalent sites in Zr 2 T (T = Fe, Co and Ni) intermetallic compounds. As all those compounds crystallize in the same C16 crystallographic structure, they offer a rare opportunity to investigate electronic structure effects coming from transition metals on the EFG at Zr site. Those results are compared with EFG values obtained from quadrupole coupling constant measurements performed with the time differential perturbed angular correlation (TDPAC) technique, using the 181 Ta probe. 
  Reference    Z. Naturforsch. 51a, 537—543 (1996); received February 13 1996 
  Published    1996 
  Keywords    Electric Field Gradient, Intermetallic Compounds, LMTO-ASA, Electronic Structure, Nuclear Quadrupole Interactions 
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 TEI-XML for    default:Reihe_A/51/ZNA-1996-51a-0537.pdf 
 Identifier    ZNA-1996-51a-0537 
 Volume    51 
8Author    G. Gowri, Tina Briere, Sudha Srinivas, Hwa-Suck Cho, T. P. Das, M. Frank, W. Kreische, K.V S Rama RaoRequires cookie*
 Title    Theory of Nuclear Quadrupole Interactions in Solid Fluoromethanes with Implanted l9 F* Nuclei. Coupling of HF* and Host Molecule  
 Abstract    The Quadrupole Coupling Constant e 2 qQ and Asymmetry Parameter rj of fluorine for fluorine-substitute methane compounds are calculated using the Hartree-Fock Roothaan procedure. Our results are compared with experimental data from measurements by the Time Differential Perturbed Angular Distribution (TDPAD) technique using excited 19 F* (spin 5/2) nuclei. The theoretical e 2 qQ's for the 19 F* nuclei in the fluoromethanes are in good agreement with experimental results. For CH 2 F 2 and CHC1F 2 molecules, where finite rj are expected from symmetry considerations, our results for ri are small, 0.12 and 0.05 respectively, in agreement with experimental observation. Besides the F* coupling constants associated with the C-F bonds in fluoromethanes, additional interesting NQI parameters, close to those in solid hydrogen fluoride, are observed in the TDPAD measurements. It is demonstrated through investigations of the total energies and electric field gradients that these additional NQI parameters for the fluoromethanes can be explained by a HF* molecule hydrogen-bonded through the hydrogen to a fluorine atom in the host molecular systems. This complexing of an ionic molecule to the host molecules in organic solids containing strongly electronegative atoms is expected to be a general feature in both implantation and conventional techniques. 
  Reference    Z. Naturforsch. 51a, 565—571 (1996); received March 8 1996 
  Published    1996 
  Keywords    Nuclear Quadrupole Interaction, 19 F* (nuclear excited state), Fluoromethane, Hartree-Fock Calculation, Hydrogen Bonding 
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 TEI-XML for    default:Reihe_A/51/ZNA-1996-51a-0565.pdf 
 Identifier    ZNA-1996-51a-0565 
 Volume    51 
9Author    Takahiro Iijima, Motohiro Mizuno, Masahiko SuharaRequires cookie*
 Title    H NMR Study of Molecular and Electron Spin Dynamics in Paramagnetic [Co(H 2 0) 6 ][SiF 6 ]  
 Abstract    The temperature dependences of 2 H NMR spectra and the spin-lattice relaxation time T\ were measured for [Co(H20)f,][SiF6]. The variation of the spectrum above room temperature can be explained by the reorientation of [Co(H20)fi] 2+ about the C3 axis. The activation energy E a and the jumping rate at infinite temperature fco for the three site jump of [Co(H20)6] 2+ were obtained as 82 kJmol -1 and 2x 10 17 s~ 1 from the spectral simulation. Below room temperature, the spectral line shape was dominated by the 180° flip of the water molecule. The minimum of T\ caused by the 180° flip of the water molecule was observed at ca. 260 K. The jumping rate of the 180° flip of the water molecule was estimated from the 2 H NMR T\ and the spectral simulation. E* = 38 kJmol -1 and fco = 6x 10 l5 s -1 for the 180° flip of the water molecule were obtained from T\. 
  Reference    Z. Naturforsch. 55a, 173—177 (2000); received August 23 1999 
  Published    2000 
  Keywords    Phase Transition, 2 H NMR, Nuclear Quadrupole Interaction, Paramagnetic Shift, Molecular Dynamics 
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 TEI-XML for    default:Reihe_A/55/ZNA-2000-55a-0173.pdf 
 Identifier    ZNA-2000-55a-0173 
 Volume    55 
10Author    Motohiro Mizuno, Takahiro Iijima, Kengo Orii, Masahiko SuharaRequires cookie*
 Title    Water Molecular Motion and Hydrogen Bond in Paramagnetic [Cu(H 2 0) 6 ][PtCl 6 ] as Studied by Single Crystal 2 H NMR  
 Abstract    The temperature and angular dependences of the 2 H NMR spectrum were measured for single crystal [Cu(H 2 0) 6 ] [PtCl 6 ]. (e 2 Qq/h, r?) = (132 kHz, 0.72) were obtained for the D nucleus averaged by the fast 180° flip of the water molecule at 297 K. D,(236 kHz, 0.10) and D 2 (246 kHz, 0.09) were obtained for two unequal D nuclei of the water molecule at 133 K. Below T c , at least three nonequivalent waters were found to exist. The jumping rate for the 180° flip of the water molecule (k) was obtained from the simulation of 2 H NMR spectra at //o||[l 11] direction. The activation energy E d and the jumping rate at infinite temperature were estimated from the temperature dependence of k to be 24kJmol _1 and 1 x 10 13 s -1 . 
  Reference    Z. Naturforsch. 55a, 178—182 (2000); received August 23 1999 
  Published    2000 
  Keywords    Phase Transition, 2 H NMR, Nuclear Quadrupole Interaction, Paramagnetic Shift, Molecular Dynamics 
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 TEI-XML for    default:Reihe_A/55/ZNA-2000-55a-0178.pdf 
 Identifier    ZNA-2000-55a-0178 
 Volume    55