bluuebunny/crossref_metadata_2025_split huggingface dataset:
Origin of Iron Meteorite Groups IAB and IIICD
Authors: Wasson John T. , Willis John , Wai Chien M. , Kracher Alfred 
Published: February 2015

Abstract
Several low-Ni iron meteorites previously assigned to group IAB are reclassified IIICD on the basis of lower Ge, Ga, W and Ir concentrations and higher As concentrations; the low-Ni extreme of IIICD is now 62 mg/g, that of IAB is 64 mg/g. The resulting fractionation patterns in the two groups are quite similar. It has long been established that, in contrast to the magmatic iron meteorite groups, IAB and IIICD did not form by fractional crystallization of a metallic magma. Other models have been proposed, but all have serious flaws. A new model is proposed involving the formation of each iron in small pools of impact melt on a parent body consisting of material similar to the chondritic inclusions found in some IAB and IIICD irons, but initially unequilibrated. These impact melts ranged in temperatures from ~ 1190 K to ~ 1350 K. The degree of equilibration between melt and unmelted solids ranged from minimal at the lowest temperature to moderate at the highest temperature. The lowest temperature melts were near the cotectic in the Fe-Ni-S system with Ni contents of ~ 12 atom %. Upon cooling, these precipitated metal having ~ 600 mg/g Ni by equilibrium crystallization. The Ni-rich melt resulted from the melting of Ni-rich sulfides and metal in the unequilibrated chondritic parent. Low-Ni irons formed in high temperature melts near the composition of the FeS-Fe eutectic or somewhat more metal rich. We suggest that the decreasing Ge, Ga and refractory abundances with increasing Ni concentration reflect the trapping of these elements in oxide phases in the unequilibrated chondritic material, and that very little entered the Ni-rich melt parental to the Oktibbeha County iron. The remaining elements tended to have element/Ni ratios in the melts that were more or less independent of temperature. The remarkable correlation between I-Xe age of the chondritic inclusions and Ni content of the host metal is explained by a detailed evolution of (mega)regolith in which these groups originated. The most Ni-rich melts could only be generated from an unequilibrated chondrite parent; as the continuing deposition of impact energy produced increasingly higher grades of metamorphism, the maximum Ni content of the impact melts (and their subsequently precipitated metal) gradually decreased.
Absolutmessung der kontinuierlichen Strahlung des Heliums im Lichtbogen von λ = 109 bis 540 nm / Measurement of the Helium Continuum Radiation from λ = 109 to 540 nm in an Arc Plasma
Authors: Thoma P. 
Published: February 2015

Abstract
Absolute helium emission coefficients have been measured from 540 nm down to 109 nm in the near vuv. The radiation originates from the axis of a cylindrical He-arc of 2 mm ∅ at one atmosphere with electron temperatures between 25000 K and 26500 K. The electron densities range from 3.0 · 1016 cm-3 to 4.0 · 1016 cm-3 and have been determined independently from other plasma parameters by means of line shape measurements. The density of atoms and their kinetic temperature have been calculated from the energy balance of the electrons and Dalton's law. Comparison of the measured helium continuum emission coefficients with theoretical calculations in the wavelength range from 540 nm to 400 nm shows that, in this experiment, the radiation due to bremsstrahlung in the field of atoms must not be neglected. Taking into account this contribution very good agreement with theoretical calculations over the whole investigated spectral range from 540 nm down to 109 nm has been found. Thus the present experiment confirms the theoretical results for the photoionisation coefficients from the n = 2 and n = 3 levels. On the basis of these results the helium continuum radiation may be used for calibration purposes, which is of particular interest in the vuv.
Calculation of the Lifetimes of Localized Electronic Vacancies in Cyclic Molecules
Authors: Spehr R. 
Published: February 2015

Abstract
For a benzenelike ring of six carbon atoms the dissipation of localized electron vacancies of π and of σ symmetry is calculated. The vacancies are described by Wannier sums. The calculation yields lifetimes of localization of about 10- 16 s in both cases. These values are shorter by two orders of magnitude than any period of molecular vibrations. Therefore such transiently localized vacancies, which can be caused by irradiation or by statistical fluctuations, will not destroy any bond in organic molecules.
On the Theory of Thermally Weighted Electron-Phonon Transition Probabilities
Authors: Schupfner J. 
Published: February 2015

Abstract
We present a refined calculation method for the phonon part (Franck-Condon Overlaps) of the transition probabilities of electron-phonon radiative and non-radiative transitions in crystals. The evaluation of the thermal averaged Franck-Condon integrals is a purely algebraic method and the transition probabilities we use are derived from first principles and completely atomistic. For the electronic transitions we take into account the frequency shift of the lattice and the change of the phonon normal coordinates. Explicit formulae of the phonon parts are derived and it is shown that the common transition probabilities used in literature are special cases of our functional calculation technique.
Part 1: X-Ray High-Angle Scattering and Ultrasonic-Measurements
Authors: Hermann Gerhard , Bek Richard , Steeb Siegfried 
Published: February 2015

Abstract
By means of X-ray scattering and ultrasonic experiments, the structure of different melts of the Cd-Ga system was investigated. The structure factors S (q) obtained for the pure elements agree well with those reported by other authors. The concentration dependence of the structure factors shows no special features. From the structure factors, the total pair-distribution functions were calculated by a Fourier transformation. The nearest-neighbour distances, obtained from the total pair-distribution functions, amount to 3.04 Å for pure Cd and 2.83 Å for pure Ga and are nearly constant for all alloys. The concentration dependence of the experimental nearest-neigh-bour distances and coordination numbers was determined and is compared with statistical distribution and macroscopic segregation models. These comparisons tend to indicate a preference for like-atom neighbours. From the long-wavelength limit S(0) of the structure factors of Cd and Ga, the isothermal compressibilities were calculated. These show a satisfactory agreement with those calculated from adiabatic sound velocity data. The anomalous ultrasonic absorption of a single melt with nearly critical concentration indicates the existence of concentration fluctuations. This result is in agreement with those obtained by X-ray smallangle scattering experiments which are described in Part 2 of this work [1].
Structure of Cd-Ga Melts Part 2: X-Ray Small-Angle Scattering
Authors: Hermann Gerhard , Rainer-Harbach Georg , Steeb Siegfried 
Published: February 2015

Abstract
X-ray small-angle scattering experiments were performed on nine melts of the Cd-Ga system at different temperatures up to 440°C. Evaluation of the data follows the Ornstein-Zernike theory of critical scattering, thus yielding correlation lengths ξ of concentration fluctuations and the long-wavelength limit Sec (0) of the Bhatia-Thornton structure factor. Studies of the concentration and temperature dependence of ξ and SCC (0) indicate that the critical point occurs at cc = 50.0 ± 1-0 at % Ga and Tc - 295.2 ± 0-1° C. For a melt with the critical concentration, SCC (0) increases up to 3500 times the ideal S1d
CC (0)=C
A
C
B-This indicates a strong segregation tendency. In the vicinity of the critical point of the Cd-Ga system, experimental correlation lengths ξ > 100 A were obtained. The critical-point exponents ν and γ were determined. It follows that the behaviour of a critical Cd-Ga melt satisfies the prediction of the classical mean-field theory for higher temperatures, whereas, within experimental accuracy, the lattice-gas predictions are satisfied upon approaching the critical temperature.
Hartree-Fock Calculations of the Interaction Potential Parameters for Noble-Gas Atoms
Authors: Bielski A. , Wasilewski J. 
Published: February 2015

Abstract
The interaction potential parameters (〈rk〉, Hindmarsh’s radius rH, C6, C8, C12) are calculated for the ground and some excited configurations of the noble-gas atoms from the Hartree-Fock functions. A formula for the C8 constant is derived.
Characteristic Normal Modes of Vibration and Generalized Normal Forces: Basic Properties and Relation to Fundamental Molecular Constants
Authors: Alix A. J. P. , Rytter E. 
Published: February 2015

Abstract
A survey is given of the simplified formulae for energy distributions, force constants, secular equations, Coriolis coupling constants, isotopic substitutions, compliances, mean amplitudes, bond moment and polarizability parameters, interaction coordinates and restoring forces in the cases where either a completely characteristic normal mode or a generalized normal force can be assumed. The obtained results may be of use for the following main purposes: (i) computation of quantities which can be employed in the assignment of spectra, band shapes, intensities ... (ii) evaluation of fundamental molecular constants and isotopic shifts which can be approximated with good accuracy. As illustration, the equations have been applied sucessfully to two-dimensional cases and to Molybdenum-hexacarbonyl.
Resonance Absorption of a Wavelength-shifted Probe Beam in a Laser-Produced Plasma
Authors: Maaswinkel A. G. M. 
Published: February 2015

Abstract
The resonance absorption of a weak probe beam in a plasma, produced by 0.53 μm laser irradiation of planar targets at 1014 W/cm2, has been investigated. The probe beam (λ= 1.06 μm) could be delayed in time relative to the 0.53 μm pulse. Thus a shift of the resonance absorption maximum towards smaller angles of incidence for increasing time delays was found. This is expected on account of the hydrodynamic expansion.
The Application of the Memory-Function Formalism to Dielectric Relaxation
Authors: Bordewijk P. 
Published: February 2015

Abstract
The application of the memory-function formalism to dielectric relaxation is reconsidered. It is shown that the so-called Corresponding Micro-Macro Correlation theorem is not valid and that for a single macroscopic dielectric relaxation time, the single-molecule dipole correlation function may nevertheless be non-exponential. The deviations from the exponential decay for the single-molecule dipole correlation function are due to spatially dependent orientational correlations, and can at least partly be interpreted in terms of dielectric friction. The unsureness about these correlations implies that it is simpler to determine the rotational diffusion coefficient from the collective orientation correlation time as determined from dielectric measurements than from the single-molecule dipole correlation function as obtained from infrared spectroscopy.
Condensed Aromatics. Part VII
Authors: Neerland Grethe , Cyvin Bjørg N. , Brunvoll Jon , Cyvin Sven J. , Klaeboe Peter 
Published: February 2015

Abstract
A simple, five-parameter force field approximation for the out-of-plane vibrations of aromatic molecules is applied to anthracene and pyrene. The calculated frequencies are remarkably well compatible with previous calculations and observed data. Among the given experimental frequencies are new data recorded in infrared for anthracene and both in Raman and infrared for pyrene.
The Molecular Structure of (Dichloromethyl)-trichlorosilane
Authors: Typke V. , Dakkouri M. , Schiele M. 
Published: February 2015

Abstract
The molecular structure of (dichloromethyl)-trichlorosilane has been determined by gas phase electron diffraction. It has been found that the effective structure of the molecule has C1-symmetry with an angle of rotation τ and a tilt angle ψ of the SiCl3-group. Several vibrational amplitudes were fixed at values calculated from transferred Urey-Bradly force constants.
Systematic errors resulting from the uncertainties of the fixed parameters have been calculated applying the rules of error propagation. The most important structural parameters (rg in Å, angles in degrees) are: r(Si-C) = 1.905(10), r(Si-Cl) = 2.019(1), r(C-Cl) = 1.774(4), r(C-H) = 1.16(4), ∢ (C-Si-Cl) = 109.8(3), ∢(Si-C-Cl) = 111.4(8), ψ= 4.1(1.0), τ= 6.7(1.4) (the errors in parenthesis include the systematic contributions).
Comparison is made with structural data of other representatives of the series CH3-mClmSiCl3 (m = 0, 1, 2, 3).
Notizen: The Inhibitor Agent in Subramanian's Dislocation Etchant for KCl
Authors: Rodriguez F. , Moreno M. 
Published: February 2015

Abstract
An optical absorption study of Subramanian's solution shows that a [FeCl4]- complex is formed. This complex is mainly responsible for the possibility of observing dislocations in KCl using this solution as etchant.
Notizen: Analysis of Higher Electronic States of Azulene and Its Halogenoderivatives in n-Pentane and n-Hexane Matrices at 77 K from Absorption Spectra
Authors: Bałuk P. , Kawski A. , Kałas M. , Jaśkiewicz S. 
Published: February 2015

Abstract
Highly resolved vibrational structures of the S2← So electronic transition and the 0-0 S3 ← So and S4 ← So transitions of azulene, 2-chloro-azulene, 1,3-dichloro-azulene, 1,3-dibromo-azulene and 1,3-diiodo-azulene in n-pentane and n-hexane at 77 K have been obtained and discussed.
The Viscosity Coefficients of Biaxial-Nematic Liquid Crystals. Phenomenology and Affine Transformation Model
Authors: Baalss Dieter 
Published: February 2015

Abstract
The viscosity tensor of biaxial-nematic liquid crystals contains 16 independent elements. A complete set of these viscosity coefficients is introduced and related to experimentally accessible quantities. Furthermore, the flow alignment and its stability against an arbitrary infinitesimal disturbance are discussed. By the affine transformation model, formerly established for the uniaxial symmetric case, one can express the viscous anisotropy of perfectly ordered biaxial ellipsoids in terms of the two viscosities of an isotropic reference system and the axes ratios of the nonspherical particles.
Molecular Ordering in Nematic MBCA and EPAPU
Authors: Sreehari Sastry S. , Venkata Rao V. , Narayana Murty P. , Satyanandam G. , Sundar Raj T. F. 
Published: February 2015

Abstract
By EPR, two nematic liquid crystals (MBCA and EPAPU) were investigated using a steroidal nitroxide spin probe. In both liquid crystals the isotropic-nematic phase transition is of first order. The observed variation of the order parameter with temperature is compared with predictions from the Maier-Saupe and Humphries-James-Luckhurst models and with results obtained by several other experimental techniques.
A Deuterium NMR Study of some Ammonium Tetraphenylborates
Authors: Gruwel Marco L. H. , Wasylishen Roderick E. 
Published: February 2015

Abstract
Deuterium nmr has been used to study the rotational dynamics of the ammonium ion in ammonium tetraphenylborate and of the cation in a series of methylammonium tetraphenylborates. The results of variable temperature 2H relaxation measurements (T1Z and T1Q) on the parent compound, ND4B(C6H5 )4 , lead to a low activation energy for reorientation of the ND4+ ion, 5.0 ± 0.5 kJ mol-1 , indicative of weak cation-anion interactions. Related studies of the tetramethyl-d12 ammonium salt indicate rapid jumps of the whole cation (τ ≪ 10-5S) over the complete temperature range investigated, 137 to 385 K, with an activation energy of 14.1 + 0.5 kJ mol-1 . Deuterium nmr lineshape studies of the methylammonium salt indicate rapid reorientation of the CD3 and ND3 groups about their C3 axes; however, the motion of the C - N axis is restricted to large amplitude librations. Similar studies of the dimethylammonium salt indicate methyl group jumps at 245 K; at temperatures above 320 K the cation also undergoes two-site jumps about the C2 axis. In the case of the trimethylammonium salt, the nmr lineshapes indicate methyl group jumps superimposed on C3 rotations of the complete cation about the N - H bond axis over the temperature interval 185-348 K. In all the tetraphenylborate salts studied, the 2H nmr lineshapes indicate substantial librational motion of the cation at room temperature.
Luminescent Centres of Td Symmetry in "Cold" Activated ZnS-Mn
Authors: Kynev K. , Maneva N. , Angelov S. 
Published: February 2015

Abstract
By coprecipitation of ZnS and MnS in excess of Na2S, luminescent centres are built differing considerably from those in zinc salt excess. ESR data give evidence of centres of Td symmetry.
Energy Gap and Line Shifts for H-Like Ions in Dense Plasmas
Authors: Kilimann K. , Ebeling W. 
Published: February 2015

Abstract
Based on the results of a foregoing paper (Z. Naturforsch. 44 a, 519 - 523 (1989)) the density-dependence of the discrete energy states and the continuum level is calculated with better accuracy. A static approximation to the line shifts is derived and discussed
Influence of Temperature on the Removal Rates of CH2(ã1A1 ) by Inert Gases and Hydrocarbons
Authors: Wagener R. 
Published: February 2015

Abstract
The reactions of CH2(ã1A1) with the inert gases He, Ar, N2 , with H2 and with the hydrocarbon reactants CH4 , C2H6 , C2H4 and C6H6 have been investigated at 210, 295 and 475 K. CH2(ã1A1) was generated by pulsed laser photolysis in a quasistatic thermostated gas cell and detected by pulsed laser induced fluorescence. Concentration profiles of CH2(ã1A1) were recorded under first order reaction conditions by varying the time delay between the photolysis and the probe laser pulses. The second order rate constants determined at room temperature are in good agreement with those of earlier work. No differences between the removal rates of ortho-and para-methylene nuclear spin states by the inert gases were observed. The experimental rate constants were fitted to an expression k = A -(77295 K)n. The results are given in the form {A ± AΔA} {n ± Δn) with A in units of 1013 cm3/mol • s:
On the Shortwave Emission of Ga-activated Single Crystals of BaCl2
Authors: Tabakova V. , Trifonova R. 
Published: February 2015

Abstract
The luminescence of BaCl2-Ga single crystals at temperatures down to liquid helium under excitation with different energies is studied. The emission consists of several bands, the intensities of which depend on the temperature and the exciting energy. The excitation spectra of the different emission bands measured at 4 K, 78 K and 293 K are also reported.
The results indicate the coexistence of centres of different structure and composition. The Jahn- Teller effect might also take place
Optical Properties of Vanadium Ions in Zinc Sulphide
Authors: Schulz H.-J. , Roussos G. , Biernacki S. W. 
Published: February 2015

Abstract
The luminescence of synthetic ZnS: V crystals is studied at low temperatures (T % 4 K). The emission spectra comprise (i) a structured band centred around v = 5600 cm-1 , assigned to 3T2(F) ->• 3A2(F) transitions of substitutional V3+ (3d2) ions in a tetrahedral field, and (ii) a band around 4800 cm-1 assigned to 4T2(F) -> 4T1(F) transitions of V2+ (3d3) ions. In the range of the narrow no-phonon lines detected with both these emission bands, a temperature rise from 2 to 5 K entails a thermalisation in the population of the spin-orbit multiplets forming the initial states of the corresponding transitions. A third emission band near 3800 cm-1 grows after annealing the crystals in Zn vapour. It is tentatively attributed to 5E(D) -> 5T2(D) transitions of V+ (3d4). A model of one-electron states represents donor-type as well as acceptor-type changes of the vanadium oxidation states, commencing from V2+ , the state with neutral effective charge. The model is substantially founded on the measured excitation spectra of the V3+ and V2+ emission bands, supplemented by transmission spectra. Besides the corresponding broad charge transfer bands, the spectra display a number of structures which are associated with excited states of the ions. These energy levels are approximated in a computation following the strong-field Tanabe-Sugano scheme but in addition allowing for different radial extensions of e- and t2-type wave functions. The method used also includes the possibility of fitting the free-ion levels. Various sets of numerical values are eventually obtained for the crystal-field splitting and the Racah parameters. Some of the levels involved are found to be subject to Jahn-Teller interaction.
High Precision Measurements of the Permittivity of Water in the Microwave Range
Authors: Steinhoff H. J. , Redhardt A. , Lieutenant K. , Chrost W. , Hess G. , Schlitter J. , Neumann H. J. 
Published: February 2015

Abstract
A practical version of a homodyne method for measuring the complex permittivity of high loss liquids at 3 and 9 GHz is described. The systematic errors are discussed in detail, because the homodyne method seems to be suitable as a simple standard method for precise measurements. The results of measurements on water in the temperature range 6 °C-45 °C are presented. The determination of all five parameters of the Debye function is possible. Finally, accuracy limiting factors for the determination of the relaxation parameters are discussed in detail
A Theoretical Study of α-CFnH3-n -substituted Cyclopropyl Cations
Authors: Khalil Salim M. , Jarjis Hayfa M. 
Published: February 2015

Abstract
MINDO-forces calculations are performed, with complete optimization of geometries, on α-Xcyclopropylcations, where X is CF3 , CF2H, and CFH2. It was found that the fluorine atom interacts with the localized empty Pπ-type orbital on α-carbon atom and forms a bridge with an angle 57.1 degree. Calculations also are performed on CF3-cyclopropyl anion and CF2H-cyclopropenyl cation. The fluorine atom in CF3 and CF2H shows no such interaction with the a-carbon atom because there is no localized empty Prc-type orbital
Electromagnetic Field of Accelerated Charges in Inertial Frames with Substratum Flow
Authors: Wilhelm H.E. 
Published: February 2015

Abstract
By means of the generalized Galilei covariant EM field equations, the EM potentials and EM fields of a charged particle moving with an arbitrary nonuniform velocity v(t) in an inertial frame with substratum flow w are calculated. It is shown that the dynamic EM fields are excitations of the EM ether caused by the motion v(t) - w of the charge relative to the wave carrier with velocity w. Qualitatively and quantitatively significant EM inductions and convective deformations of EM fields by the ether flow w exist in inertial frames with ether velocities w~c0 comparable to the velocity of light. For many terrestrial applications, the ordinary Maxwell equations agree in good approximation with the Galilei covariant EM field equations since w/c0~ 10-3 on the earth
Hyperfine Structure in the Rotational Spectrum of tert-Butyl Bromide
Authors: Harder H. , Stahl W. , Dreizler H. 
Published: February 2015

Abstract
We reinvestigated the rotational spectra of tert-butyl bromide (CH3)3C79Br and (CH3)3C81Br, with the high precision of microwave Fourier transform spectroscopy. The rotational and quadrupole coupling constants were improved, the centrifugal distortion and bromine spin-rotation constants were determined
Multipoint Wronskian Method Applied on Model Potentials and Numerical Potential of Triplet H2
Authors: Ergun Yenal , Önder Pamuk H. , Yurtsever Ersin 
Published: February 2015

Abstract
The multipoint Wronskian method is applied to one-dimensional vibrational eigenvalue problems with two different potential functions. Systematic ways of selecting points are discussed. The errors introduced by interpolation methods and the effect of including higher derivatives of the potential are analyzed.