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1975 (294)
1Author    P. M. Grootes, W. G. Mook, J. C. Vogel, A. E. De Vries, A. Haring, J. KistemakerRequires cookie*
 Title    Enrichment of Radiocarbon for Dating Samples up to 75,000 Years  
 Abstract    The range of the radiocarbon dating method can be extended by about 20,000 years by means of thermal diffusion isotopic enrichment. A description of the Clusius-Dickel type enrichment columns and their operation is given. Prior to enrichment the carbonaceous sample material is combusted to C02 and then reduced to CO. The enriched sample is re-oxidized to C02 . The combustion-, reduction-and oxidation-apparatus and their operation are described. The performance of the thermal diffusion columns has been tested and an empirical, volume independent relation between the isotope separation factors of 14 C 16 0 and all molecules with mass (30) is given g 14 -l = (1.13 ±0.05) (<? 30 -l) + (0.035 ±0.005) (g 30 -l) 2 . The influence of contaminations on the reliability of 14 C dates obtained with this method is discussed. Laboratory contaminations can be kept below the detection limit as is shown by the preparation of two anthracite samples. Still there may be some influence on dates obtained for very old samples. As far as laboratory contaminations are concerned, dates up to 75,000 years can be obtained. 
  Reference    (Z. Naturforsch. 30a, 1—14 [1975]; received September 2 1974) 
  Published    1975 
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 TEI-XML for    default:Reihe_A/30/ZNA-1975-30a-0001.pdf 
 Identifier    ZNA-1975-30a-0001 
 Volume    30 
2Author    A. Kawski, J. KamińskiRequires cookie*
 Title    Energieübertragung zwischen gleich-und ungleichartigen Molekülen in Lösung II. Experimente über Konzentrationsdepolarisation der Fluoreszenz  
 Abstract    Radiationless energy transfer between like molecules (homotransfer) in thin rigid cellulose acetate films was studied by the concentration depolarization of the photoluminescence. The inves-tigated substances are rhodamine B, 9-methylanthracene and 5-methyl-2-phenylindole. The experi-mental results have been compared with the "multi-shell model" of a luminescent centre. Good agreement was found with the equation which takes into account the excitation energy remigration. Concentration —depolarization measurements show that the critical distances R1, at which the probability of transfer of the excitation equals that of emission, are dependend on the excited wavelength. This is due to the failure of thermal relaxation of the exciting molecules with their environment. 
  Reference    (Z. Naturforsch. 30a, 14—151273 [1975]; eingegangen am 9. Oktober 1974) 
  Published    1975 
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 TEI-XML for    default:Reihe_A/30/ZNA-1975-30a-0014.pdf 
 Identifier    ZNA-1975-30a-0014 
 Volume    30 
3Author    M. P. Bhutra, S. P. Tandon, P. P. VaishnavaRequires cookie*
 Title    A New Relation between Dissociation Energy and Molecular Constants of Diatomic Molecules  
 Abstract    An accurate relation, connecting dissociation energy D0, force constant for infinitesimal ampli-tude Are and internuclear equilibrium distance re has been deduced from Varshni and Shukla's potential function. It is of the form D0=ke {A -f B re 2 + C re 4), where A, B and C are constants and are the same for groups of similar diatomic molecules. The values of D0 estimated by this relation are in better agreement with the observed ones than those estimated by Somayajulu, and Tandon et al. 
  Reference    (Z. Naturforsch. 30a, 21—27 [1975]; received September 10 1974) 
  Published    1975 
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 TEI-XML for    default:Reihe_A/30/ZNA-1975-30a-0021.pdf 
 Identifier    ZNA-1975-30a-0021 
 Volume    30 
4Author    Ulrich Krauß, Gerhard LehmannRequires cookie*
 Title    EPR of Fe 3+ in Low Quartz Isomorphs A(III)B(V)04  
 Abstract    Electron spin resonance spectra of Fe 3+ in hydrothermally grown single crystals of A1P04 , GaP04, A1AS04 and GaAs04 were measured at X-band and analyzed using a Spin-Hamiltonian for rhombic symmetry. The zero field splitting was found to be between about one and two times the microwave frequency, increasing regularly from A1P04 to GaAs04. This increase is largely due to an increase in the axial parameter D whereas the second order rhombic parameter E is practically constant. The fourth order parameter a increases exponentially with the lattice parameter ratio c0/a0 . The variation of D indicates a site distortion for GaP04 about twice as large as in A1P04 . For the arsenates, influences of increased covalency are apparent in addition to site distortions of comparable size. Halfwidths in the range of 18 Gauss for the phosphates and 38 Gauss for the arsenates indicate hyperfine interactions with 31 P and 75 As, and estimates of 0.5 and 1% spin den-sity resp. at these nuclei are obtained, again showing increased covalency for the arsenate com-pounds. 
  Reference    (Z. Naturforsch. 30a, 28—34 [1975]; received November 28 1974) 
  Published    1975 
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 TEI-XML for    default:Reihe_A/30/ZNA-1975-30a-0028.pdf 
 Identifier    ZNA-1975-30a-0028 
 Volume    30 
5Author    SilasE. Gustafsson, Ernest Karawacki, Isao OkadaRequires cookie*
 Title    A Method for Measuring Interdiffusion Coefficients in Liquids by Wave-front-shearing Interferometry  
 Abstract    A new method for measuring interdiffusion coefficients in transparent liquids is presented. By using a diffusion vessel made of fused quartz with optically flat surfaces perpendicular to the optic axis it is possible to follow the complete concentration distribution with a wave-front-shearing inter-ferometer during the diffusion process. 
  Reference    (Z. Naturforsch. 30a, 35—37 [1975]; received November 26 1974) 
  Published    1975 
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 TEI-XML for    default:Reihe_A/30/ZNA-1975-30a-0035.pdf 
 Identifier    ZNA-1975-30a-0035 
 Volume    30 
6Author    J. SzydłowskiRequires cookie*
 Title    Hydrogen Isotope Fractionation between HC12" Ion and HCl  
 Abstract    Hydrogen isotope fractionation between hydrogen dichloride ion in the condensed phase and gaseous hydrogen chloride has been studied both theoretically and experimentally. Quite good agreement between the experimental tritium fractionation factor and that theoretically calculated for two sets of vibrational data was found. Theoretical calculations of the fractionation factors of both deuterium and tritium over the large temperature range of 100—2000 K revealed some anomalies (minima and crossover points) in their temperature dependences. The relative tritium-deuterium isotope effect has also been discussed within the framework of the presently accepted statistical-thermodynamic theory in the harmonic approximation and recent works by Stern et al. 
  Reference    (Z. Naturforsch. 30a, 38—43 [1975]; received July 9 1974) 
  Published    1975 
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 TEI-XML for    default:Reihe_A/30/ZNA-1975-30a-0038.pdf 
 Identifier    ZNA-1975-30a-0038 
 Volume    30 
7Author    A. Wagendristel, E. SöllnerRequires cookie*
 Title    Über die Temperaturabhängigkeit der Dichte von dünnen Kupferaufdampfschichten  
 Abstract    A short literature survey on the subject is given with special emphasis on discrepancies and contradictional interpretations of results. Our own experiments on thin copper films evaporated onto glass substrates at different condensation temperatures are reported. Density values were calculated from the film thickness, which was measured by Kiessig's method and from the deposited mass determined by atomic absorption spectrometry as well as gravimetric measurements. The density defect decreases with increasing film thickness, as already established, and also with temperature. From these results together with those obtained from films which were deposited during a rapid temperature rise from the low substrate temperature to room temperature we conclude that the density defect is localized at the substrate — film boundary. 
  Reference    (Z. Naturforsch. 30a, 44 [1975]; eingegangen am 11. November 1974) 
  Published    1975 
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 TEI-XML for    default:Reihe_A/30/ZNA-1975-30a-0044.pdf 
 Identifier    ZNA-1975-30a-0044 
 Volume    30 
8Author    N. C. Haider, R. L. WourmsRequires cookie*
 Title    Electronic Density of States of Noncrystalline Si and Ge: I. Spherically Symmetric Interference Function Approach  
 Abstract    The electronic density of states have been calculated for amorphous and liquid phases of Si and Ge, using pseudopotential perturbation theory. These calculations are carried out on the basis of experimental radial distribution functions for the appropriate phases, and second order in electron energy. The density of states generated by this method compare favorably with those obtained by other computational methods. 
  Reference    (Z. Naturforsch. 30a, 55—63 [1975]; received September 24 1974) 
  Published    1975 
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 TEI-XML for    default:Reihe_A/30/ZNA-1975-30a-0055.pdf 
 Identifier    ZNA-1975-30a-0055 
 Volume    30 
9Author    H. C. Brookes, R. L. PaulRequires cookie*
 Title    Densities and Excess Volumes of Fused Halides  
 Abstract    Densities of molten AgBr-AX (A = Li, Na, K, Rb, Cs; X = Br or CI), AgBr-AgCl, KBr-NaBr, KBr-CsBr, KCl-KBr, and KCl-CsBr mixtures have been measured at 0.5 mole fraction using the method of Archimedean displacement. The excess volumes of mixing are all positive, except for the AgBr-LiBr system. Attempts to relate the excess volumes of the binary AgBr-ABr systems to the second order conformal solution theory of Reiss, Katz, and Kleppa are unsuccessful, since V E is large even when the diameter difference parameter, Ö12, is close to zero. However, the excess vol-umes of the reciprocal AgBr-ACl systems at 0.5 mole fraction are found, within experimental error, to have a linear dependence on S12. The positive deviations from conformal solution theory which occur for the alkali halide mixtures have been interpreted in terms of non-Coulombic polarisation and van der Waals interactions. 
  Reference    (Z. Naturforsch. 30a, 64—68 [1975]; received September 3 1974) 
  Published    1975 
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 TEI-XML for    default:Reihe_A/30/ZNA-1975-30a-0064.pdf 
 Identifier    ZNA-1975-30a-0064 
 Volume    30 
10Author    Kazutaka Kawamura, Isao Okada, Osamu OdawaraRequires cookie*
 Title    Internal Cation Mobilities in the Molten Systems LiN03-TlN03 and RbN03-TlN03  
 Abstract    The relative differences in internal cation mobilities are measured for the molten systems LiN03-T1N03 and RbN03-TlN03 over a wide range of temperature and concentration by means of counter-current electromigration technique (Klemm's method), and the internal mobilities are calculated from the existing data on the electric conductivity for these systems. For the system LiN03-TlN03 , a marked dependence of the relative internal mobility differences on temperature is found particu-larly in the Li + rich region, and a considerable concentration dependence is found over the in-vestigated temperature range. This is qualitatively explained in terms of a model which takes into account mainly the differences of the cation-anion pair potentials and of the sizes of the two cations. On the other hand, for the system RbN03-TlN03, only a slight temperature dependence is observed and no concentration dependence, if present, is detected within the experimental accuracy. 
  Reference    (Z. Naturforsch. 30a, 69 [1975]; received November 4 1974) 
  Published    1975 
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 TEI-XML for    default:Reihe_A/30/ZNA-1975-30a-0069.pdf 
 Identifier    ZNA-1975-30a-0069 
 Volume    30 
11Author    Vladislav Ljubimov, Arnold LundénRequires cookie*
 Title    Isotope Effect of Cation Electromigration in Molten Lithium Chloride-Nitrate-Mixtures  
 Abstract    Molten mixtures of lithium chloride and nitrate, including the decomposition products nitrite and oxide, were electrolysed at about 600 °C with gaseous electrodes. The relative mobilities of the lithium isotopes were studied. The mass effect (relative difference in mobility divided by relative difference in mass) is 0.063 for a mixture with 20% Cl~ and 0.069 for 80% CI", which both are more than 30% smaller than those interpolated from the isotope effects of pure LiN03 and LiCl. It is concluded that the lithium ions interact more strongly (with the anions and/or with each other) in a melt containing several anions than in a pure melt. The experiments also yield some informa-tion about the mobilities of the anions present in the melt. 
  Reference    (Z. Naturforsch. 30a, 75—78 [1975]; received August 28 1974) 
  Published    1975 
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 TEI-XML for    default:Reihe_A/30/ZNA-1975-30a-0075.pdf 
 Identifier    ZNA-1975-30a-0075 
 Volume    30 
12Author    W. H. De Jeu, ThW. LathouwersRequires cookie*
 Title    Dielectric Constants and Molecular Structure of Nematic Liquid Crystals II. Variation of the Bridging Group  
 Abstract    Measurements are presented of the dielectric constants of some nematic compounds with the structure CHaO-^-X-O-CsHu The following bridging groups X are considered: C=C, CH = CH, CC1 = CH, N = N, CH = N, N = CH, CO — O and O —CO. Starting from the compounds with non-polar bridging groups the in-fluence of the group X on the dielectric properties is systematically evaluated. 
  Reference    (Z. Naturforsch. 30a, 79—82 [1975]; received November 6 1974) 
  Published    1975 
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 TEI-XML for    default:Reihe_A/30/ZNA-1975-30a-0079.pdf 
 Identifier    ZNA-1975-30a-0079 
 Volume    30 
13Author    Chiara Margheritis, Cesare SinistriRequires cookie*
 Title    Monte Carlo Computations on Molten Caesium Bromide  
 Abstract    Molten CsBr was computer simulated tat 1 atm and four different temperatures using the Monte Carlo method. Structural and thermodynamic properties of the melt were obtained on the basis of pair potentials. In particular, radial distribution functions, volume, and energy with its coulomb, dipole-dipole, and repulsive components were determined. Separately, the polarization energy was also evaluated: this quantity increases with increasing temperature and ranges between 2 and 4% of the total energy. 
  Reference    (Z. Naturforsch. 30a, 83—86 [1975]; received November 1974) 
  Published    1975 
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 TEI-XML for    default:Reihe_A/30/ZNA-1975-30a-0083.pdf 
 Identifier    ZNA-1975-30a-0083 
 Volume    30 
14Author    Liliana Jannelli, Americo Inglese, Antonio Sacco, Pietro CianiRequires cookie*
 Title    Thermodynamic and Physical Behaviour of Binary Mixtures Involving Sulfolane Viscosity, Dielectric Constant and Solid + Liquid Phase Diagram of Mixtures of Dioxane + Sulfolane  
 Abstract    Excess functions, H^E, for activation of viscous flow, as well as the dielectric con-stants of dioxane (1) — sulfolane (2) mixtures were determined: slight negative deviations from ideality were observed in both cases, with a minimum at x ^ 0.5. Solid-liquid equilibrium temperatures were also measured over the entire composition range. Solid solutions were observed in the region in which mesomorphic sulfolane is in equilibrium with the liquid. Two phase diagrams may be drawn, in the region 0.33 <! x2 0.98: one is of the simple eutectic type and the other exhibits two eutectics and a flat maximum corresponding to a 1 : 2 molecular compound, the occurrence of which is supposed to be caused by weak electrostatic attractions in a system of favorable crystal geometry rather than by bonding. A lessening of these interactions, with increasing temperature, would result in the liquid solution regular behaviour. 
  Reference    (Z. Naturforsch. 30a, 87—91 [1975]; received November 8 1974) 
  Published    1975 
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 TEI-XML for    default:Reihe_A/30/ZNA-1975-30a-0087.pdf 
 Identifier    ZNA-1975-30a-0087 
 Volume    30 
15Author    Detlef Schneider, Rolf Kruse, Helmut NeubauerRequires cookie*
 Title    Magnetowiderstand und Bandverschiebungen an halbleitenden Wismut-Antimon-Legierungen unter hohem hydrostatischem Druck  
 Abstract    Magnetoresistance The magnetoresistance of semiconducting BiioO-xSbx single crystals (x = 5.5 and 6.3 at % Sb) at T — 297, 77 and 63 K was measured in magnetic fields up to B = 15 T. In this region, the dependence of the magnetoresistance on the magnetic field strength exhibits a negative slope, which is characteristic for semiconductor-semimetal or semiconductor-quasimetal transitions, as previously observed by other authors in Bi-Sb alloys in the liquide He-temperature range. The influence of hydrostatic pressure (p 15 kbar) on the extrema of magnetoresistance oscil-lations at T = 77 and 63 K arising from the Shubnikov-de Haas effect has been examined. The results confirm the concept of approaching and mutually repelling L-point conductivity and valence bands. For the samples investigated, the energy gaps [Eg (a;=5.5) =6.94 meV and Eg(x=6.3) = 7.64 meV] show pressure dependences of d£/dp= —1.16-10 -6 eV/bar at 77 K and —1.39-10 -6 eV/bar at 63 K, respectively. Preparation of the samples, their characterization in terms of chemical microanalysis and dis-location densities as well as the method of applying high hydrostatic pressure are described in detail. 
  Reference    (Z. Naturforsch. 30a, 92 [1975]; eingegangen am 7. November 1974) 
  Published    1975 
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 TEI-XML for    default:Reihe_A/30/ZNA-1975-30a-0092.pdf 
 Identifier    ZNA-1975-30a-0092 
 Volume    30 
16Author    T. Babeliowsky, J. BrulmansRequires cookie*
 Title    The Density at 25 °C of D20 with Natural Oxygen Isotopic Composition  
 Abstract    In measuring the influence of oxygen isotopic composition and of hydrogen content on the density of heavy water an extrapolation was made to 100% D20 with natural oxygen isotopic composition, starting with the density of a highly enriched heavy water (99.95% D20, about natural oxygen iso-topic composition). A value of 1104.481 kg/m 3 at 25 °C was obtained. 
  Reference    (Z. Naturforsch. 30a, 103—106 [1975]; received November 9 1974) 
  Published    1975 
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 TEI-XML for    default:Reihe_A/30/ZNA-1975-30a-0103.pdf 
 Identifier    ZNA-1975-30a-0103 
 Volume    30 
17Author    J. Brulmans, J. Verdonck, H. L. EschbachRequires cookie*
 Title    Thermal Expansion of Heavy Water between 7 and 26 °C  
 Abstract    Using six carefully calibrated quartz floats the thermal expansion of water with a D20 content of 99.74 mole % has been measured between 7 and 26 °C. The extrapolation to 100% D20 with natural oxygen isotopic composition is made. 
  Reference    (Z. Naturforsch. 30a, 107—108 [1975]; received November 9 1974) 
  Published    1975 
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 TEI-XML for    default:Reihe_A/30/ZNA-1975-30a-0107_n.pdf 
 Identifier    ZNA-1975-30a-0107_n 
 Volume    30 
18Author    H. HinkelmannRequires cookie*
 Title    Factor of the Electrons in Metals  
 Abstract    For a metal a simple relation between the dynamical form factors Sei (9, <*>) and Sion(9< <o) is given for co^qvi From this the phonon contribution to the electronic 
  Reference    (Z. Naturforsch. 30a, 109—110 [1975]; received September 16 1974) 
  Published    1975 
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 TEI-XML for    default:Reihe_A/30/ZNA-1975-30a-0109_n.pdf 
 Identifier    ZNA-1975-30a-0109_n 
 Volume    30 
19Author    S. HessRequires cookie*
 Title    Magnetic-field Induced Change of the Viscosity of Diamagnetic Gases with Anisotropic Magnetic Susceptibility  
 Abstract    The influence of a high magnetic field on the viscosity of diamagnetic gases of linear, symmetric and asymmetric top molecules is studied within the frame-work of the kinetic theory based on the Waldmann-Snider equation. The quadratic Zeeman effect associated with the anisotropic magnetic susceptibility is taken into account in addition to the usual linear Zeeman splitting. 
  Reference    (Z. Naturforsch. 30a, 111—116 [1975]) 
  Published    1975 
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 TEI-XML for    default:Reihe_A/30/ZNA-1975-30a-0111.pdf 
 Identifier    ZNA-1975-30a-0111 
 Volume    30 
20Author    W. E. KöhlerRequires cookie*
 Title    Waldmann-Snider Collision Integrals and Nonspherical Molecular Interaction II. DWBA-Scattering Amplitude and Cross Sections for Linear Molecules  
 Abstract    The binary scattering amplitude matrix is derived from the general interaction potential between linear molecules. The first order distorted wave Born approximation (DWBA) is used which is applicable for small nonsphericity of the interaction. The molecular cross sections determining the most important Waldmann-Snider collision integrals are calculated. In particular, the scattering cross section, the orientation cross sections for vector-and tensor polarization and the reorientation cross sections for the tensor polarization of the rotational angular momenta are treated. For a simple interaction model for HD (HT) molecules the DWBA-scattering amplitude is evaluated analytically. The relaxation cross section of the tensor polarization, o T , and the coupling cross section of friction pressure tensor and tensor polarization, ov>T, are calculated for room temperature and compared with experimental values. 
  Reference    (Z. Naturforsch. 30a, 117—133 [1975]; received November 18 1974) 
  Published    1975 
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 TEI-XML for    default:Reihe_A/30/ZNA-1975-30a-0117.pdf 
 Identifier    ZNA-1975-30a-0117 
 Volume    30 
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