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1976 (300)
141Author    H. Ewald, W. FranzRequires cookie*
 Title      
 Abstract    The scattering of a polarized photon by a polarized free electron is completely calculated in covariant form using Clifford's alternating vector algebra. The result is compared with several special results of the existing literature. 
  Reference    (Z. Naturforsch. 31a, 808—814 [1976]; received May 3 1976) 
  Published    1976 
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 TEI-XML for    default:Reihe_A/31/ZNA-1976-31a-0808.pdf 
 Identifier    ZNA-1976-31a-0808 
 Volume    31 
142Author    J. Schröter, H.-P StormbergRequires cookie*
 Title    Näherungslösung einer verallgemeinerten Nernst-Planck-Gleichung für ein eindimensionales Membranmodell  
 Abstract    Approximative Solution of a Generalized Nernst-Planck-equation for a one Dimensional Membran-model The starting-point of this paper are generalized Nernst Planck equations, which are deduced microscopically. Using a perturbation approach a result of this equation is given for a constant external field and a membran, which has a low concentration of fixed charges. The used conditions give a zeroth approximation which describes the homogeneous electrolyte. The first approximation shows the influence of the fixed charges, the friction between ions and membran and the influence of the correlations. The flows and the concentrations are then calculated for a system with equal concentrations on both sides of the membran. 
  Reference    (Z. Naturforsch. 31a, 815—822 [1976]; eingegangen am 24. Oktober 1975) 
  Published    1976 
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 TEI-XML for    default:Reihe_A/31/ZNA-1976-31a-0815.pdf 
 Identifier    ZNA-1976-31a-0815 
 Volume    31 
143Author    FriedrichW. Hehl, G.David Kerlick, Paul Von Der HeydeRequires cookie*
 Title    On Hypermomentum in General Relativity III. Coupling Hypermomentum to Geometry  
 Abstract    In Part 1 1 of this series we presented the notion of the material hypermomentum current and motivated its introduction into general relativity. In Part II 2 we showed that a general, linearly connected manifold with symmetric metric (L4, g) is the appropriate geometrical framework for such an introduction. The present paper completes the picture by giving dynamical definitions for energy-momentum and hypermomentum for a minimally coupled material Lagrangian. We derive and discuss the field equations of a new metricaffine gravitational theory which embodies these notions. 
  Reference    (Z. Naturforsch. 31a, 823—827 [1976]; received May 12 1976) 
  Published    1976 
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 TEI-XML for    default:Reihe_A/31/ZNA-1976-31a-0823.pdf 
 Identifier    ZNA-1976-31a-0823 
 Volume    31 
144Author    G.Van HooydonkRequires cookie*
 Title    Reactivity, Equilibrium and Electronegativity  
 Abstract    The enthalpy AH of general displacement reactions AB + CD AD + CB is derived with the aid of the ionic approximation to chemical bonding. This enthalpy compares favourably well with Pauling's corresponding equation AH—— 46 (%B— ^d) (%A — XC)-These ex-pressions are used as a basis to discuss various aspects of chemical reactivity: reversals in reactivity, ambident reactivity, the Hammett relation, the McDaniel-Yingst equation, the Drago E —C equa-tion, the resolution of acid strength, the proton affinities of negative and neutral species and the hard and soft acid-base (HSAB) rule. Qualitatively, and in some cases even quantitatively, reasonable results are obtained, demonstrating the great flexibility of an electronegativity-based theory of chemical reactivity. 
  Reference    (Z. Naturforsch. 31a, 828—839 [1976]; received May 17 1976) 
  Published    1976 
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 TEI-XML for    default:Reihe_A/31/ZNA-1976-31a-0828.pdf 
 Identifier    ZNA-1976-31a-0828 
 Volume    31 
145Author    F. Scappini, H. DreizlerRequires cookie*
 Title    Microwave Spectrum of Acetyl Cyanide in the Ground and Excited States. I  
 Abstract    The microwave spectra of acetyl cyanide, CH3COCN, in the ground and in the two lowest excited states have been investigated. The rotational constants and the quadrupole coupling con-stants have been evaluated for all these states. The internal rotation parameters have been refined with respect to previous works. Evidence for a rotation—torsion —vibration interaction has been found in the spectra of the excited states. 
  Reference    (Z. Naturforsch. 31a, 840—846 [1976]; received May 20 1976) 
  Published    1976 
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 TEI-XML for    default:Reihe_A/31/ZNA-1976-31a-0840.pdf 
 Identifier    ZNA-1976-31a-0840 
 Volume    31 
146Author    H. D. Lutz, P. Willich, H. Haeuseler, Gesamthochschule SiegenRequires cookie*
 Title    Gitterschwingungsspektren * XVII. Kraftkonstanten-und Normalkoordinatenrechnungen an Übergangsmetall- Dichalkogeniden und -Diphosphiden mit Pyritstruktur  
 Abstract    Force constants and normal coordinates of MnS2 , FeS2 , RuS2, RuSe2, RuTe2, OsS2 and PtP2 are calculated based on the five ir active vibrations of the pyrite lattice. By setting up a valence force field consisting of short and long range M —X, X2 —X2 and M —M stretching constants it has proved possible to obtain good agreement between experimental and calculated frequencies with expection of FeS2 and RuS2 . The force constants corresponding to the shortest metal chalcogen distances (MnS2: 0.30, RuSe,: 0.88, RuTe2: 0.62, OsS2: 1.32, PtP2: 1.22 mdyn/A) are mainly responsible for the ir frequencies. For RuSe2 and RuTe, the forces between adjacent X2 groups are not negligible. Whereas the force constants of OsS2 and PtP2 are of comparable strength, the forces in MnS2 are significantly weaker than those in the other compounds. The normal coordinates of MnS2, OsS2 and PtP2 , and RuSe2 and RuTe2 show significant differences according to both the contribution of the 6 symmetry coordinates to the 5 ir active vibrations and the assignment of the spectra. 
  Reference    (Z. Naturforsch. 31a, 847—852 [1976]; eingegangen am 5. Mai 1976) 
  Published    1976 
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 TEI-XML for    default:Reihe_A/31/ZNA-1976-31a-0847.pdf 
 Identifier    ZNA-1976-31a-0847 
 Volume    31 
147Author    B. Boddenberg, J. A. MorenoRequires cookie*
 Title    Oriented Adsorption of Benzene Molecules on Graphitized Carbon Black  
 Abstract    A new model for the oriented adsorption of benzene mole-cules on graphitized carbon black at low temperatures is pro-posed which explains NMR relaxation data. Highly graphitized carbon blacks are known to possess energetically homogeneous surfaces as is well documented by numerous adsorption studies. This property is explainable with the notion that the faces of the polyhedral 1 particles are the graphite basal planes. There is much controversy in the literature about the structure and the dynamical state of the adsorption layer of molecules in the mono-and sub-monolayer regions 1> 2 . 
  Reference    (Z. Naturforsch. 31a, 853 [1976]; received June 8 1976) 
  Published    1976 
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 TEI-XML for    default:Reihe_A/31/ZNA-1976-31a-0853_n.pdf 
 Identifier    ZNA-1976-31a-0853_n 
 Volume    31 
148Author    K. E. Zimen, R. BritsRequires cookie*
 Title    971 nach Messungen von Wein-Äthanol  
 Abstract    14 C in the Atmosphere from 1952 to 1971 According to Measurements of Wine Ethanol Previous measurements of 14 C in German wines (vintages 1952 — 1967) have been extended up to 1971 and are supple-mented by a series of samples from the southern hemisphere. 
  Reference    (Z. Naturforsch. 31a, 854—855 [1976]; eingegangen am 21. Mai 1976) 
  Published    1976 
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 TEI-XML for    default:Reihe_A/31/ZNA-1976-31a-0854_n.pdf 
 Identifier    ZNA-1976-31a-0854_n 
 Volume    31 
149Author    EscaG. Distefano, G. Spunta, F. P. Colonna, S. PignataroRequires cookie*
 Title    Transmission of Electronic Effects in Substituted Pyridine-N-Oxides Studied  
  Reference    (Z. Naturforsch. 31a, 856—857 [1976]; received February 2 1976) 
  Published    1976 
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 TEI-XML for    default:Reihe_A/31/ZNA-1976-31a-0856_n.pdf 
 Identifier    ZNA-1976-31a-0856_n 
 Volume    31 
150Author    Klaus GärtnerRequires cookie*
 Title    Ein neues Verfahren zur Präparation von Tantal/Silber und Niob/Silber Tunnel- kontakten A New Method for the Preparation of Tantalum/Silver and Niobium/Silver Tunneling Contacts  
 Abstract    The preparation starts from material in wire-form. One end of the wire is degassed under ultrahigh-vacuum condi-tions by a very simple electron-gun and finally melted to form a small smooth sphere. The tunneling barrier is formed by thermal oxidation of the investigated superconductor with oxygen under reduced pressure. The handling of the whole sample (masking and contacting procedures included) is very simple and allows to use this method for systematic tunneling-studies of the transition metal superconductors. 
  Reference    (Z. Naturforsch. 31a, 858—859 [1976]; eingegangen am 31. Mai 1976) 
  Published    1976 
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 TEI-XML for    default:Reihe_A/31/ZNA-1976-31a-0858_n.pdf 
 Identifier    ZNA-1976-31a-0858_n 
 Volume    31 
151Author    K. Gärtner, A. HahnRequires cookie*
 Title    Eigenschaften von Tunnelkontakten auf den fünfwertigen supraleitenden Übergangsmetallen Nb, Ta und V  
 Abstract    Properties of Tunneling Junctions on the Superconducting Transition-Metals Nb, Ta, and V Well-developed phonon-structures are observed on Ta/Ta-Oxid/Ag and Nb/Nb-Oxid/Ag tunneling junctions, if the conditions of oxidation are suitably choosen. These structures are analyzed ac-cording to McMillan's numerical program and the results are discussed. From the nonlinear current-voltage characteristics in the normal state, informations are obtained on the electronic structure of the semiconducting oxid presenting the barrier. Impurity concentration leading to a nonideal semiconductor gap in the oxid, seems to be largely reduced if oxidation is performed with low oxygen pressure. 
  Reference    (Z. Naturforsch. 31a, 861—871 [1976]; eingegangen am 31. Mai 1976) 
  Published    1976 
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 TEI-XML for    default:Reihe_A/31/ZNA-1976-31a-0861.pdf 
 Identifier    ZNA-1976-31a-0861 
 Volume    31 
152Author    A. Friederich, W. GerlingRequires cookie*
 Title    Wiek-Regeln mit Zwischenzuständen und die Neue Tamm-Dancoff-Methode mit Zwischenzuständen On Wick Rules with Intermediate States and the New Tamm-Dancoff Method with Intermediate States  
 Abstract    Instead of emphasizing the ground state as is done in Green's function method, we take a finite-dimensional subspace of the Hilbert space: the space of the "intermediate states". A systematic introduction of intermediate states is effected by an extension of the method of generating functionals: we combine the generating functionals of the n-point Green's functions to a "matrix functional" T, and form new matrix functionals, which are matrix functions of T. The aim of this paper is to develop the functional calculus in such a way that the transition from scalar functionals to matrix functionals is straightforward, and the method of obtaining further results becomes clear. Following the lines of Dürr and Wagner we get u rj-and £-rules with intermediate states". Using them we define a truncation procedure for the equations of motion of the n-point Green's functions, the "New Tamm-Dancoff method with intermediate states". This extension makes it possible to treat the effect of nearby levels in many body systems with Green's functions. In ad-dition to well-known approximations, such as the Hartree-Fock and the Hartree-Bogoliubov theory, the RPA and the quasiparticle RPA, we obtain a series of new approximations. Among these are the "Hartree-Fock theory with intermediate states" and the "random-phase approximation with intermediate states", which we already applied with great success to some exactly soluble models. 
  Reference    (Z. Naturforsch. 31a, 872—886 [1976]; eingegangen am 11. Mai 1976) 
  Published    1976 
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 TEI-XML for    default:Reihe_A/31/ZNA-1976-31a-0872.pdf 
 Identifier    ZNA-1976-31a-0872 
 Volume    31 
153Author    J. D. StephensonRequires cookie*
 Title    A Determination of Screening Constants for Incomplete Atomic Shells of Elements Z = 2 to 23 from Experimental Ionization Potentials — X-ray Photoelectric Mass Absorption Coefficients for Elements Z = 6 to 15 for 33 Characteristic Energies between 1 and 25 keV  
 Abstract    A method is proposed, which primarily determines screening constants for incomplete atomic shells from the experimental ionization potentials of spin-paired Pauli-type orbitals. The method is complimentary and in addition to the standard Sommerfeld approach, which derives screening constants from X-ray spin doublet term differences. Atomic photoelectric absorption cross sections are computed from screened hydrogen-like eigen-functions for low atomic number elements Z = 6 to 15, using a range of incident photon energies between 1 and 30 keV. Comparison with experiment and alternate more exact theories shows, that improved cross sections are obtained for the more important incomplete L-shell contributions. X-ray photoelectric mass absorption coefficients for low Z elements (Z= 6 to 15), employing 33 characteristic X-ray energies {NiKa (0.852 keV) to AgKß (24.942 keV)}, are given. 
  Reference    (Z. Naturforsch. 31a, 887—897 [1976]; received June 16 1976) 
  Published    1976 
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 TEI-XML for    default:Reihe_A/31/ZNA-1976-31a-0887.pdf 
 Identifier    ZNA-1976-31a-0887 
 Volume    31 
154Author    A. Meyer, Gwo-Ching Wang, W. H. YoungRequires cookie*
 Title    The von Weizsäcker Coefficient in Density Functional Theoryt  
 Abstract    For any given potential, linear response theory tells us the size that the von Weizsäcker coef-ficient must assume in order to obtain the correct energy in the weak coupling limit. With this necessarily imposed choice, the quality of results is investigated as the coupling is strengthened. From the study of a number of model problems (the harmonic oscillator, the Yukawa well and the Mathieu potential) it is concluded that good results can be maintained to high couplings. 
  Reference    (Z. Naturforsch. 31a, 898—903 [1976]; received May 31 1976) 
  Published    1976 
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 TEI-XML for    default:Reihe_A/31/ZNA-1976-31a-0898.pdf 
 Identifier    ZNA-1976-31a-0898 
 Volume    31 
155Author    E. SigmundRequires cookie*
 Title    The T-t Jahn-Teller System: Solution of the Fundamental Combinatorial Problem and its Application to Moments and Zero Phonon Line  
 Abstract    The solution of the T—t fundamental combinatorial problem is given in a purely analytic form as a sum over binomials. This simplifies other calculations considerably. For an illustration the moments of the optical absorption line shape in the strong coupling limit are derived in a closed form. Furtheron, the optical zero phonon line is calculated. An application to a T — t phase transition chain is indicated. 
  Reference    (Z. Naturforsch. 31a, 904—910 [1976]; received May 28 1976) 
  Published    1976 
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 TEI-XML for    default:Reihe_A/31/ZNA-1976-31a-0904.pdf 
 Identifier    ZNA-1976-31a-0904 
 Volume    31 
156Author    E. Buluggiu, A. VeraRequires cookie*
 Title    Effective g Tensor of a Pair of Dissimilar Ions in the Strong Isotropic Exchange Limit  
 Abstract    A study of the spin-pair Hamiltonian with regard to the effective g-factor in the strong isotropic exchange limit is presented. The case of two different spins with anisotropic g(0 and D(0 tensors is considered. Effective g s and D s tensors for the various total spin S values are deduced in terms of the corresponding single-ion parameters. The characteristics of the resultant g s -tensor, in the case of an ion-pair with C a symmetry, are treated in detail. The principal values are linear expressions of the single-ion principal values and the principal directions relative to different 5 values result to be correlated in a characteristic manner. The limits of the present strong exchange treatment are also discussed. 
  Reference    (Z. Naturforsch. 31a, 911—914 [1976]; received June 5 1976) 
  Published    1976 
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 TEI-XML for    default:Reihe_A/31/ZNA-1976-31a-0911.pdf 
 Identifier    ZNA-1976-31a-0911 
 Volume    31 
157Author    H. Lehrke, K. G. MüllerRequires cookie*
 Title    Elektronentransport in nichtthermischen Edelgasplasmen  
 Abstract    Transport of Electrons in Non-Thermal Noble Gas Plasma For the transport of electrons in a non-thermal, weakly ionized plasma an analytical model and a detailed numerical calculation is presented. The following transport coefficients: mean energy, characteristic energy, mobility, diffusion coefficient, excitation and ionization coefficient for He, Ne, Ar, Kr, Xe are calculated in the region of reduced electric field 0.01 V/cm Torr < Elp < 100 V/cm Torr. The parameters of the model are developed using the existing experimental and our numerical data. With increasing £/p the dominant energy loss of the electrons changes from elastic to inelastic collisions and here from constant to increasing effective excitation energy. Three model regions of Elp result, in which the transport coefficients can be described as a power of £/p. The data pre-sented here provide a starting point for further investigations of similarity rules and models of non-thermal plasmas. 
  Reference    (Z. Naturforsch. 31a, 915—923 [1976]; eingegangen am 21. Mai 1976 **) 
  Published    1976 
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 TEI-XML for    default:Reihe_A/31/ZNA-1976-31a-0915.pdf 
 Identifier    ZNA-1976-31a-0915 
 Volume    31 
158Author    B. Lammers, U. Oberlack, H. Schlüter, 0. VogelRequires cookie*
 Title    Untersuchungen der Wellenabsorption im Bereich der unteren Hybridresonanz an einem Plasma hoher Ionenmasse Investigations of Wave Absorption Near the Lower Hybrid Resonance in a Plasma of High Ion Mass  
 Abstract    The propagation and absorption of waves in the vicinity of the lower hybrid resonance are investigated under linear conditions in a cesium plasma generated by a Q-machine. The results of the measurements are compared with linear theories based on the fluid model. It is shown that in the case of high ion mass plasma only a theory including a finite &||-spectrum yields an appropriate description of wave absorption near the lower hybrid resonance. 
  Reference    (Z. Naturforsch. 31a, 924—933 [1976]; eingegangen am 24. April 1976) 
  Published    1976 
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 TEI-XML for    default:Reihe_A/31/ZNA-1976-31a-0924.pdf 
 Identifier    ZNA-1976-31a-0924 
 Volume    31 
159Author    G. Himmel, E. Möbius, A. PielRequires cookie*
 Title    Investigation of the Structure and the Plasma Parameters in a "Critical Velocity" Rotating Plasma  
 Abstract    The structure and the plasma parameters of a rotating plasma showing Alfven's critical velocity were investigated for the first time by means of Langmuir probes. It was demonstrated that the occurrence of the critical velocity is causally connected with the formation of a spoke structure. The electron temperature and the plasma density were determined with local resolution by which a detailed balance concerning the plasma density and the current transport became possible. The importance of turbulent electron heating for rapid ionization at the critical velocity is emphasized. In this process the modified two-stream-instability obviously plays an outstanding role. 
  Reference    (Z. Naturforsch. 31a, 934—941 [1976]; received June 29 1976) 
  Published    1976 
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 TEI-XML for    default:Reihe_A/31/ZNA-1976-31a-0934.pdf 
 Identifier    ZNA-1976-31a-0934 
 Volume    31 
160Author    E. FrehlandRequires cookie*
 Title    l//-noise Generated by Constrained Diffusion through a Flux-controlling Boundary  
 Abstract    Calculations for constrained (one-dimensional) diffusion of current carriers in an external field are made, which concern the spectral density of fluctuations resulting from the relaxation of spatial concentration perturbations. Two different model calculations are presented: First diffusion in an infinite medium. In this case the spectral density of concentration fluctuations shows a 1// be-haviour, but the spectral density of current fluctuations does not. Second the diffusion in a semi-infinite medium is treated. The flux through the boundary (e. g. pore end) is assumed to be pro-portional to the concentration of current carriers at this boundary. In this case concentration as well as current exhibit 1// behaviour. The results indicate that the existence of flux controlling boundaries (contacts) may be decisive for the occurence of 1// noise. 
  Reference    (Z. Naturforsch. 31a, 942—948 [1976]; received May 3 1976) 
  Published    1976 
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 TEI-XML for    default:Reihe_A/31/ZNA-1976-31a-0942.pdf 
 Identifier    ZNA-1976-31a-0942 
 Volume    31 
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