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2000[X]
81Author    P. Babinec, E. Jakubíková, J. LeszczynskiRequires cookie*
 Title    Transition from Regular to Stochastic Vibrational Motion in Hj Molecule: An ab initio Classical Trajectory Study  
 Abstract    An ab initio classical trajectory study of intramolecular vibrational dynamics in H3 molecule revealed a transition from regular quasiperiodic to stochastic motion at an energy slightly higher than the zero point vibrational energy. 
  Reference    Z. Naturforsch. 55a, 478—480 (2000); received December 13 1999 
  Published    2000 
  Keywords    H3 Molecule, Vibrational Dynamics, ab initio Stochastic Motion 
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 TEI-XML for    default:Reihe_A/55/ZNA-2000-55a-0478.pdf 
 Identifier    ZNA-2000-55a-0478 
 Volume    55 
82Author    H. Dreizler, N. HansenRequires cookie*
 Title    High Resolution Microwave Spectroscopy of Ethyl Vinyl Ether: Accurate Determination of the Methyl Top Internal Rotation Barrier  
 Abstract    We have performed an investigation of the internal rotation of the methyl group in trans-cis ethyl vinyl ether by using molecular beam-Fourier transform Microwave (MB-FTMW) spectroscopy. Rotational spectra (up to J = 20) were recorded in the frequency region 4-19 GHz. Due to the internal rotation of the methyl group, some rotational transitions were split and the torsional barrier could be determined to V 3 (CH 3) = 1074.4(4) cm -1 . 
  Reference    Z. Naturforsch. 55a, 481—185 (2000); received February 9 2000 
  Published    2000 
  Keywords    Molecular Beam, Microwave Spectroscopy, Internal Rotation 
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 TEI-XML for    default:Reihe_A/55/ZNA-2000-55a-0481.pdf 
 Identifier    ZNA-2000-55a-0481 
 Volume    55 
83Author    HolgerS P Müller, Ralf Gendriesch, Frank Lewen, Gisbert WinnewisserRequires cookie*
 Title    The Submillimeter-wave Spectrum of the Formaldehyde Isotopomer H 2 C ls O in its Ground Vibrational State  
 Abstract    The ground state rotational spectrum of H 2 C ls Ohas been studied between 485 and 835 GHz with a sample of natural isotopic composition. Additional lines have been recorded around 130 GHz and near 1.85 THz, using a recently developed far-infrared laser-sideband spectrometer. The accurate new line frequencies were fit together with previously published data to obtain greatly improved spectroscopic constants. Both Watson's S and A reduced Hamiltonians have been employed yielding the rotational constants A s = 281 961.215 (82), B s = 36 902.275 51 (36), C S = 32 513.405 89 (36), A A = 281 961.371 (82), B A = 36 904.173 32 (91), and C A = 32 511.524 65 (86) MHz, respectively. 
  Reference    Z. Naturforsch. 55a, 486—490 (2000); received February 11 2000 
  Published    2000 
  Keywords    Rotational Spectroscopy, Interstellar Molecule, Astrophysics, Astrochemistry, Reduced Hamiltonian 
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 TEI-XML for    default:Reihe_A/55/ZNA-2000-55a-0486.pdf 
 Identifier    ZNA-2000-55a-0486 
 Volume    55 
84Author    HolgerS P Müller, Sven Thorwirth, Luca Bizzocchi, Gisbert WinnewisserRequires cookie*
 Title    The Submillimeter-wave Spectrum of Propyne, CH 3 CCH  
 Abstract    The ground state rotational spectrum of propyne has been studied in selected regions between 509 and 820 GHz spanning the quantum numbers 29 < J < 48 and 0 < K < 21. The accurate new line frequencies were fit together with previously published data to obtain greatly improved spectroscopic constants. 
  Reference    Z. Naturforsch. 55a, 491—94 (2000); received March 16 2000 
  Published    2000 
  Keywords    Rotational Spectroscopy, Interstellar Molecule, Astrophysics, Astrochemistry 
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 TEI-XML for    default:Reihe_A/55/ZNA-2000-55a-0491.pdf 
 Identifier    ZNA-2000-55a-0491 
 Volume    55 
85Author    Z. Akdeniz, M. P. TosiRequires cookie*
 Title    Static and Dynamic Structure of AU 2 C1 6 , AUA1C1 6 and AuFeCl 6 Clusters  
 Abstract    Fourfold coordination of trivalent metal ions by chlorines in molecular dimers changes from tetrahedral in A1 2 C1 6 and Fe 2 Cl 6 to planar in Au 2 Cl 6 . Within an ionic model we interpret this transition in the stable molecular shape as due to the quadrupolar polarizability of the gold(III) ion. We also demonstrate within the same model that a mixed tetrahedral-planar coordination is stable in AUA1C1 6 and AuFeCl 6 clusters. Quantitative comparisons are presented for the calculated molecular structures and vibrational frequencies against the available experimental data from crystalline diffraction and from Raman spectra of the crystal and of vapours. 
  Reference    Z. Naturforsch. 55a, 495—198 (2000); received February 12 2000 
  Published    2000 
  Keywords    Ionic Clusters, Molecular Vapours, Molecular Crystals 
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 TEI-XML for    default:Reihe_A/55/ZNA-2000-55a-0495.pdf 
 Identifier    ZNA-2000-55a-0495 
 Volume    55 
86Author    G. Concas, F. Congiu, G. Spano, A. Speghini, K. Gatterer, M. H. BartlRequires cookie*
 Title    Hyperfine Interactions at Lanthanide Sites in Europium Doped Oxide Glasses  
 Abstract    A series of europium doped Na 2 0-B 2 0 3 -Si0 2 , Pb0-Ge0 2 and Zn0-Te0 2 glasses was investi-gated by means of 5l Eu Mössbauer spectroscopy. The distortion of the Eu sites has been evaluated in the Na 2 0-B 2 0 3 -Si0 2 glasses by means of the quadrupolar interaction parameter and the asym-metry parameter; the disorder has been estimated by the line width. The occupancy of the sites in the borosilicate glasses is discussed. The correlation of the isomer shift with the optical basicity of the glass is discussed in terms of the degree of covalence of the Eu-0 bond. 
  Reference    Z. Naturforsch. 55a, 499—506 (2000); received December 14 1999 
  Published    2000 
  Keywords    Europium, Oxide Glasses, Borosilicates, Germanates, 15 'Eu Mössbauer Spectroscopy 
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 TEI-XML for    default:Reihe_A/55/ZNA-2000-55a-0499.pdf 
 Identifier    ZNA-2000-55a-0499 
 Volume    55 
87Author    I. Gutman, J. H. Koolen, V. Moulton, M. Parac, T. Soldatović, D. VidovićRequires cookie*
 Title    Estimating and Approximating the Total 7r-Electron Energy of Benzenoid Hydrocarbons  
 Abstract    Lower and upper bounds as well as approximate formulas for the total 7r-electron energy (E) of benzenoid hydrocarbons are deduced, depending only on the number of carbon atoms (n) and number of carbon-carbon bonds (to). These are better than the several previously known (n, m)-type estimates and approximations for E. 
  Reference    Z. Naturforsch. 55a, 507—512 (2000); received January 27 2000 
  Published    2000 
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 TEI-XML for    default:Reihe_A/55/ZNA-2000-55a-0507.pdf 
 Identifier    ZNA-2000-55a-0507 
 Volume    55 
88Author    Toshiyuki Takamuku, Toshio Yamaguchi, Masaki Asato, Masaki Matsumoto, Nobuyuki NishiRequires cookie*
 Title    Structure of Clusters in Methanol-Water Binary Solutions Studied by Mass Spectrometry and X-ray Diffraction  
 Abstract    The structure of clusters in methanol-water solutions in its dependence on the methanol mole fraction x M has been investigated by mass spectrometry on clusters isolated from submicron droplets by adiabatic expansion in vacuum and by X-ray diffraction on the bulk binary solutions. The mass spectra have shown that the average hydration number, (n m), of m-mer methanol clusters decreases with increasing x M , accompanied by two inflection points at x M = ~0.3 and ~0.7. The X-ray diffraction data have revealed a similar change in the number of hydrogen bonds per water and/or methanol oxygen atom at ~2.8 A. On the basis of both results, most likely models of clusters formed in the binary solutions are proposed: at 0 < x M < 0.3 the tetrahedral-like water cluster is the main species, at 0.3 < x M < 0.7 chain clusters of methanol molecules gradually evolve with increasing methanol content, and finally, at x M > 0.7 chain clusters of methanol molecules become predominant. The present results are compared with clusters previously found in ethanol-water binary solutions and discussed in relation to anomalies of the heat of mixing of methanol-water binary solutions. 
  Reference    Z. Naturforsch. 55a, 513—525 (2000); received February 11 2000 
  Published    2000 
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 TEI-XML for    default:Reihe_A/55/ZNA-2000-55a-0513.pdf 
 Identifier    ZNA-2000-55a-0513 
 Volume    55 
89Author    Maciej Bujak, Jacek ZaleskiRequires cookie*
 Title    Structure and Phase Transition in (C 2 H 5 NH 3 ) 3 Sb 2 CI 9 (C 2 H 5 NH 3 )SbCl 4 ; X-ray, DSC and Dielectric Studies  
 Abstract    The structure of (C 2 H 5 NH 3) 3 Sb 2 Cl 9 • (C 2 H 5 NH 3)SbCl 4 at 295 K has been determined. The crystals are orthorhombic, space group Pna2! (a -16.925(3), b = 24.703(5), c = 7.956(2) A, V = 3326.4(12) A 3 , Z = 4, d c = 2.018, d m = 2.01(1) Mg m -3). They consist of an anionic sublattice composed of two different polymeric zig-zag chains. One is built of Sb 2 Cl 9 3-units (corner sharing octahedra) and the other one is made of corner sharing SbCl^ 2-square pyramids. In the cavites between the polyanionic chains four non-equivalent ethylammonium cations are located. Three of them are disordered. The cations are connected to the anions by weak N-H...C1 hydrogen bonds. A first order phase transition of the order-disorder type was found at 274 K. It was studied by DSC, dielectric and X-ray diffraction methods. The mechanism of the phase transition is attributed to the ordering of at least one of the ethylammonium cations. 
  Reference    Z. Naturforsch. 55a, 526—532 (2000); received January 10 2000 
  Published    2000 
  Keywords    Ethylamine, Chloroantimonate(III), Structure, Phase Transition 
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 TEI-XML for    default:Reihe_A/55/ZNA-2000-55a-0526.pdf 
 Identifier    ZNA-2000-55a-0526 
 Volume    55 
90Author    A. Wiirflinger, M. SandmannRequires cookie*
 Title    Thermodynamic Measurements on w-Hexadecane (C 16 H 34 ) and /z-Heptadecane (C 17 H 36 ) at Elevated Pressures  
 Abstract    Specific volumes of/7-hexadecane (H-Ci 6 H 34) and n-heptadecane (fl-C 17 H 36) are presented for tem-peratures between 298 and 348 K and pressures up to 280 MPa. The melting curve for /7-C j6 H 34 was determined with differential thermal analysis. ThepVTdata are established for the liquid, solid and (in the case of J?-C| 7 H 36) rotator phases. Forn-C 16 H 34 the density immediately below the freezing temper-ature is larger than for n-Ci 7 H 36 immediately below the rotational transition temperature. Changes of volume, enthalpy, and entropy along the phase transitions are reported. The volume change of melting decreases distinctly with increasing pressure, whereas the volume change at the rotational transition is much less pressure-dependent. Enthalpy and entropy changes have been calculated with the aid of the Clausius-Clapeyron equation. 
  Reference    Z. Naturforsch. 55a, 533—538 (2000); received February 16 2000 
  Published    2000 
  Keywords    Hexadecane, Heptadecane, DTA, /?V7, High Pressure, Phase Transitions 
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 TEI-XML for    default:Reihe_A/55/ZNA-2000-55a-0533.pdf 
 Identifier    ZNA-2000-55a-0533 
 Volume    55 
91Author    Wen-Chen Zheng, Shao-Yi WuRequires cookie*
 Title    Explanation of the ^-factors and Hyperfine Structure Constants of Co 2+ in Tetragonal K 2 ZnF 4  
 Abstract    The formulas of the ^-factors g n , g ± and the hyperfine structure constants A,,. for 3d 7 ions in tetra-gonal octahedral crystals are established from a cluster approach. Differing from previous formulas, in these formulas the role of configuration interaction (CI)-and covalency (CO)-effects is considered, and the parameters related to both effects are obtained from the optical spectra and the structural parame-ters of the studied crystal. From these formulas, the EPR parameters g, and A t for K 2 ZnF 4 :Co 2+ are cal-culated. The results show good agreement with the observed values. The contributions to the EPR para-meters gi and 4, from the CI and CO effects, and the relationship between the sign of Ag {=g ± -g n) and the tetragonal distortion (elongated or compressed) of the ligand octahedron are discussed. 
  Reference    Z. Naturforsch. 55a, 539—544 (2000); received January 19 2000 
  Published    2000 
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 TEI-XML for    default:Reihe_A/55/ZNA-2000-55a-0539.pdf 
 Identifier    ZNA-2000-55a-0539 
 Volume    55 
92Author    Chandan Kr, A.Roy Das, ChowdhuryRequires cookie*
 Title    Complete Integrability Prolongation Structure and Backlund Transformation for the Konno-Onno Equation  
 Abstract    Painleve analysis is used to study the complete integrability of the recently proposed Konno-Onno equation, which also leads to a general form of solutions of the system. An independent study, using the prolongation theory, gives the explicit form of the Lax pair which is then used to obtain the Backlund transformation connecting two sets of solutions of the system. The existence of the Lax pair and the positive result of the Painleve test indicate the complete integrability of the system. 
  Reference    Z. Naturforsch. 55a, 545—549 (2000); received February 11 2000 
  Published    2000 
  Keywords    Integrability, Backlund Transformation, Prolongation Structure, Lie Algebra 
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 TEI-XML for    default:Reihe_A/55/ZNA-2000-55a-0545.pdf 
 Identifier    ZNA-2000-55a-0545 
 Volume    55 
93Author    A. B. Kawski, P. Kukliński, BojarskiRequires cookie*
 Title    Thermochromic Shifts of Absorption and Fluorescence Spectra and Excited State Dipole Moment of PRODAN  
 Abstract    Using the thermochromic shift method of absorption and fluorescence spectra, the dipole moments in the ground, /LLÜ, and excited. /i e , state are simultaneously determined for PRODAN in ethyl acetate. The obtained values for /i" and /i c are compared with those previously determined by the solvatochrom-ic method for two different Onsager radii, and a satisfactory agreement has been obtained. in the ground and excited states: PRODAN. 
  Reference    Z. Naturforsch. 55a, 550—554 (2000); received March 2 2000 
  Published    2000 
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 TEI-XML for    default:Reihe_A/55/ZNA-2000-55a-0550.pdf 
 Identifier    ZNA-2000-55a-0550 
 Volume    55 
94Author    ValentinP. Feshin, ElenaV. FeshinaRequires cookie*
 Title    Correlation between the 35 CI NQR Parameters of Chloro-containing Organic and Organometallic Compounds and the Results of ab initio Calculations  
 Abstract    The results of comparison of experimental 35 C1 NQR parameters for a great number of organic and organometallic compounds and estimated ones using ab initio calculations at the RHF/6-31G(d) level were systematized. The NQR frequency changes on going from one compound to another depend, in general, on the changes of populations of the CI atom p"-orbitals in these compounds and, first of all, of populations of their less diffuse parts. 
  Reference    Z. Naturforsch. 55a, 555—559 (2000); received December 15 1999 
  Published    2000 
  Keywords    ab initio Calculations, p-orbital Populations, 35 C1 NQR Frequency, Asymmetry Parameter, Chloro-containing Organic and Organometallic Compounds 
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 TEI-XML for    default:Reihe_A/55/ZNA-2000-55a-0555.pdf 
 Identifier    ZNA-2000-55a-0555 
 Volume    55 
95Author    E. J. BaranRequires cookie*
 Title    Mean Amplitudes of Vibration of the Novel [ReFBr 5 ] 2 " Anion  
 Abstract    Mean amplitudes of vibration of the recently described square-bipyramidal [ReFBr s ] 2 ~ anion have been calculated from vibrational spectroscopic data, over a wide temperature range. The results are briefly discussed in relation with its struc-tural peculiarities and some comparisons with related species are made. 
  Reference    Z. Naturforsch. 55a, 560—561 (2000); received February 7. 2000 
  Published    2000 
  Keywords    Montluoropentabromorhenate (IV), Mean Ampli-tudes of Vibration, Bond properties 
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 TEI-XML for    default:Reihe_A/55/ZNA-2000-55a-0560_n.pdf 
 Identifier    ZNA-2000-55a-0560_n 
 Volume    55 
96Author    Sidney GoldenRequires cookie*
 Title    Non-Kinematicity of the Dilation-of-time Relation of Einstein for Time-intervals  
 Abstract    Light-pulses that are reflected recurrently to one another by two kinematically equivalent dy-namically identical inertial systems moving collinearly and irrotationally with uniform relative velocity generate sequences of contiguous time-intervals in both. By means of clocks stationed in the two systems, each time-interval is both measurable locally and calculable non-locally in accord with basic requirements of special relativity theory. Their ratio yields the velocity depen-dent dilation-of-time relation of Einstein, but an equivalent spatially dependent version of it is obtained as well, because the time-intervals involved are actually determined by the distances that exist between the systems when the reflections occur. As a result, the Einstein relation involves no time-rates of clocks that are actually affected kinematically by the systems containing them. 
  Reference    Z. Naturforsch. 55a, 563—569 (2000); received September 27 1999 
  Published    2000 
  Keywords    Non-kinematic, Time Dilation, Locally-measurable, Non-locally-calculable 
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 TEI-XML for    default:Reihe_A/55/ZNA-2000-55a-0563.pdf 
 Identifier    ZNA-2000-55a-0563 
 Volume    55 
97Author    M. Grottel, Z. Pająk, R. JakubasRequires cookie*
 Title    NMR Study of Cation Motions in Ferroic [C(NH 2 ) 3 ] 3 Bi 2 Br 9  
 Abstract    The proton NMR second moment and spin-lattice relaxation time of polycrystalline [QNHi^lsBioBry were studied in a wide-temperature range. Dynamical inequivalence of two crystallographically different guanidinium cations has been revealed . The C 3 reorientation of the two types of cations was found to be hindered by different potential barriers (25.1 kJ/mol and 34.7 kJ/mol). At higher temperatures an overall reorientation of the cations was revealed. The existence and order-disorder character of the phase transitions at 333, 350, 415, and 425 K have been confirmed. 
  Reference    Z. Naturforsch. 55a, 570—574 (2000); received March 9 2000 
  Published    2000 
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 TEI-XML for    default:Reihe_A/55/ZNA-2000-55a-0570.pdf 
 Identifier    ZNA-2000-55a-0570 
 Volume    55 
98Author    Z. Akdeniz, M. Çaliskan, Z. Çiçek, M. P. TosiRequires cookie*
 Title    Polymerie Structures in Aluminium and Gallium Halides  
 Abstract    The anionic species (Al" X3 n+ iwith X = CI or Br and n > 1 have been recognized for a number of years to form in acidic liquid mixtures of aluminium chloride or bromide with the corresponding halides of alkali or organic cations, in relative proportions which vary with the composition of the mixture. In this work we evaluate the structure and the energetics of such polymeric series in a comparative study of Al and Ga compounds. To this end we first extend an earlier study of the ionic interactions in the A1 2 C1 6 molecule] to determine microscopic ionic models for Ga 2 Cl 6 , Al 2 Br 6 , and Ga 2 Br 6 . The models are then used (i) to evaluate the polymeric clusters for n < 4 in the two trivalent-metal chlorides, and (ii) to explore the potential-energy hypersurface of alkali counterions in the case n = 2. We present tests of the results against available data and an evaluation of the convergence of the energy of the polymeric series towards a value of about 0.5 eV per monomer. 
  Reference    Z. Naturforsch. 55a, 575—580 (2000); received February 18 2000 
  Published    2000 
  Keywords    Ionic Clusters, Molecular Vapours, Molten Salts 
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 TEI-XML for    default:Reihe_A/55/ZNA-2000-55a-0575.pdf 
 Identifier    ZNA-2000-55a-0575 
 Volume    55 
99Author    G. A. Ennas, Falqur, G. Piccaluga, S. Solinas, D. Gatteschi, C. Sangregorio, A. BenedettiRequires cookie*
 Title    Properties of Nanocrystalline Nickel Particles in Ni-Si0 2 Composites  
 Abstract    Nickel-Silica nanocomposites with a nickel content equal to 10, 15, 20 wt% have been prepared by a sol-gel method starting from ethanolic solutions of tetraethoxysilane and nickel nitrate hex-ahydrate. After selation the samples were reduced in H-> flow at selected temperature (450 °C < T < 600 °C). The morphological, structural and magnetic properties were investigated by transmission electron microscopy (TEM), wide and small angle X-ray scattering (WAXS, SAXS), magnetic susceptibility in zero field cooled and field cooled mode (ZFC and FC), and magnetic hysteresis loop. Nanometric nickel particles are observed in all the investigated samples. TEM, WAXS and SAXS techniques indicate that the average nickel particle size grows slightly but almost regularly with the nickel concentration. TEM results moreover indicate that also the width of the particle size distribution, which can be simulated by log-normal functions, follows this trend. All the sample treated in hydrogen show superparamagnetic behaviour. The magnetisation falls to reach saturation up to highest measuring field of 70 kOe even at 3 K, while the observed coercivity H c is much higher than the theoretical bulk one. Some uncertainty in the complete interpretation of the sequence of magnetic measurements is attributed to a progressive oxidation of the samples when these are air exposed. 
  Reference    Z. Naturforsch. 55a, 581—588 (2000); received March 9 2000 
  Published    2000 
  Keywords    Nanocomposites, Nickel-Silica, X-ray Diffraction, TEM, Magnetic Properties 
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 TEI-XML for    default:Reihe_A/55/ZNA-2000-55a-0581.pdf 
 Identifier    ZNA-2000-55a-0581 
 Volume    55 
100Author    Ji Lin, Sen-Yue Lou, Kelin WangRequires cookie*
 Title    (3+l)-Dimensional Integrable Models with Infinitely Dimensional Virasoro Type Symmetry Algebra and the Painleve Property  
 Abstract    In this paper, some Virasoro integrable models are obtained by means of the realizations of the generalized centerless Virasoro-type symmetry algebra, [<j(/i), a(/o)] = o"(/ 2 /i — /i/:)-It is interesting that some of them may be not only Virasoro integrable but also Painleve integrable. 
  Reference    Z. Naturforsch. 55a, 589—594 (2000); received April 1 2000 
  Published    2000 
  Keywords    Virasoro Symmetry Algebra, (3+l)-Dimensional Integrable Model, Group Invariant Equation, Painleve Integrability 
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 TEI-XML for    default:Reihe_A/55/ZNA-2000-55a-0589.pdf 
 Identifier    ZNA-2000-55a-0589 
 Volume    55 
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