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1992[X]
181Author    H. G. Kreul, R. Waldinger, A. WürflingerRequires cookie*
 Title    Differential Thermal Analysis and Dielectric Studies on Neopentanol under Pressure  
 Abstract    Differential thermal analysis (DTA) and dielectric measurements have been performed on 2,2-di-methyl-l-propanol (neopentanol) up to 200 MPa. Neopentanol exhibits at least one orientationally disordered (ODIC) phase (solid I) that transforms at lower temperatures to a non-plastic phase (solid II). There is evidence of a further ODIC phase denoted as solid I'. The pressure dependence of the phase transitions and the dielectric behaviour up to frequencies of 13 MHz are described. Activation enthalpies and volumes are derived from the dielectric relaxation time and compared with results for other alcohols. 
  Reference    Z. Naturforsch. 47a, 1127—1134 (1992); received July 27 1992 
  Published    1992 
  Keywords    High pressure, DTA, Phase transitions, Dielectric constant, and relaxation 
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 Identifier    ZNA-1992-47a-1127 
 Volume    47 
182Author    S. V. Stockhausen, HornhardtRequires cookie*
 Title     
 Abstract    The dielectric spectra of liquid cyclopentanol, cyclohexanol, cycloheptanol and cyclooctanol are reported for frequencies up to 72 GHz and temperature 20 (cyclohexanol solid), 30 and 40 °C. The absorption spectra are peculiar in exhibiting a remarkably developed high frequency shoulder which is attributed to single molecule and internal motion, while the principal absorption is due to association as with other alcohols. 
  Reference    Z. Naturforsch. 47a, 1135—1137 (1992); received August 11 1992 
  Published    1992 
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 TEI-XML for    default:Reihe_A/47/ZNA-1992-47a-1135.pdf 
 Identifier    ZNA-1992-47a-1135 
 Volume    47 
183Author    M. Klatt, M. Röhrig, H. Gg, WagnerRequires cookie*
 Title    About the Radical Formation in the Pyrolysis of Formic Acid at High Temperatures  
 Abstract    The formation of radicals in the HCOOH pyrolysis was investigated in the temperature and density range between 1450 and 2450 K and 2 • 10~ 6 and 1.2 • 10" 5 mol /cm 3 , respectively. The small amount of radicals found indicates that a radical forming reaction path in the formic acid pyrolysis is smaller than 0.2% of the total decomposition rate. 
  Reference    Z. Naturforsch. 47a, 1138—1140 (1992); received September 12 1992 
  Published    1992 
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 TEI-XML for    default:Reihe_A/47/ZNA-1992-47a-1138.pdf 
 Identifier    ZNA-1992-47a-1138 
 Volume    47 
184Author    Ilona Merke, Helmut DreizlerRequires cookie*
 Title    Quadrupole Hyperfine Structure in the Rotational Spectra of Sulfur Dichloride  
 Abstract    The nuclear quadrupole coupling of [ 35 C1, 35 C1]-and [ 35 Cl, 37 Cl]-sulfur dichloride was investigated using waveguide microwave Fourier transform (MWFT) spectroscopy. The analysis was performed with direct diagonalization of the Hamilton matrix. Due to some measured transitions with near degeneracy it was possible to determine the off diagonal elements xab °f th e quadrupole coupling tensor with high accuracy. S 35 C1 2 : x afl (35 Cll) = x aa (35 C12) --38.671(11) MHz, Zcc (35 CU) = Xcc (35 C\2) = 47.7945(66) MHz, Zflfc (35 Cll) = —x ab (C\2) = ± 53.76(23) MHz. S 35 C1 36 C1: * aa (35 Cl) = -37.756(13) MHz, x cc (35 Cl) = 47.7915(75) MHz, X ah (35 Cl) = ± 54.018(83) MHz, * aa (35 Cl) --31.217(13) MHz, X cc (37 C1) = 37.6759(66) MHz, x ab (31 C1) = + 42.285(98) MHz. We also determined the quadrupole coupling constants in their principal axes system. In comparison with the restructure the z-axis of the coupling tensor was found to be tilted 1.3° out of the S-Cl bond axis. 
  Reference    Z. Naturforsch. 47a, 1141—1144 (1992); received August 26 1992 
  Published    1992 
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 TEI-XML for    default:Reihe_A/47/ZNA-1992-47a-1141.pdf 
 Identifier    ZNA-1992-47a-1141 
 Volume    47 
185Author    H. D. Lutz, M. SchmidtRequires cookie*
 Title    Lattice Vibration Spectra. LXXV. IR Single Crystal Reflection Spectra of Sr(C10 3 ) 2  
 Abstract    Polarized infrared reflection spectra of Sr(C10 3) 2 single-crystal plates are recorded and analysed for the frequencies of the transversal and longitudinal optical zone-centre phonon modes and other oscillator parameters by Kramers-Kronig analyses and both the classical 3 parameter (dielectric sum-function) and the 4 parameter (factorized form) oscillator-fit methods. The frequencies com-puted are compared with the results of previous single-crystal Raman studies. Because of the great distortion of the C10 3 ions (site symmetry CJ, no intraionic coupling of the CIO vibrations to symmetric (vj and asymmetric (v 3) stretching modes occurs. The TO/LO splittings of respective CIO unit-cell group modes rank like the vector elements of the corresponding CIO bonds with respect to the crystal axes. 
  Reference    Z. Naturforsch. 47a, 1145 (1992); received August 17 1992 
  Published    1992 
  Keywords    Strontium chlorate, IR reflection spectra, Oscillator-fit calculations, LO phonon modes 
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 TEI-XML for    default:Reihe_A/47/ZNA-1992-47a-1145.pdf 
 Identifier    ZNA-1992-47a-1145 
 Volume    47 
186Author    Ilona Merke, Helmut DreizlerRequires cookie*
 Title    Nuclear Quadrupole Coupling in the Rotational Spectrum of Thionyl Chloride  
 Abstract    We report on the analysis of the chlorine quadrupole hyperfine structure of thionyl chloride, S0 35 C1 Cl, observed with a molecular beam microwave Fourier transform spectrometer. 
  Reference    Z. Naturforsch. 47a, 1150—1152 (1992); received September 12 1992 
  Published    1992 
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 TEI-XML for    default:Reihe_A/47/ZNA-1992-47a-1150.pdf 
 Identifier    ZNA-1992-47a-1150 
 Volume    47 
187Author    Ilona Merke, Helmut DreizlerRequires cookie*
 Title    Quadrupole Hyperfine Structure in the Rotational Spectra of Sulfuryl Chloride  
 Abstract    The nuclear quadrupole coupling of [ 35 C1, 35 C1]-and [ 35 Cl, 37 Cl]-sulfuryl chloride, S0 2 C1 2 was investigated using waveguide microwave Fourier transform (MWFT) spectroscopy. The analysis was performed with direct diagonalization of the Hamiltonian matrix. It was possible to determine the complete coupling tensor with high accuracy. S0 2 35 C1 2 : * aa (35 Cll) = * aa (35 C12) = -33.049(6) MHz, Xcc (35 C11) = x cc (35 C12) = 40.356 (9) MHz, Zfli (35 CU) = -x afc (35 C12) = + 52.67 (63) MHz. S0 2 35 C1 37 C1: x aa (35 Cl)= -29.582(17) MHz, * cc (35 Cl) = 40.340(25) MHz, Zafc (35 Cl)= +52.3(14) MHz, Xflfl (37 Cl)= -28.723(18) MHz, * cc (37 Cl) = 31.822(28) MHz, * ai ,(37 Cl) = + 37.3(19) MHz. We also determined the quadrupole coupling constants in their principal axes system. In com-parison with the structure, the z-axis of the coupling tensor was found to be tilted 2.0° out off the S-Cl bond axis. 
  Reference    Z. Naturforsch. 47a, 1153—1156 (1992); received September 12 1992 
  Published    1992 
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 Identifier    ZNA-1992-47a-1153 
 Volume    47 
188Author    S. Głowinkowski, S. Jurga, E. SzcześniakRequires cookie*
 Title    Interrelation Between Molecular Motions and Structure in Solid Trimethylamine-boron-trichloride as Studied by NMR  
 Abstract    The temperature dependences of proton second-moment and spin-lattice relaxation times (T : and T le) have been measured in solid (CH 3) 3 NBC1 3 . The nature of reorientation processes occurring in the complex has been established and the activation parameters determined. The motions are discussed in relation to the molecular structure of the complex. 
  Reference    Z. Naturforsch. 47a, 1157—1160 (1992); received July 14 1992 
  Published    1992 
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 TEI-XML for    default:Reihe_A/47/ZNA-1992-47a-1157.pdf 
 Identifier    ZNA-1992-47a-1157 
 Volume    47 
189Author    H. KötzRequires cookie*
 Title    A Technique to Classify the Similarity Solutions of Nonlinear Partial (Integro-)Differential Equations. I. Optimal Systems of Solvable Lie Subalgebras  
 Abstract    Lie group analysis is a powerful tool for obtaining exact similarity solutions of nonlinear (integro-) differential equations. In order to calculate the group-invariant solutions one first has to find the full Lie point symmetry group admitted by the given (integro-)differential equations and to determine all the subgroups of this Lie group. An effective, systematic means to classify the similarity solutions afterwards is an "optimal system", i.e. a list of group-invariant solutions from which every other such solution can be derived. The problem to find optimal systems of similarity solutions leads to that to "construct" the optimal systems of subalgebras for the Lie algebra of the known Lie point symmetry group. Our aim is to demonstrate a practicable technique for determining these optimal subalgebraic systems using the invariants relative to the group of the inner automorphisms of the Lie algebra in case of a finite-dimensional Lie point symmetry group. Here, we restrict our attention to optimal subsystems of solvable Lie subalgebras. This technique is applied to the nine-dimensional real Lie point symmetry group admitted by the two-dimensional non-stationary ideal magneto-hydrodynamic equations. 
  Reference    Z. Naturforsch. 47a, 1161—1173 (1992); received July 9 1992 
  Published    1992 
  Keywords    Group theory, Magnetohydrodynamics, Compressible flows 
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 TEI-XML for    default:Reihe_A/47/ZNA-1992-47a-1161.pdf 
 Identifier    ZNA-1992-47a-1161 
 Volume    47 
190Author    Berthold-Georg Englert, MarianO. Scully, Georg Süssmann, Herbert WaltherRequires cookie*
 Title    Surrealistic Böhm Trajectories  
 Abstract    A study of interferometers with one-bit which-way detectors demonstrates that the trajectories, which David Böhm invented in his attempt at a realistic interpretation of quantum mechanics, are in fact surrealistic, because they may be macroscopically at variance with the observed track of the parti-cle. We consider a two-slit interferometer and an incomplete Stern-Gerlach interferometer, and propose an experimentum crucis based on the latter. 
  Reference    Z. Naturforsch. 47a, 1175—1186 (1992); received September 22 1992 
  Published    1992 
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 Identifier    ZNA-1992-47a-1175 
 Volume    47 
191Author    T. Schilling, B. Tesche, G. LehmpfuhlRequires cookie*
 Title    Reconstructed Au (100) Surface Imaged with Scanning Tunneling Microscopy in Air  
 Abstract    Scanning tunneling microscopy (STM) of Au(100) was performed in air with a NanoScope II. Regions of 150 x 150 nm with atomatically flat areas fragmented by atomic steps were observed. The reconstructed (100) surface, deformed to a twisted hexagon with an interatomic distance of 0.27 + 0.02 nm, could be seen and a corrugation of about 0.05 nm depth was measured. These results are in good agreement with Reflection Electron Microscopy measurements and STM investigations in UHV. 
  Reference    Z. Naturforsch. 47a, 1187—1190 (1992); received September 19 1992 
  Published    1992 
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 TEI-XML for    default:Reihe_A/47/ZNA-1992-47a-1187.pdf 
 Identifier    ZNA-1992-47a-1187 
 Volume    47 
192Author    YuA. Babanov, A. F. Sidorenko, V. R. Shvetsov, M. Bionducci, G. Licheri, G. Navarra, A. L. Ageev, V. V. VasinRequires cookie*
 Title    Combination of EXAFS and Differential Anomalous X-ray Scattering for Studying Ni 2 Zr Amorphous Alloy  
 Abstract    In this paper we report a first application of the new idea of combining EXAFS and differential anomalous scattering techniques to obtain partial distribution functions for a binary amorphous sample. This method has been successfully employed in extracting Ni-Ni and Ni-Zr pair distribu-tion functions for Ni 2 Zr prepared by mechanical alloying. A comparison with results from previous studies is also reported. 
  Reference    Z. Naturforsch. 47a, 1191—1196 (1992) 
  Published    1992 
  Keywords    Metallic glasses, Synchrotron radiation, Partial pair distribution functions 
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 TEI-XML for    default:Reihe_A/47/ZNA-1992-47a-1191.pdf 
 Identifier    ZNA-1992-47a-1191 
 Volume    47 
193Author    Wolfram Bodenmüller, Andreas Ruoff, Laurent ManceronRequires cookie*
 Title    FTIR Study of the v 12 and the v 12 + v 14 — v 14 Bands of 1,3,5-Triazine Near 740 cm -1  
 Abstract    The infrared spectrum of the v 12 fundamental and its accompanying hot band v 12 + v 14 — v 14 of triazine has been measured by means of a Fourier transform spectrometer with a resolution of about 0.0023 cm" 1 . A total of about 2779 rovibrational transitions has been assigned. The ground state constants have been considerably improved whilst the parameters for the excited states tf 12 =l, i; 14 = l and tf 12 =i> 14 = l have been obtained for the first time. The standard deviations were 2.92 • 10" 4 cm" 1 for the ground state constants and 1.53 • 10" 4 cm 1 for the excited state parame-ters of v 12 showing the latter to be unperturbed. The upper state of the hot band v 12 + v 14 — v 14 was found to be perturbed by an accidental resonance. 
  Reference    Z. Naturforsch. 47a, 1197—1203 (1992); received October 20 1992 
  Published    1992 
  Keywords    1, 3, 5-triazine, High resolution FTIR spectroscopy, Ground state constants Funda-mental constants, Hot band constants 
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 Identifier    ZNA-1992-47a-1197 
 Volume    47 
194Author    A. Kawski, B. Kukliński, A. KubickiRequires cookie*
 Title    Isomerization of Diphenyl Polyenes. Part III. Absorption and Fluorescence Properties of l,4-Diphenyl-l,3-butadiene in Polyvinyl alcohol) Film  
 Abstract    The effect of temperature on the absorption and fluorescence properties of l,4-diphenyl-l,3-buta-diene (DPB) in polyvinyl alcohol) film (PVA) was investigated in the range from 293 to 423 K. Upon heating above 353 K, the optical density in the long wavelength region (at 339 nm) increases five times only, whereas for l,6-diphenyl-l,3,5-hexatriene (DPH) and l,8-diphenyl-l,3,5,7-octatetraene (DPO) ten and twenty times, respectively. However, the total quantum yield ($ F = 0.68) at 293 K is greater than that for the trans-trans form (<P F = 0.63) and decreases with growing temperature. Both this effect and broadening effect in the fluorescence band at 293 K evidence the existence of two emission centres, i.e. the trans-trans and cis-trans conformers. 
  Reference    Z. Naturforsch. 47a, 1204—1210 (1992); received November 11 1992 
  Published    1992 
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 Identifier    ZNA-1992-47a-1204 
 Volume    47 
195Author    M. E. Grypeos, G. A. Lalazissis, S. E. Massen, C. P. PanosRequires cookie*
 Title    Debye-Waller Type Expressions for the Nuclear Elastic Form Factors at Small Momentum Transfers  
 Abstract    The problem of estimating the nuclear elastic form factors in Born approximation is discussed in the region of small momentum transfers q. It is shown that approximate expressions of the Debye-Waller type are suitable for estimates of these form-factors in the oscillator shell model for sufficiently small q and compare favorably with other simple expressions. 
  Reference    Z. Naturforsch. 47a, 1211—1216 (1992); received June 30 1992 
  Published    1992 
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 Identifier    ZNA-1992-47a-1211 
 Volume    47 
196Author    F. WinterbergRequires cookie*
 Title    Cosmological Implications of the Planck Aether Model for a Unified Field Theory  
 Abstract    In the previously proposed Planck aether model of a unified theory, the vacuum ground state consists of a dense assembly of positive and negative Planck masses obeying an exactly nonrelativis-tic law of motion. The Planck aether is superfluid, and it can without expenditure of energy form a tangle of quantized vortex filamants permitting the transmission of two types of waves: One associated with a symmetric displacement of the vortex lattice leading to gravitational waves, and one associated with an antisymmetric displacement leading to electromagnetic waves. Dirac spinors are explained in this model as excitons made up from positive and negative energy resonances of the vortex lattice. Because the number of positive and negative Planck masses is assumed to be equal, the cosmo-logical constant is equal to zero. With the Dirac spinors formed as bound states from the Planck aether, the sum of the positive kinetic energy and negative gravitational energy must remain exactly equal to zero, resulting in ß = l as the exact value for the cosmological mass parameter. To make up for the unobserved missing mass, estimated to be about 10 times larger than the baryonic mass, it is conjectured that this mass consists of rotons, which in the superfluid Planck aether would come from the cut-off of the energy spectrum near the Planck energy. Because of their unusual dispersion relation, rotons possess a large momentum, even if their velocity vanishes. They are, for this reason, a promising candidate for the nonbaryonic dark matter, combining properties of hot and cold dark matter. The critical value Q= 1 requires that the number density of the rotons is equal to n r cs 2 x 10" 25 cm -3 . This value corresponds to an average distance of separation between the rotons of the order n~ 1/3 ~ 6000 km. The small number of rotons per unit volume combined with their weak gravitational coupling constant would make it difficult to detect them directly, but the gravitational field these roton masses generate in the vicinity of galaxies could explain the observed flat rotation curves of disc galaxies. Finally, because the gravitational waves have a cut-off at the vortex lattice scale at 10 15 -10 16 GeV, there can be no singularity in the course of a gravitational collapse, as it happens for solutions of Einstein's gravitational field equations. A generalization of Einstein's gravitational field Lagrangian, taking into account the existence of a smallest wave length, rather predicts a conversion of all mass into electromagnetic (or gravitational) radiation in approaching the singularity. The predicted con-version of mass into radiation in the course of gravitational collapse may provide an explanation for the large energy release of quasars. 
  Reference    Z. Naturforsch. 47a, 1217—1226 (1992); received June 15 1992 
  Published    1992 
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 Identifier    ZNA-1992-47a-1217 
 Volume    47 
197Author    R. C. Sharma, SunilRequires cookie*
 Title    Rayleigh-Taylor Instability of a Partially Ionized Plasma in a Porous Medium in Presence of a Variable Magnetic Field  
 Abstract    The Rayleigh-Taylor instability of a partially ionized plasma in a porous medium is considered in the presence of a variable magnetic field perpendicular to gravity. The cases of two uniform partially ionized plasmas separated by a horizontal boundary and exponentially varying density, viscosity, magnetic field and neutral particle number density are considered. In each case, the magnetic field succeeds in stabilizing waves in a certain wave-number range which were unstable in the absence of the magnetic field, whereas the system is found to be stable for potentially stable configuration/stable stratifications. The growth rates both increase (for certain wave numbers) and decrease (for different wave numbers) with the increase in kinematic viscosity, medium permeability and collisional frequency. The medium permeability and collisions do not have any qualitative effect on the nature of stability or instability. 
  Reference    Z. Naturforsch. 47a, 1227—1231 (1992); received July 8 1992 
  Published    1992 
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 Identifier    ZNA-1992-47a-1227 
 Volume    47 
198Author    A. Klemm, A. Banerjee, S. HoernesRequires cookie*
 Title    Further Study of Intersectorial Isotope Fractionation in Quartz  
 Abstract    It is shown that the intersectorial boundary in crystals must be straight if the intersectorial isotope effect is to be measured in the presence of isotopical mantle zoning. 
  Reference    Z. Naturforsch. 47a, 1232—1234 (1992); received November 15 1992 
  Published    1992 
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 TEI-XML for    default:Reihe_A/47/ZNA-1992-47a-1232.pdf 
 Identifier    ZNA-1992-47a-1232 
 Volume    47 
199Author    A. L. Alexe-Ionescu, R. Barberi, G. Barbero, T. Beica, R. Moldovan, I.N F MRequires cookie*
 Title    Surface Energy for Nematic Liquid Crystals: A New Point of View  
 Abstract    The surface energy of nematic liquid crystals is deduced from a phenomenological point of view. The idea of an easy surface tensor order parameter is proposed. An expression similar to a Landau expansion for the free energy of a system characterized by two order parameters is deduced and analysed. An interpretation similar to the one usually accepted for magnetic materials is given. The possibility of surface transitions induced by temperature is discussed. PACS 61.30 V, 64.70 Md, 61.30 Gd. 
  Reference    Z. Naturforsch. 47a, 1235—1240 (1992); received August 19 1992 
  Published    1992 
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 Identifier    ZNA-1992-47a-1235 
 Volume    47 
200Author    Michael Krüger, Ilona Merke, Helmut DreizlerRequires cookie*
 Title    Dipole Moment and High Resolution Rotational Spectrum of Fluorocyanoacetylene, FCCCN  
 Abstract    The title molecule was produced in a dc discharge from pentafluoro benzonitrile, C 6 F 5 CN. The dipole moment of fluorocyanoacetylene was found to be 3.05(15) D from the Stark effect. The 14 N nuclear quadrupole coupling constant % zz ~ — 4.2513 (47) MHz was determined from high resolution rotational spectra obtained with a pulsed nozzle molecular-beam microwave Fourier transform spectrometer. 
  Reference    Z. Naturforsch. 47a, 1241—1242 (1992); received September 18 1992 
  Published    1992 
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 Identifier    ZNA-1992-47a-1241 
 Volume    47 
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