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1Author    A. Thern, H.-D LüdemannRequires cookie*
 Title    p, T Dependence of the Self Diffusion Coefficients and Densities in Liquid Silicone Oils  
 Abstract    Self diffusion coefficients and densities from a series of commercial silicones have been studied in the temperature range between 290 and 410 K at pressures up to 200 MPa. The densities are fitted to a modified Tait equation. The self diffusion coefficients are discussed in terms of the rough hard sphere model and tested against the Rouse-model. 
  Reference    Z. Naturforsch. 51a, 192—196 (1996); received January 26. 1996 
  Published    1996 
  Keywords    Self diffusion, densities, silicones 
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 TEI-XML for    default:Reihe_A/51/ZNA-1996-51a-0192.pdf 
 Identifier    ZNA-1996-51a-0192 
 Volume    51 
2Author    Heinrich-Schramm, W. E. Price, H.-D LüdemannRequires cookie*
 Title     
 Abstract    Self-diffusion in ethanol/hexane and dimethylether/hexane mixtures of various compositions has been measured at 215-350 K and up to 200 MPa. Qualitative analysis of the results indicates that, as expected, hydrogen bonding retards the self-diffusion of ethanol in the mixture, especially at the low temperatures. Dimethylether shows a slight effect of dipole-dipole interactions on the self-diffu­ sion, as seen by a higher AE* value than for the alkane. However there is no significant difference in the pressure dependence for both mixtures. This is shown by considering the ratio of the two diffusion coefficients, which suggests that, contrary to what is observed for pure alcohols, pressure has little effect upon the hydrogen bonding of ethanol in the mixture. In additon, there is surprisingly little concentration dependence on the ratios for either mixture. 
  Reference    Z. Naturforsch. 50a, 149—154 (1995); received October 5 1994 
  Published    1995 
  Keywords    Binary mixtures, Self diffusion, High pressure 
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 TEI-XML for    default:Reihe_A/50/ZNA-1995-50a-0149.pdf 
 Identifier    ZNA-1995-50a-0149 
 Volume    50 
3Author    Roman GocRequires cookie*
 Title    Calculation of the NMR Second Moment for Solid Benzene with Rotation and Diffusion of Molecules -Numerical Approach  
 Abstract    Numerical calculations of the NMR second moment in case of rotation and diffusion of molecules were performed. As an example computer simulations of molecular reorientation and self-diffusion in solid benzene have been performed. For each model and rate of motion the Van Vleck's second moment of the proton NMR absorption spectrum was calculated, and these values were compared with experimental data. It is concluded that restricted self-diffusion must be implied in order to obtain better agreement between calculated and experimental NMR second moments. The temperature at which self-diffusion was detected through NMR line-width narrowing was found to be about 120 K, nearly 80 K less than the temperature at which the self-diffusion was detected by T lp relaxation measurements. 
  Reference    Z. Naturforsch. 52a, 477—184 (1997); received March 29 1997 
  Published    1997 
  Keywords    NMR, molecular rotation, self-diffusion, numerical approach 
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 TEI-XML for    default:Reihe_A/52/ZNA-1997-52a-0477.pdf 
 Identifier    ZNA-1997-52a-0477 
 Volume    52 
4Author    Liuping Chen, Hans-Dietrich LüdemannRequires cookie*
 Title    Influence of Conformational Equilibria upon the Self-Diffusion of the Conformers in Neat Liquids  
 Abstract    The self-diffusion coefficients D of the isomers of liquid N-isopropyl-N-methylacetamide (IPMAA) and acetylacetone (AC AC) are studied as functions of temperature. For AC AC also pressure dependent studies were undertaken. In IPMAA the eis and trans conformers have almost identical D. In liquid ACAC, D Kclo is always smaller than D cnol , this difference being 15% around 300 K. 
  Reference    Z. Naturforsch. 55a, 605—608 (2000); received April 19 2000 
  Published    2000 
  Keywords    Conformers, Self Diffusion, Neat Liquids, Pressure 
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 TEI-XML for    default:Reihe_A/55/ZNA-2000-55a-0605.pdf 
 Identifier    ZNA-2000-55a-0605 
 Volume    55 
5Author    C. Herdlicka, J. Richter, M. D. ZeidlerRequires cookie*
 Title    Self-Diffusion in Molten Lithium Nitrate  
 Abstract    Self-diffusion coefficients of 7 Li + ions have been measured in molten LiN0 3 with several com-positions of 6 Li + and 7 Li + over a temperature range from 537 to 615 K. The NMR spin-echo method with pulsed field gradients was applied. It was found that the self-diffusion coefficient depends on the isotopic composition and shows a maximum at equimolar ratio. At temperatures above 600 K this behaviour disappears. 
  Reference    Z. Naturforsch. 47a, 1047—1050 (1992); received July 16 1992 
  Published    1992 
  Keywords    Molten salts, Self-diffusion, Isotope effect, NMR spin-echo 
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 TEI-XML for    default:Reihe_A/47/ZNA-1992-47a-1047.pdf 
 Identifier    ZNA-1992-47a-1047 
 Volume    47 
6Author    Hiroyuki Ishida, Masakazu Kato, Hiroshi Ono, Ryuichi IkedaRequires cookie*
 Title    Cationic Self-diffusion in Solid Choline Perchlorate Studied by NMR  
 Abstract    The 1 H spin-lattice and spin-spin relaxation times, and the second moment of the 1 H NMR linewidth of choline Perchlorate, [(Cff^NCfFCHiOHJClC^, were measured in its highest-temperature solid phase, i. e. above 275 K. X-ray powder patterns taken at ca. 380 K revealed that in this phase the crystal has a CsCl-type cubic structure (a = 6.326(4) A and Z = 1). From *H NMR experiments it was found that the cations in this phase undergo isotropic rotation and translational self-diffusion. From the 1 H T, measurements, the activation energies of the cationic rotation and self-diffusion were evaluated to be 21.4 ± 0.4 and 62 ± 3 kJ mol -1 , respectively. 
  Reference    Z. Naturforsch. 52a, 637—639 (1997); received May 28 1997 
  Published    1997 
  Keywords    Ionic plastic phase, Self-diffusion, Crystal structure, Nuclear magnetic resonance 
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 TEI-XML for    default:Reihe_A/52/ZNA-1997-52a-0637.pdf 
 Identifier    ZNA-1997-52a-0637 
 Volume    52 
7Author    Mineyuki Hattori, Yoshito Onoda, Tomoki Erata, M. E. Smith, Bruker Analytische, M. Esstechnik, G. M. Bh, Masakazu Hattori, Hiroshi Ohki, Ryuichi IkedaRequires cookie*
 Title    Ionic motion and Disordered Structure in the Rotator Phase of Butylammonium Chloride Studied by Temperature Dependences of 35C1 and 2HNMR  
 Abstract    Temperature dependences o f 35C1 and 2H quadrupole coupling constants and 35C1 N M R spin-lat­ tice relaxation times in polycrystalline samples were measured in the rotator phase of the butylam ­ m onium chlorides C 4H 9N H 3C1 and C4H 9N D 3C1, obtainable above the phase transition tempera­ ture o f 241 K. A rapid decrease o f the quadrupole coupling constants of both nuclei upon heating is attributed to increasing dynam ic disorder formed around the polar head. The presence of self-dif-fussion o f C P ions was revealed from the spin-spin relaxation time and resonance line-width in single crystals, and confirmed by measuring the dc electrical conductivity. 
  Reference    Z. Naturforsch. 49a, 291 (1994); received July 23 1993 
  Published    1994 
  Keywords    Solid N M R, Quadrupole coupling constant, Spin-lattice relaxation time, Self-diffusion, Rotator phase 
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 TEI-XML for    default:Reihe_A/49/ZNA-1994-49a-0291.pdf 
 Identifier    ZNA-1994-49a-0291 
 Volume    49