bluuebunny/crossref_metadata_2025_split huggingface dataset:
1,2,4-Triazole Complexes XII * . Magnetic properties of Fe (1, 2, 4-triazole)2 (NCS)2, a quasi two-dimensional S = ½. antiferromagnet with hidden canting.
Authors: Engelfriet D. W. , Groeneveld W. L. , Nap G. M. 
Published: February 2015

Abstract
Fe(trz)2(NCS)2 has been investigated by means of magnetic susceptibility and magnetization measurements on single crystals at temperatures 1.8-300 K, heat capacity measurements at 1.5-90 K and neutron powder diffraction at 1.2 K. The compound orders antiferromagnetically at Tc = 8.46(2) K. The susceptibilities along the orthorhombic axes are strongly anisotropic, the a axis being the preferred direction. The susceptibility data along a and the heat capacity results are in reasonable agreement with the predictions for the quadratic layer, S = ½. Ising antiferromagnet, with an intralayer exchange constant J/k = - 7.2(2) K. Below Tc the magnetization curve along the a axis reveals a metamagnetic transition at 1.74 kOe. In accordance with the Ising-like properties, a direct transition from the antiferromagnetic to the paramagnetic state is observed along a at 50 kOe.
Hidden canting is found to be present. At 1.2 K the compound appears to be monoclinically distorted with α = 88.3° (with respect to Aba2, the space group at 300 K). The magnetic structure consists probably of four sublattices with the magnetic moments lying in the planes z = 0 and z =½ (with respect to the distorted cell in Aba2) along directions that are at an angle of 8° with the a axis.
Ligand bonding parameters are discussed in terms of the angular overlap model.
Untersuchungen zur Anwendbarkeit des CNDO/S-CI-Verfahrens für die Berechnung der Anregungsenergien organischer Verbindungen am Beispiel von Phthalsäurederivaten / Investigations on the Applicability of the CNDO/S-CI method for the Calculation of Excitation energies of Organic compounds using Derivatives of Phthalic acid as Examples
Authors: Fabian Walter 
Published: February 2015

Abstract
The influence of the choice of geometrical parameters and the approximations used to evaluate the two centre coulombic integrals upon excitation energies as calculated by the CNDO/S-or INDO/S-CI method is discussed.
Influence of Doping on the Crystal Potential of Silicon investigated by the Convergent Beam Electron Diffraction Technique
Authors: Voss R. , Lehmpfuhl G. , Smith P. J. 
Published: February 2015

Abstract
Low index structure potentials of silicon were determined by convergent beam electron diffraction (Kossel-Möllenstedt technique) from very small crystal areas of about 100 Å in diameter. The values of 111, 222, 220, 113 and 004, determined to an accuracy of ±0.03 volts, are in excellent agreement with the accurate X-ray results of Aldred and Hart (see [6], p. 239). Heavy arsenic or phosphorous doping was found to cause a shift of 0.15 volts in the 111 structure potential. Absorption potentials were also determined and found to be 1/3 of the theoretical values published by Radi [20].
Convergence Problems and Energetic Regions in π Excited States of Certain Conjugated Molecules
Authors: Giambiagi Myriam S. de , Giambiagi Mario , Barros Henrique G. P. Lins de 
Published: February 2015

Abstract
When calculating π bond orders of excited and superexcited states of conjugated molecules, difficulties arise in applying the variation method; besides, the convergence problems involved are well known. For pyridazine, chosen for discussion, 27 states are considered; the convergence problem is envisaged through two criteria in the choice of a parameter introduced in the compromise Hamiltonian. This convergence parameter is related to the variation method. There exist three particular solutions for bond orders, which divide the 27 states into energetical regions.
On the Measurement of Elastic Constants in Nematic Liquid Crystals: Comparison of Different Methods
Authors: Gerber Paul R. , Schadt Martin 
Published: February 2015

Abstract
Different methods of measuring elastic constants of nematic liquid crystals by deformation of homogeneously and homeotropically oriented layers through external magnetic and electric fields, respectively, are critically examined. Possible sources of uncertainties are quantitatively explored. An approximative numerical fitting procedure is proposed allowing to take conductivity effects in electrically deformed layers up to large conductivities and/or temperatures into account. A novel, accurate and simple monitoring method to determine twist elastic constants is described. The measurements of the temperature dependence of the splay bend and twist elastic constants of the positive dielectric mixture R0-TN-403 are presented.
Unrestricted Harmonic Balance
Authors: Seelig Friedrich Franz 
Published: February 2015

Abstract
Periodic structures in chemical kinetic systems can be evaluated by an extension of the well-known method of harmonic balance, which yields very simple expressions in the case of linear systems containing only zero and first order reactions. The far more interesting non-linear systems containing e.g. second order reactions which in case of open systems far from thermodynamic equilibrium give rise to non-classical phenomena like oscillations, chemical waves, excitability, hysteresis, multistability, dissipative structures etc. can be treated in a similar way by introducing new pseudo-linear quantities utilizing certain group properties of harmonic expansions. The resulting complicated implicit non-linear algebraic equations are solved by a method developed by Powell and show good convergence. Since this method - in contrast to the conventional method of simulation - is independent from the stability of the periodic structure to be evaluated it can even be applied to unstable cases where the simulation method necessarily fails. An evaluation of the stability is included in the developed computer program.
Equilibrium Positron Decay Rates in Helium
Authors: Grover P. S. , Muhammed M. S. A. , Sami S. A. 
Published: February 2015

Abstract
Equilibrium positron decay rates in helium gas have been computed over a wide range of temperatures and electric fields based on the model due to McEachran et al. [7]. Agreement between the theoretical and experimental values of the decay rate at room temperature and zero electric field is quite good.
Mass Spectrometry of Polymers: Polypropylene Glycol
Authors: Neumann Gregory M. , Cullis Peter G. , Derrick Peter J. 
Published: February 2015

Abstract
Mass spectra have been measured, using the field desorption technique, for polypropylene glycols with nominal mass-average relative molecular masses of 1000, 2000, 3000 and 4000. Ions of up to m/z 7400 have been observed. Major peaks in the spectra correspond to (M + H)+ ions. (M + Na)+ ions are observed if sodium iodide is added to the sample. There are strong peaks corresponding to fragmentation of the polymer chains close to their termini. It is suggested that these fragmentations are induced by the strong electric fields at the emitter.
The Kinetics of Plastic Flow
Authors: Faucher B. , Krausz A. S. 
Published: February 2015

Abstract
The plastic flow associated with the three main methods of combining deformation mechanisms is described in terms of deformation kinetics. It is shown that the determination of the deformation kinetics as the initial step in the analysis is indispensable to the establishment of the activation parameters in functional forms. To this purpose, the effects of stress and temperature on the plastic strain rate are determined for three types of combined mechanisms, and qualitative comparison with experimental results is presented.
Temperature Coefficient of the Refractive Index of H2O and D2O and Proposed Models of Water Structure
Authors: Abbate G. , Bernini U. , Ragozzino E. , Somma F. 
Published: February 2015

Abstract
The temperature coefficient of the refractive index, (∂n/∂T)p, has been measured for deuterium oxide. The observed values are considered together with those previously obtained for water. The experimental data cannot be explained with the best known models of molecular polarizability, at least in the approximation generally used in these models. Therfore they are discussed on the basis of a different approximation, suggested by a well-known structural model of liquid water. It is shown that the experimental results are very well explained, in a wide range of temperature, with the hypothesis of the existence of "structural voids".
Thionine Fluorescence Quenching by Metal Cations
Authors: Köhler G. , Solar S. , Getoff N. 
Published: February 2015

Abstract
The mechanism of the fluorescence quenching of aqueous thionine by various metal ions (Ce3+, Fe2+, Mn2+, Mg2+, Cs+ and Na+) was studied at pH = 2.5. The following Stern-Volmer constants (Ksv) were determined: KSV(Fe2+) == 1.13 dm3 mol-1, KSV(Mn2+) = 0.24 dm3 mol-1, KSV(Ce3+) = 0.24 dm3 mol-1, KSV(Cs+) - 0.03 dm3 mol-1. At concentrations below 1 mol.dm-3 Na2SO4 and MgSO4 are very weak quenchers (KSV(Na+ or Mg2+) = 0.007), but the influence on the fluorescence yield increases considerably at higher cation concentrations. This was attributed to the formation of ground state complexes between thionine and SO4
2- ions. The salt concentration affects considerably the quenching rate of Fe2+ ions, but much less so that of the other cations. Fluorescence quenching mechanisms are discussed.
Experimental Observation of Chaotic Behavior in CO Oxidation in Lumped and Distributed Catalytic Systems
Authors: Rathouský J. , Puszynski J. , Hlaváček V. 
Published: February 2015

Abstract
Measurements of the catalyst temperature and outlet conversion in differential, integral and honeycomb systems give evidence that the catalytic CO oxidation may proceed chaotically in time over a range of inlet CO concentrations and temperatures. Development of aperiodic oscillations from periodic oscillations was experimentally investigated. In distributed systems chaotic behavior may exist only in a narrow range of inlet temperatures.
Zur Bildung von Mg2Si- und CaSi2-Schichten auf einkristallinen Siliciumsubstraten
Authors: Braungart R. , Sigmund H. 
Published: February 2015

Abstract
Thin layers of Mg2Si or CaSi2 (10-20 μm) on silicon substrates can be prepared by the reaction of the corresponding metal vapor with silicon wafers. The resulting poly crystal line silicides have a purity of more than 99.95%; their surface roughness is about 2 μm. The layer thickness and the dimensions of the crystallites may be controlled by the conditions of the preparation. An oriented growth on the <111>-silicon surface is observed in the case of CaSi2- The method described seems generally well suited for growing silicide layers of metals with high vapor pressure. The Mg2Si- and the CaSi2-layers were used as starting material in a special "sandwich"-epitaxy in order to prepare Mg- and Ca-doped Si-layers.
Evidence for Triplet Exciplex Formation in the Reaction of Amines with 1 -Pheny l-2-acetoxy-2-methy 1-propanone-1
Authors: Salmassi A. , Eichler J. , Herz C. P. , Schnabel W. 
Published: February 2015

Abstract
1-Phenyl-2-acetoxy-2-methylpropanone-1 has been irradiated with 25ns flashes of 347 nm light in benzene or cyclohexane solution. Absorption measurements yielded the following: at the end of the flash the triplet-triplet spectrum was observed (triplet decay rate constant: kT = (3.0 ±0.2) 105 s-1). In the presence of aliphatic amines (e.g. triethanol amine) radicals were formed much more slowly than triplets disappeared, as clearly indicated by spectral changes at wave lengths between 330 and 380 nm. The radical precursor thus evidenced is presumed to be an exciplex. Rate constants: kT + amine: (1.2 + 0.2) 109 l/mol s; kexciplex: (9± 1) 106 s-1 .
Zur approximativen Lösung der Einelektronen-Schrödinger-Gleichung mit Hilfe eines Differenzen-Hamilton-Operators demonstriert am Beispiel des H-Atoms in einer sphärischen Box
Authors: Fleischhauer Jörg , Gerlach Eckard 
Published: February 2015

Abstract
For an H-atom in a spherical box with variable radii R it is shown that the energy and the ESR-splitting constant for the groundstate calculated with a difference-hamiltonian are in good agreement with the results obtained by other methods. The dependence of the energy on the number n of discrete points and their distance for a given radius R is considered.
Electron-Nuclear Hyperfine Interactions of 53Cr 3+ in Mg2SiO4 (Forsterite)
Authors: Rager H. 
Published: February 2015

Abstract
The magnetic hyperfine interaction between the electron and nuclear spin system of 53Cr3+ was studied at the Mg sites, M1 and M2, in Mg2SiO4. The study was undertaken at room temperature and 9.52 GHz. The hyperfine structure data exhibit a covalent Cr-O bonding of approximately 10% indicating a mainly but not purely ionic bonding. Including the corresponding results obtained for 57Fe 3+ [1] and 55Mn2+ [2] in Mg2SiO4, this is interpreted such that the bonding of transition metal ions is mainly dominated by the oxygen sublattice in Mg2SiO4 and less by the properties of the transition metal ions themselves. The small variation of the hyperfine splitting parameters found for 53Cr3+ at M1 and M2, and also for 57Fe3+ at these positions indicates that the hyperfine interaction varies also with varying average metal oxygen distances as well as with changes in the oxygen coordination size.
Temperature Dependence of the 72P States Mixing and Quenching in Caesium-Deuterium Collisions
Authors: Łukaszewicz Marek 
Published: February 2015

Abstract
Temperature dependent mixing and effective quenching cross-sections for the 72P doublet in caesium, induced in collisons with molecular deuterium, were determined experimentally using the sensitized fluorescence method. The character of the temperature dependence exhibits an isotope effect compared to the data for caesium-hydrogen collisions obtained earlier.
Ne Emissions from a He Discharge Flow System: II. Products of the Reaction He(21S)+Ne(11S)
Authors: Haak H. K. , Wittig B. , Stuhl F. 
Published: February 2015

Abstract
A windowless He discharge was used to produce metastable singlet He(21S) by the photolysis process He(11S) + 58.4 nm→ He(21P) and He(21P) → He(21S) + 2058 nm. Metastable He(21S) were found to transfer their energy to Ne to populate the Ne 5s, 5s′, 4d, 4d′, 3d, and 3d′ states. In the present work the detailed relative population of these states and their rates of population are determined.
X-Ray Diffraction and Structural Properties of Aqueous Solutions of Divalent Metal-Chlorides
Authors: Caminiti R. , Licheri G. , Paschina G. , Piccaluga G. , Pinna G. 
Published: February 2015

Abstract
X-ray diffraction data are reported for aqueous solutions of CaCl2 (6.30 M), CdCl2 (0.87 and 1.26 M) and NiCl2 (1.96 and 3.88 M). The highly concentrated CaCl2 solution shows a medium range order resembling that of the corresponding hydrate crystal. The CdCl2 solutions are characterized by the presence of complexes with chloride ions in the first coordination sphere of the cation. In NiCl2 solutions, a first sphere Ni-Cl coordination can be excluded and the existence of six Ni-H2O nearest neighbour contacts is clearly confirmed. In these solutions no evidence was found for the existence of highly ordered structures; hexa-aquo cations interact with external water molecules and, at the highest concentration, some outer sphere Ni-Cl correlation is possible as due to packing.
1,2,4-Triazole Complexes XIII
Authors: Engelfriet D. W. , Groeneveld W. L. , Nap G. M. 
Published: February 2015

Abstract
Powdered samples of β-Ni(trz)2(NCS)2 have been investigated by measurements of the magnetic susceptibility (in the temperature range T = 15-300 K), magnetization (at T = 4.2 K) and heat capacity (T = 1-90 K). From the magnetization measurements the material is found to be a weak ferromagnet, with a zero-field magnetic moment of ~ 0.015 μB. The ordering temperature is determined as Tc = 10.14(2) K. The susceptibility and heat capacity data are in reasonable agreement with predictions from high-temperature series expansions for the quadratic layer, S = 1, Heisenberg antiferromagnet, with an intralayer exchange constant J/k = - 4.5(1) K.
1,2,4-Triazole Complexes XIV
Authors: Engelfriet D. W. , Groeneveld W. L. , Nap G. M. 
Published: February 2015

Abstract
Heat capacity measurements on Mn(trz)2(NCS)2 in the range 1 - 90 K are reported. A λ-anomaly is found at Tc = 3.292(6) K. From a comparison of the high-temperature specific heat to the predictions from series expansions the intralayer exchange constant is found to be J/k = 0.245(5) K. From the total magnetic energy involved in the transition the value J/k = - 0.254(8) K is calculated. These results compare favourably with previous data from susceptibility measurements.
From very recent X-ray diffraction experiments on a single crystal the space group is found to be Pbcn instead of Aba2, as was reported previously.
Magnetic Field Influence on Coulomb Relaxation of Anisotropic Electron-Ion-Plasmas
Authors: Hübner G. , Schamel H. 
Published: February 2015

Abstract
The relaxation of velocity-space-anisotropies due to Coulomb collisions is studied within the class of bi-Maxwellian distributions in the presence of an external homogeneous magnetic field, both analytically and numerically. It is found that the anisotropy dependence of the energy exchange collision frequency well separates from its magnetic field dependence. In a certain region of magnetic field strength, the latter can be approximated by a substitution of the thermal electron's Larmorradius for the Debye-length in the Coulomb-logarithm, as has been conjectured earlier.
Relativistic Energy States of the A-Particle in Hypernuclei Using Gaussian Potentials
Authors: Koutroulos C. G. 
Published: February 2015

Abstract
The Dirac equation with scalar potential and fourth component of vector potential of the Gaussian form is solved numerically for potential parameters obtained by a least squares fitting of the ground state binding energies of the A in a number of hypernuclei. The binding energies in the ground and excited states for various hypernuclei are determined. The spacings between the various levels are also given
Decomposition of Positive Sesquilinear Forms and the Central Decomposition of Gauge-Invariant Quasi-Free States on the Weyl-Algebra
Authors: Honegger Reinhard 
Published: February 2015

Abstract
A decomposition theory for positive sesquilinear forms densely defined in Hilbert spaces is developed. On decomposing such a form into its closable and singular part and using Bochner's theorem it is possible to derive the central decomposition of the associated gauge-invariant quasifree state on the boson C*-Weyl algebra. The appearance of a classical field part of the boson system is studied in detail in the GNS-representation and shown to correspond to the so-called singular subspace of a natural enlargement of the one-boson testfunction space. In the example of Bose-Einstein condensation a non-trivial central decomposition (or equivalently a non-trivial classical field part) is directly related to the occurrence of the condensation phenomenon.
The Influence of the Skin Effect on the Amplitude of Single Pulse Gamma Detected NMR on Oriented Nuclei Signals
Authors: Isbister D. J. , Chaplin D. H. 
Published: February 2015

Abstract
The effects of skin depth on gamma detected single pulse Nuclear Magnetic Resonance on Oriented Nuclei (NMRON) signals are theoretically explored for narrow, intermediate and broad line metallic samples, using the density matrix approach describing a pure Zeeman system. It is shown that the skin effect distortion of the signal can dominate over intermediate to broadline distortions for that range of experimental conditions generally applicable to ferromagnetic hosts. In particular, the skin effect distortions of the first maximum, obtained when the excitation pulse width is lengthened, are significant and can determine the accuracy of calibration of the radiofrequency "(rf)" field amplitude at the resonating nuclei when assigning an average turn angle to this maximum.
Fluorescence Spectra and Determination of the Energy of O-O Transitions of Coumarins in Liquid Solutions
Authors: Bączyński A. , Targowski P. , Ziętek B. , Radomska D. 
Published: February 2015

Abstract
Analytical expressions of absorption and fluorescence spectra of some coumarins in ethyl alcohol at room temperature are given. Satisfactory agreement of measured and calculated spectra is obtained. It was possible to obtain the pure electronic transition energies immediately after excitation (from absorption spectra) and after the thermal and orientational equilibrium is reached (from fluorescence). An optical transition carries a dye-solvent system to a state in which the mutual interaction energy is larger than in the initial state
X-ray Diffraction Analysis of NdCl3 Melt
Authors: Igarashi Kazuo , Kosaka Mineo , Ikeda Masahiro , Mochinaga Junichi 
Published: February 2015

Abstract
The structure of molten NdClj at 800 CC has been investigated by X-ray scattering and the correlation method. The nearest neighbor distance and coordination number of Nd-Cl are 2.77 Ä and 5.5 A, respectively. The Nd-Nd and CI-CI distances are 5.08 and 4.04 Ä, respectively. The average nearest neighbor distance and coordination number decrease markedly on melting, and the resulting short range structure of the melt is approximately octahedral
X-ray- and Neutron-diffraction Studies with Quasicrystalline and Amorphous Al-V- and Al-Mn-alloys
Authors: Seehafer S. , Lamparter P. , Steeb S. 
Published: February 2015

Abstract
Amorphous and quasicrystalline samples of Al84Mn16 and Al84V16 were produced by sputtering and melt-spinning, respectively. From X-ray and neutron-diffraction-results the total structure factors were evaluated. For amorphous as well as for quasicrystalline Al84V16 the partial SAl-Al- and SAl-V-structure factors were obtained, which yield the corresponding partial pair correlation functions, the atomic distances, and the partial coordination numbers. Also some information concerning the partial Bhatia-Thornton correlation functions could be obtained.
Both the amorphous and the quasicrystalline Al-V-alloys show a linear expansion by a factor of 1.03 compared to the corresponding Al-Mn-alloy. The two amorphous alloys can be designed as isomorphous, whereas the quasicrystalline ones show pronounced deviations in the distance between unequal atoms. The shortest atomic distance in amorphous Al84V16 is 2.69 A, being,formed by Al-V-pairs with a coordination number 2. The nearest Al-Al-distance amounts to 2.84 A with a coordination number 8. The partial density-concentration correlation function clearly deviates from the hard sphere model.
With the quasicrystalline specimens, the isomorphous substitution of Mn- and V-atoms is not perfect. The Al-V-correlation is split up, and this is not observed for the Al-Mn-correlation. Comparison of the amorphous and the corresponding quasicrystalline alloy shows some similarities
On Electromagnetic Fields in a Periodically Inhomogeneous Chiral Medium
Authors: Lakhtakia Akhlesh , Varadan Vijay K. , Varadan Vasundara V. 
Published: February 2015

Abstract
Electromagnetic fields in a periodically inhomogeneous chiral medium are examined. The constitutive properties of the chiral medium vary along the z axis, and reduced fields with prescribed x-variations are used. Coupled first-order differential equations are derived to describe the reduced fields. Two special cases -(i) piecewise constant inhomogeneity, and (ii) constant impedance inhomogeneity, - are discussed in detail, and solution procedures are provided