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1995[X]
61Author    E. Detscher, H. G. Hertz, M. Holz, Xi-An MaoRequires cookie*
 Title    Io n -I o n D e -A s  
 Abstract    s o c ia tio n a n d A s s o c ia tio n o f S tr o n g E le c tro ly te s a t H ig h D ilu tio n fro m N u c le a r M a g n e tic R e la x a tio n M e a s u r e m e n ts Dedicated to Professor E. Wicke on the occasion of his 80th birthday Proton magnetic relaxation rates in the system N(CH)3)4Br/NiBr2/D20, N(CH3)4Br/MnBr2/ D20, Ni(00CCH3)2/D20 and Mn(00CCH3)2/D20 have been measured as a function of the solute concentration in the range 0.002 < c* <> 1 m. Division by the concentration c* and by a quantity characterizing the ionic motion yields the association parameter (4-parameter). A de­ creases and increases with decreasing concentration for the systems involving cation-cation and cation-anion interaction, respectively. The relaxation rates of 35C1~, 133Cs , and 25Mg+ + in diamagnetic aqueous solutions have also been measured down to high dilution. Here as well in most cases we have found an increase of the ^-parameter with decreasing salt concentration, indicating ion-ion association at high dilution. A comparison with the results of the Debye-Hückel theory is given; there is qualitative agreement. Our experimental results for 35C1~ generally do not support theoretical considerations in the literature, where a C1~-C1~ association was postulated. 
  Reference    Z. Naturforsch. 50a, 487—501 (1995); received January 28 1995 
  Published    1995 
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 Identifier    ZNA-1995-50a-0487 
 Volume    50 
62Author    D. Büsing3, M. Jenau3, J. Reuter3, A. Würflinger3, J.Li TamaritbRequires cookie*
 Title    Differential Thermal Analysis and Dielectric Studies on 2-Methyl-2-Nitro-Propane under High Pressure  
 Abstract    Differential thermal analysis and dielectric studies under pressures up to 300 MPa and temperatures of about 200 to 350 K have been performed on 2-methyl-2-nitro-propane (TBN). TBN displays an orientationally disordered phase (ODIC), solid I, and two non-plastic phases, solids II and III. The coexistence region of the plastic phase I increases with increasing pressure, whereas the low-temperature phase II apparently vanishes at a triple point I, II, III, above 300 MPa. The static permittivity increases on freezing, char­ acterizing the solid I as an ODIC phase. In the frame of the Kirkwood-Onsager-Fröhlich theory the ^-factor is about unity, discounting specific dielectric correlations. The dielec­ tric behaviour of TBN is similar to previously studied related compounds, such as 2-chloro-2-methyl-propane or 2-brome-2-methyl-propane. 
  Reference    Z. Naturforsch. 50a, 502—504 (1995); received December 3 1994 
  Published    1995 
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 Identifier    ZNA-1995-50a-0502_n 
 Volume    50 
63Author    K. Funke3, T. Lauxtermanna, D. Wilmera, S. M. BenningtonbRequires cookie*
 Title      
 Abstract    Dedicated to Professor Ewald Wicke on the occasion of his 80th birthday Complete ionic conductivity spectra as well as quasielastic and inelastic neutron scattering spectra have been taken of solid silver bromide at various temperatures. High-amplitude vibrational move­ ments, essentially of the silver ions, contribute to both kinds of spectra. In particular, a conductivity maximum, located at about 500 GHz, reflects oscillations of individual silver ions along <111 > directions. -The microwave and millimetre-wave conductivities are dominated by a thermally ac­ tivated Debye-type relaxation process. The effect is consistently explained by the frequent hopping of silver ions from regular octahedral lattice sites into tetrahedral interstitial sites and back again, i.e., by the frequent creation and recombination of Frenkel pairs. -The effect is also responsible for the existence of thermally activated quasielastic components in the neutron scattering spectra. The width of the coherent quasielastic scattering shows that the forward-backward hopping of a silver ion is accompanied by fast correlated movements of ions in its immediate neighbourhood. C r e a tio n a n d R e c o m b in a tio n o f F r e n k e l D e fe c ts in A g B r 
  Reference    Z. Naturforsch. 50a, 509—520 (1995); received November 14 1994 
  Published    1995 
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 Identifier    ZNA-1995-50a-0509 
 Volume    50 
64Author    H. BrodowskyRequires cookie*
 Title     
 Abstract    a tio n a l I n te r p o la tio n F o r m u la e f o r th e E x c e s s F u n c tio n s o f B in a ry M ix t u r e s A variation of the commonly used polynomial interpolation formulae for the excess functions of binary mixtures is proposed, in which the cross-calculation of the coefficients of partial and integral molar functions is greatly facilitated. 
  Reference    Z. Naturforsch. 50a, 521—524 (1995); received November 14 1994 
  Published    1995 
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 Identifier    ZNA-1995-50a-0521 
 Volume    50 
65Author    N. Burkert8, R. Grüne8, H. Schmalzried8, S. RahmanbRequires cookie*
 Title      
 Abstract    Dedicated to Professor Dr. E. Wicke on occasion of his 80th birthday Decomposition morphologies of supersaturated spinel solid solutions in the quasi-binary system Co2Ti04-CoAl20 4 at 973 K show all pertinent features of spinodal decomposition. Since the de­ composition morphology may not be considered as sufficient evidence for a spinodal process, the thermodynamics of the spinel solid solutions and the linear transport theory of spinodal decompo­ sition were combined to corroborate the experimental results of the early decomposition reaction. Simultaneous ordering, a common property of ternary and higher nonequilibrium solid solutions, was also observed. These ordering processes occur locally in distinct regions of the spinel crystal. Moreover, the spinodal wavelength X increases in time according to X cc t, which is unusual and will be discussed in the light of cation diffusion in semiconducting oxides with two cation sublattices. S o m e A s p e c ts o f S p in o d a l D e c o m p o s itio n in S p in e l S o lid S o lu tio n s 
  Reference    Z. Naturforsch. 50a, 525—532 (1995); received December 16 1994 
  Published    1995 
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 Identifier    ZNA-1995-50a-0525 
 Volume    50 
66Author    H. Dobrileit, ZüchnerRequires cookie*
 Title     
 Abstract    Dedicated to Professor Dr. E. Wicke on occasion of his 80th birthday Characteristic secondary ion emission patterns of several metal-hydrogen systems have been measured by SIMS to get information about the metal-hydrogen bonding and the structure of these systems. Results on SmCo5D" and LaNi5Hn, and on H-D-loaded samples of the pure components are presented. The emission patterns of the secondary ions show a stronger bonding of hydrogen to Co and Ni than to Sm and La, although these transition metals, contrary to Sm or La, do not form stable hydrides under normal conditions. In these AB5-compounds the transition metal seems to be transformed to a "hydride forming material" due to the presence of the rare earth element. The secondary ion emission patterns of the hydrogen loaded intermetallics are explained and compared to those of the hydrogen loaded pure components. The similarity in the secondary ion emission patterns of the SmCo5Dn and LaNi5H" systems points to a general characteristic of AB5H" materials. S I M S In v e s tig a tio n s o n th e S m C o 5D " a n d L a N i 5H B S y s te m s 
  Reference    Z. Naturforsch. 50a, 533—538 (1995); received December 16 1994 
  Published    1995 
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 Identifier    ZNA-1995-50a-0533 
 Volume    50 
67Author    Ch Karmonik®, R. Hempelmann3, Th Matzkeb, T. SpringerbRequires cookie*
 Title     
 Abstract    r o to n D iffu s io n in S tr o n tiu m C e r a te C e ra m ic s s tu d ie d b y Q u a s ie la s tic N e u tr o n S c a tte r in g a n d Im p e d a n c e S p e c tr o s c o p y Perovskite structured strontium cerate doped with ytterbium and water, e.g. SrCe0 95Yb005 H0 02O2 985, is a well known proton conductor at elevated temperatures. We have studied its proton conductivity or diffusivity, respectively, by impedance spectroscopy, IS, and by quasielastic neutron scattering, QENS. While the former method yields a macroscopic proton diffusion coefficient, the latter method allows to elucidate the microscopic proton diffusion mechanism. It consists of a se­ quence of free diffusion and trapping/escape events with the Yb3 + ions acting as trapping centers. The self-diffusion coefficient obtained with QENS agrees with the conductivity diffusion coefficient obtained with IS. 
  Reference    Z. Naturforsch. 50a, 539—548 (1995) 
  Published    1995 
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 Identifier    ZNA-1995-50a-0539 
 Volume    50 
68Author    P. Hugo, J. Leonhardt, S. WagnerRequires cookie*
 Title     
 Abstract    o m p u te r -A id e d A r r h e n i u s -E v a l u a ti o n o f K in e tic D a ta Dedicated to Prof. E. Wicke on the occation of his 80th birthday A new evaluation method is presented to analyse the temperature dependance of reactions with rates that can be separated into a temperature dependent and a concentration dependent part. The proposed method allows to evaluate isothermal, adiabatic, isoperibolic and temperature programmed measurements in an unified manner. To determine the activation energy an Arrhenius law but no explicite kinetic model has to be assumed. The application of the method is demonstrated using experimental data of different reactions from former investigations. 
  Reference    Z. Naturforsch. 50a, 549—554 (1995); received December 16 1994 
  Published    1995 
  Keywords    Kinetic modeling, non-isothermal measurements, reaction kinetic, Arrhenius law, Differential Scanning Calorimetry 
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 Identifier    ZNA-1995-50a-0549 
 Volume    50 
69Author    Rudolf HoppeRequires cookie*
 Title    New Pathways to use it as a Tool in Solid State Chemistry (Part 1)  
 Abstract    Zeiten und Winde des Lebens verwehen uns Menschen im Räume -doch der Erinnerung Bild bindet für immer das Herz. The Born-Haber Cycle (BHC) is critically reviewed, the origin of severe limitations in its appli­ cation is shown. Partly this is based on the construction of the third step, partly it is connected with the fact that most of the "classical" anions of inorganic chemistry are instable, "unobservable" gaseous entities. The Madelung Part of Lattice Energy, MAPLE*, is extentionally analyzed (e.g. Ti02) to demonstrate that the similarity of thermodynamical properties like A//298 of all modifica­ tions, reflected in MAPLE, is non-trivial. The analogous analysis with e.g. BaTi03 proves that neither the classical "central ion" (here Ti4 +) nor the "completing" cation (here Bai +) but the "anions" coordinating the last mentioned cation BaO gain energy and, in this sense, "stabilize" the complex. Even simple compounds (e.g. A-La20 3) show surprising geometrical arrangements, in striking contrast to often used but simple minded concepts like "Bond Length/Bond Strength" and its derivatives like CHARDI, whereas such "oddities" are explained by MAPLE. The application of the theorem of additivity of MAPLE (MAPLEpoiynary = X MAPLEbinary), that passes even in the case of hydrates, and its limitations are discussed. Guided by MAPLE, surprisingly complicated structures (e.g. Cs2Li3I5) of polynary derivatives of structurally exceedingly simple binary com­ pounds become "understandable". If "molecular" entities like SÖ3 are involved, limitations can be excluded using "increments". Last not least, MAPLE is the first known guide to a multi-dimen-sional but strict scheme of characterisation of Solid State Structures in the sense of Linne's ideas, based on geometrical facts only. 
  Reference    Z. Naturforsch. 50a, 555—567 (1995); received December 16 1994 
  Published    1995 
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 Identifier    ZNA-1995-50a-0555 
 Volume    50 
70Author    Steffen Hein, Dieter VortmeyerRequires cookie*
 Title    W a n  
 Abstract    d g e k ü h lte c h e m is c h e F e s tb e t tr e a k t o r e n u n d d e re n M o d e llie ru n g m it E in -u n d Z w e ip h a s e n m o d e lle n Modelling of wall-cooled fixed-bed chemical reactors with one-and two-phase models Experimentally determined temperature and concentration profiles in a wall-cooled fixed-bed catalytic reactor are modelled equally well by the quasihomogeneous and heterogeneous model at a Reynolds number of Rep = 32. In both cases the good agreement between measured and calculated data is only achieved if the equations are solved for a radially uneven flow distribution and for a boundary condition at the reactor wall ensuring the same temperature of catalyst and wall at the contact point. The numerical solutions of the two-phase model demonstrate that the differences between solid and fluid temperature are low, even in the presence of a highly exothermic reaction like the oxidation of ethane. 
  Reference    Z. Naturforsch. 50a, 568—576 (1995); received December 16 1994 
  Published    1995 
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 Identifier    ZNA-1995-50a-0568 
 Volume    50 
71Author    H. Teuscher, P. KramerRequires cookie*
 Title     
 Abstract    e c o m p o s itio n o f P l a n e W a v e s in to I r r e d u c i b le R e p r e s e n t a t i o n s o f S p a c e G r o u p s Using a relation between representation theory of crystallographic space groups and a Dirichlet type of boundary problem for the Laplacian, we derive the solutions for the Dirichlet problem, as well as for a similar Neumann boundary problem, by a complete decomposition of plane waves into irreducible representations of a particular space group. This decomposition corresponds to a basis transformation in L2(Q) and yields a new set of basis functions adapted to the symmetry of the lattice considered. 
  Reference    Z. Naturforsch. 50a, 577—583 (1995); received December 16 1994 
  Published    1995 
  Keywords    Group Theory, Representation Theory, Boundary-Value problem, Basis Set for Band Calculations, Free Particle in a Box 
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 Identifier    ZNA-1995-50a-0577 
 Volume    50 
72Author    Barbara Szafrańska, Zdzisław PająkRequires cookie*
 Title     
 Abstract    o le c u la r M o tio n in S o lid T e tr a e th y l-a n d T e tra p ro p y la m m o n iu m T e tr a f lu o r o b o r a te s Proton and fluorine NMR second moments and spin-lattice relaxation times for polycrystalline tetraethyl-and tetrapropylammonium tetrafluoroborates have been measured over a wide range of temperatures. Solid-solid phase transitions were found for both compounds and confirmed by DSC. Methyl group C3 reorientation followed by more complex cation motions was evidenced in the low temperature phases. Overall cation reorientation characterises the high temperature phases of both compounds. Isotropic anion reorientation was found in both salts in both phases. 
  Reference    Z. Naturforsch. 50a, 584—588 (1995); received August 15 1994 
  Published    1995 
  Keywords    NMR, Molecular motions, Phase transitions 
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 Identifier    ZNA-1995-50a-0584 
 Volume    50 
73Author    Ingo Dierking, Frank Gießelmann, Peter ZugenmaierRequires cookie*
 Title     
 Abstract    n O p tic a l M e th o d f o r th e D e te r m in a tio n o f th e C h o le s te r ic P itc h in L iq u id C r y s ta ls Preparation of a cholesteric liquid crystalline phase in planar orienting liquid crystal cells exhibits discontinuous colour changes with temperature when viewed between crossed polarizers. The trans­ mission spectra of such a system can be described by a modified de Vries equation, with the bire­ fringence dispersion included in a simplified single-band model. With a suitable choice of the cell gap as compared to the cholesteric pitch, the procedure can be used as a new method to determine the temperature dependence of the cholesteric pitch. 
  Reference    Z. Naturforsch. 50a, 589—594 (1995); received December 17 1994 
  Published    1995 
  Keywords    Liquid crystal, cholesteric mesophase, pitch determination, birefringence dispersion, twist inversion 
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 Identifier    ZNA-1995-50a-0589 
 Volume    50 
74Author    Bo Gestbloma, Stanislaw UrbanRequires cookie*
 Title      
 Abstract    The time domain spectroscopy (TDS) method has been used for the measurement of the complex dielectric permittivity in the isotropic phase and for perpendicular and parallel orientations in the nematic phase of 5PCH (4-(/raHs-4-pentyl-cyclohexyl)-benzonitrile). The accessible frequencies range from ca 15 MHz to ca. 1.5 GHz. The obtained spectra are well consistent with the spectra measured recently in the frequency domain (T. Brückert et al., Mol. Cryst. Liq. Cryst., in press). From the relaxation times r fl, r x and t is we have calculated the activation enthalpies and the retar­ dation factors gn and g ± that allow to obtain the nematic potential q. The validity of some assump­ tions of the mean-field theories of the nematic state are discussed. Key words: Liquid crystals, 4-(/ra«s-4-pentyl-cyclohexyl)-benzonitrile (5PCH), dielectric relax­ ation, time domain spectroscopy. 
  Reference    Z. Naturforsch. 50a, 595—600 (1995); received November 25 1995 
  Published    1995 
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 Identifier    ZNA-1995-50a-0595 
 Volume    50 
75Author    F. WinterbergRequires cookie*
 Title    Q u a n  
 Abstract    tu m M e c h a n ic s D e riv e d fro m B o ltz m a n n 's E q u a tio n f o r th e P l a n c k A e th e r In the Planck aether hypothesis it is assumed that space is densely filled with an equal number of locally interacting positive and negative Planck masses obeying a nonrelativistic law of motion. If described by a quantum mechanical two-component nonrelativistic nonlinear operator field equa­ tion, this model has a spectrum of particles greatly resembling the particles of the standard model, with Lorentz invariance as a derived dynamical symmetry valid in the limit of energies small com­ pared to the Planck energy. Here we show that quantum mechanics itself can be derived from the Newtonian mechanics of the Planck aether as an approximate solution of the Boltzmann equation for the positive and nega­ tive Planck masses, with departures from quantum mechanics suppressed by the Planck length. 
  Reference    Z. Naturforsch. 50a, 601—605 (1995); received December 13 1994 
  Published    1995 
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 Identifier    ZNA-1995-50a-0601 
 Volume    50 
76Author    A. M. Raevsky, G. K. Semin, T. L. KhotsyanovaRequires cookie*
 Title    3 5 C I N Q  
 Abstract    R o f I m p u r ity M o le c u le s o f T e tra c h lo r id e s o f G ro u p IV E le m e n ts in M a t r i x C r y s ta ls o f G ro u p I V E le m e n t H a lid e s 35C1 NQR spectra of the impurity molecules E'C14 (1.5-5% mol) (E' = C, Si, Ge, Sn) in the matrix crystals of Group IV tetrachlorides EC14 (E = Si, Ge, Sn, Ti) have been measured at 77 K. The mixtures of the above components are substitution solid solutions. Changes in the 35C1 NQR spectra of the impurity molecules have been analysed as to packing factors and nearest environment. 
  Reference    Z. Naturforsch. 50a, 606—610 (1995); received December 8 1994 
  Published    1995 
  Keywords    NQR, 35C1, solid solutions, tetrachlorides of Group IV elements 
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 Identifier    ZNA-1995-50a-0606 
 Volume    50 
77Author    Josef Böcker3, Eckhard Spohrb, Karl Heinzinger2Requires cookie*
 Title    Density Profiles at a Water/Liquid Mercury Interface  
 Abstract    A molecular dynamics simulation of the water/liquid mer­ cury interface has been performed. The potentials describing the water-metal interactions are derived from ab initio calcu­ lations of a water molecule on a mercury cluster. The mer­ cury-mercury potential is based on pseudopotential theory. As a first result the density profiles of the mercury, oxygen, and hydrogen atoms are presented. 
  Reference    Z. Naturforsch. 50a, 611—612 (1995); received March 23 1995 
  Published    1995 
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 Identifier    ZNA-1995-50a-0611_n 
 Volume    50 
78Author    C. Cramer3, K. Funke3, T. Saatkamp3, D. Wilmer3, M. D. IngrambRequires cookie*
 Title     
 Abstract    ig h -F re q u e n c y C o n d u c tiv ity P l a te a u a n d Io n ic H o p p in g P r o c e s s e s in a T e r n a r y L ith iu m B o r a te G la s s Dedicated to Prof. W . Müller-Warmuth on the occasion of his 65th birthday Complete conductivity spectra of a lithium ion conducting glass of composition B20,-0.56Li20 -0.45 LiBr have been taken at twelve temperatures from 173 K to 573 K, covering the frequency range from a few Hertz up to about 50 THz. For the first time, a separation of the hopping and vibrational contributions to the spectra has been performed. The resulting frequency dependent hopping conductivity displays a high-frequency plateau similar to those known to exist in crystalline solid electrolytes like RbAg4I5 and Na-/?-alumina. In the dispersive regime of the conductivity, there is an increase of the apparent power-law exponent from p = 0.6 to q = 1.3. The spectra are evaluated by combined application of the jump relaxation model and the dynamic structure model. Besides the translational hopping of the lithium ions via the preferred A sites, more localized kinds of motion are also detected, viz., hops into the less favoured C sites (and mostly back again) as well as smaller displacements of the ions within their local environment. 
  Reference    Z. Naturforsch. 50a, 613—623 (1995); received November 8 1995 
  Published    1995 
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 Identifier    ZNA-1995-50a-0613 
 Volume    50 
79Author    M. A. Baker, J. Haupt, W. GisslerRequires cookie*
 Title      
 Abstract    Dedicated to Prof. W . Müller-Warmuth on the occasion of his 65 th birthday For the determination of x and y of TiN, and TiB^N coatings two Auger methods are presented, one circumventing and the other minimising the difficulties arising from the overlap of the KL23L23 and L3M23M23 peaks of N and Ti, respectively. The first method, developed for TiNx coatings, is based on the L3M23M45 valence band peak of Ti which develops a distinct second peak on nitridation, 3.9 eV below the main peak, labelled the L3M23Hybrid peak. After a simple Shirley background correction, a linear dependence of the L3M23Hybrid/L3M23M45 peak height ratio on the N/Ti ratio was found. This allows the determination of the N content of a TiNx compound. For TiBxNy coatings, a more complex shape of the L3M23M45 peak is obtained due to the presence of more than one phase, rendering this peak unusable for quantification. Therefore the N/Ti ratio is obtained from the L3M23M23/L3M23M4, peak intensity ratio for Ti. To minimise influences of the fine structure and improve the accuracy of the method, the negative peak excursions were artificially broadened. The N/Ti ratio so obtained is used in combination with the B concentration determined from the KL23L23 peak of B to yield the Ti-B-N composition. D e te rm in a tio n o f th e C o m p o sitio n o f T iN x a n d T iB xN j, F ilm s by A E S 
  Reference    Z. Naturforsch. 50a, 624—630 (1995); received December 9 1994 
  Published    1995 
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 Identifier    ZNA-1995-50a-0624 
 Volume    50 
80Author    U. Schlenz, A. Dölle, H. G. HertzRequires cookie*
 Title     
 Abstract    o le c u la r M o tio n in L iq u id s : T h e P a r ti a ll y R ig id M o le c u le 1,2 ,3 » 4 -T e tr a h y d r o -5 ,6 -D im e th y l-l ,4 -M e th a n o n a p h th a le n e . T e m p e r a tu r e D e p e n d e n c e o f 13C M a g n e tic R e la x a tio n a n d C o r r e la tio n T im e s Dedicated to Professor W . Müller-Warmuth on occasion of his 65 th birthday For the hydrocarbon l,2,3,4-tetrahydro-5,6-dimethyl-l,4-methanonaphthalene (5,6-Me2-THMN) 13C longitudinal relaxation times and NOE factors were measured over a wide temperature range at frequencies of 22.63 and 100.62 MHz. Additionally, 13C transversal relaxation times were mea­ sured at 100.62 MHz. The relaxation data show that the dispersion region is already reached at moderate temperatures. The experimental data were modeled by the combination of the Vogel-Fulcher-Tammann ansatz and a scaling of the dipolar coupling constant with a factor of 0.70. From the fit of the data also activation parameters of the rotational motion of the molecules were obtained. Although the molecules of 5,6-Me2-THMN have a rigid structure (except the two inter­ nally rotating methyl groups), the model of the rotational diffusion of rigid bodies does not satisfactorily describe the relaxation data. 
  Reference    Z. Naturforsch. 50a, 631—642 (1995); received December 16 1994 
  Published    1995 
  Keywords    Liquids, Rotational Diffusion, Rotational Correlation Times, 13C Nuclear Magnetic Resonance, Relaxation 
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 Identifier    ZNA-1995-50a-0631 
 Volume    50 
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