Go toArchive
Browse byFacets
Bookbag ( 0 )
Facet   section ZfN Section A  [X]
Facet   Publication Year 1995  [X]
Results  170 Items
Sorted by   
Publication Year
1995[X]
1Author    Tooru Hasebe, Kazuko TanakaRequires cookie*
 Title    7L i -N M  
 Abstract    R S tu d ie s o n M o le c u la r M o tio n o f H y d r a te d L ith iu m Io n s in C o n c e n tr a te d A q u e o u s S o lu tio n s o f L iC l, L iB r , a n d L iS C N a t L o w T e m p e r a tu r e s Dedicated to Prof. Hitoshi Ohtaki on the occasion of his 60th birthday Nuclear spin-lattice relaxation times, 7\, of 7Li in 13.8mol/kg LiCl-H20 and 12.3 mol/kg LiCl-D20 solutions have been measured in the temperature range 80K-313K. They showed similar temperature dependences with the same minimum values (27 ± 1 ms) which proved that the electric quadrupole interaction is dominant for the relaxation of 7Li-NMR. The Tx and T2 values of 7Li-NMR in concentrated aqueous solutions of LiCl (8-14 mol/kg), LiBr (8-10 mol/kg) and LiSCN (8-14 mol/kg) at 80 K to 300 K have been studied to obtain information concerning the dynamic properties of Li+ ions and the effect of anions. Ti at temperatures higher than the glass transition point is governed by a tumbling motion of the hydrated lithium ions. 
  Reference    Z. Naturforsch. 50a, 1—6 (1995); received October 5 1994 
  Published    1995 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/50/ZNA-1995-50a-0001.pdf 
 Identifier    ZNA-1995-50a-0001 
 Volume    50 
2Author    Hiroyasu Nomura, Shinobu Koda, Takashi SakuraiRequires cookie*
 Title      
 Abstract    Dedicated to Prof. Hitoshi Ohtaki on the occasion of his 60th birthday The Raman band of the Vj(Ax) mode of S04~ of Li2S04 dissolved in water and water-dimethyl-formamide mixtures was measured in the concentration range 0.01 to 0.2 mol • dm-3. The central frequency of the sulfate ion increases with sulfate concentration. The limiting frequency at infinite dilution depends on the DMF content. The Raman band becomes asymmetric with increasing concentration of Li2S04 in 20 wt% DMF mixtures and with addition of LiCl to the aqueous solution of Li2S04. The vibrational relaxation behavior of the v1(A1) mode was investigated by analyzing the vibrational correlation function based on Kubo's stochastic theory. D y n a m ic s o f th e S u lfa te Io n in D ilu te W a te r -D M F S o lu tio n s 
  Reference    Z. Naturforsch. 50a, 7—10 (1995); received November 4 1994 
  Published    1995 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/50/ZNA-1995-50a-0007.pdf 
 Identifier    ZNA-1995-50a-0007 
 Volume    50 
3Author    Makoto Koide, Shin-Ichi IshiguroRequires cookie*
 Title     
 Abstract    h e r m o d y n a m ic s a n d S t r u c t u r e o f I s o th io c y a n a te C o m p le x e s o f M a n g a n e s e (I I) , C o b a l t(I I) a n d Z i n c (I I) Io n s in N ,N -D im e th y la c e ta m id e Dedicated to Prof. Dr. Ohtaki on his occasion of 60th birthday The complexation of manganese (II), cobalt (II) and zinc(II) with thiocyanate ions has been studied in N,N-dimethylacetamide (DMA) by calorimetry and spectrophotometry at 298 K. In these metal systems the formation of a series of four isothiocyanato complexes, [M(NCS)J<2-n)+ (n = 1-^4; M = Mn, Co, and Zn) was established, and their formation constants, enthalpies and entropies were determined. Interestingly, the complexation behavior in DMA is significantly different from that in N,N-dimethylformamide (DMF), despite of the similarity of the physicochemical properties of these solvents. The complexation is indeed enhanced significantly in DMA over DMF and is more exothermic in the former solvent. Furthermore, with cobalt(II) an octahedral to tetrahedral coordi­ nation geometry change was found to occur in DMA at an earlier step of complexation than in DMF. These results suggest that six-coordination of DMA molecules to a metal ion is severely sterically hindered. 
  Reference    Z. Naturforsch. 50a, 11—17 (1995); received September 26 1994 
  Published    1995 
  Keywords    Thiocyanato complexes, Transition metal(II) ions, N, N-dimethylacetamide, Calorime­ try, Spectrophotometry 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/50/ZNA-1995-50a-0011.pdf 
 Identifier    ZNA-1995-50a-0011 
 Volume    50 
4Author    A. D. Trokhymchuk, M. F. Holovkob, K. Heinzinger0Requires cookie*
 Title      
 Abstract    The possibility of the existence of a pre-preak in the structure factor of water at 0.6 Ä ~1 is discussed on the basis of the combination of computer simulation and integral equation theory techniques. It indicates spatial correlations in water at distances of the order of 10 A. 
  Reference    Z. Naturforsch. 50a, 18—20 (1995); received November 4 1994 
  Published    1995 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/50/ZNA-1995-50a-0018.pdf 
 Identifier    ZNA-1995-50a-0018 
 Volume    50 
5Author    Ingmar Persson, Magnus Sandström, Haruhiko Yokoyama, Monika Chaudhry, JapanRequires cookie*
 Title     
 Abstract    tr u c tu r e o f th e S o lv a te d S tr o n tiu m a n d B a riu m I o n s in A q u e o u s, D im e th y l S u lfo x id e a n d P y r id in e S o lu tio n , a n d C r y s ta l S tr u c tu r e o f S tr o n tiu m a n d B a r iu m H y d r o x id e O c t a h y d r a te Dedicated to Prof. Hitoshi Ohtaki on the occasion of his 60th birthday Single crystal X-ray data, collected at 298 K, are used to redetermine the crystal structure of the non-isomorphic compounds [Sr(H20)8](0H)2 and [Ba(H20)8](0H)2. The eight water oxygen atoms form distorted Archimedean antiprisms around the octahydrated metal ions with mean metal ion-oxygen distances 2.62 and 2.79 Ä for strontium and barium, respectively. A second coordination shell of 24 hydrogen-bonded oxygen atoms with mean metal ion-oxygen distances M • • • O" 4.76 and 4.80 A, respectively, is observed. The hydroxide ions in both structures have an unusual hydrogen bond arrangement with 5 bonds accepted and one donated. The structure of the solvated strontium and barium ions in aqueous, dimethyl sulfoxide and pyridine solutions has been studied by means of large angle X-ray scattering and extended X-ray absorption fine structure spectroscopy techniques. In aqueous solution independent determinations of the first-sphere metal-oxygen coordination by the two techniques resulted in the bond lengths Sr-O 2.63 (2) and Ba-O 2.81 (3) A, and for both metal ions a hydration number of 8.1 (3). The second coordination spheres are very diffuse with only about 13 water molecules at similar M • • • O" distances as in the crystal structures and 2-3 water molecules closer to the metal ions. In dimethyl sulfoxide solution both ions were found to coordinate 6.0 (5) solvent molecules with the distances Sr-O 2.54(1), Sr -S 3.77(1) A, and Ba-O 2.76(1), Ba -S 3.99(1) A. For the solvated ions in pyridine solution EXAFS measurements yielded the distances Sr-N 2.57 (2) and Ba-N 2.78 (3) A, with a probable solvation number of 6. Correlations of hydration enthalpies and partial molar volumes with experimental M-O bond distances in aqueous solution are used to discuss hydration numbers and bond character for all of the alkaline earth metal ions. 
  Reference    Z. Naturforsch. 50a, 21—37 (1995); received November 8 1994 
  Published    1995 
  Keywords    Barium, Strontium, Hydration, Solvation, Structure 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/50/ZNA-1995-50a-0021.pdf 
 Identifier    ZNA-1995-50a-0021 
 Volume    50 
6Author    PiaC. Schoester3, ManfredD. Zeidlera, Tamäs Radnaib, PhilippeA. BoppcRequires cookie*
 Title     
 Abstract    o m p a ris o n o f th e S t r u c t u r e o f L iq u id A m id e s a s D e te rm in e d b y D if fr a c tio n E x p e r im e n ts a n d M o le c u la r D y n a m ic s S im u la tio n s Dedicated to Professor Hitoshi Ohtaki on the occasion of his 60th birthday The intermodular structures of liquid formamide, N-methylformamide and N,N-dimethylfor-mamide at room temperature are studied by means of NVE molecular dynamics computer simula­ tions. Newly developed flexible models are used. X-ray and neutron weighted structure and total radial pair distribution functions are computed from the simulated site-site pair distribution func­ tions. They are compared with experimental results. The agreement is usually satisfactory as far as heavy atom pairs are concerned while the lengths of the hydrogen bonds are found to be systemat­ ically too long in the simulations. 
  Reference    Z. Naturforsch. 50a, 38—50 (1995); received October 8 1994 
  Published    1995 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/50/ZNA-1995-50a-0038.pdf 
 Identifier    ZNA-1995-50a-0038 
 Volume    50 
7Author    Y. MarcusRequires cookie*
 Title    T r a n  
 Abstract    s f e r G ib b s F r e e E n e r g ie s o f D iv a le n t A n io n s fro m W a te r to O r g a n ic a n d M ix e d A q u e o u s -O r g a n ic S o lv e n ts Dedicated to Professor Hitoshi Ohtaki on the occasion of his 60th birthday The standard molar Gibbs free energies of transfer of divalent anions, in particular sulfate, from water into methanol, ethanol, ethylene glycol, dioxane, tetrahydrofuran, acetone, N-methylform­ amide, N,N-dimethylformamide, pyridine, acetonitrile, and dimethylsulfoxide and mixtures of some of them with water or some other solvent have been obtained from the literature. The tetraphenyl-arsonium tetraphenylborate extrathermodynamic assumption has been used as far as possible in order to obtain the single ion values. The generally unfavorable transfers from water (or protic solvents) into polar aprotic ones are interpreted in terms of the properties of the anions and of the solvents, dominated by the hydrogen-bonding acidity of water. 
  Reference    Z. Naturforsch. 50a, 51—58 (1995); received October 6 1994 
  Published    1995 
  Keywords    Divalent anions, Ion properties, Sulfate, Solvent properties, Transfer Gibbs energy 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/50/ZNA-1995-50a-0051.pdf 
 Identifier    ZNA-1995-50a-0051 
 Volume    50 
8Author    Heinz Gamsjäger1, Harald Marhold1, Erich Königsberger1, YiJung Tsai1, Hans Kolmer2Requires cookie*
 Title    S o lid - 3) 4 * **H20  
 Abstract    S o lu te P h a s e E q u ilib ria in A q u e o u s S o lu tio n s IX . T h e rm o d y n a m ic A n a ly s is o f S o lu b ility M e a s u r e m e n ts : L a (0 H) M(C 0 Dedicated to Prof. Hitoshi Ohtaki on the occasion of his 60th birthday The aqueous solubilities of La(OH)p^(COaJjA 0.1 H20, basic lanthanum carbonate of ancylite type, have been investigated as a function of ionic strength at 25.0 °C. The stoichiometric solubility constants defined by log* K1 0 = log [La3 + ] + 1.1 log pco — 3 log [H+1 have the values 11.10, 11.32, 11.42, 11.63, and 11.70 for / = 0.1, 0.25, 1.0, 2.0, and 4.0 mol kg (Na)C104 respectively. The extrapolation to infinite dilution using the Pitzer equations resulted in a "thermodynamic" solubility constant, log* K° 0 = 10.48 ± 0.08. This in turn led to the Gibbs energy of ancylite formation: Af G f98 {La(OH)08(CO3)11 0.1 H20} = -1.531.5 kJ mol-1. 
  Reference    Z. Naturforsch. 50a, 59—64 (1995); received October 1 1994 
  Published    1995 
  Keywords    Solubility, Carbonates, Lanthanum, Thermodynamics, Pitzer model 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/50/ZNA-1995-50a-0059.pdf 
 Identifier    ZNA-1995-50a-0059 
 Volume    50 
9Author    J. Barthel, K. Bachhuber, R. BüchnerRequires cookie*
 Title     
 Abstract    ie le c tr ic R e la x a tio n o f N a C 1 0 4 S o lu tio n s in F o r m a m id e , N -M e th y lf o r m a m id e , a n d N ,N -D im e th y lf o rm a m id e Dedicated to Prof. Hitoshi Ohtaki on the occasion of his 60th birthday Complex permittivity spectra in the frequency range 0.95 < v/[GHz] < 89 for N,N-dimethylform-amide (DMF), N-methylformamide (NMF), formamide (FA) and their solutions of NaC104 are investigated to study the change of liquid structure and dynamics arising from the availability of one hydrogen-bond acceptor site together with no (DMF), one (NMF), or two (FA) donor sites on the same molecule. Three solvent relaxation processes are observed for NMF and two for FA and DMF. The relaxation parameters are used to determine solvation numbers. They show that ion-solvent interactions lead to a reduction of the average length of the H-bonded NMF chains but have only moderate influence on the FA structure. An additional solute relaxation process in DMF solutions is due to the diffusion-controlled formation and decomposition of solvent-shared ion pairs. 
  Reference    Z. Naturforsch. 50a, 65—74 (1995); received October 22 1994 
  Published    1995 
  Keywords    Dielectric relaxation, Formamides, Solvation, Solvent dynamics, Ion association 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/50/ZNA-1995-50a-0065.pdf 
 Identifier    ZNA-1995-50a-0065 
 Volume    50 
10Author    Moshe Belinskii, Ivano Bertini2, Oleg Galas2, Claudio Luchinat3Requires cookie*
 Title     
 Abstract    h e E le c tro n ic S tr u c t u r e o f th e F e 4S4 + C lu s te r in P r o te in s : T h e I m p o r ta n c e o f D o u b le E x c h a n g e P a r a m e te r Dedicated to Prof. Hitoshi Ohtaki on the occasion of his 60th birthday The recently obtained Mössbauer and EPR parameters of the Fe4S4+ polymetallic center in the High Potential Iron-Sulfur Protein (HiPIP) II from E. halophila have been reproduced with models based on pure Heisenberg exchange. The role of double exchange versus ./-inequivalence is dis­ cussed. An evaluation of the upper limit of the double exchange parameter in the Fe4S |+ bimetallic center is also presented. The present calculations shed further light on the electronic structure of the Fe4S4+ center. 
  Reference    Z. Naturforsch. 50a, 75—80 (1995); received September 21 1994 
  Published    1995 
  Keywords    Heisenberg exchange, Double exchange, Iron-sulfur proteins 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/50/ZNA-1995-50a-0075.pdf 
 Identifier    ZNA-1995-50a-0075 
 Volume    50 
11Author    GlennH. Penner3, Baiyi Zhaoa, KennethR. Jeffrey0Requires cookie*
 Title      
 Abstract    The molecular dynamics of solid (CH3)3NBH3 is investigated by deuterium NMR spectroscopy. Variable temperature lineshape analyses yield activation energies of 27 + 3, 19 + 2, and 12.5 ± 2 kJ/mol for -CH3, -N(CH3)3 and -BH3 rotation, respectively. Analysis of the temperature depen­ dence of the spin-lattice relaxation times, Tt , gives activation energies of 33 + 3, 15 + 1.5, and 14 + 1.5 kJ/mol, respectively. Direct comparison of rotational exchange rates (from lineshape simu­ lations) an of rotational correlation times (from Tx analyses) for -N(CH3)3 and -BH3 rotation indicate that the two motions are correlated in solid (CH3)3NBH3 and together constitute a whole molecule reorientation about the N-B bond. This is supported by an internal rotational barrier of 18.0 kJ/mol for-BH3 rotation, obtained from ab initio molecular orbital calculations at the MP2/6-31G* level. 
  Reference    Z. Naturforsch. 50a, 81—89 (1995); received September 22 1994 
  Published    1995 
  Keywords    NMR spectroscopy, Molecular dynamics, NMR relaxation 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/50/ZNA-1995-50a-0081.pdf 
 Identifier    ZNA-1995-50a-0081 
 Volume    50 
12Author    P. Hartmann, G. SchelerRequires cookie*
 Title      
 Abstract    Herrn Prof. W . Müller-Warmuth zum 65. Geburtstag gewidmet Is solid state 91 Zr NMR feasible? 91Zr solid state NMR spectra have been observed for samples possessing different zirconium local-site environments (e.g. phosphates, fluorides). Depending on the quadrupole coupling, different NMR experiments have been utilized. In case of weak quadrupole coupling, magic angle spinning (MAS) is suitable. Otherwise, spin echo techniques are necessary to overcome "acoustic ringing" and receiver dead-time limitations. Using the step echo method, the detection of the very broad 91Zr signals is not limited by non-uniform spectral excitation. The obtained 91Zr chemical shifts range from —246 ppm to 208 ppm, the quadrupole coupling frequencies from 50 kHz to 2.7 MHz.. I s t 91Z r -F e s tk ö r p e r -K e r n r e s o n a n z s p e k tr o s k o p ie p r a k tik a b e l? 
  Reference    Z. Naturforsch. 50a, 90—94 (1995); received September 26 1994 
  Published    1995 
  Keywords    Solid state NMR, Zirconium-91, MAS, Spin echo, Acoustic ringing 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/50/ZNA-1995-50a-0090.pdf 
 Identifier    ZNA-1995-50a-0090 
 Volume    50 
13Author    A. Detken, P. Focke, H. Zimmermann, U. Haeberlen, Z. Olejniczak, Z. T. LalowiczRequires cookie*
 Title     
 Abstract    e u te r o n N M R o f M e th y l G r o u p s in t h e T u n n e lin g R e g im e . A S in g le C r y s ta l S tu d y o f A s p ir in -C D 3 We dedicate this paper to Prof. Dr. Werner Müller-Warmuth on the occasion of his 65th birthday. Z. T. L. and U. H. owe much to his advice. We report the first single crystal deuteron NMR spectra of CD3 groups which display the so-called ±ß, ± (|a| ± ß) and ±(2|a| ± ß) lines characteristic of rotational tunneling in a sufficiently clear manner to allow a quantitative comparison with the respective theory developed in 1988 by the group of W. Müller-Warmuth. The molecular system we study is aspirin-CD3. We recorded spectra for differently oriented single crystals and measured spin-lattice relaxation times T\ in a wide temperature range. At 12.5 K we exploit the dependence of the ±(|a| ± ß) and ±(2|a| ± ß) lines on the orientation of the applied field Bo for determining the equilibrium orientation of the CD3 group in the crystal lattice. The spectra display features which allow, by comparison with simulated spectra, a measurement of the tunnel frequency ut. Its low temperature limit is (2.7 ± 0.1) MHz. It allows to infer the height V3 of the potential V(</?) in which the CD3 group moves, provided that this potential is purely threefold. We get V3 = (47.2 ± 0.5) meV. The transition from the tunneling to the classical, fast reorienting regime occurs in the 15 K ~ T ~ 35 K temperature range. In this range we observe a broadening, merging and eventually narrowing of the ± |a | and ±2|a| lines in very much the way predicted by Heuer. His theory, however, must be extended by taking into account all librational levels. The behaviour of the ± ß lines in the transition temperature range signalizes a reduction of the observable tunnel frequency with increasing temperature. This reduction allows an independent measurement of the potential height and represents a test of the assumption of a purely threefold potential. From the T\ -data we derive the temperature dependence of the correlation time t c of the reorientational jumps. The plot of log rc vs. 1 /T follows a straight line for more than five decades. From its slope we get yet another independent number for the potential height. It agrees well with the other ones, which confirms the assumption of the essentially threefold potential V(<p) in aspirin-CD 3. 
  Reference    Z. Naturforsch. 50a, 95—116 (1995); received October 41994 
  Published    1995 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/50/ZNA-1995-50a-0095.pdf 
 Identifier    ZNA-1995-50a-0095 
 Volume    50 
14Author    D. P. Cooper, E. SchöllRequires cookie*
 Title      
 Abstract    It is demonstrated numerically that by using Pyragas' method of chaos self-control a stable semiconductor oscillator can be designed based on driven real-space transfer oscillations in a modulation-doped heterostructure. By application of a small time-continuous delayed feedback voltage control signal, different unstable periodic orbits embedded in the chaotic attractor can be stabilized. Thus different modes of self-generated periodic voltage oscillations can be selected by choosing an appropriate delay time. This provides tunability to different discrete frequencies. PACS numbers: 05.45.+ b, 72.20 Ht. 
  Reference    Z. Naturforsch. 50a, 117—124 (1995); received November 5 1994 
  Published    1995 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/50/ZNA-1995-50a-0117.pdf 
 Identifier    ZNA-1995-50a-0117 
 Volume    50 
15Author    GurpreetK. Gill, S. K. TrehanRequires cookie*
 Title     
 Abstract    x p lo s iv e I n s ta b ility in S u p e rp o s e d F lu id s in H y d r o m a g n e tic s We study the resonance interaction between two marginally unstable modes of small but finite amplitude waves in the Kelvin-Helmholtz flow model using the method of multiple scales. We find that, as magnetic field increases, the amplitudes of the disturbance diverge at a very high rate while for a fluid of higher density ratio e, the amplitudes diverge very slowly. 
  Reference    Z. Naturforsch. 50a, 125—130 (1995); received 
  Published    1995 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/50/ZNA-1995-50a-0125.pdf 
 Identifier    ZNA-1995-50a-0125 
 Volume    50 
16Author    H. Hartwig, U. Kretschmer, H. DreizlerRequires cookie*
 Title     
 Abstract    h e 33S N u c le a r Q u a d r u p o le H y p e r f ln e S tr u c tu r e in th e R o ta tio n a l S p e c tr u m o f 32S , 33S D im e th y l D is u lfid e We investigated the rotational spectrum of 32S, 33S dimethyl disulfide in natural abundance by molecular beam Fourier transform microwave spectroscopy. We were able to determine the com­ plete 33S quadrupole coupling tensor, the rotational and centrifugal distortion constants and the internal rotation parameters of the two methyl tops. The rotational constants were found to be A = 8113.8847(23) MHz, B = 2800.6203(30) MHz and C = 2557.2245 (32) MHz. The results are compared with former publications. 
  Reference    Z. Naturforsch. 50a, 131—136 (1995) 
  Published    1995 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/50/ZNA-1995-50a-0131.pdf 
 Identifier    ZNA-1995-50a-0131 
 Volume    50 
17Author    Laaksonen, RoderickE. WasylishenRequires cookie*
 Title    Aatto  
 Abstract    Nitrogen (14N) and deuterium (2H) nuclear quadrupolar coupling constants, x(14N) and *(2H), have been calculated for liquid ammonia at 197 K, 232 K, and 271 K, using a combination of molecular dynamics simulations and ab initio molecular orbital calculations. The basis set and cluster size dependence of the calculated results has been examined. The calculated value of x(14N) for liquid ammonia at 197 K, —3.45 MHz, is found to be close to the accepted solid-state value. At 232 K and 271 K, the magnitudes of the calculated values are about 5 — 10% greater: —3.56 MHz and —3.67 MHz, respectively, but still well below the accepted gas-phase value, —4.09 MHz. The calculated values of X (2H) for liquid ammonia are by about 20% smaller than the corresponding values calculated for the gas-phase monomer. On the basis of the calculations presented here and those of previous workers it is clear that the accepted experimental value of x(2H) for solid ammonia-d3 is too small. C a lc u la tio n s o f 14N a n d 2H N u c le a r Q u a d r u p o la r C o u p lin g C o n s ta n ts f o r L iq u id A m m o n ia 
  Reference    Z. Naturforsch. 50a, 137—144 (1995); received October 5 1994 
  Published    1995 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/50/ZNA-1995-50a-0137.pdf 
 Identifier    ZNA-1995-50a-0137 
 Volume    50 
18Author    A. Heinrich-Schramm, W. E. Price, H.-D LüdemannRequires cookie*
 Title     
 Abstract    h e In flu e n c e o f D ip o le -D ip o le I n te r a c tio n a n d H y d r o g e n B o n d in g U p o n T r a n s la tio n a l D iffu s iv ity in S im p le F lu id s Self-diffusion coefficients of dimethylether have been measured as a function of temperature (185-458 K) and pressure (up to 200 MPa) by pulse-gradient field spin-echo NMR. Calculated activation volumes (AV*) fall from 15 (10-6 m3/mole) at the highest temperature to 7 (10~6 m3/mole) at the lowest. This trend is in keeping with values for other non-associating liquids. Comparison with self diffusion data for propane and ethanol reveals that the translational diffusivity in dimethylether is influenced by the substance's modest dipole moment (1.3 Debye). The effect is small but measur­ able and becomes more pronounced at lower temperatures. S e lf-D iffu s io n in C o m p re s s e d D im e th y le th e r : 
  Reference    Z. Naturforsch. 50a, 145—148 (1995); received October 5 1994 
  Published    1995 
  Keywords    Dimethylether, Diffusion, High Pressure 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/50/ZNA-1995-50a-0145.pdf 
 Identifier    ZNA-1995-50a-0145 
 Volume    50 
19Author    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 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/50/ZNA-1995-50a-0149.pdf 
 Identifier    ZNA-1995-50a-0149 
 Volume    50 
20Author    V. Massarotti, D. Capsoni, M. BiniRequires cookie*
 Title     
 Abstract    ta b ility o f (N i 1_ xL i x) (L i 1_ J,N iJ?) 0 2 O r d e r e d S o lid S o lu tio n The stability of ordered solid solutions (OSS) with LiNi02 structure has been studied in a wide range of the lithium cationic fraction (0.22 < xt < 0.42). The OSS is obtained from the reactive system Ni0/Li2C 03 at 800 °C starting with high nominal lithium content (xt = 0.5). By analysis of the decrease of x, observed after annealing, during which evaporation and a contact reaction occurs, structure-composition relationships can be obtained. The transformation of the ordered phase, due to a cation exchange process, is observed for xt < 0.31 by accurate X-Ray powder pattern analysis (Rietveld method). By increasing the annealing time (decreasing lithium content), the data can be explained on the basis of progressive formation of the simple solid solution (SSS) with only one cation site and halved c axis value. The variations of structural parameters during the transformation are compared with those reported in the litera­ ture. The coherence domains of the OSS become smaller and the phase percentage decreases, while the SSS percentage increases. The rate of such a process can be well described on the basis of a two dimensional diffusion mechanism. 
  Reference    Z. Naturforsch. 50a, 155—168 (1995); received November 21 1994 
  Published    1995 
  Keywords    Lithium Nickel Oxides, Solid state reaction, Solid solution, Order-Disorder Transfor­ mation 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/50/ZNA-1995-50a-0155.pdf 
 Identifier    ZNA-1995-50a-0155 
 Volume    50 
1
2
3
4
5
...
Next