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1993[X]
81Author    LuisA. Leal, J. C. López, J. L. Alonso, A. GuarnieriRequires cookie*
 Title    The Centimeter and Millimeter Microwave Spectrum of l,l-Difluoro-2-Chloroethylene  
 Abstract    The rotational spectra of both 35 C1 and 37 C1 l,l-difluoro-2-chloroethylene isotopomers have been measured in the frequency range 12-225 GHz. A first order quadrupole coupling analysis has been performed for both isotopic species. The calculated quadrupole coupling constants for the 37 C1 species not previously reported are x = — 49.2 (2), = 14.2 (1), and x cc = 28.7 (1). Accurate rota-tional constants, quartic and some sextic centrifugal distortion constants have also been determined for both isotopomers from the fit to the observed central frequencies. 
  Reference    Z. Naturforsch. 48a, 514—518 (1993); received November 11 1992 
  Published    1993 
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 TEI-XML for    default:Reihe_A/48/ZNA-1993-48a-0514.pdf 
 Identifier    ZNA-1993-48a-0514 
 Volume    48 
82Author    E. L. Gartstein, R. A. CowleyRequires cookie*
 Title    The Intensity Patterns with a Multi-Crystal Diffractometer Observed at a Synchrotron Source  
 Abstract    The intensity is calculated employing the expressions developed for a multi-crystal diffractometer. Comparison with the measurements shows the reliability of the formalism and enables better interpretation of the experimental results. 
  Reference    Z. Naturforsch. 48a, 519—522 (1993); received September 21 1992 
  Published    1993 
  Keywords    Crystal optics, High resolution, Structure characterization 
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 TEI-XML for    default:Reihe_A/48/ZNA-1993-48a-0519.pdf 
 Identifier    ZNA-1993-48a-0519 
 Volume    48 
83Author    PrakashK. Muhuri, DilipK. HazraRequires cookie*
 Title    Viscosity B Coefficients of Some Tetraalkylammonium Bromides, Lithium Tetrafluoroborate and Tetrabutylammonium Tetraphenyl borate in Propylene Carbonate  
 Abstract    The viscosities of solutions of tetraalkylammonium bromides, R 4 NBr (R = -C 2 H 5 to -C 7 H 1?), lithium tetrafluoroborate (LiBFJ and tetrabutylammonium tetraphenylborate (Bu 4 NBPh 4) in propylene carbonate (PC) have been measured at 25, 35 and 45 °C. The relative viscosities have been analyzed using the Jones-Dole equation in the form of unassociated electrolytes, and the viscosity B-coefficients have been evaluated. The thermodynamic parameters have been calculated using the transition-state treatment and the measured temperature dependencies. Ionic B values have also been derived and discussed in terms of Einstein's equation. The analysis shows that Li + is highly solvated compared to other cations and anions in this medium. 
  Reference    Z. Naturforsch. 48a, 523—528 (1993); received September 2 1992 
  Published    1993 
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 TEI-XML for    default:Reihe_A/48/ZNA-1993-48a-0523.pdf 
 Identifier    ZNA-1993-48a-0523 
 Volume    48 
84Author    R. Jakubas, G. Bator, M. Foulon, J. Lefebvre, J. MatuszewskiRequires cookie*
 Title    Structural Phase Transitions in (/i-C 3 H 7 NH3) 2 SbBr 5  
 Abstract    Dielectric, DSC, thermal expansion and preliminary X-ray diffraction studies on (/i-C 3 H 7 NH3) 2 SbBr 5 are reported. It was found that this crystal undergoes a complex sequence of phase transitions. On cooling: phase I phase II at 188.7 K (continuous), II -» • III at 165 K (1st order, z!S = 26.8 J/mol K), III IV at 137 K (1st order, 1.6 J/mol K). On heating: IV III at 154 K, III II' at 168 K, II' -> II at 177 K (1st order, 2.8 J/mol K), II I at 189 K. All 1st order phase transitions are likely due to the motion of the n-C 3 H 7 NH3 cations. The dielectric dispersion studies between 100 Hz-1 MHz within the phases I and II indicate a fast reorientational motion of dipoles with T < 10" 7 s. 
  Reference    Z. Naturforsch. 48a, 529—534 (1993); received October 7 1992 
  Published    1993 
  Keywords    Alkylammonium halogenoantimonates, Phase transition, Dielectric, DSC, Thermal expansion 
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 TEI-XML for    default:Reihe_A/48/ZNA-1993-48a-0529.pdf 
 Identifier    ZNA-1993-48a-0529 
 Volume    48 
85Author    H. KötzRequires cookie*
 Title    A Technique to Classify the Similarity Solutions of Nonlinear Partial (Integro-)Differential Equations. II. Full Optimal Subalgebraic Systems  
 Abstract    "Optimal systems" of similarity solutions of a given system of nonlinear partial (integro-)differen-tial equations which admits a finite-dimensional Lie point symmetry group G are an effective systematic means to classify these group-invariant solutions since every other such solution can be derived from the members of the optimal systems. The classification problem for the similarity solutions leads to that of "constructing" optimal subalgebraic systems for the Lie algebra 'S of the known symmetry group G. The methods for determining optimal systems of s-dimensional Lie subalgebras up to the dimension r of 'S vary in case of 3 < s < r, depending on the solvability of 'S. If the r-dimensional Lie algebra 'S of the infinitesimal symmetries is nonsolvable, in addition to the optimal subsystems of solvable subalgebras of 'S one has to determine the optimal subsystems of semisimple subalgebras of 'S in order to construct the full optimal systems of s-dimensional subal-gebras of 'S with 3 < s <r. The techniques presented for this classification process are applied to the nonsolvable Lie algebra 'S of the eight-dimensional Lie point symmetry group G admitted by the three-dimensional Vlasov-Maxwell equations for a multi-species plasma in the non-relativistic case. 
  Reference    Z. Naturforsch. 48a, 535—550 (1993); received December 24 1992 
  Published    1993 
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 TEI-XML for    default:Reihe_A/48/ZNA-1993-48a-0535.pdf 
 Identifier    ZNA-1993-48a-0535 
 Volume    48 
86Author    A. Kawski, J. Gryczyński, Z. GryczyńskiRequires cookie*
 Title    Fluorescence Anisotropies of 4-Dimethylamino-a>- diphenylphosphinyl-fra/is-Styrene in Isotropic Media in the Case of One-and Two-Photon Excitation  
 Abstract    Fluorescence emission anisotropies, r, and mean lifetimes of 4-dimethylamino-codiphenylphos-phinyl-trans-styrene (DDPS) were measured in n-butanol at different temperatures from 20 to 80 °C for one-and two-photon excitation. When increasing the temperature, the lifetime decreased from 32 to 12 ps, the r values, however, remained constant (0.315 and 0.445 for one-and two-photon excitation, respectively) and were found to be temperature independent. For DDPS in glycerol at — 5°C, where rotational diffusion does not occur during the excited state lifetime, the limiting emission anisotropies were r 0 = 0.382 and r 0 = 0.545 for one-and two-photon excitation, respec-tively, very little differing from the fundamental emission anisotropies r f = 2/5 and r f = 4/7. The small differences r f — r 0 can be due to vibrations performed after excitation by the DDPS molecule as a result of the initial shock. 
  Reference    Z. Naturforsch. 48a, 551—556 (1993); received December 14 1992 
  Published    1993 
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 TEI-XML for    default:Reihe_A/48/ZNA-1993-48a-0551.pdf 
 Identifier    ZNA-1993-48a-0551 
 Volume    48 
87Author    B. H. LavendaRequires cookie*
 Title    Doppler Line Broadening from the Asymptotic Cauchy Distribution  
 Abstract    The half-width of Doppler broadening is derived without assuming Maxwell's distribution for the velocities of the radiating atoms. In the absence of Doppler broadening there is only natural radiation broadening, and by thermalizing the asymptotic Cauchy distribution one obtains asymp-totic double exponential distributions for the largest (blue) and smallest (red) values of the frequency shift. These are the relevant extreme value distributions for largest and smallest values. Since the mean values are opposite and equal there is a zero shift in the line, while the standard deviation gives an expression for the half-width to within 2% of the Doppler half-width obtained from the Maxwellian when the damping coefficient is taken as the ratio of the natural radiation damping coefficient to the fine structure constant. 
  Reference    Z. Naturforsch. 48a, 557—559 (1993); received February 2 1993 
  Published    1993 
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 TEI-XML for    default:Reihe_A/48/ZNA-1993-48a-0557.pdf 
 Identifier    ZNA-1993-48a-0557 
 Volume    48 
88Author    F. Köksal, Ş. Osmanoğlu, R. TapramazRequires cookie*
 Title    ESR of Gamma Irradiation Damage Centers in Single Crystals of Some Phenol Derivatives  
 Abstract    Phenoxy radicals have been observed and identified in gamma irradiated 2-t-bu-4-methylphenol, 2,6-di-t-bu-4-methylphenol and 2-amino-4-methylphenol single crystals. 
  Reference    Z. Naturforsch. 48a, 560—562 (1993); received November 30 1992 
  Published    1993 
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 TEI-XML for    default:Reihe_A/48/ZNA-1993-48a-0560.pdf 
 Identifier    ZNA-1993-48a-0560 
 Volume    48 
89Author    Stefan Jurga, Kazimierz Jurga, EduardC. Reynhardt, Piotr KatowskiRequires cookie*
 Title    A Proton NMR Study of n-Decylammonium Chain Dynamics in the Perovskite-type Layered Compound (C 10 H 21 NH3) 2 CdCl4  
 Abstract    A detailed proton second moment and spin-lattice relaxation time investigation of the bilayered compound (C 10 H 21 NH 3) 2 CdCl 4 is reported. In the low temperature phase the methyl group exe-cutes a classical threefold reorientation, while the NH 3 group is involved in a similar reorientation in an asymmetric potential well. Evidence for defect chain motions in this phase has been found, and infomation regarding the potential wells associated with these motions has been extracted from the data. In the high temperature phase, slow chain defect motions and fast fourfold reorientations of chains about their long axes, parallel to the normal to the bilayer, have been observed. 
  Reference    Z. Naturforsch. 48a, 563—569 (1993); received October 9 1992 
  Published    1993 
  Keywords    Bilayered compounds, Phase transition, Spin-lattice relaxation, Molecular motions, Defect motions 
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 TEI-XML for    default:Reihe_A/48/ZNA-1993-48a-0563.pdf 
 Identifier    ZNA-1993-48a-0563 
 Volume    48 
90Author    N. Heineking, H. DreizlerRequires cookie*
 Title    Nuclear Quadrupole Hyperfine Structure and Methyl Torsional Fine Structure in the Rotational Spectra of N,N-Dimethylformamide and N-Nitrosodimethylamine  
 Abstract    The complicated nuclear quadrupole hyperfine structure and methyl torsional fine structure in the rotational spectra of N,N-dimethylformamide and N-nitrosodimethylamine have been studied using microwave Fourier transform spectroscopy. It has been found that both molecules are rather similar in terms of their parameters of methyl group internal rotation as well as in terms of their amino nitrogen quadrupole coupling constants. 
  Reference    Z. Naturforsch. 48a, 570—576 (1993); received February 4 1993 
  Published    1993 
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 TEI-XML for    default:Reihe_A/48/ZNA-1993-48a-0570.pdf 
 Identifier    ZNA-1993-48a-0570 
 Volume    48 
91Author    Z. NaturforschRequires cookie*
 Title    Aristophanes Metropoulos  
 Abstract    We present a general multi-state orthogonal transformation program that generates a set of diatomic electronic diabatic states from a set of vibronically interacting adiabatic states of the same symmetry. 
  Reference    Z. Naturforsch. 48a, 577—580 (1993); received November 2 1992 
  Published    1993 
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 TEI-XML for    default:Reihe_A/48/ZNA-1993-48a-0577.pdf 
 Identifier    ZNA-1993-48a-0577 
 Volume    48 
92Author    Helmut BirkRequires cookie*
 Title    The Diode Laser Spectrum of Bromine Monofluoride (BrF) in the Ground Electronic State  
 Abstract    The infrared absorption spectra of the two isotopic forms of bromine monofluoride in natural abundance (79 BrF: 50.54%, 81 BrF: 49.46%) in their ground electronic state (^T) have been measured, using a diode laser spectrometer. These data were fitted along with the published infrared and microwave spectra to produce an improved set of Dunham F-parameters and a set of mass-indepen-dent parameters. Also, the coefficients of the Dunham potential function of bromine monofluoride were determined by a direct fit to the experimental data. 
  Reference    Z. Naturforsch. 48a, 581—583 (1993); received February 28 1993 
  Published    1993 
  Keywords    Infrared spectroscopy, Laser spectroscopy, Diatomic molecule, BrF, Dunham parameters 
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 TEI-XML for    default:Reihe_A/48/ZNA-1993-48a-0581.pdf 
 Identifier    ZNA-1993-48a-0581 
 Volume    48 
93Author    GeorgR. Siegert, RolandG. Winkler, Peter ReinekerRequires cookie*
 Title    Deterministic Chaos in the Dynamics of a Freely Jointed Chain with Three Degrees of Freedom  
 Abstract    The dynamics of a short freely jointed chain of three segments is investigated numerically. The chain consists of mass points connected by massless rigid rods, its initial and final points being fixed. Thus the chain represents a holonomically constrained system with three degrees of freedom. It is shown that the motion of the mass points can be chaotic; the occurrence of chaos depends on the initial conditions of the motion, the end-to-end distance of the chain, and the angular momentum about the axis of the stretching direction. Moreover, the chain more likely exhibits regular than chaotic behavior. The numerical results are presented in the form of Poincare surfaces of section, including the use of a slice technique, as well as in the form of power spectra. 
  Reference    Z. Naturforsch. 48a, 584—594 (1993); received February 1 1993 
  Published    1993 
  Keywords    Deterministic chaos, Freely jointed chain, Constraints, Poincare surface of section, Powerspectra 
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 TEI-XML for    default:Reihe_A/48/ZNA-1993-48a-0584.pdf 
 Identifier    ZNA-1993-48a-0584 
 Volume    48 
94Author    V. A. Khokhlov, A. O. Kodintseva, E. S. FilatovRequires cookie*
 Title    "Anomalous" Thermal Conductivity of Crystalline Alkali Halides Close to Their Melting Point  
 Abstract    The thermal conductivity of crystalline alkali halides MX (M = Li, Na, K, Rb, and Cs; X = C1, Br, and I) close to their melting point has been measured by the steady-state coaxial-cylinders method. It was found to change anomalously as the temperature varied. A minimum of the thermal conduc-tivity at a characteristic temperature depends on the ionic composition of the crystal. This effect is ascribed to the formation of cooperating defects in the melting lattice. An expression relating the thermal conductivity of the ionic crystal near the melting point to the concentration of these defects is proposed. 
  Reference    Z. Naturforsch. 48a, 595—598 (1993); received April 25 1992 
  Published    1993 
  Keywords    Thermal conductivity, High temperature, Melting point, Ionic crystal, Alkali halide 
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 TEI-XML for    default:Reihe_A/48/ZNA-1993-48a-0595.pdf 
 Identifier    ZNA-1993-48a-0595 
 Volume    48 
95Author    G. Ennas, A. Musinu, G. Paschina, G. Piccaluga, G. PinnaRequires cookie*
 Title    Effect of Cooling Rate on the Structure of Sodium Borate Glasses  
 Abstract    Sodium borate glasses with two different compositions have been prepared using cooling rates in the range 7 • 10" C/s-2 • 10 2 °C/s. Structural characterization has been carried out by X-ray diffraction, and glass transition temperatures have been measured by Differential Scanning Calorimetry. The samples exhibit slightly different density values and glass transition temperatures. However, radial distribution functions appear extremely similar and the sodium coordination shell does not change in going from fast to slowly quenched glasses, showing that the short and medium range order is not affected by thermal treatment. 
  Reference    Z. Naturforsch. 48a, 599—604 (1993); received January 19 1993 
  Published    1993 
  Keywords    Glass, structure, diffraction 
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 TEI-XML for    default:Reihe_A/48/ZNA-1993-48a-0599.pdf 
 Identifier    ZNA-1993-48a-0599 
 Volume    48 
96Author    OttoL. StiefvaterRequires cookie*
 Title    High-Resolution Vibrational Spectra of Furazan III. The A t Fundamentals v 3 at ~ 1316 cm -1 and v 4 at ~ 1036 cm -1 from Fourier-Transform Infrared Spectroscopy  
 Abstract    With prior information on vibrationally excited states from DRM microwave spectroscopy, two B-type high-resolution FT-IR bands of furazan were examined to yield the band origins v° = 1316.2254 cm -1 and = 1036.1689 cm -1 with an estimated absolute uncertainty of ±0.0001 cm -1 . The rotational and distortion constants of both fundamental states were refined by the combination of rotational with rovibrational data in the least-squares fits of the bands. 
  Reference    Z. Naturforsch. 48a, 605—612 (1993); received January 25 1993 
  Published    1993 
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 TEI-XML for    default:Reihe_A/48/ZNA-1993-48a-0605.pdf 
 Identifier    ZNA-1993-48a-0605 
 Volume    48 
97Author    S. Wappmann, I. Tarassov, H.-D LüdemannRequires cookie*
 Title    Pressure and Temperature Dependence of Self Diffusion in Fluid Binary Propane/Tetradecane Mixtures  
 Abstract    Self diffusion data were measured for both compounds of the binary propane/tetradecane mixture by the NMR pulsed gradient spin echo technique. A new autoclave for the investigation of binary gas/liquid mixtures in the fluid range up to pressures of 200 MPa is presented. The activation energies and volumes of both components are found to be identical for the mixtures under investi-gation (2.5 and 89 mole% propane). 
  Reference    Z. Naturforsch. 48a, 613—618 (1993); received March 2 1993 
  Published    1993 
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 TEI-XML for    default:Reihe_A/48/ZNA-1993-48a-0613.pdf 
 Identifier    ZNA-1993-48a-0613 
 Volume    48 
98Author    B. Röhricht, P. Eschle, S. Dangel, R. HolznerRequires cookie*
 Title    Nonlinear Behavior of Circularly Polarized Laser Beams Propagating through Sodium Vapor  
 Abstract    A variety of surprising effects arise from the nonlinear light-matter interaction of circularly polarized laser light propagating through sodium vapor. We present experimental evidence for an asymmetry in the absorption of left hand and right hand circularly polarized light as well as for the creation of a collimated light beam of apposite polarization within the light-matter interaction region. Both effects are not yet explained by common theories. 
  Reference    Z. Naturforsch. 48a, 621—623 (1993); received February 16 1993 
  Published    1993 
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 TEI-XML for    default:Reihe_A/48/ZNA-1993-48a-0621.pdf 
 Identifier    ZNA-1993-48a-0621 
 Volume    48 
99Author    R. Richter, A. Kittel, J. ParisiRequires cookie*
 Title    Anomalous Frequency Scaling of a Saddle-Node Bifurcation on a Limit Cycle Disclosed in a Semiconductor Experiment  
 Abstract    During low-temperature impact ionization breakdown in extrinsic germanium, spontaneous current and voltage oscillations can be observed. The onset of periodic oscillatory behavior is governed by a saddle-node bifurcation on a limit cycle. Besides the well-known square-root law of control parameter dependence, we find a different scaling in the vicinity of the bifurcation point. Such anomalous behavior is reproduced by a simple model approach. 
  Reference    Z. Naturforsch. 48a, 624—626 (1993); received February 16 1993 
  Published    1993 
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 TEI-XML for    default:Reihe_A/48/ZNA-1993-48a-0624.pdf 
 Identifier    ZNA-1993-48a-0624 
 Volume    48 
100Author    J. Parisi, R. Badii, E. Brun, L. Flepp, C. Reyl, R. Stoop, O. E. Rössler, A. Kittel, R. RichterRequires cookie*
 Title    Explicit Realization of Chaos Control in an NMR-Laser Experiment  
 Abstract    The usefulness of the Ott-Grebogi-Yorke control method is demonstrated by stabilizing a chaotic NMR-laser system around an unstable period-one orbit. We have used a six-dimensional delay-coordinate embedding technique in order to fully determine the stability properties of the orbit controlled. Our analysis yields small time-dependent perturbations of the system quality factor capable to perform real-time control. 
  Reference    Z. Naturforsch. 48a, 627—628 (1993); received January 27 1993 
  Published    1993 
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 TEI-XML for    default:Reihe_A/48/ZNA-1993-48a-0627.pdf 
 Identifier    ZNA-1993-48a-0627 
 Volume    48 
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