bluuebunny/crossref_metadata_2025 huggingface dataset:
Zur Verteilung von Mn und Co in K(Zn,Mn,Co) F3-Einkristallen / The Distribution of Mn and Co in K(Zn, Mn, Co) F3-Single Crystals
Authors: Dickten G. , Recker K. , Triché C.
Published: February 2015

For the investigation of perfection, homogenity, absorption and luminescence a large number of K(Zn, Mn, Co) F3-single crystals with variable Mn and Co contents were grown by the Stockbarger-Bridgman method under vacuum and argon protection gas. From these crystals the Mn-and Co-contents were determined quantitatively as a function of the crystal region by means of the electron-microprobe- and absorption-techniques. The distribution curves [cS/c0 = f(x)] are discussed as a function of the crystal growth parameters. The distribution-coefficients have been determined with the help of Pfann's formula and a proposed formula which permits the computation of the distribution-coefficient for every crystal region. Both methods lead to the same results:

for Mn in KZnF3 : ke = 1.73, for Co in KZnF3 : ke = 1.64 (at growth-begin).
Molekularthermodynamische Interpretation der Phasentrennung und der kritischen Phänomene / A Molecular Thermodynamic Approach to Phase Separation and Critical Phenomena
Authors: Becker Friedrich
Published: February 2015

As we have shown in a recent paper5, the principle of competition between "statistical" and "chemical" mixing represents a molecular thermodynamic approach to all known types of phase separation. This principle is effective if the contributions of two independent spontaneous processes enter into the thermodynamic potential by which the resulting equilibrium state of the system is determined. This is equivalent with the statement that two different forms of entropy exist which are not interchangeable, and for which the law of increasing entropy independently must be valid. As "cooperativity" is introduced by this principle, critical phenomena may be described by simple equilibrium models in which only nearest-neighbour interactions are considered.

Starting from the molar Gibbs free energy GM of the most simple binary equilibrium model z = 1 with nearest-neighbour pairs, nonclassical critical-point exponents α = 0.33 of the molar heat capacity, β = 0.33 of the coexistence curve, γ = 1.33 of the isothermal compressibility, and δ = 4.33 of the critical isotherm, are derived, which are consistent with the well-known exponent in­ equalities. These non-classical critical-point exponents are independent of the chemical nature of the particles because they are obtained by applying thermodynamic arguments on the coupling constant τ, by which the contribution of "statistical mixing" to GM is weighted.
Asymetric Dielectric Dispersionin Glycols
Authors: Rajyam B. S. , Sastry C. V. Rama , Murty C. R. K.
Published: February 2015

Dielectric dispersion studies of two pure liquid glycols, diethylene glycol and 1,3-butane diol, and of 2,2-dimethyl 1,3-propane diol dissolved in dioxane, have been carried out at radio, ultrahigh and microwave frequencies at 30 °C. The dispersion nature of the two pure liquids and the solution conforms to the Cole-Davidson type. The dispersion data on the glycol solution show a significant asymmetric behaviour. Comparison of the dispersion parameter β, and relaxation time τ0 , of the present glycols with those of other glycols reveals that both β and τ0 increase with the number of intervening carbon atoms between the two hydroxyl groups.
The Suppression of Contamination in the Convergent-Beam Electron Diffraction Camera
Authors: Dowell W. C. T. , Goodman P.
Published: February 2015

It has been demonstrated that specimen contamination in convergent-beam diffraction operation can be prevented by maintaining the specimen temperature between -110 °C and -165 °C, without the use of especially high or clean vacuum conditions. At these temperatures, surface migration of molecules causing contamination is evidently inhibited. Precautions to prevent deposition from the vapour phase both before and after cooling are also required.
Energieübertragung in verschiedenen flüssigen organischen Szintillatorsystemen / Energy Transfer in Some Liquid Organic Scintillator Systems
Authors: Kawski A. , Waśniewski T.
Published: February 2015

Energy Transfer in Some Liquid Organic Scintillator Systems Experimental results of fluorescence induced by high energy (gamma radiation) excitation in solutions of various solutes (isoeugenole, methylisoeugenole, 2-phenylindole, N-phenyl-2-naphthyl-amine, acenaphthene, 2,6-dimethylnaphthalene and 2,5-diphenyloxazole) in various solvents (benzene, toluene, xylene and xylene/n-butanol) are compared with the Bothe equation. Good agree­ ment was found with the Bothe equation which takes into account the fluorescence of solute and solvent. A linear dependence of the fluorescence intensity maximum Jmax on P/(R-K) for different solutes in a given solvent was found. A similar dependence was also found for 2,5-diphenyloxazole in xylene/n-butanol mixtures. An interpretation of the observed effects is given.
Short Range Order in Liquid Lithium-Sodium Alloys
Authors: Ruppersberg Henner , Knoll Walter
Published: February 2015

The short range order of a liquid lithium sodium alloy with nearly critical composition has been studied by small-angle and high-angle neutron diffraction at 10 and 145 K above the critical temperature. In this temperature range the small-angle scattering yields linear Ornstein-Zernike plots from which formally critical exponents and amplitudes could be determined. The atoms prefer like nearest neighbors and the extent of this preference varies only slowly with temperature.
Ligand-Field Calculations on Pseudo-Tetragonal High-Spin Fe(II) Compounds
Authors: Vermaas A. , Groeneveld W. L. , Reedijk J.
Published: February 2015

The paramagnetic susceptibility behaviour as well as the Mössbauer quadrupole splitting are calculated for high-spin d6 systems with a tetragonal or an orthorhombic point-symmetry. The calculations include a simultaneous perturbation of the 5D multiplet by spin-orbit interaction and static octahedral-tetragonal and orthorhombic fields. The lattice contribution to the electric-field gradient is calculated on the basis of a crystal-field model that directly relates crystal-field energy parameters to the lattice contribution. It appears that, espacially for compounds with large Ds values, the lattice contribution to the quadrupole splitting cannot be ignored.
T The Structure of NO3
– in Molten Monovalent Metal Nitrates by Pulsed Neutron Diffraction
Authors: Suzuki Kenji , Fukushima Yoshiaki
Published: February 2015

The structure factor of molten monovalent metal nitrates was measured over a wide range of scattering vectors by time-of-flight pulsed neutron diffraction using epithermal neutrons generated from an electron LINAC. It is found that the NO3
- ion forms an isosceles triangle in molten LiNO3, AgNO3 and TlNO3, and a regular triangle in molten NaNO3, KNO3, RbNO3 and CsNO3.
The High Resolution Rotational Spectrum of Silylbromide, SiH3
81Br
Authors: Dössel K.-F. , Sutter D. H.
Published: February 2015

The microwave spectrum of SiH3
81Br has been reanalysed in the frequency range 8-40 GHz under high resolution. From 64 observed hyperfine transitions improved values for the rotational constant B = 4292646.2(4) kHz and the quadrupole coupling constant eqQ = 279825(5) kHz were obtained. Furthermore the centrifugal distortion constants DJ = 1.81(1) kHz and DJK = 29.19(4) kHz and the spin-rotation constants CN = -2.32(40) kHz and CK = -34.2(11) kHz were determined. From the values of CN and CK the 81Br nuclear shielding tensor is calculated. An improved value of ∣μ∣ - 1.319(8) D is given for the molecular electric dipole-moment.
Nonlinear Patterns in Chemical Networks as Symmetries of Transformation Groups
Authors: Busse H.-G. , Havsteen B.
Published: February 2015

The origin of a stable spatial pattern in chemical reaction systems has been traced back to symmetries characterized by one-parameter transformation groups. The chemical reaction-diffusion system of Dreitlein and Smoes served as a model for the mathematical approach. The procedure is based on the conversion of sets of partial differential equations to equivalent systems of first order in more parameters. The latter generally admit one-parameter groups, which are related to singularities observed as pattern. It is also shown how models may be constructed from Lie-algebras using the constraints of integrability.
Multiple Coulomb and Nuclear Excitation of 238U with Very Heavy Ions
Authors: Oberacker Volker , Soff Gerhard
Published: February 2015

Coupled channel calculations for Coulomb and nuclear excitation of the systems 136Xe-238U and 238U-238U have been performed using the rotation-vibration model. The impact parameter-, energy-and spin-dependence of the excitation probabilities are discussed for the ground state-, β-and γ-band up to Jπ = 36+. It is shown that the energy levels and quadrupole matrix elements are strongly influenced by the rotation-vibration interaction. Analytic expressions for the elastic and coupling potentials are presented.
The Complete Structure of Maleic Anhydride by DRM Microwave Spectroscopy
Authors: Stiefvater Otto L.
Published: February 2015

Double resonance modulation (DRM) microwave spectroscopy has been used for the study of rotational spectra of normal and 3,4-d2 maleic anhydride, and for the investigation of the iso­ topic species spectra due naturally occurring 13C-and 18O-species of the aforementioned two parent forms. From the experimental data the complete structures of the normal and the 3,4-d2-species were deduced independently to yield the following, averaged bond lengths (in Å) and angles (in degrees) for this planar, C2v-symmetrical molecule:

C-O =1.3876 C-O-C = 108.06

C=O = 1.1962 O-C-C = 108.07

C-C = 1.4849 C-C=C = 107.90

C=C = 1.3331 O-C=0 = 122.32

C-H = 1.0791 C=C-H =129.99

The compatibility of these averaged parameters with individual values obtained for the normal and the 3,4-d2 species is better than 0.0004 Å and 0.01° for distances and angles, respectively.

The internal consistency of the rS parameters is discussed, and the vibrational contributions to the change in the moments of inertia under isotopic substitution of carbon and oxygen atoms near a principal axis are deduced.

The present structure data are compared with previous results by diffraction methods, and the bond lengths in maleic anhydride are discussed in relation to those in chemically similar substances.
Crystal Equilibrium and Lattice Dynamical Study of α-Iron and Chromium
Authors: Gupta O. P. , Hemkar M. P.
Published: February 2015

Studies of the phonon dispersion, the temperature dependence of Debye-Waller factor, the Debye temperature, and the mean square displacement of α-iron and chromium have been made by means of a lattice dynamical model proposed by the authors. The model considers short range pairwise forces effective up to the second neighbours and electron-ion interactions on the lines of Bhatia using an appropriate value of the screening parameter. The volume force is aver­ aged over the whole Wigner-Seitz sphere. The ionic lattice is in equilibrium in a medium of electrons. The computed results compare well with experimental data.
Photoelectron Spectra of Bromo- and Iodotrifluoromethane
Authors: Cvitaš T. , Güsten H. , Klasinc L. , Novadj I. , Vančik H.
Published: February 2015

The Hel and Hell photoelectron spectra of the title compounds have been recorded and an­ alysed on the basis of comparison with chlorotrifluoromethane and methyl halides. Spin-orbit splitting could be observed in the ground state of CF3I+ where it amounts to 0.73 eV and is unresolved in CF3Br+. Vibrational fine structure observed in two band systems D and E in CF3Br+, and X and E in CF3I+ is also discussed.
Source Functions of CO2 and Future CO2 Burden in the Atmosphere
Authors: Zimen K. E. , Offermann P. , Hartmann G.
Published: February 2015

A logistic source function for CO2 was derived which takes into account the input arising from the burning of fossil fuels, the stimulation of photosynthesis by the increasing partial pressure of CO2, and the decrease of biomass through deforestation etc. The parameters in a 5-box-model for the kinetics of CO2 were adjusted to fit the new Mauna Loa data on CO2 concentrations in air. Using these parameters and a buffer factor ξ(t) for the absorption of CO2 into the sea, the future CO2 burden was calculated for status quo conditions and for different values of the growth coefficient of fossil fuel consumption.

The results show that one can change the deforestation factor in rather wide limits without changing very much the future CO2 concentration in air during the next 80 years or so (cf. Figure 4). On the other hand, the future C02 burden depends strongly on the growth rate of fossil fuel consumption and will double under status quo conditions early in the next century (cf. Figure 5).
Electron Emission of CuBe on Bombardement with Parent and Fragment Ions of Ammonia and Phosphine
Authors: Märk T. D.
Published: February 2015

The secondary electron emission of the first dynode of a CuBe-alloy sixteen dynode electron multiplier has been studied in the course of electron impact ionization studies of ammonia and phosphine. Relative secondary electron emission coefficients have been obtained for the singly and doubly charged parent and fragment ions of ammonia. ammonia-d3, phosphine and phosphine-d3 for kinetic energies of 5.25 and 10.5 keV. It has been found that in general deuterated ions have smaller γ coefficients than protonated ions, that ammonia ions have larger γ coefficients than phosphine ions, and that the γ coefficient increases with the complexity of the ion under study.
Fluoreszenzlöschung alternierender und nicht-alternierender polycyclischer aromatischer Kohlenwasserstoffe durch Nitroverbindungen / Fluorescence Quenching of Alternant and Non-alternant Polycyclic Hydrocarbons by Nitro Compounds
Authors: Zander M.
Published: February 2015

Fluorescence Quenching of Alternant and Non-alternant Polycyclic Hydrocarbons by Nitro Compounds Fluorescence quenching of polycyclic aromatic hydro­ carbons by nitromethane or nitrobenzene in fluid solutions is due to an electron transfer mechanism. The non diffusion controlled rate constant of quenching is very much greater for alternant than for non-alternant hydrocarbons with equal singlet excitation energy. This is explained by the known more positive reduction potential of non-alternant compared to alternant hydrocarbons.
Zum Gedankenexperiment von Einstein , Podolsky und Rosen
Authors: Weber M.
Published: February 2015

The EPR-gedankenexperiment in the general case of systems with angular momentum of arbitrary magnitude is analyzed within the quantum theoretical measuring process. With respect to the time reversal symmetry of the systems under consideration it will be shown that the contradictions between the EPR experiment and quantum theory do not occur.
Vector Polarization Induced by a Viscous Gas Flow in a Magnetic Field
Authors: Köhler W. E.
Published: February 2015

It is shown that a viscous flow of a polyatomic gas in a magnetic field can give rise to a vector polarization of the molecular rotational angular momenta. This viscomagnetic vector polarization is calculated from an appropriate set of moment equations pertaining to the linearized Waldmann-Snider equation. In particular, the transverse effect is discussed and an estimate of its order of magnitude is given for nitrogen.
Spektrographische Bestimmung von Halogenspuren mit Hilfe einer Impulsquelle Einfluß von Natur und Druck des umgebenden Gases / Determination of Halogens by means of Emission Spectroscopy with a Pulsed Source. Influence of the Nature and Pressure of the Surrounding Gas
Authors: Heshmat-Chaaban G. , Triché Cl.
Published: February 2015

A high power pulsed source has been employed for emission spectrographic determination of halogens. The experiments were conducted in various gases (rare or diatomic gas). This method may be applied to all metalloids. The sensitivity can be improved in comparison with that obtained in air under normal pressure: 100 ppm instead of 400 for fluorine (He: 460 Torr), 1 ppm instead of 10 for the bromine (Ar: 380 Torr). Depending on the nature and pressure of the working-gas, collisions of the second kind or quenching collisions are predominant.
Phase Transitions in Caesium n.C5-n.C12 Alkanoates
Authors: Sanesi M. , Ferloni P. , Zangen M. , Franzosini P.
Published: February 2015

DSC analysis was performed on caesium n.C5-n.C12 alkanoates between 330 and about 700 K. The temperatures of clearing and/or melting, and of solid state transitions were evaluated together with the associated heat effects. The occurrence of metastable melting was also put into evidence for the higher terms of the series.
Toroidal Oscilation in a 3-Variable Abstract Reaction System
Authors: Rössler Otto E.
Published: February 2015

An example of a chemical reaction system producing a type of oscillation that is close to a quasi-periodic oscillation is presented. Such system may help clarify the relationship between quasi-periodicity and chaos.
Enhancement of the Scattering Intensity for the Hyper-Raman Effect in Connection with Statistical Properties of the Excitation Light Source
Authors: Altmann K. , Strey G.
Published: February 2015

The scattering intensity for the hyper-Raman effect is found to depend on statistical properties of the excitation light source. In close correspondence to the two-photon absorption process also for the hyper-Raman effect there arises an amplification factor of 3/2 up to 2 for the superposition of two or an infinite number, respectively, of incoherent light waves, polarized parallel. This result is derived in semiclassical terms so that the origin of the effect can be followed more clearly than in quantum electrodynamical calculations. It is shown that natural light in nonlinear optics can be represented mathematically alternatively by superposing linearly or circularly polarized light waves as in linear optics, but with the important modification that one should superpose an infinite number of incoherent components instead of only two of them. A new experimental method is proposed to observe the hyper-Raman effect using the mode locking technique. It is shown that the scattering intensity can be increased in this way by a factor of approximately ⅔ M where M is the number of modes coupled together with a constant frequency separation ⊿ω.
On the Thermal Behaviour of Long-chain Potassium n.alkanoates
Authors: Ferloni P. , Spinolo G. , Zangen M. , Franzosini P.
Published: February 2015

Differential scanning calorimetry was performed between 110 K and the isotropic melt region on potassium n.alka­-noates from octanoate to dodecanoate. Clearing, melting and (crystalline) solid state transition temperatures and heat effects were measured. In the higher homologues the occur­ rence of phases (likely “waxy”) intermediate between crystalline solid and mesomorphic liquid could also be argued. The phase relationships are discussed in comparison with some roentgenographic and microscopic results of previous authors.
A Double Hard Sphere Model of Supercooled Liquid Gallium
Authors: Orton B. R.
Published: February 2015

A double hard sphere model, already successfully applied to liquid Ge and Sb, has been used to reproduce the inter­ ference function of supercooled liquid Ga at 23 °C. The model interference function was composed of two partial interference functions which corresponded to packing den­ sities of 0.50 and 0.47 and diameters 2.78 Å and 2.25 Å. Additional justification for the model has been found in recent theoretical work.
Reversed Kinetic Isotope Effect during Penetration of Cathodic Hydrogen/Deuterium into NiCu30 Alloy
Authors: Bauer H. J. , Grosselfinger J. , Zwick M.
Published: February 2015

The cathodic charging with H/D of a NiCu alloy containing 30 At.-% Cu followed by magnetic measurements indicates that D penetrates faster into the alloy than H.
Harmonie Force Fields and Bond Orders for Naphthalene, Anthracene, Biphenylene and Perylene with Mean Amplitudes for Perylene
Authors: Whitmer J. C. , Cyvin S. J. , Cyvin B. N.
Published: February 2015

Complete normal coordinate analyses were performed for naphthalene, anthracene, biphenylene and perylene, starting from a simple force field with seven adjustable force constants. A relationship between bond orders and carbon-carbon stretching force constants was deduced from: (a) bond distances as a function of bond orders, (b) a version of Badger's rule relating stretching force constants to the bond distances. The relationship was used to modify the initial seven-parameter force field, and the vibrational frequencies calculated from both the initial and modified force fields are discussed. In general the simple force field approximation produces sets of frequencies in remarkably good agreement with experimental assignments. The force field approximation failed badly when applied to benzene. No obvious explanation was found for this unexpected feature, which makes it worth while to continue the investigations. The mean amplitudes of vibration were calculated. For perylene an account of the complete set of mean amplitudes is given for the first time.
Triplet-State Electron Spin Resonance of Chlorophyll a and b Molecules and Complexes in PMMA and MTHF. I: Experimental Determination of Fine-Structure and Rate Constants
Authors: Hagele W. , Schmid D. , Wolf H. C.
Published: February 2015

The triplet state zero-field splittings and the rate constants for the population and depopulation of the triplet spin sublevels have been investigated for chlorophyll a and chlorophyll b in polymethylmethacrylate (PMMA) and methyltetrahydrofurane (MTHF) as a function of the concentration. In PMMA both chlorophyll a and chlorophyll b yielded only one ESR spectrum in the entire range of concentration which could be covered (1.5 × 10-5 - 1 × 10-3 mole/1). In MTHF the results were more complicated. At low concentrations (up to 103 mole/1) only one spectrum was observed, at higher concentrations additional spectra were detectable (all together two for chlorophyll a and five for chlorophyll b at 10-1 mole/1). The assignment of these spectra was facilitated by observing the "triplet resonance-field identity" which connects the resonancefield strengths for the canonical orientations of one particular species. Furthermore, the rate constants for some of these species could be determined.
Triplet-State Electron Spin Resonance of Chlorophyll a and b Molecules and Complexes in PMMA and MTHF. II: Interpretation of the Experimental Results
Authors: Hagele W. , Schmid D. , Wolf H. C.
Published: February 2015

ESR spectra of various triplet species, obtained with solutions of chlorophyll a or chlorophyll b in PMMA or MTHF, are attributed to isolated chlorophyll molecules, to chlorophyll-solvent complexes and to dimeric structures. The structure of the proposed dimer is determined using the experimental results for the fine-structure and the rate constants and by assuming an incoherent triplet-energy exchange. Based on this model the structure of the reaction center in photosynthetic bacteria was also reevaluated using the experimental data which were published by various authors.
Quadrupole Splittings of Alkali NMR Signals in Decylammoniumchloride Mesophases
Authors: Gauß W. , Kronenbitter J. , Lutz  , Nolle A. , Siegloch G. E.
Published: February 2015

In lyotropic mesophases of decylammoniumchloride the NMR signals of the alkali nuclei 6Li, 7Li, 23Na, 39K, 85Rb, 87Rb and 133Cs solubilized in these mesophases have been observed. The linewidths of the signals are comparable with the linewidths in aqueous solutions. Apart from 6Li and 39K for all other alkali nuclei in the mesophases first-order quadrupole splitted spectra have been observed. For the rubidium isotopes 85Rb and 87Rb a ratio of the quadrupole splitting of 2.01 ± 0.05 has been determined. Further the chemical shifts of the solubilized alkali nuclei relative to infinitely diluted aqueous solutions have been measured.
Electronic Properties of Möbius Systems
Authors: Gutman Ivan
Published: February 2015

The main π-electron properties (energy level distribution, total electron energy, charge distribution) of Möbius systems are analysed. A number of results, known previously for Hückel systems is generalized and/or modified for Möbius systems. The main conclusions of the work are summarized in Rules 1-7.
1H Spin-Gitter-Relaxationszeitmessungen an Alkoholen / 1H Spin-Lattice Relaxationtime Measurements on Alcohols
Authors: Sterk H. , Kopp H.
Published: February 2015

1H spin-lattice relaxationtimes T1 have been measured on alcohols, ethers, acetylacetone and cyclohexandione-1,3, solved in CCl4 and pure. The relaxationtime T1 increases characteristically with decreasing chain length, molecular size and viscosity, as well as with the distance from the OH-group and CCl4 dilution. Segmental motions and the breaking of hydrogen bondings are determined as the reason of this behaviour. Deuteron substitution and T1 measurements at different temperatures show that the dipol-dipol interaction is the predominant mechanism of relaxation.
Primary Reactions during the Free Anionic Polymerization of β Nitrostyrene
Authors: Dinh-Ngoc Binh , Schnabel Wolfram
Published: February 2015

β-Nitrostyrene (βNS) was irradiated at r. t. in solutions of hexamethylphosph. triamide (HMPT) with 50 ns pulses of 15 MeV electrons. It was found that βNS reacts with solvated electrons almost encounter controlled (k(e-
solv + βNS) = (9 ± 3) · 109 l/mol s) forming the radical anion · βNS-. The optical absorption spectrum of the latter was recorded in dilute solutions ([βNS] < 5 × 10-3 mol/l). At higher βNS concentrations the formation of an additional optical absorption after the pulse in the wavelength range between 460 nm and 570 nm was detected, which is attributed to the reaction of βNS with · βNS- yielding the dimeric radical anion (· βNS-βNS-). The rate constant for this process is 4 × 107 l/mol s. At low βNS concentrations ( < 5 × 10-3 mol/l) the transient spectrum decayed by a second order process (k2 - (2.2 ± 0.5) · 109 l/mol s). This process is correlated to the neutralization of radical anions by cations formed initially. At [βNS] > 5 × 10-3 mol/l only the band at 630 nm decays according to second order kinetics. This band is correlated to the part of the anions with the highest electron density, the nitro groups. At wavelengths below 570 nm the absorptions of various species overlap. These species decay by different rate laws.
Zur Eignung von Edelgas- bzw. Edelgas-Stickstoff-Gemischen als Detektionsgase in Proportional-Szintillations-Detektoren / Suitability of Noble Gases and their Mixtures, Partly with Nitrogen, as Detection Gases in Proportional Scintillation Counters
Authors: Brunner G. , Morgenstern P.
Published: February 2015

Ar, Ar/N2, Ar/Xe, Kr and Kr/Xe were tested in a spherical gas scintillation counter. The examinations led to the conclusion that only the four lowest lying states 3P2, 3P1, 3P0, 1P1 of the noble gas atoms in the luminescence process are involved. From a practical point of view, the best energy resolution could be reached by Xe. We got a full width at half maximum of 83 eV for boron X-rays (183 eV).
Quantitative Isotopenanreicherung im Thermodiffusionstrennrohr / Quantitative Isotope Enrichment in Thermal Diffusion Separation Column
Authors: Kretner R. , Dickel G.
Published: February 2015

In applying the theory of the thermal diffusion separation column with containers at both ends to quantitative isotope enrichment, the volume of the column has not yet been exactly accounted for. A formula is derived which describes the effective volume as a function of the characteristic values of the enrichment apparatus. An iteration method for calculation of the effective volume is presented. The theoretical values are compared with experimental results in the case of time dependent enrichment of two isotopes (13CH4, 14CH4) and three different ways of enrichment. Agreement within the experimental limits of error of ± 6% was found.
Relative Stabilities of Dihaloethylenes and Dihaloethanes. A Theoretical Study [1]
Authors: Nascimento Carlos C. , Brinn Ira Mark
Published: February 2015

CNDO/2-type calculations have been carried out on 1,1-dihaloethylenes, 1,2-dihaloethylenes and 1,2-dihaloethanes treating all four halogens. The energy was minimized with respect to the coordinates by use of the FORCE method. The results are consistent with experimental isomer and conformer stabilities and it is shown, by means of a cis-trans correlation diagram and calculated intramolecular atomic interaction energies, that previous explanations of the apparent halogen-halogen attraction are inconsistent with our results.
Low Frequency Dielectric Dispersion in 1,4-Butanediol
Authors: Pethig R.
Published: February 2015

The earlier reported dielectric properties of solid 1,4-Butanediol are critically examined in terms of conventional dipolar orientational theory. An explanation of the low frequency dielectric dispersion that involves molecular orientational effects associated with lattice deformations appears to require a value of the order 0.53 to 0.58 for the so-called Kirkwood dipole moment reduction factor. A model involving the hopping of charge carriers between localized energy states is offered as an alternative mechanism for the dielectric dispersion.
The Field Equations of Metric-Affine Gravitational Theories
Authors: Aldersley S. J.
Published: February 2015

The notions of conservation of charge and dimensional consistency are used to obtain conditions which uniquely characterize the field equations of electromagnetism and gravitation in a metric-affine gravitational framework with a vector potential. Conditions for the uniqueness of the choice of field equations of a metric-affine gravitational theory (in the absence of electromagnetism) follow as a special case. Some consequences are discussed.
Acceleration of Filamentary Macroparticles to Very Large Velocities in High Voltage Diodes
Authors: Winterberg F.
Published: February 2015

An attempt is made to explain the observed very large velocities of macroscopic particles in pulsed high voltage diodes. It is assumed that the macroscopic particle has the shape of a filament which is pulled out of the anode surface by electrostatic forces. It is furthermore assumed that a vacuum spark will originate from the tip of this filament If the current of the spark discharge is very large and the filament radius sufficiently small, it will be held together by a large magnetic field. This large magnetic field then also permits the filament to become highly charged and it is shown that this large charge in conjunction with the applied large diode field can explain the observed very high velocities.
Matrix Elements of the Linearized Collision Operator for Multi-temperature Gas-mixtures
Authors: Weinert Ulrich
Published: February 2015

For a multi-component and multi-temperature gas-mixture the matrix elements of the linearized Boltzmann collision operator are investigated for isotropic interaction potentials. The representation by means of Burnett basis functions simplifies the algebraic structure and enables closed expressions for the general results, which can also be used for an investigation of inelastic collisions. For the elastic case those collision terms are given explicitely which appear in the balance equations for mass, momentum, energy and heat flux-vector.
Modified Heisenberg's Approach for the Mean Charged Hadron Multiplicity in High Energy Collisions
Authors: Ghosh D. C. , Daftari I. K. , Bhattacharjee D. K. , Naha S. C. , Chowdhury A. Roy , Roy T.
Published: February 2015

The semiempirical formulation of Ghosh et al. for the energy dependence of multiplicity in hadronic collisions has been applied to account for the experimental multiplicity data of π±p and K±p collisions. A remarkable agreement has been found over the entire energy range.
A Cell for Countercurrent Electromigration Experiments for Molten Nitrates
Authors: Okada Isao
Published: February 2015

A new type of cell for countercurrent electromigration of molten nitrates is proposed, in which molten NH4NO3 is employed just above its melting point in a large cathode compartment. This cell can be used effectively without trouble of corrosion for the purpose of (1) enrichment of 6Li, (2) enrichment of heavier isotopes such as 7Li, and (3) measurements of relative internal mobility differences of cations and/or isotopes.
Hydrogen Stretching Band of Hydrogen Bonded Complex: Molecular Dynamics Approach
Authors: Pumpernik D. , Borštnik B. , Ažman A.
Published: February 2015

The molecular dynamics is used to evaluate the hydrogen stretching band in the hydrogen bonded system. The vibrational relaxation is the main mechanism influencing the band profile.
13C- and Proton-ENDOR Studies of 13C-labelled Organic Radicals
Authors: Fey H.-J. , Lubitz W. , Zimmermann H. , Plato M. , Möbius K. , Biehl R.
Published: February 2015

As part of a systematic non-proton ENDOR-in-solution study results are reported for 13C in several isotopically enriched model compounds. Methods for synthesizing these labelled compounds are also presented. The optimum 13C ENDOR temperatures are found to be considerably higher than for protons on account of the larger hyperfine anisotropy. Cross relaxation effects are used to determine rotational correlation times. The isotropic 13C hyperfine couplings are in satisfactory agreement with INDO results
Untersuchung der elektrischen Leitfähigkeit im nematischen und smektischen Phasenbereich von 4-Alkyloxy-4'-cyanobiphenylen / Study of the Electrical Conductivity in the Nematic and Smectic Phases of 4-Alkyloxy-4''-cyanobiphenyls
Authors: Schneider F.
Published: February 2015

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 conductivity. 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 electrical 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
The Structure of the Other Rotamer of Formic Acid, cis-HCOOH1,2
Authors: Bjarnov E. , Hocking W. H.
Published: February 2015

The very weak microwave spectra of six isotopically substituted species of formic acid in the cis rotamer form (i.e. with the two hydrogen atoms cis to each other) have been studied. From the data on HC18OOH, HCO18OH, H13COOH, 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=O) = 1.195(3) A, rs(C-O) = 1.352(3) Å, rs(O-H) = 0.956(5) Å, ∢(OCO) = 122.1(4)°, ∢(HC-O) = 114.6(6)° and ∢(COH) = 109.7(4)°
High Energy Sputtering from Cleaned Metal Foils
Authors: Krueger F. R. , Wien K.
Published: February 2015

Positive and negative secondary ions desorbed from metal foils by bombardment with 252Cf 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 , O2 , N2 , CO, C2H4 , C2H6 and C3H7OH up to several 100 L. The yields of metal ions from clean metal surfaces are in agreement with Sigmund' theory.
Nachweis der verschiedenen Phasen und Phasenübergänge des Systems Fe-Ga im Konzentrationsbereich 25,7 bis 28,3 At-% Ga bei Temperaturen von 20 °C bis 720 °C mit Hilfe des Mössbauer- Effekts
Authors: Tiemann K. , Schmand J.
Published: February 2015

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 -DO3 between 180 and 260 °C, a transition DO3 -Ll2 between 280 and 380 °C, a transition Ll2 -DO19 in a small temperature interval at 610 °C, and a further one DO19 - DO3 (or DO19-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.
Magnetische Suszeptibilität von destilliertem Lithium zwischen 294 und 3,7 K
Authors: Lueken Heiko
Published: February 2015

The magnetic susceptibility of distilled lithium has been determined over the temperature range 294 - 3.7 K. The obtained room temperature value of the mass susceptibility is (3.44±0.08)·10-6 cm3 g-1 (cgs units). Below 20 K the susceptibility of the mixture of hexagonal close-packed and body-centered cubic lithium has increased at a rate of about 16%.
Kinetic Theory of Nonequilibrium Alignment Phenomena in Dilute Polyatomic Gases in External Magnetic and Electric Fields
Authors: Köhler W. E. , Knaap H. F. P. , Eggermont G. E. J. , Hooft G. W. ’t
Published: February 2015

The inverse operator technique for the solution of the linearized Waldmann-Snider equation in first order Chapman-Enskog-approximation is used to calculate non-equilibrium rotational angular momentum polarizations caused by a temperature- or a velocity gradient. The presence of an external homogeneous magnetic or electric field is taken into account. In particular, the viscom agnetic vector- and tensor polarization for linear molecules and the thermoelectric vectorand tensor polarization for polar symmetric top molecules are treated. Detailed expressions are given in terms of Waldmann-Snider collision cross sections. While for the tensor polarizations the self-adjoint part of the collision operator gives the major contribution, the vector polarizations occur due to the existence of a non-selfadjoint part.
The Evaluation of Partial Pressures from MD-Simulations of Liquids
Authors: Klemm A.
Published: February 2015

In the simulation of liquids by the periodic cube model the pressure can be evaluated by adding up the forces exerted by the particles on one side of a plane on the particles on the other side of the plane, or by an application of the virial theorem. The pressure also occurs in some relations between velocity-velocity- and force-position-autocorrelation functions.
MHD Stability for a Class of Tokamak Equilibria with Fixed Boundaries
Authors: Kerner W.
Published: February 2015

The stability behavior with respect to internal modes is discussed for a class of tokamak equilibria with non-circular cross-sections and essentially flat current profiles. The stability analysis is done by computer both symbolically and numerically with the help of a normal mode code, which extremizes the Lagrangian of the system . It is found that the stability limit agrees well with that of the Mercier criterion. There are stable high-beta equilibria in this model.
Nahordnung in Fe-C-Schmelzen mittels Neutronenstreuung
Authors: Weber Michael , Steeb Siegfried
Published: February 2015

Neutron diffraction measurements were done with Fe-C-melts (5; 13; and 17 at % C) using the method of isotopic substitution. The neutron small angle scattering effect observed could be explained by magnetic scattering, caused by spin-fluctuations still existing in the molten state far away from the Curie temperature. Total structure factors were calculated from observed intensities taking into account the correction for magnetic scattering. For each carbon concentration two alloys were investigated, one using iron o f natural isotopic abundance and the other using enriched 57Fe. From a comparison of the q-region below the first maximum of the total structure factor as obtained using Fenat or 57Fe, respectively, a tendency to the preference of unlike nearest neighbours is concluded, the distance between Fe-C-pairs being 2.2 Å.
Contributions to the Theory of Mass Action Kinetics. I. Enumeration of Second Order Mass Action Kinetics
Authors: Willamowski K.-D. , Rössler O. E.
Published: February 2015

By investigating the reaction diagram in its own right, it is possible to solve the problem of enumerating all the different types of mass action kinetics up to second order. The amount of non isomorphic complex sets for a given number of species and of non isomorphic reaction networks and reversible reaction networks which can be derived from a given number of complexes is given.
A Method for Calculation of Resonance Energy of Benzenoid Hydrocarbons
Authors: Gutman Ivan
Published: February 2015

A semiempirical topological formula (2) is derived, which reproduces Aihara’s resonance energy [1] of benzenoid hydrocarbons with a chemically negligible error of 2 -3%.
Stability of Plasmas Hold by Radiation Pressure
Authors: Tasso H. , Mulser P.
Published: February 2015

An extension of a simplified model of Brillouin scattering instability to arbitrarily inhomogeneous media is presented. It is shown that light pressure, if treated self-consistently, always drives the plasma unstable.
The Effect of the Δ (1236)-Resonance in Nuclear Matter
Authors: Manzke W.
Published: February 2015

The effect of the resonant ⊿ (1236)-states in nuclear matter, is studied within the framework of the exp(S)-formalism [1, 2]. Treating the Schrödinger-Equation of the ground state of an A-particle fermion system with the help of the exp (S)-formalism one obtains a system of A coupled equations which all together are equivalent to the A particle Schrödinger equation. Neglecting three- and more particle forces as well as more particle effects the ground state of the A -particle system is described by the coupled system of one particle and two-particle-equations. Considering the special conditions of nuclear matter the one particle equations turn out to be trivial while the two particle equations reduce to a generalized Bethe-Goldstone-equation. After decomposition of these equations into partial waves we obtain a computable set of coupled integro-differential equations. These equations are fully selfconsistently solved including all partial waves up to total spin J = 2. Numerical calculation shows that the effects produced by ⊿-⊿-partial waves are comparable to those produced by N -⊿-partial waves. Transitions from the N-N channels to N-⊿ or ⊿-⊿ channels are caused by nonrelativistic potentials obtained from the static limit of meson theory. The N-N-interaction is described by a Reid-potential which is modified in order to reproduce the two particle dates (N-N phase shifts, deuteron).
On the Reliability of the Re/Os Chronometer
Authors: Conrad J. , Zeh H. D.
Published: February 2015

Plausible astrophysical conditions may have substantially increased the rate of 187Re-decay, thereby invalidating the Re/Os nuclear chronometer. Moreover, if one assumes that solar system matter has not been exposed to such conditions, then discrepancies between the obtained age of the nuclei and presently accepted Hubble ages appear to exist. These discrepancies prevail with certainty if the Os/Re abundance ratio resulting from empirical abundance systematics is accepted instead of the somewhat lower ratio measured for meteorites.
Magnetische Wechselwirkung der Elektronen II / Magnetic Interaction of Electrons
Authors: Heitzmann Martha K.
Published: February 2015

The dipolmoments of the electrons destruct the infinite coulomb potential, forming a potentialwell with a surrounding wall instead, if they are in the right position. The possible eigenvalues can be seen in the exited states of the helium atom . They also must contribute to the energy of the Helium atom and other two-electron systems in the groundstate. The negative ion H- and the molecule H2 are included.
X-Ray LIII Absorption Edges of Bismuth Halides
Authors: Sarode P. R .
Published: February 2015

The position of the bismuth LIII absorption discontinuity has been studied in pure bismuth metal and in its halides, BiF3, BiCl3, BiBr3 and BiI3 using a focussing spectrograph of the transmission (Cauchois) type. In all these compounds the discontinuity is found to shift towards the high energy side with respect to that in the pure metal. The experimental material presented in this study convincingly shows that the position of the LIII absorption edge is determined by the partial charge of the absorbing atom and not by its valence.
Contributions to the Theory of Mass Action Kinetics
Authors: Willamowski Klaus-Dieter
Published: February 2015

By introducing the notion of μ-molar mass action kinetics it will be shown that μ-molar mass action kinetics describe completely the qualitative dynamical behaviour of all mass action kinetics. Since there are much fewer μ-molar mass action kinetics than general mixed molar ones, this notion reduces the complexity of investigating mass action kinetics.
The Creation of a Photon: A Heuristic Calculation of Planck’s Constant ħ or the Fine Structure Constant α
Authors: Barut A. O.
Published: February 2015

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A dynamical mechanism is presented to calculate Planck’s constant ħhence α. Because the charge inside the electron performs a zitterbewegung, the relativistic radiation theory is applied to this motion of the charge, rather than to its “center of mass” motion. With a small Doppler-correction the value obtained is α-1 = 137.03. Some tests of the theory are suggested.
Die Bedeutung von Donor-Acceptor-Wechselwirkungen im äußeren Schweratom-Effekt von AgNO3 auf das Lumineszenzverhalten von Aza-aromaten und Carbazolen / The Significance of Donor-Acceptor Interactions in the External Heavy Atom Effect of AgNO3 on the Luminescence Behaviour of Aza-aromatic Systems and Carbazoles
Authors: Zander M.
Published: February 2015

The transition probabilities of spin-forbidden processes become much more enhanced in the case of aza-aromatic systems than for structurally related aromatic hydrocarbons when AgNO3 is used as an external heavy atom perturber. This is explained with the strong electron donor properties of aza-aromatic systems thus causing strong interaction between the π-electronic system and the perturber. Since carbazoles are weaker electron donors than aza-aromatic systems, the enhancement of the phosphorescence/fluorescence quantum yield ratio by AgNO3 is lower than for aza-aromatic systems. The different behaviour of aza-aromatic systems and aromatic hydrocarbons in the heavy atom experiment with AgNO3 can find applications in fluorescence analysis.
Temperature Dependence of the Nuclear Quadrupole Frequencies of 23Na and 187Re in NaReO4
Authors: Günther S. , Lutz O. , Nolle A. , Schrade P. G.
Published: February 2015

The temperature dependence of the quadrupole frequency of 187Re measured by NQR and of 23Na measured by NMR has been determined for temperatures between 170 Kand 300 K in NaReO4. For both nuclei the quadrupole frequency decreases with increasing temperature. The dependence is stronger for 187Re than for 23Na.
Fourier Transform NM R Investigations of 77Se in Aqueous Solutions
Authors: Koch W. , Lutz O. , Nolle A.
Published: February 2015

In solutions of H2SeO3, Na2SeO3 , NaHSeO3 and Na2SeO4 in H2O NMR signals of 77Se have been observed. In these solutions chemical shifts were determined. In a 4 molal solution of Na2SeO3 the ratio of Larmor frequencies υ(77Se)/υ(1H) has been measured with a high-resolution probe. A value of the magnetic moment of 77Se in Na2SeO3 at infinite dilution in H2O is given: |μ(77Se)| = 0.533 299 6(7)μN. Relaxation times T1 have been measured by the inversion-recovery method. In a 4 molal solution of Na2SeO3 in H2O a NOE enhancement of 0.4(1) could be observed.