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1978[X]
81Author    Anil Kumar, John Sheridan, OttoL. StiefvaterRequires cookie*
 Title    The Microwave Spectrum of Oxazole II. Dipole Moment and Quadrupole Coupling Constants  
 Abstract    The dipole moments and the quadrupole coupling constants of the normal and the three mono-deuterated species of oxazole have been measured. The dipole moment of 1.50 ± 0.03 D is found to deviate by 10.8° from the external bisector of the CNC angle towards the C(2) carbon atom. The principal values of the quadrupole coupling tensor are determined as Xzz = —4.04^ 0.02 MHz and %Xx — 1-66 =L 0.02 MHz along the axes in the molecular plane, so that the gradient perpendicular to this plane is %yy = 2.38 MHz. The direction of the largest gradient deviates by 5.7° from the external bisector of the CNC angle towards the carbon atom C(4). An attempt is made to correlate these results and the geometry of oxazole with the electron distribution in this molecule. 
  Reference    Z. Naturforsch. 33a, 549 (1978); received February 11 1978 
  Published    1978 
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 TEI-XML for    default:Reihe_A/33/ZNA-1978-33a-0549.pdf 
 Identifier    ZNA-1978-33a-0549 
 Volume    33 
82Author    G. S. HallRequires cookie*
 Title    Riemannian Curvature and the Petrov Classification  
 Abstract    A connection is shown between the Riemannian Curvatures of the wave surfaces of a null vector I at a point p in space-time and the Petrov type of the space-time at p. Some other results on Riemannian Curvature are discussed. 
  Reference    Z. Naturforsch. 33a, 559—562 (1978); received November 11 1977 
  Published    1978 
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 TEI-XML for    default:Reihe_A/33/ZNA-1978-33a-0559.pdf 
 Identifier    ZNA-1978-33a-0559 
 Volume    33 
83Author    Norbert FürstenauRequires cookie*
 Title    A Method for the Study of Correlated Events in Time-of-Flight Mass-Spectrometry and its Application to Fission-Fragment Induced Desorption  
 Abstract    For experiments on fission-fragment induced desorption the detection of significant correlations between desorbed ions has been reported [1]. In this paper the method for the detection and quan-titative description of these correlations will be described. The statistics of the desorption-process leads to equations for mass-line intensities of ion spectra. Using a time-to-amplitude-converter for flight-time measurements these intensities depend on interdependences of different ions desorbed by the same fission-fragment. The equations allow the computation of correlation-coefficients whose interdependence with desorption probabilities of the respective ions can be shown in Venn-diagrams. Results are given and an interpretation is suggested for fission-fragment desorbed thiamine molecular and fragment ions. 
  Reference    Z. Naturforsch. 33a, 563—570 (1978); received November 11 1977 
  Published    1978 
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 TEI-XML for    default:Reihe_A/33/ZNA-1978-33a-0563.pdf 
 Identifier    ZNA-1978-33a-0563 
 Volume    33 
84Author    R. HammRequires cookie*
 Title    Mikrowellenspektren schwingungsangeregter Zustände und allgemeines Valenzkraftfeld von 12 C 32 SF 35 Cl  
 Abstract    Microwave Spectra of Some Vibrational Excited States of 12 C 32 SF 35 Cl The microwave spectra of some vibrational excited states of CSFC1 were measured with a con-ventional stark modulation spectrometer. As the spectra of the upper two stretching vibrations could not be found for lack of intensity, the equilibrium structure which had been estimated using Kuchitsu's procedure could not yet be determined. Nevertheless a general internal force field of CSFC1 was obtained, using the inertial defects of the measured excited states in the fit program NCA in addition to vibration frequencies and centrifugal distortion constants. More-over, from the determined anharmonic part of the rotation vibration interaction constants, linear relations between some cubic force constants were established. 
  Reference    Z. Naturforsch. 33a, 571—580 (1978); eingegangen am 2. März 1978 
  Published    1978 
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 TEI-XML for    default:Reihe_A/33/ZNA-1978-33a-0571.pdf 
 Identifier    ZNA-1978-33a-0571 
 Volume    33 
85Author    P. J. Mjöberg, S. 0. Ljunggren, J. E. BäckvallRequires cookie*
 Title    Microwave Spectrum of Cyclopentene-3,5-dione  
 Abstract    The microwave spectra of cyclopentene-3,5-dione in the ground state and the first four excited states of the ring bending vibration have been studied in the frequency region 26.5 to 40.0 GHz and the corresponding rotational constants have been determined. The ground state spectrum of one isotopically substituted species, 4-deuteriocyclopentene-3,5-dione, has also been assigned. The following values of the ground state rotational constants (MHz) were obtained from the spectra: unsubstituted species 4-deuterio species A 6668.970 ± 0.003 6354.794 ± 0.007 B 2202.614 ± 0.002 2195.611 ± 0.004 C 1673.893 ± 0.002 1657.454 ± 0.004 From intensity and inertial-defect considerations the ring configuration was shown to be planar in the ground state. In addition, the nearly straight-line behaviour of the rotational constants as functions of the ring-puckering vibrational quantum number indicates that the ring-puckering vibration is nearly harmonic with a fundamental frequency of approximately 90 cm -1 . The electric dipole moment for the unsubstituted species in the vibrational ground state was found to be 1.680 ± 0.009 Debye units. 
  Reference    Z. Naturforsch. 33a, 581—587 (1978); received December 24 1977 
  Published    1978 
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 TEI-XML for    default:Reihe_A/33/ZNA-1978-33a-0581.pdf 
 Identifier    ZNA-1978-33a-0581 
 Volume    33 
86Author    P. Ortoleva, M. DelledonneRequires cookie*
 Title    Turbulent Spatio-Temporal Dynamics in Reacting-Diffusing Systems: Results for a Soluble Model  
 Abstract    A class of soluble three "species" reaction-diffusion type systems is presented Exact solutions are obtained which show turbulent spatio-temporal evolution All homogeneous evolution tends asymptotically toward an attractor which is shown to be a two layered two dimensional manifold in the three dimensional species space. Sustained aperiodic spatio-temporal solutions are also found. By considering particular model systems we show that turbulent solutions may exit as finite amplitude instabilities or as bifurcations which are aperiodic arbitrarily close to the bifurcation point and hence do not arise as a transition starting out essentially periodically. A perturbation scheme is used to show that d parameter families of spatio-temporal evolution are admitted by more general systems with attracting d dimensional manifolds in the homogeneous chemical kinetics. 
  Reference    Z. Naturforsch. 33a, 588—596 (1978); received January 12 1978 
  Published    1978 
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 TEI-XML for    default:Reihe_A/33/ZNA-1978-33a-0588.pdf 
 Identifier    ZNA-1978-33a-0588 
 Volume    33 
87Author    SlavkoV. Mentus, MilenkoV. ŠušićRequires cookie*
 Title    The Electric Conductivity of the Molten Systems BiBr3-HgBr2 and BiBr3-CdBr2  
 Abstract    The electric conductivity of the molten binary mixtures BiBr3-HgBr2 and BiBr3-CdBr2 was measured for different molar compositions of the mixtures over the temperature ranges 500—770 K and 720—870 K, respectively. The curves of the specific conductivity as a function of composition show in the BiBr3-HgBr2 system negative and positive deviations from additivity in the HgBr2-rich and BiBr3-rich composition regions, respectively. In the BiBr3-CdBr2 system the isotherms of specific conductivity deviate positively from additivity over the entire composition range. 
  Reference    Z. Naturforsch. 33a, 597—600 (1978); received March 10 1978 
  Published    1978 
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 TEI-XML for    default:Reihe_A/33/ZNA-1978-33a-0597.pdf 
 Identifier    ZNA-1978-33a-0597 
 Volume    33 
88Author    F. SchneiderRequires cookie*
 Title    Untersuchung der elektrischen Leitfähigkeit im nematischen und smektischen Phasenbereich von 4-Alkyloxy-4'-cyanobiphenylen  
 Abstract    The electrical conductivity of tetrabutylammonium picrate is measured in the liquid crystal phases of two 4-alkyloxy-4'-cyanobiphenyls as a function of the temperature and of the electrolyte concentration. The conductivity is corrected for the electrode polarization and the dielectric relaxation which are determined from the frequency dependence of the conduc-tivity. The equivalent conductivity values in the nematic phase of a mixture of 4-pentyloxy-4'-cyanobiphenyl and 4-heptyloxy-4'-cyanobiphenyl are extrapolated to infinite dilution. The elec-trical conductivity in 4-octyloxy-4'-cyanobiphenyl is measured in the nematic and in the smectic phase. It changes continuously with the temperature in the region of the phase transition. The anisotropy ratio for both liquid crystals under investigation yields a strong dependence upon the concentration of the electrolyte. This behaviour is compared with results obtained for other liquid crystals. 
  Reference    Z. Naturforsch. 33a, 601—609 (1978); eingegangen am 23. Februar 1978 
  Published    1978 
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 TEI-XML for    default:Reihe_A/33/ZNA-1978-33a-0601.pdf 
 Identifier    ZNA-1978-33a-0601 
 Volume    33 
89Author    E. Bjarnov, W. H. HockingRequires cookie*
 Title    The Structure of the Other Rotamer of Formic Acid, eis-HCOOH 12  
 Abstract    The very weak microwave spectra of six isotopically substituted species of formic acid in the eis rotamer form (i.e. with the two hydrogen atoms eis to each other) have been studied. From the data on HC 18 OOH, HCO^OH, H^COOH, HCOOD, DCOOH and DCOOD, together with the previously published data for HCOOH, the complete substitution structure of the eis rotamer of formic acid has been derived. The structure is: rs(C—H) = 1.105(4) A, rs(C=0) = 1.195(3) A, rs(C—0) = 1.352(3) Ä, rs(0-H) = 0.956(5) A, <£s(OCO) = 122.1(4)°, <s(HC-0) = 114.6(6)° and <£s(COH) = 109.7(4)°. 
  Reference    Z. Naturforsch. 33a, 610—618 (1978); received February 26 1978 
  Published    1978 
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 TEI-XML for    default:Reihe_A/33/ZNA-1978-33a-0610.pdf 
 Identifier    ZNA-1978-33a-0610 
 Volume    33 
90Author    M. SorgRequires cookie*
 Title    Retarded Integration in Classical Electrodynamics  
 Abstract    The bound and emitted four-momentum of an accelerated point charge is calculated in a direct manner without use of Gauß' or Stokes' integral theorems. This new integration procedure ac-counts most naturally for the retarded character of the electromagnetic interactions and, if applied to the bound four-momentum, reveals that the asymptotic condition of uniform motion in the distant past can be weakened essentially. 
  Reference    Z. Naturforsch. 33a, 619—626 (1978); received März 31 1978 
  Published    1978 
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 TEI-XML for    default:Reihe_A/33/ZNA-1978-33a-0619.pdf 
 Identifier    ZNA-1978-33a-0619 
 Volume    33 
91Author    0. SeebergRequires cookie*
 Title    On the Validity of the Master Equation for Finite Closed Systems  
 Abstract    Two equations for the macroscopic part W of the statistical operator are considered: 1. the master equation W = — MW, t 2. the exact equation W = — J K(t — r) W (r) dr. 0 It follows from the physical equivalence of the solutions together with a stability assumption and the assumption that there is a time r* after which also the derivatives of the solutions are equivalent, that r* is the life-time of the kernel K and that M — f K(T) dr. Conversely, the equiv-6 alence of the solutions follows from assumptions on the life-time of the kernel K together with a stability assumption and a smoothness assumption on the initial statistical operator 1F(0). 
  Reference    Z. Naturforsch. 33a, 627—637 (1978); received March 8 1978 
  Published    1978 
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 TEI-XML for    default:Reihe_A/33/ZNA-1978-33a-0627.pdf 
 Identifier    ZNA-1978-33a-0627 
 Volume    33 
92Author    F. R. Krueger, K. WienRequires cookie*
 Title    High Energy Sputtering from Cleaned Metal Foils  
 Abstract    Positive and negative secondary ions desorbed from metal foils by bombardment with 252 Cf fission products have been investigated by time-of-flight mass spectroscopy. The measurements were performed under UHV conditions using metal foils of Cu, Ni and Al cleaned by Ar-ion etching. Spectra were taken with cleaned surfaces and also under the exposure of H2 , 02, N2 , CO, C2H4 , C2H6 and C3H70H up to several 100 L. The yields of metal ions from clean metal sur-faces are in agreement with Sigmund' theory. 
  Reference    Z. Naturforsch. 33a, 638—643 (1978); received March 30 1978 
  Published    1978 
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 TEI-XML for    default:Reihe_A/33/ZNA-1978-33a-0638.pdf 
 Identifier    ZNA-1978-33a-0638 
 Volume    33 
93Author    K. Tiemann, J. SchmandRequires cookie*
 Title    Nachweis der verschiedenen Phasen und Phasenübergänge des Systems Fe-Ga im Konzentrationsbereich 25,7 bis 28,3 At-°/o Ga bei Temperaturen von 20 °C bis 720 °C mit Hilfe des Mössbauer- Effekts  
 Abstract    25.7 to 28.3 at% and Temperatures from 20 °C to 720 °C with the Mössbauer Effect Fe-Ga-absorbers, bcc-unordered at 20 °C, with 25.7, 27.0, and 28.3 at-% Ga were analyzed up to 720 °C with the Mössbauer effect in order to clear disagreements of former experiments of us with the then known phase diagrams. We found proofs for an ordering transition A2 —D03 be-tween 180 and 260 °C, a transition D03 —Ll2 between 280 and 380 °C, a transition Ll2 —D019 in a small temperature interval at 610 °C, and a further one D019 — D03 (or D019—B2) at 630 °C. The temperature dependence of the magnetically induced Ll2-field gradient q was analyzed. Probably q is negative, while the direction of the magnetic field is parallel [1, 0, 0] in agreement with other experiments at low temperatures. Above 630 °C there seems to exist a further so far unknown ordered phase, which is probably non-cubic with at least two different Fe-sites. Our results are in considerable agreement with recently published phase diagrams, though some of our spectra allow different interpretations. 
  Reference    Z. Naturforsch. 33a, 644—650 (1978); eingegangen am 25. März 1978 
  Published    1978 
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 TEI-XML for    default:Reihe_A/33/ZNA-1978-33a-0644.pdf 
 Identifier    ZNA-1978-33a-0644 
 Volume    33 
94Author    H. Auweter, U. Mayer, D. SchmidRequires cookie*
 Title    Singlet-Exciton Energy Transfer in Naphthalene Doped with Anthracene Following Two-Photon Picosecond Excitation: Dependence on Dopant Concentration  
 Abstract    The time dependence of the sensitized fluorescence of anthracene-doped naphthalene crystals following two-photon picosecond excitation was studied for various dopant concentrations. The experimental results indicate that the characteristic of the energy transfer rate is significantly different for different anthracene concentrations. This behaviour is discussed in terms of different transfer mechanisms taking place at low and high dopant concentrations. 
  Reference    Z. Naturforsch. 33a, 651—657 (1978); received April 8 1978 
  Published    1978 
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 TEI-XML for    default:Reihe_A/33/ZNA-1978-33a-0651.pdf 
 Identifier    ZNA-1978-33a-0651 
 Volume    33 
95Author    J. Schröter, H. P. StormbergRequires cookie*
 Title    Ion and Water Transport through Ion Exchange Membranes  
 Abstract    An ion exchange membrane system is considered in which the concentration of the membrane particles is low. With the help of a perturbation procedure the transport equations for ions and solvent, the so called generalized Nernst-Planck equations can be solved up to the first order. Prescribing concentration differences for the ions, a pressure difference and an electrical field as external conditions, the fluxes and densities of ions and solvent, and the pressure within the system are calculated. 
  Reference    Z. Naturforsch. 33a, 658—665 (1978); received March 15 1978 
  Published    1978 
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 TEI-XML for    default:Reihe_A/33/ZNA-1978-33a-0658.pdf 
 Identifier    ZNA-1978-33a-0658 
 Volume    33 
96Author    A. NolleRequires cookie*
 Title    Isotropie and Anisotropie Nuclear Magnetic Shielding of 113 Cd in Cadmiumhalides, Cadmiumchalcogenides and in Cadmiumcarbonate  
 Abstract    The NMR signals of 113 Cd have been observed in powder samples of the cadmium halides CdF,, CdCl2, CdBr2'4H20, Cdl2, of the cadmium chalcogenides CdO, CdS, CdSe, CdTe and of CdC03 . For m Cd in CdCl2 , CdBr2-4H20, CdS and in CdSe anisotropics of the nuclear magnetic shielding have been detected. The shielding tensor in these powders is axially symmetric. For the other specimens no anisotropics of the magnetic shielding have been found. The principal values of the magnetic shielding tensor and the shielding constants are given in an atomic reference scale. 
  Reference    Z. Naturforsch. 33a, 666—671 (1978); received March 15 1978 
  Published    1978 
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 TEI-XML for    default:Reihe_A/33/ZNA-1978-33a-0666.pdf 
 Identifier    ZNA-1978-33a-0666 
 Volume    33 
97Author    S. GanzRequires cookie*
 Title    Die Reabsorption in Anthracenkristallen im Temperaturbereich 4 < T < 300 K  
 Abstract    The Reabsorption in Anthracene Crystals in the Temperature Range 4 < T < 300K Fluorescence spectra and decay curves of pure anthracene crystals in dependence of the emis-sion wave length have been investigated using different exciting frequencies. A computer program using Monte Carlo Techniques is described which simulates absorption, emission, reflection and reabsorption of photons in a crystal. This program allows the calculation of fluorescence spectra and decay curves. By comparing the results of this program with experimental data, it is possible to correct the decay time for reabsorption and to calculate the reabsorption coefficient in depen-dence of temperature. 
  Reference    Z. Naturforsch. 33a, 672—683 (1978); eingegangen 12. April 1978 
  Published    1978 
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 TEI-XML for    default:Reihe_A/33/ZNA-1978-33a-0672.pdf 
 Identifier    ZNA-1978-33a-0672 
 Volume    33 
98Author    G. Nentwich, H. HofmannRequires cookie*
 Title    Magnetische Widerstandsänderung von kornorientierten Magnetblechen  
 Abstract    Magnetoresistance of grainoriented magnetic steel sheet The resistance-tensor has been measured on iron sheets with Goss-structure. The results are compared with measurements of magnetisation and magnetostriction. 
  Reference    Z. Naturforsch. 33a, 684—686 (1978); eingegangen am 23. März 1978 
  Published    1978 
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 TEI-XML for    default:Reihe_A/33/ZNA-1978-33a-0684.pdf 
 Identifier    ZNA-1978-33a-0684 
 Volume    33 
99Author    A. Hasan, G. KlagesRequires cookie*
 Title    Dielectric Relaxation of Aliphatic Ethers in Dilute Solutions  
 Abstract    Dielectric relaxation of nine primary aliphatic ethers — seven symmetric ethers of chain length Cß to C32, one asymmetric ether and one molecule with three ether groups in the chain — has been studied by loss measurements at 11 frequencies between 0.3 and 300 GHz in dilute cyclohexane and mesitylene solutions at 20°C. The absorption curves are shown not to be sym-metrical. The main region has been analysed in terms of a symmetric distribution of relaxation times; the high frequency contribution due to the far infrared absorption was always less than 20%. Symmetric ethers show an increasing mean relaxation time and broadening of its distri-bution with increasing chain length. The spectra of cyclohexane solutions are found to contain additional short relaxation times. Compared with a, co-dichlorides the mean relaxation times of symmetric ethers generally are shorter, which suggests a high mobility around C—O bonds becoming more effective in the unsymmetric ethers and even more so in the chain molecule with two methoxy end groups. 
  Reference    Z. Naturforsch. 33a, 687—692 (1978); received March 23 1978 
  Published    1978 
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 TEI-XML for    default:Reihe_A/33/ZNA-1978-33a-0687.pdf 
 Identifier    ZNA-1978-33a-0687 
 Volume    33 
100Author    P. Schattschneider, A. WagendristelRequires cookie*
 Title    X-Ray Diffraction Profiles of Inhomogeneous Binary Solids  
 Abstract    A general expression for x-ray interference profiles of a binary alloy showing crystals of dif-ferent concentration and thus different lattice dimensions is deduced. This expression contains previously reported relations as special cases, which are discussed briefly. It is not restricted to systems of total solid solubility or cubic lattice. 
  Reference    Z. Naturforsch. 33a, 693—696 (1978); received April 5 1978 
  Published    1978 
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 TEI-XML for    default:Reihe_A/33/ZNA-1978-33a-0693.pdf 
 Identifier    ZNA-1978-33a-0693 
 Volume    33 
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