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1976 (300)
121Author    W. BauhoffRequires cookie*
 Title    Angular Momentum and Discrete Symmetries in the Spinor Bethe-Salpeter Equation. II  
 Abstract    The classification of states in the fermion-fermion Bethe-Salpeter equation is discussed. They are related to the states in the fermion-antifermion case discussed before. This enables us to obtain restrictions on the interaction in quark models. Some models used in the literature are thereby found to lead to unphysical predictions. 
  Reference    (Z. Naturforsch. 31a, 690—692 [1976]; received April 30 1976) 
  Published    1976 
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 TEI-XML for    default:Reihe_A/31/ZNA-1976-31a-0690.pdf 
 Identifier    ZNA-1976-31a-0690 
 Volume    31 
122Author    R. KimmichRequires cookie*
 Title    Consequences of Restricted Defect Diffusion on NMR and Dielectric Relaxation  
 Abstract    Nuclear magnetic and dielectric relaxation formulas are given for a model of limited diffusion of defects. The limitation is introduced by the assumption of fixed reflecting barriers on both sides of the defect. The diffusion process is assumed to be one-dimensional and continuous. The effect of the finite length of the defects is included in the presented treatment. 
  Reference    (Z. Naturforsch. 31a, 693—696 [1976]; received May 3 1976) 
  Published    1976 
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 TEI-XML for    default:Reihe_A/31/ZNA-1976-31a-0693.pdf 
 Identifier    ZNA-1976-31a-0693 
 Volume    31 
123Author    S. Ariga, R. SigelRequires cookie*
 Title    Picosecond Microphotography as a Diagnostic Method for Laser Produced Plasmas  
 Abstract    A single picosecond pulse from a mode-locked dye laser was used for time resolved microphoto-graphy of the gasdynamic phenomena occurring in a lasertarget interaction experiment. A time resolution of 5 ps and a spatial resolution of better than 10 ^m were experimentally obtained. Results are presented for the case of laser irradiation of a thin foil, shock wave propagation in a transparent target, expansion of the hot plasma and blast wave formation in a background gas. 
  Reference    (Z. Naturforsch. 31a, 697—706 [1976]; received May 8 1976) 
  Published    1976 
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 TEI-XML for    default:Reihe_A/31/ZNA-1976-31a-0697.pdf 
 Identifier    ZNA-1976-31a-0697 
 Volume    31 
124Author    V. Kroop, W. BehmenburgRequires cookie*
 Title    Depolarization of NaD2 Fluorescence under Pulsed Laser Excitation  
 Abstract    The intensity and polarization state of the NaD2-fluorescence (3 2 P3/2 3 2 Si/2 , 2 5890 Ä) from a cell containing pure Na vapor, selectively excited by a flash lamp pumped dye laser was investi-gated. Measurements were performed both for excitation with si-and o-light of spectral density ranging between 10~ 23 and 10~ 17 Ws 2 cm -3 and with Na number densities between 2.8 X10® and 4.0 X 10 10 cm -3 . The results are interpreted in terms of population of the 2 P3/2 state and of hyper-fine and Zeeman pumping of the 2 Si/2 substates. The values for the degree of linear polarization measured at the smallest excitation densities and Na pressures agree well with theoretical values. 
  Reference    (Z. Naturforsch. 31a, 707—710 [1976]; received April 21 1976) 
  Published    1976 
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 TEI-XML for    default:Reihe_A/31/ZNA-1976-31a-0707.pdf 
 Identifier    ZNA-1976-31a-0707 
 Volume    31 
125Author    G. Riekert, P. Lamparter, S. SteebRequires cookie*
 Title    Mass Spectrometric Determination of Activities and their Dependence on Temperature in Liquid Bismuth-Tin Alloys  
 Abstract    Liquid alloys of the Bi-Sn system have been studied to determine thermodynamic properties. Ion currents have been measured by a double-focusing mass spectrometer. The thermodynamic values were calculated by application of the monomer-dimer ratio technique and the integration technique. Special attention was paid to the correction of fragmentation effects. Activities of both components versus composition in the temperature range from 1023 K to 1323 K and values of Gibbs energies and heats of mixing are reported as results. At 1200 K the species Bi2 , Bi3, Bi4 , BiSn, and Bi2Sn were observed in the gaseous phase above the Bi50Sn50 alloy. The discussion shows a tendency to segregation of the liquid Bi-Sn alloys. 
  Reference    (Z. Naturforsch. 31a, 711—716 [1976]; received May 5 1976) 
  Published    1976 
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 TEI-XML for    default:Reihe_A/31/ZNA-1976-31a-0711.pdf 
 Identifier    ZNA-1976-31a-0711 
 Volume    31 
126Author    Michio NishidaRequires cookie*
 Title    Note on Population Densities in an Expanding Helium-Neon Plasma Flow  
 Abstract    The axial population distributions in an expanding helium-neon mixture plasma flow have been calculated for three cases of the concentration of neon ions. The results show that the electron temperature distributions are strongly dependent on the concentration of the neon ions and that the populations of the upper levels of the helium atom depend on the electron temperature near down-stream and on the flow expansion far downstream. Hurle and Hertzberg firstly proposed the promo-tion of population inversion between electronically excited states by fluid mechanical technique 1 , where the possibility of population inversion between the 3p-and 4s-state of the neon atoms in a rapidly ex-panding helium-neon plasma flow was stated. The He(2s 3 S) metastables transfer their energy to the near-resonant Ne(4s) levels and the Ne(4s) levels decay to the Ne(3s) levels through the Ne(3p) states. The radiative lifetime of the 3p — 4s and 3s —3p transitions are 1.5xl0 -7 sec and 7 X 10~ 9 sec, respectively 2 . Therefore, if the expansion is made so rapidly that the flow time becomes suf-ficiently small compared with collisional transition time, the population inversion between the 3p-and 4s-state of the neon atoms will become possible. In the present paper the behaviour of the populations of the helium and neon atoms in a source flow ex-pansion of a He-Ne plasma is investigated as a preliminary study to pursue the possibility of a helium-neon laser by fluid mechanical technique. In a previous paper 3 the populations of the helium atoms in a source flow expansion were studied, where it was stated that the behaviour of the elec-tron temperature was quite similar to that of the heavy particles. This phenomenon was explained as the result of the small mass of the helium atoms. In the helium-neon gas mixture the different behaviour of the electron temperature will be expected, which will likely produce the different behaviour of the helium populations. In addition the energy transfer from He(2s 3 S) to Ne(4s) will also affect the popu-lation distributions. 
  Reference    (Z. Naturforsch. 31a, 717—722 [1976]; received April 25 1976) 
  Published    1976 
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 TEI-XML for    default:Reihe_A/31/ZNA-1976-31a-0717.pdf 
 Identifier    ZNA-1976-31a-0717 
 Volume    31 
127Author    Fumio HigashinoRequires cookie*
 Title    An Analysis of Nonsimilar Problems on Spherical Blast Waves  
 Abstract    An approximate analytical method that is valid for the entire propagation regime of a blast wave is established for point explosions. The method is based on an application of the shock ex-pansion method to boundary conditions. The numerical calculations were carried out for spherical flows with constant adiabatic exponent. The results show that the value of the shock decay coefficient gives good agreement with the numerically exact solution by Goldstine and von Neumann. The profiles of the pressure, density, and particle velocity behind the shock were obtained. The solutions show the possible profiles as compared to other existing analyses. 
  Reference    (Z. Naturforsch. 31a, 723—727 [1976]; received April 24 1976) 
  Published    1976 
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 TEI-XML for    default:Reihe_A/31/ZNA-1976-31a-0723.pdf 
 Identifier    ZNA-1976-31a-0723 
 Volume    31 
128Author    A. S. RrauszRequires cookie*
 Title    On the Analysis of the Activation Volume  
 Abstract    The stress and temperature dependence of the activation volume is often explained by a similar dependence of the measured stress sensitivity. This explanation cannot be reconciled with the nonconservative motion of jogs, with dislocation climb, nor with the intersection mechanism. It is in contradiction with the results obtained in direct dislocation velocity measurements as well. It is now shown that when the backward movement of the dislocations is taken into consideration an explanation, consistent with the rate theory and with the dislocation mobility observations, can be developed. The analysis shows that with constant activation volume the stress sensitivity is stress and temperature dependent, in agreement with the corresponding measurements and mechanisms. The determination of the activation volume as-sociated with the rate controlling mechanism is of great importance in the analysis of thermally acti-vated processes. It is usually assumed that the ex-perimental, or Arrhenius, rate equation and because yp = A exp AEe— Ve(ref{) re{{ kT (1) 
  Reference    (Z. Naturforsch. 31a, 728—730 [1976]; received March 28 1976) 
  Published    1976 
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 TEI-XML for    default:Reihe_A/31/ZNA-1976-31a-0728.pdf 
 Identifier    ZNA-1976-31a-0728 
 Volume    31 
129Author    FriedrichFranz SeeligRequires cookie*
 Title    Chemical Oscillations by Substrate Inhibition A Parametrically Universal Oscillator Type in Homogeneous Catalysis by Metal Complex Formation  
 Abstract    The general reaction X+Y-^-P + Q, catalyzed by a metal M via M-fX^MX and MX+Y 
  Reference    (Z. Naturforsch. 31a, 731—738 [1976]; received May 12 1976) 
  Published    1976 
  Keywords    Chemical Oscillation, Substrate Inhibition, Homogeneous Catalysis, (Transition) Metal Complexes 
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 TEI-XML for    default:Reihe_A/31/ZNA-1976-31a-0731.pdf 
 Identifier    ZNA-1976-31a-0731 
 Volume    31 
130Author    J. Bormann, D. PoppeRequires cookie*
 Title    Reorientierung des Drehimpulses von Li2-Molekülen beim Stoß mit Edelgasatomen  
 Abstract    Reorientation of the Angular Momentum of Li2-Molecules due to Collisions with Noble Gas Atoms Laser-induced fluorescence has been used to investigate the reorientation of the molecular angu-lar momentum due to inelastic collisions with atoms. We report on experiments for the Li2 (^u)-rare gas system, where the degree of polarisation of the emitted fluorescence has been measured. Within the framework of a classical theory mean angles for reorientation have been derived. Their dependence on the collision partner and the initial and final angular momentum is discussed. 
  Reference    (Z. Naturforsch. 31a, 739—747 [1976]; eingegangen am 30. April 1976) 
  Published    1976 
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 TEI-XML for    default:Reihe_A/31/ZNA-1976-31a-0739.pdf 
 Identifier    ZNA-1976-31a-0739 
 Volume    31 
131Author    J. Friedrich, G. Weinzierl, F. DörrRequires cookie*
 Title    Untersuchung zur externen Spin-Bahn-Kopplung bei aromatischen Molekülen  
 Abstract    External Spin-Orbit-Coupling in Aromatic Molecules The influence of ethylhalogenes on the polarization of the phosphorescence of naphthalene was studied by means of the photoselection technique. It is shown that with increasing concentration and with increasing nuclear charge of the heavy atom the phosphorescence of naphthalene becomes increasingly depolarized. The influence of the external heavy atom on the T x -and 7^-substate is stronger than on the T^-substate. From the concentration dependence of the depolarizatign con-clusions concerning the mechanism of the external spin-orbit-coupling are drawn. The dirept spin-orbit-coupling mechanism is ruled out. In the model discussed the variation of the external heavy atom effect with the intermolecular distance is related to overlap integrals. 
  Reference    (Z. Naturforsch. 31a, 748—753 [1976]; eingegangen am 11. Mai 1976) 
  Published    1976 
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 TEI-XML for    default:Reihe_A/31/ZNA-1976-31a-0748.pdf 
 Identifier    ZNA-1976-31a-0748 
 Volume    31 
132Author    N. Boes, H. ZüchnerRequires cookie*
 Title    Herstellung wasserstoffdurchlässiger V-, Nb-und Ta-Folien mit Hilfe der UHV-Bedampfungstechnik  
 Abstract    A new sample preparation method for eliminating the hydrogen impermeable oxide surface layers of base metals like V, Nb and Ta is described. Applying UHV-techniques the metal foils are heated inductively and subsequently coated with a thin metallic Pd-film. By this method the metals are cleaned, at the same time annealed, and pro-tected successfully against the formation of new passive layers, as is shown by x-rays, SIMS, and AES investigations. 
  Reference    (Z. Naturforsch. 31a, 754—759 [1976]; eingegangen am 8. April 1976) 
  Published    1976 
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 TEI-XML for    default:Reihe_A/31/ZNA-1976-31a-0754.pdf 
 Identifier    ZNA-1976-31a-0754 
 Volume    31 
133Author    N. Boes, H. ZüchnerRequires cookie*
 Title    Anwendung elektrochemischer Verfahren zur Untersuchung der Diffusion von Wasserstoff-Isotopen in V, Nb und Ta  
 Abstract    Application of Electrochemical Techniques for Studying Diffusion of Hydrogen Isotopes in V, Nb and Ta After suitable preparation (improvement) of samples H (D) -diffusion coefficients of V-, Nb-, and Ta-foils can be measured reliably at low H (D) -concentrations in the temperature range 0 to 100 °C by means of an electrochemical time-lag method. A modified strain model indicates that the tetrahedral sites in bcc lattices have to be taken as the stable positions for the dissolved hydrogen. The elementary jump in the diffusion process from one tetrahedral site to the next passes directly through a tetrahedral plane. This model describes qualitatively the experimental results concerning the sequence of the activation energies for hydrogen diffusion in the three Vb-metals [E (Ta) > E (Nb) > £ (V) ]. 
  Reference    (Z. Naturforsch. 31a, 760—768 [1976]; eingegangen am 8. April 1976) 
  Published    1976 
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 TEI-XML for    default:Reihe_A/31/ZNA-1976-31a-0760.pdf 
 Identifier    ZNA-1976-31a-0760 
 Volume    31 
134Author    G. Goldmann, K. TödheideRequires cookie*
 Title    Equation of State and Thermodynamic Properties of Molten Potassium Chloride to 1320 K and 6 kbar  
 Abstract    From the Tait equation an equation of state containing five adjustable parameters was developed which fits experimental density data of molten potassium chloride to 1320 K and 6 kbar with a standard deviation of 0.04%. The thermal expansion coefficient, isothermal compressibility, internal pressure, and molar heat capacities at constant pressure and constant volume were calculated as functions of pressure and temperature from the equation of state and were compared with computer simulation results. A method for an estimate of high-pressure PVT data for molten salts is sug-gested which yields results superior to the best computed data presently available. 
  Reference    (Z. Naturforsch. 31a, 769—776 [1976]; received April 28 1976) 
  Published    1976 
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 TEI-XML for    default:Reihe_A/31/ZNA-1976-31a-0769.pdf 
 Identifier    ZNA-1976-31a-0769 
 Volume    31 
135Author    M. V. Šušić, S. V. MentusRequires cookie*
 Title    A Conductometric Study of the Bi-Hgl2 System  
 Abstract    The electric conductivity of the homogeneous liquid Bi-Hgl2 system was measured in the tem-perature range 260—540 °C for several Bi mole fractions ranging from 0.00 to 0.38. The specific conductivity-composition isotherms are indicative of the occurrence of electronic conductivity also before reaching a bismuth concentration sufficient for a complete conversion of Hgl2 into Hg2I» • As the temperature rises the share of electronic conductivity in the total conductivity abruptly increases. Comparing the properties of this system with those of the Bil3-Bi system the conclusion is drawn that electronic conductivity in liquids is due to free metal atoms. 
  Reference    (Z. Naturforsch. 31a, 777—780 [1976]; received May 12 1976) 
  Published    1976 
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 TEI-XML for    default:Reihe_A/31/ZNA-1976-31a-0777.pdf 
 Identifier    ZNA-1976-31a-0777 
 Volume    31 
136Author    S. Sharafi-Ozeri, L. Muszkat, K. A. MuszkatRequires cookie*
 Title    Electronic Overlap Population as Reactivity Measure IV. Bond Cleavage and Bond Formation Processes  
 Abstract    Electronic overlap population is explored as a reactivity measure for several bond cleavage and bond formation processes. The reactions considered include: I. decarboxylation of carboxylic acids and of their anions; II. carbon-hydrogen bond cleavage in y-radiolysis of glutaric, methyl-malonic and 3-hexendioic acids; and, III. hydrogen atom addition to butadiene and to sorbic acid. 
  Reference    (Z. Naturforsch. 31a, 781—785 [1976]; received April 5 1976) 
  Published    1976 
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 TEI-XML for    default:Reihe_A/31/ZNA-1976-31a-0781.pdf 
 Identifier    ZNA-1976-31a-0781 
 Volume    31 
137Author    Jürgen Nehring, MagedA. OsmanRequires cookie*
 Title    Liquid Crystalline Phases in N-(4-n-alkylbenzylidene)-4'-n-alkylanilines  
 Abstract    The mesomorphic behavior of N-(4-n-alkylbenzylidene)-4'-n-alkylanilines is investigated and nematic as well as smectic-B phases are found at comparatively low temperatures. Long aliphatic substituents on the aldehyde side of the molecule favor the smectic-B phase. Observations on smectic-B textures, transition enthalpies and density measurements are reported. The simple method used to determine transition temperatures despite impure samples can also be applied to other compounds, e. g. yielding 21.6 — 47.5 °C for the nematic range of MBBA. 
  Reference    (Z. Naturforsch. 31a, 786—792 [1976]; received April 14 1976) 
  Published    1976 
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 TEI-XML for    default:Reihe_A/31/ZNA-1976-31a-0786.pdf 
 Identifier    ZNA-1976-31a-0786 
 Volume    31 
138Author    H. Sterk, J. J. Suschnigg, K. ThonhoferRequires cookie*
 Title    Versuche zur Berechnung der 13 C chemischen Verschiebung in mesoionischen Verbindungen Attempts Concerning Calculations of 13 C-chemical Shifts in Mesoionic Compounds  
 Abstract    The existence of a linear relationship the form Y—a x^b x2+c between the charge density — calculated by semiempirical SCF —LCAO —MO—methods — and the 13 C —chemical shifts of mesoionic compounds has been shown. An influence of substituents in pyridinium betaines on the chemical shift is not observable. 
  Reference    (Z. Naturforsch. 31a, 793—795 [1976]; eingegangen am 30. April 1976) 
  Published    1976 
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 TEI-XML for    default:Reihe_A/31/ZNA-1976-31a-0793.pdf 
 Identifier    ZNA-1976-31a-0793 
 Volume    31 
139Author    S. Zuca, M. OlteanuRequires cookie*
 Title    Electrical Conductance of Single Molten Lithium Halides  
 Abstract    The specific conductivities and densities of molten LiCl, LiBr and Lil have been investigated as a function of temperature. A comparison between the data in literature and the present data has been made and the reliability of the different data is discussed. The electrical conductance is perhaps the most extensively studied property of molten salts. Never-theless, for many salts there is a large scatter of the published data and for others the experimental data are scarce. Both these are true for the lithium halides. We therefore have reinvestigated their electrical conductances and also their densities. Experimental 
  Reference    (Z. Naturforsch. 31a, 796—799 [1976]; received May 6 1976) 
  Published    1976 
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 TEI-XML for    default:Reihe_A/31/ZNA-1976-31a-0796.pdf 
 Identifier    ZNA-1976-31a-0796 
 Volume    31 
140Author    Karl Hiltrop, Fred FischerRequires cookie*
 Title    Radial Poiseuille Flow of a Homeotropic Nematic LC Layer  
 Abstract    A two-dimensional Poiseuille flow in a radial direction allows to study simultaneously a whole range of flow rates. Three different deformation modes of the director field have been observed, the 'bow' mode, the 'screw' mode, and the 'peak' mode. Above a critical flow rate the bow mode transforms into the screw mode. Right and left screw mode can be produced side by side. The peak mode reached by temporary high flow rates is metastable at low flow rates. Quantitative results are reported and discussed. By reversing the flow direction in the screw mode region the left screw mode is transformed into the right screw mode and vice versa. By reversing the flow direction in the peak mode region special tube-like deformation structures are obtained. Each open tube has a point disclination at either end. Both are of opposite strength ± 1. 
  Reference    (Z. Naturforsch. 31a, 800—807 [1976]; received May 10 1976) 
  Published    1976 
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 TEI-XML for    default:Reihe_A/31/ZNA-1976-31a-0800.pdf 
 Identifier    ZNA-1976-31a-0800 
 Volume    31 
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