bluuebunny/crossref_metadata_2025 huggingface dataset:
Multiple Diffraction of X-Rays
Authors: Colella Roberto
Published: February 2015

The phenomenon of n-be&m diffraction (n>2) is discussed with particular attention being devoted to the Bragg case of diffraction. The general method of solution is outlined, and some applications to specific situations are discussed. These include experiments in which strong quasi- monochromatic phonon beams are excited in a crystal using the Acousto-Electric effect, phase determination using the concept of „Virtual Bragg Scattering”, and high resolution Bragg reflec­tion topographs. In all cases the agreement between theory and experiment has been found excellent.
X-Ray Dynamical Diffraction Process Inside a Distorted Crystal
Authors: Takagi S.
Published: February 2015

It is shown that the dynamical diffraction process inside a distorted crystal consists of ordinary dynamical progression inside perfect portions of the crystal and scattering at distortions. The scattered waves proceed as in the perfect crystal and can be multiply scattered. The sum of the primary wave induced at the entrance surface and the waves scattered at distorted parts inside the “inverted Borrmann triangle” gives the resultant wave field at the exit surface.
Coherent Interaction of Multiple Diffracted X-Rays in Crystals
Authors: Chang Shih-Lin
Published: February 2015

Coherent dynamical interaction in a 6-beam Borrmann diffraction experiment leading to an unusual intensity enhancement of X-ray transmission in crystals is investigated by using a synchrotron radiation source. A sharp enhanced intensity spot of two seconds of arc beam- divergence is observe 1 on the direct beam at the exact 6-beam diffraction position. The plane- wave dynamical theory is employed to account for the experimental results. The polarization dependence of the crystal excitation by the incident beam is discussed.
Limits of the X-Ray Collimation by One Asymmetrical Bragg Reflection
Authors: Brümmer  , Höche H. R. , Nieber J.
Published: February 2015

In connection with the production of highly collimated X-rays the study of extremely asymmetrical Bragg reflections became of interest. In this paper the so-called extended dynamical theory of X-ray diffraction will be tested experimentally. As a result of this investigations the optimum conditions for X-ray collimation by means of one asymmetrical Bragg reflection are being discussed.
Intensity Attenuation and Enhancement in 3-beam Diffraction
Authors: Post Ben , Wang Po Wen , Horn Tommy
Published: February 2015

A simplified version of the x-ray dispersion surface is described for use in the interpretation of simultaneous 3-beam Borrmann diffraction photographs. Examples of such photographs are discussed and analyzed in terms of the simplified dispersion surfaces.
Influence of Rotational Relaxation on Tropospheric OH Laser Induced Fluorescence Measurements
Authors: Gericke K.-H. , Comes F. J.
Published: February 2015

Rotational relaxation of OH molecules in the 2II electronic ground state has been observed to occur in collisions with water molecules with gas kinetic probability. It causes an additional contribution to the already well known sources of interference when LIF is used to monitor tropospheric OH. As the laser generated OH is originally produced mostly in high rotational states, the fast relaxation phenomenon leads to a further population of OH in low rotational states. These states are used to monitor tropospheric OH by spectroscopic methods. The observed effect therefore increases the interference. A mathematical analysis is presented, revealing the effect of all relevant parameters.
Elektrische und optische Eigenschaften von Gd2Cl3 und Tb2Cl3 / Electrical and optical properties of Gd2Cl3 and Tb2Cl3
Authors: Bauhofer Wolfgang , Simon Arndt
Published: February 2015

Electrical and optical properties of Gd2Cl3 and Tb2Cl3 The electrical resistivity of Gd2Cl3 and Tb2Cl3 has been investigated as a function of temperature. Conventional measurements on powder pellets as well as contactless microwave measurements on small single crystals yield a semiconducting behaviour for both componds with energy gaps of about 0.85 eV for Gd2Cl3 and 1.1 eV for Tb2Cl3. The measurements indicate a strong anisotropy of the resistivity. The reflectivity of Tb2Cl3 has been studied in the energy range from 1.1 to 4 eV.
Transition to Semiconducting Characteristics in Liquid Alkalimetal-Antimony-Alloys
Authors: Redslob H. , Steinleitner G. , Freyland W.
Published: February 2015

The paper reports new measurements of the electrical conductivity, thermoelectric power, magnetic susceptibility, and molar volume of liquid Cs-Sb alloys and, partly, Na-Sb and K-Sb alloys. From the temperature and composition dependence of the electronic properties it is concluded that typical semiconducting behavior similar to liquid chalgogen based alloy semiconductors exists over a wide composition range. The change in bonding for 0.25≦XSb≦0.5 is qualitatively discussed and it is found that these liquid alloys are not essentially ionic in character.
Structural Requirements for Intramolecular Charge-Transfer in Excited State of 4-(9-Anthryl)-N,N-dimethylaniline
Authors: Siemiarczuk Aleksander , Koput Jacek , Pohorille Andrzej
Published: February 2015

Excited state kinetics and other photophysical features of 4-(9-anthryl)-N,N-dimethylaniline and two model compounds have been thoroughly examined in order to establish the structural conditions for highly polar excited state formation.

Also quantum chemical calculations by means of INDO/S CI and PCILO methods have been performed to obtain potential energy curves, dipole moments and atomic charge densities for the ground and lowest excited singlet states as a function of the angle of twist between anthryl and dimethylaniline subunits.

Both the experimental and theoretical results confirm the previously proposed TICT (Twisted Intramolecular Charge-Transfer) model predicting the perpendicularity between electron donor and acceptor moieties as a condition for nearly full charge-separation in excited states for some classes of aromatic compounds.
Bragg Case in Laue Case Diffraction A Maybe Novel Statement on Wave Field Beams
Authors: Renninger M.
Published: February 2015

The boundaries of wave field beams in Laue case diffraction are in their function identical with crystal surfaces parallel to the lattice planes, reflecting in the symmetrical Bragg case. On extreme presumptions the wellknown Darwin-Ewald total reflection may occur.
Enskog-Boltzmann-Equation for a Fluid of Nonspherical Particles
Authors: Thurn H. , Hess S.
Published: February 2015

The Enskog-Boltzmann-equation is generalized to fluids of nonsperical particles with fixed orientation, i.e. for overdamped rotational motion. General relations between the interparticle position vector at the instant of contact, the impact parameter and the differential cross section are derived. The dependence of these quantities of the orientations of the colliding particles is studied for the special case of hard ellipsoids.
Thermodynamic Study of Al-Ge-Sn Ternary Alloys by E.M.F. Measurements
Authors: Eslami H. , Gambino M. , Bros J. P.
Published: February 2015

An electrode potential study of liquid Al-Ge-Sn alloys has been conducted with the cell Al | Al3+ in KCl + LiCl | Al in Al-Ge-Sn in the temperature range 683 K ≦ T ≦ 1273 K. Aluminium partial mixing functions were determined for alloys. These measurements allow us to give the surface corresponding to aluminium partial free energy at 1273 K and the liquidus surface of the Al-Ge-Sn phase diagram.
On a Unified Potential Energy Function for Ionic and Non-ionic Bonds and the Question of Chemical Bonding
Authors: Hooydonk G. Van
Published: February 2015

For 39 diatomic ionic and non-ionic molecules, the anomalous behaviour of the spectral para-meters αe and ωχxe with respect to the bond type is reviewed. It is shown that on using a "uni-versal" Sutherland parameter defined as ⊿ = ½kere
2/Dion, the anomalous behaviour disappears. Hard spectroscopic evidence is thus presented, for the first time to the author's knowledge, that just one bond type, in fact an ionic one, can account, in first approximation, for the spectral behaviour of both non-ionic and ionic bonds, H2 included.
Vorschlag einer Neutronendiagnostik für Fusionsplasmen
Authors: Pinkau K.
Published: February 2015

A diagnostic method for the measurement of neutrons from thermonuclear plasma devices is proposed on the basis of the neutron telescope applied in neutron astronomy. The method utilizes the elastic scattering of the neutron from a proton by measuring the directions and energies of the proton and the scattered neutron. The expected count rate is estimated, and methods of suppressing the background count level are indicated
Turbulent Diffusion — A Rigorous Treatment
Authors: Gräff Pitter , Pfirsch Dieter
Published: February 2015

The problem of passive diffusion by strong turbulence is described by equations of motions of the form dx/dt = V(t, x), V(t, x) being a stochastic velocity field with strong nonlinear dependence on x. Present-day theories are based on certain plausible approximations rather than on a systematic treatment, e.g. in form of a perturbation theory with respect to some smallnes parameters. In this paper a method is described to construct stochastic velocity fields with reasonable velocity distributions and correlations, and to obtain at the same time the exact solution of the corresponding diffusion problem. Brownien motion is a special case of such models. The models can serve to check existing approximate theories, to simulate real turbulence, and to get altogether better insight into turbulent diffusion
On the Existence of Eigenmodes of Linear Quasi-Periodic Differential Equations and their Relation to the MHD Continuum
Authors: Salat A.
Published: February 2015

The existence of quasi-periodic eigensolutions of a linear second order ordinary differential equation with quasi-periodic coefficient f{ω1t, ω2t) is investigated numerically and graphically. For sufficiently incommensurate frequencies ω1, ω2, a doubly indexed infinite sequence of eigenvalues and eigenmodes is obtained.

The equation considered is a model for the magneto-hydrodynamic “continuum” in general toroidal geometry. The result suggests that continuum modes exist at least on sufficiently ir-rational magnetic surfaces
Resistive Ballooning Modes in Three-Dimensional Configurations
Authors: Correa-Restrepo D.
Published: February 2015

Resistive ballooning modes in general three-dimensional configurations are studied on the basis of the equations of motion of resistive MHD. Assuming small, constant resistivity and perturbations localized transversally to the magnetic field, a stability criterion is derived in the form of a coupled system of two second-order differential equations. This criterion contains several limiting cases, in particular the ideal ballooning mode criterion and criteria for the stability of symmetric systems. Assuming small growth rates, analytical results are derived by multiple-length-scale expansion techniques. Instabilities are found, their growth rates scaling as fractional powers of the resistivity
Finite Field Harmonics for Stellarators with Improved Aspect Ratio
Authors: Dommaschk W.
Published: February 2015

A set of stellarator fields with magnetic surfaces of small aspect ratio is found by superposing recently introduced, easily computable field harmonics. The law of superposition is found analytically by closely approaching “helical symmetry” of these “new” fields in suitable orthogonal coordinates
Singlet-Exciton Energy Transfer in Tetracene-doped Anthracene Crystals as Studied by Time-Resolved Spectroscopy
Authors: Braun A. , Mayer U. , Auweter H. , Wolf H. C. , Schmid D.
Published: February 2015

The time-resolved sensitized fluorescence of tetracene-doped anthracene crystals following a two-photon picosecond-pulse excitation was investigated experimentally as a function of dopant concentration and temperature. Even at the optimum time resolution achieved in these experiments (about 5ps) the time dependence of the host fluorescence was always purely exponential, that of the guest fluorescence a superposition of two exponentials. Thus no time dependence of the energy-transfer rate could be identified. The temperature dependence of the energy-transfer rate is explained tentatively in terms of a "hopping model" (hopping time th ≈ 5.8·10-14s) and thermal reactivation from shallow exciton traps (trap depth 43 cm-1) in the vicinity of the guest molecules.

In pure anthracene crystals the intrinsic exciton lifetime (observed at 20 K) is (5.0 ± 0.5) ns. At higher temperatures it increases to about 15.5 ns at 300 K due to reabsorption processes. Below 20 K it decreases to about 1.5 ns at 1.6 K because of exciton trapping at shallow X-traps (trap depth 23 cm -1). When using conventional one-photon excitation exciton-exciton annihilation was observed with an annihilation constant γss ≈ 1.0 × 10-8 cm3 s-1.
Kinetic and Spectroscopic Behaviour of Proflavin Transients Studied by Pulse Radiolysis
Authors: Solar Sonja , Solar Wolfgang , Getoff Nikola
Published: February 2015

The semireduced transients of proflavin were studied in airfree acid aqueous solutions by a combined pulse radiolysis-computer optimization procedure. The main product, semiquinone (C-radical; 75%), formed with k=6.4 × 109dm3mol-1s-1 , decays by dimerisation (2k=2 × 109dm3mol-1s-1) and dismutation (2k=0.5 x 109dm3mol-1s-1). It possesses several absorption bands (ε270 = 1900, ε360 = 1530, ε460 = 2250 and ε530 = 200 m2mol-1 ). The second transient, R·-species (N-radical; 16.5%), is produced with k=1.4 × 109dm3mol-1s-1 and decays preferentially by transformation into semiquinone with k = 2 × 105s-1; its absorption bands are: ε295 = 2300, ε380 = 1000, ε440 = 5000 and ε680 = 530m2mol-1. Finally H-adducts on various positions of the aromatic ring (8.5%) are arising with k = 0.7 × 109dm3mol-1s-1 , decay according to a pseudo first order reaction, k = 1.1 × 104s-1, and have absorption bands at ε270 = 2100 and ε435 = 1580m2mol-1. The obtained results are of particular interest for the photochemical and photoelectrochemical solar energy utilization.
Limitations of LEED-Structure Determination of Reconstructed Crystal Surfaces
Authors: Jagodzinski H.
Published: February 2015

Although a strictly ordered reconstructed crystal surface may have the two-dimensional symmetry prescribed by the bulk (two-dimensional subsymmetry of the 3-dimensional space group), it belongs more frequently to a subgroup. In the LEED-pattern a lower symmetry of the translation group can easily be detected on account of the superstructure reflections observed. In this case anti-phase domains can hardly be avoided. An even more difficult situation arises if the symmetry of the point group is violated, although the symmetry of the diffraction pattern is not altered at the end of the reconstruction. Twin domains without changes of lattice constants have to be taken into account.

Dynamical scattering of anti-phase domains is calculated by applying the "Cluster embedded chain"-method for various distributions of domains. It is shown that the incoherent superposition of scattering amplitudes, normally applied in LEED-calculations may lead to serious errors in structure determination. This effect is even more pronounced for twin domains. As an example we discuss the reconstruction of the (001)-surface of Si and Ge, and show that the wellknown (2 X 1)-structure is an averaged structure only, consisting of anti-phase domains with the (4 x 2)-structure. It may be concluded therefrom that none of the present model structures of this reconstruction agrees with this experimental observation.
Hydroxybenzoic Acids — A Study of Their Electronic Spectra, Structure and Reactivity
Authors: Namboodiri K. P. Krishnan , Viswanathan S. , Bhasu V. C. lyothi
Published: February 2015

The three isomeric hydroxybenzoic acids were subjected to all-valence-electron CNDO/2 calculations. The σ-core charges from these calculations and subsequently revised valence-state ionization potentials and one-centre two-electron integrals were used in Pariser-Parr-Pople (PPP) CI calculations for the title compounds following the Nishimoto-Forster scheme to explain their electronic spectra. The spectra were all recorded in aqueous media. The results from the CNDO/2 calculations were used to obtain useful electronic structural parameters and to study the chemical reactivity of these molecules. All the results were compared with the basic compounds, namely phenol and benzoic acid.
Microwave Fourier Transform Double Resonance Experiment and Theory
Authors: Dreizier H. , Fliege E. , Mäder H. , Stahl W.
Published: February 2015

We present the first experience with a three-level double resonance experiment performed with a microwave Fourier transform spectrometer. The results are described by a theoretical treatment based on three-level Bloch equations.
Force Field and Mean Amplitudes of Vibration of (NH2)2CX Compounds ( X = O, S, Se)
Authors: Campos Marcelo , Díaz Guillermo
Published: February 2015

Normal coordinate analysis of urea, thiourea and selenourea was performed on the basis of the general valence force field; Wilson’s FG matrix method has been used. The final force fields were obtained through an iterative selfconsistent method. The vibrational assignment for these molecules is discussed. Calculated mean amplitudes of vibration for the urea series and their deuterated derivatives are reported.
On Some Physical Properties of a Unified Lepton-Hadron Field Model with Composte Bosons
Authors: Stumpf H.
Published: February 2015

In preceding papers a lepton-hadron unified field model was introduced by means of a third order nonlinear spinorfield equation. In this paper an improved interpretation to this model is given which tries to incorporate the advantages of various current matter models and to avoid their drawbacks. In particular charge and lepton number are introduced, while the extended unstable baryon states are distinguished from lepton states by an intrinsic parity. A theorem is derived which allows a biunique decomposition of the nonlinear higher order spinorfield equation into nonlinear first order spinorfield equations and the simultaneous introduction of a permutation group of the subfields. These subfields are identified as pseudo-color fields.
Information Dimension and the Probabilistic Structure of Chaos
Authors: Farmer J. Doyne
Published: February 2015

The concepts of entropy and dimension as applied to dynamical systems are reviewed from a physical point of view. The information dimension, which measures the rate at which the information contained in a probability density scales with resolution, fills a logical gap in the classification of attractors in terms of metric entropy, fractal dimension, and topological entropy. Several examples are presented of chaotic attractors that have a self similar, geometrically scaling structure in their probability distribution; for these attractors the information dimension and fractal dimension are different. Just as the metric (Kolmogorov-Sinai) entropy places an upper bound on the information gained in a sequence of measurements, the information dimension can be used to estimate the information obtained in an isolated measurement. The metric entropy can be expressed in terms of the information dimension of a probability distribution constructed from a sequence of measurements. An algorithm is presented that allows the experimental determination of the information dimension and metric entropy.
Ion Formation from Alkali Iodide Solids by Swift Dust Particle Impact
Authors: Knabe W. , Krueger F. R.
Published: February 2015

Swift Fe-dust particles (0.2-20 μmØ ; 1-50 km/s) are utilized to generate transiently ions from alkali iodide coated metal foils, analyzed by time-of-flight mass spectrometry. By means of a thermodynamic treatment it is shown that simple heating by the impact cannot be hold responsible for the ion formation. However, this process is very much related to the non-adiabatic ion formation by pulsed laser irradiation. The damage caused by the impact particle resulting in cratering and thermal effects, which are long-term processes, is not related to the instantaneous ion formation.
Condensed Aromatics. Part XX. Coronene
Authors: Cyvin S. J. , Cyvin B. N. , Brunvoll J. , Whitmer J. C. , Klaeboe P.
Published: February 2015

The molecular vibrations of coronene, both in-plane and out-of-plane, are studied. The simple Hückel molecular orbitals are derived and the CC bond Oiders calculated. The bond orders are used to fix the CC stretching force constants. A complete set of independent symmetry coordinates is constructed. The in-plane vibrational frequencies are calculated by (a) the five-parameter approximation and (b) the Califano-Neto method; those of the out-of-plane vibrations only by the five-parameter approximation. The calculated frequencies are compared with observed values and previous calculations. A few new Raman bands are reported along with the presumably most complete set of infrared frequencies reported so far. A complete assignment of the infrared- active (E1u and A2u) fundamentals is proposed. A majority of the Raman-active frequencies (A1g, E1g and E2g) are also assigned, using Raman, fluorescence and phosphorescence spectra.
The Determination of Molecular Quantities from Measurements on Macroscopic Systems.II. The Determination of Electric Dipole Moments
Authors: Liptay Wolfgang , Becker Jürgen , Wehning Detlev , Lang Werner , Burkhard Oswald
Published: February 2015

Some bulk quantities appropriate for the description of dielectric and refractometric measurements on macroscopic systems are defined and their properties are discussed. Based on three molecular models (Lorentz model, Onsager model in spherical approximation, and in ellipsoidal approximation) model molar quantities are introduced, which depend on intrinsic properties of the molecule, i.e. the electric dipole moment and the polarizability. The relations will be applied for the evaluation of the results of dielectric and refractometric measurements on eight aromatic molecules.
The Determination of Molecular Quantities from Measurements on Macroscopic Systems.III. Electro-optical Absorption Measurements on Michler's Ketone
Authors: Liptay Wolfgang , Becker Jürgen
Published: February 2015

Some bulk quantities appropriate for the description of electro-optical absorption measurements on macroscopic systems are defined and their properties are discussed. Based on three molecular models (Lorentz model, Onsager model in spherical approximation and in ellipsoidal approximation) model molar quantities are introduced, which depend on intrinsic properties of the molecule (dipole moments and polarizabilities in the ground and excited state, transition dipole moment and transition polarizability). The relations will be applied for the evaluation of the results of electro-optical absorption measurements on Michler's ketone in cyclohexane in a wavenumber interval near 30 · 105 m-1 . The angles between the dipole moments in the ground and the excited state and the transition dipole moment will be determined; the magnitude of the dipole moment in the corresponding excited state is μaG = 30 · 10-30 Cm. The data show that the symmetry of a solute Michler's ketone molecule most probably corresponds, at least approximately, to the pointgroup Cs.
The Determination of Molecular Quantities from Measurements on Macroscopic Systems.V. Existence and Properties of 1:1 and 2:1-Electron-Donor-Acceptor Complexes of Hexamethylbenzene with Tetracyanoethylene
Authors: Liptay Wolfgang , Rehm Torsten , Wehning Detlev , Schanne Lothar , Baumann Wolfram , Lang Werner
Published: February 2015

The formation of electron-donor-acceptor complexes of hexamethylbenzene (HMB) with tetracyanoethylene (TCNE) was investigated by measurements of the optical absorptions, the densities, the permittivities and the electro-optical absorptions of solutions in CCl4. The careful evaluation of data based on some previously reported models, has shown that the assumption of the formation of the 1: 1 and the 2 : 1 complex agrees with all experimental data, but that the assumption of the formation of only the 1: 1 complex is contradictory to experimental facts even if the activity effects on the equilibrium constant and of the solvent dependences of observed molar quantities are taken into account. The evaluation leads to the molar optical absorption coefficients and the molar volumes of both complexes and to their electric dipole moments in the electronic ground state and the considered excited state. According to these results the complexes are of the sandwich type HMB-TCNE and HMB-TCNE-HMB. In spite of the fact that the 2: 1 complex owns a center of symmetry, at least approximately, there is a rather large electric dipole moment in its excited state. Furthermore, values for the equilibrium constants and for the standard reaction enthalpies of both complex formation reactions are estimated from experimental data.
Zum Tieftemperaturverhalten von Na3NO3
Authors: Jansen Martin
Published: February 2015

Low temperature Guinier photographs of Na3NO3 ( + 20° → - 140 °C) indicate two phase transitions to M-Na3NO3 and T-Na3NO3 at - 53±3°C and - 122±3°C, respectively. During the phase transitions the main structural features (NO2-[ONa3]: antiperovskite type of structure) remain unchanged. The dynamically disordered NO2- in H-Na3NO3 order to form an antiferroelectric arrangement in T-Na3NO3. Crystal structures for M-Na3NO3 and T-Na3NO3 are proposed.
Exzeßenthalpien des Systems MgJ2 · 8 H2O/Äthanol
Authors: Christahl M. , Peschel W.
Published: February 2015

For the binary system MgJ2 · 8H2O/ethanol the integral enthalpies of mixing are experimentally determined. The mixing is exothermic, with an excess enthalpy increasing with salt concentration and reaction temperature as well. From the mathematical approximation of experimental data the differential enthalpies of solution and of dilution are obtained. It is concluded that the coordinated water molecules can only hardly be replaced by ethanol molecules.
Melting Behavior of Hydrocarbon Chain Molecules with Ionic End:Groups: Primary n-Alkylammonium Halides
Authors: Busico V. , Scopa A. , Vacatello M.
Published: February 2015

Stepwise melting behavior for a series of primary long chain n-alkylammonium chlorides was pointed out. A plastic phase, a smectic mesophase and a “clear” liquid possibly unisotropic were observed. The same trend seems to be common to other hydrocarbon molecules with ionic endgroups, including alkali metal n-alkanoates.
Theoretical Study of the Spin Hamiltonian Parameters of Vanadium Ions V2+ in CsMgX3 (X = Cl, Br, I)
Authors: Gao Xiu-Ying , Wu Shao-Yi , Wei Wang-He , Yan Wei-Zi
Published: February 2015

The spin Hamiltonian g factors and the hyperfine structure constants for V2+ in CsMgX3 (X = Cl, Br, I) are theoretically studied by using the perturbation formulas of these parameters for a 3d3 ion in octahedral symmetry, based on the cluster approach. In such formulas, the contributions from the s-orbitals of the ligands were usually neglected. Here they are taken into account. The theoretical results (particularly the g factor for CsMgI3) show a significant improvement compared with those in absence of the ligand s-orbital contributions in the previous studies.
A Classical Model for the Extended Electron I
Authors: Lortz Dietrich
Published: February 2015

In order to avoid divergence of its self-energy the free electron at rest is described as a relativistic continuum of finite extent. It has the form of an axisymmetric torus of finite aspect ratio, which rigidly rotates around its axis of symmetry with superluminal speed (v > c). It is shown that there is a class of stationary solutions of the free-boundary value problem. The parameter dependence of these solutions is related to experimental data.
Carbon σ-Electron Densities and C-H Stretching Vibration Frequencies of Phenanthrene
Authors: Kubba Rehab M. , Al-ani Raghida I. , Shanshal Muthana
Published: February 2015

MINDO/3-FORCES calculations were carried out for the vibration frequencies and IR absorption intensities of phenanthrene radical ions. The obtained frequencies were compared with the experimental values possible. It was found that the C-H stretching frequencies are directly related to the carbon σ -electron densities of the relevant atoms.
A Molecular Dynamics Simulation of the Transport Properties of Molten (La1/3, K)Cl
Authors: Matsumiya Masahiko , Seo Koichi
Published: February 2015

Molecular dynamics simulations of molten (La1/3, K)Cl at 1123 K have been performed in order to investigate the correlation between simulated dynamical properties such as the self-exchange velocity (ν), the self-diffusion coefficient (D) and the electrical conductivity (κ) and the corresponding experimental values. The simulated results revealed that v and D of potassium decrease with increasing mole fraction of lanthanum, as expected from the experimental internal cation mobilities, b. The decrease of bK, νK and DK is ascribed to the tranquilization effect by La3+, which strongly interacts with Cl−. In contrast, bLa, νLa, and DLa increase with increasing concentration of La3+. The distorted linkage of the network structure of [LaCl6]3− units was disconnected with increasing the concentration of the alkali chloride. This might be attributed to the stronger association of La3+ with Cl− due to the enhanced charge asymmetry of the two cations neighboring Cl−. The sequence of the calculated v’s, D’s, and κ’s is consistent with those of the referred experimental results.
Metal Complex Formation in Melts of Acetamide-Ammonium Nitrate-Water Mixtures, Part I. Cobalt(II) Chloride Complexes
Authors: Zsigrai István J. , Gadžurić Slobodan B. , Matijević Borko
Published: February 2015

The complex formation between cobalt(II) and chloride ions in molten NH4NO3・2.61H2O, NH4NO3・CH3CONH2・1.61H2O and NH4NO3・2.61CH3CONH2 has been investigated. Absorption spectra of cobalt(II) chloride containing variable amounts of ammonium chloride were recorded at 45 to 60 °C. In the absence of chloride, the solutions show spectra typical for octahedral co-ordination of cobalt(II). Addition of chloride caused a shift of the absorption maximum toward lower energies and an increase of the molar absorption coefficient with increasing chloride concentration. The position of the absorption maximum and the intensity of the absorption indicate tetrahedral or severely distorted octahedral co-ordination. The stability constants for [Co(NO3)4]2−, [Co(NO3)2Cl2]2− and [CoCl4]2− complex formation in NH4NO3・2.61CH3CONH2 are reported.
Investigations Of The G Factors Of Fe+ In Mgo And Cao
Authors: Wu Shao-Yi , Dong Hui-Ning
Published: February 2015

The g factors of Fe+ in MgO and CaO are theoretically investigated by the perturbation formula of the g factor of a 3d7 ion in cubic octahedral symmetry based on the cluster approach. By considering the partial quenching of the spin-orbit coupling interaction and the effective Land´e factor due to the dynamic Jahn-Teller effect (DJTE), the experimental g factors of the studied systems are reasonably interpreted. It can be suggested that the small g factors of the Fe+ centers in MgO and CaO can be likely attributed to the DJTE, rather than the covalency effect within the scheme of the static crystalfield model.
Investigation Of The Epr Parameters Of An Orthorhombic Cu2+ Center In Cs2zncl4 Crystal
Authors: Dong Hui-Ning , Wu Shao-Yi , Liu Xian-Rong , Chen Wei-Dong
Published: February 2015

The electron paramagnetic resonance (EPR) anisotropic g-factors gx, gy and gz and hyperfine structure constants Ax, Ay and Az of Cu2+ in Cs2ZnCl4 crystal are theoretically investigated by the method of diagonalizing the full Hamiltonian matrix. The crystal-field parameters are obtained from the crystal structure by the superposition model. The results, agreeing reasonably with the observed values, are discussed.
Study On The Second Order Optical Properties Of N-(2,4-Dichloro)-Salicylaldimine
Authors: Karakaş Aslı , Ünver Hüseyin , Elmali Ayhan , Svoboda Ingrid
Published: February 2015

N-(2,4-Dichloro)-salicylaldimine was synthesized, characterized by elemental analysis, FT-IR, and UV-visible spectroscopy, and its crystal structure was determined. The title compound is almost planar and contains short intramolecular O-H. . .N hydrogen bonds [O1-N1 2.601(1) A° ]. It remains transparent in the visible region and has solvatochromic behavior in the UV region in the range 198 - 349 nm, implying non-zero microscopic first hyperpolarizability. The ab-initio quantum mechanical calculations (finite field second-order Møller Plesset perturbation theory) of the studied compound have been carried out to compute the electric dipole moment (μ) and the first hyperpolarizability (β ) values. The ab-initio results also show that this ligand might have microscopic nonlinear optical behavior with non-zero values.
A Thermodynamic Study of The Association of K+ And Rb+ Cations with 1,3-Bis(Benzyloxy)-p-tert-butylcalix[4]crown-5 in a CHCl3–Methanol Mixture
Authors: Mizyed Shehadeh A. , Ashram Muhammad
Published: February 2015

The conductivity during the complexation reaction between K+ or Rb+ and 1,3-bis(benzyloxy)- p-tert-butylcalix[4]crown-5 in a CHCl3-methanol mixture at 288 - 303 K has been measured. The conductivity data were analyzed using a computer program based on 1 : 1 stoichiometry. The stability constants of the resulting complexes were determined, indicating that K+ is more stable than Rb+ in the solvents used. The ΔH and Δ S values for the complexation processes were determined from the temperature dependence of the complexation constants. Their significance as well as the solvent effect is discussed.
Investigation of the Electric-field Effect in EPR Spectra of Fe3+ in KTaO3
Authors: Zheng Wen-Chen , Tang Sheng , Wu Xiao-Xuan
Published: February 2015

The displacements of Fe3+ (at the Ta5+ site) along the [001] direction in KTaO3 crystal, caused by the electric field, have been studied by calculating the electric-field-induced zero-field splittings from the microscopic mechanisms and the empirical superposition model. It is found that the Fe3+ displacements obtained by the two methods at the same electric-field strength and temperature are close to each other. These displacements are also close to that estimated from the force-balance equation. It is suggested that the electric-field-induced zero-field splitting can be attributed primarily to the above displacement and the temperature dependence of the electric-field-induced zero-field splitting is mainly due to the change in the dielectric constant of KTaO3 with temperature.
Studies of the EPR Parameters and the Local Tetragonal Distortion of V4+-Doped SrTiO3 Crystal
Authors: Zheng Wen-Chen , Fan Ying-Juan , Wu Xiao-Xuan
Published: February 2015

The EPR parameters (g factors g||, g⊥ and hyperfine structure constants A||, A⊥) of V4+ ion in the tetragonal phase of SrTiO3 crystal were studied by high-order perturbation formulas based on a two-spin-orbit-parameter model, where the contributions from the spin-orbit-coupling-parameter of central 3dn ion and that of ligands are considered. It is found that the oxygen octahedron surrounding

the impurity ion V4+ changes from elongation along the tetragonal axis in the pure crystal to compression and the magnitude of tetragonal distortion of oxygen octahedron (characterized by |ΔR|=|R||−R⊥|) inV4+ center is much greater than the corresponding value in the pure crystal. The cause related to the strong Jahn-Teller effect is discussed.
Quantitative Electron Diffraction Data of Amorphous Materials
Authors: Ankele Jürgen , Mayer Joachim , Lamparter Peter , Steeb Siegfried
Published: February 2015

A method has been developed to obtain quantitative electron diffraction data up to a value of Q = 20 Å−1 of the modulus of the scattering vector. The experiments were performed on a commercially available transmission electron microscope equipped with a so-called omega energy filter. An analytical multiple scattering correction was applied. The electron diffraction results obtained with amorphous germanium were compared with X-ray and neutron diffraction data and showed good agreement. For an amorphous Ni63Nb37 sample it was shown that it is possible to estimate the multiple scattering intensity without exact knowledge of the sample thickness. This technique was applied to derive the structure factor for electron diffraction of two precursor-derived amorphous Si-C-N ceramics (a-Si24C43N33 and a-Si40C24N36). The results are consistent with corresponding X-ray diffraction data and with an existing structural model for such ceramics.
Blow-Up Of Solutions For The Damped Boussinesq Equation
Authors: Polat Necat , Kaya Doğan , Tutalar H. Ilhan
Published: February 2015

We consider the blow-up of solutions as a function of time to the initial boundary value problem for the damped Boussinesq equation. Under some assumptions we prove that the solutions with vanishing initial energy blow up in finite time
FT-IR Spectroscopic Study of M(Cyclopentanone)2Ni(CN)4 Complexes (M = Ni, Cd and Co)
Authors: Kartal Zeki , Ölmez A.
Published: February 2015

Cyclopentanone-tetracyanonickel complexes, given by the general formula of M(cyclopentanone)2Ni(CN)4 (M = Ni, Cd and Co), were obtained for the first time. The similarities of the observed spectra with Hofmann-type complexes indicate that the obtained compounds are new examples of Hofmann-type complexes. - PACS: 33.20.Ea, 33.20.Tp
Investigations of the Defect Structure for Cu2+ in SrLaAlO4
Authors: Wei Wang-He , Wu Shao-Yi , Dong Hui-Ning
Published: February 2015

The defect structure for Cu2+ in SrLaAlO4 is theoretically investigated by the perturbation formulas of the spin Hamiltonian parameters (g factors g‖, g⊥ and the hyperfine structure constants A‖ and A⊥) for a 3d9 ion in tetragonally elongated octahedra. Based on these studies, the tetragonal center may be attributed to Cu2+ occupying the host Al3+ site, associated with one hole delocalized at the four oxygen ligands in planar coordination. Furthermore, the four Cu,O bonds (perpendicular to the four-fold axis) are found to suffer an outward stretch of about 0.06 Å due to (i) the local tenseness in this plane, arising from the size mismatching substitution of the smaller Al3+ by the larger Cu2+ and (ii) the weaker electrostatic attraction of the less charged Cu2+ acting upon the four oxygen ions containing the delocalized hole. The calculated spin Hamiltonian parameters agree well with the experimental data. The defect structure of this center is discussed.
Studies on the EPR Parameters for the Rhombic Co2+ Center in Magnesium Acetate
Authors: Wu Shao-Yi , Dong Hui-Ning
Published: February 2015

The electron paramagnetic resonance (EPR) g factors gi (i = x,y, z) and the hyperfine structure constants Ai for the rhombic Co2+ center in magnesium acetate are theoretically studied from the perturbation formulas of these parameters for a 3d7 ion under rhombic symmetry. In these formulas, the contributions from the admixture among different states, covalency effect and rhombic crystal-fields are taken into account. The related crystal-field parameters are determined from the superposition model and the local geometrical relationship of the impurity center. The calculated results show reasonable agreement with the observed values. In addition, the nuclear quadrupole interaction constant Q is analyzed, and its negative sign is verified theoretically.
Mean Amplitudes of Vibration of Phosphine Borane and Trifluorophosphine Borane
Authors: Baran Enrique J.
Published: February 2015

The mean amplitudes of vibration of PH3BH3 and PF3BH3 were calculated from known spectroscopic and structural data between 0 and 1000 K and compared with those of related species. Bond peculiarities are also briefly discussed.
A Hypothetical Mechanism of Generating Magnetically Charged Fermions by CP-symmetry Breaking
Authors: Stumpf Harald
Published: February 2015

Based on the assumption that electroweak bosons, leptons and quarks possess a substructure of elementary fermionic constituents, in a previous paper it was demonstrated that under CP-symmetry breaking “electric” and “magnetic” electroweak bosons coexist, where the latter transmit magnetic monopole interactions. In this paper the calculation is extended to the derivation of the effective theory for electroweak bosons and leptons. It is shown that under the influence of CP-symmetry breaking charged leptons are transmuted into dyons, the interactions of which are mediated by electric and magnetic electroweak bosons. The dynamical law of the fermionic constituents is assumed to be given by a relativistically invariant nonlinear spinor field theory with local interaction, canonical quantization, selfregularization and probability interpretation. The corresponding effective theory is derived by means of weak mapping theorems and turns out to be an extension of the Standard model for dyons where owing to CP-violation SU(2)-symmetry is simultaneously broken. A mechanism of inducing CP-symmetry violation in the low energy range is proposed
Reduktion eines Bis(chlorphenylphosphanyl)methylids zum entsprechenden Diphosphan und Tetraphosphinan Reduction of a Bis(chlorophenylphosphanyl)methylide to the Corresponding Diphosphane and Tetraphosphinane
Authors: Breitsameter F. , Schmidpeter A. , Nöth H. , Knizek J.
Published: February 2015

The bis(phosphanyl)ylides Ph3PC(PPh2)2, Ph3PC(PPhCl)2 (3) and Ph3PC(PCl2)2 have analogous molecular structures. Details reflect the different charge transfer from the ylide center to the phosphanyl substituents. Chlorination destroys the chirality of 3. Reduction leads to the diphosphane 8 and the 1,2,4,5-tetraphosphinane 9 which are also included in the structural comparison.
The Stereochemistry of Chloro-bis(N-morpholino)phenylsilane
Authors: Huber Gerald , Schier Annette , Schmidbaur Hubert
Published: February 2015

Treatment of phenyltrichlorosilane with an excess of morpholine and N-lithium-morpholide in pentane/toluene affords only the disubstitution product Cl(Ph)Si(Mor)2 with Mor = O(CH2CH2)2N-. The third halogen atom is not replaced owing to sterical hindrance. The title compound crystallizes with two independent molecules in the unit cell. These two molecules can be classified as enantiomers, because a disrotatory twist of the two morpholino ligands away from the potential mirror plane induces a chiral conformation. In benzene solution there is racemization owing to completely free rotation, chair/boat interconversion, and nitrogen inversion of the morpholino groups on the NMR time scale, but all CH2 protons remain anisochronous (diastereotopic).
The Intermetallic Zirconium Compounds ZrNiAl, ZrRhSn, and ZrPtGa - Structural Distortions and Metal-Metal Bonding in Fe2P Related Compounds
Authors: Zumdick Markus F. , Hoffmann Rolf-Dieter , Pöttgen Rainer
Published: February 2015

ZrNiAl, ZrPtGa, and ZrRhSn have been prepared by reacting the elements in an arc-melting furnace and subsequent annealing at 970 K. These compounds have previously been investigated only by use of X-ray powder data for ZrPtGa and ZrRhSn and single crystal film data for ZrNiAl. Precise single crystal diffractometer data are reported in the present paper. The structure of ZrNiAl is confirmed. It adopts a substitution variant of the Fe2P type: P6̄2m, a = 691.5(2), c = 346.6(1) pm, Z = 3, wR2 = 0.0538, 320 F2 values, 14 parameters. The structure refinement reveals a large displacement parameter U33 for one nickel position, indicative of a slight nickel dislocation. Weak superstructure reflections could be found on Guinier powder patterns for ZrPtGa and ZrRhSn. These compounds crystallize with the HfRhSn type structure (Z = 6 , space group P6̄2c), a superstructure of the Fe2P type: a = 714.5(1), c = 706.3(2) pm, wR2 = 0.0651, 594 F2 values, 18 parameters for ZrPtGa and a = 734.2(2), c = 721.8(2) pm, wR2 = 0.0349, 355 F2 values, 18 parameters for ZrRhSn. Structural motifs of these compounds are transition metal centered trigonal prisms formed by the zirconium, aluminium, gallium, and tin atoms. While these trigonal prisms are regular in ZrNiAl, significant distortions occur in the structures of ZrPtGa and ZrRhSn. Due to the distortions of the trigonal prisms in the superstructures, some platinum and rhodium atoms are dislocated from the subcell mirror planes towards Pt-Pt and Rh-Rh pairs with distances of 310 and 313 pm, respectively. The formation of the superstructure is most likely due to packing reasons. Chemical bonding in ZrRhSn was investigated on the basis of an extended Hückel calculation.
Darstellung und Kristallstruktur von [OsFPy5][BF4] · H2O · CH2Cl2/Synthesis and Crystal Structure of [OsFPy5][BF4] · H2O · CH2Cl2
Authors: Kolf S. , Preetz W.
Published: February 2015

In the reaction of K2[OsF6] with glycerine and pyridine [OsFPy5]+ (5%) is formed as a byproduct which can be separated chromatographically from the main product frans-[OsF2Py4]. The X-Ray structure has been determined on a single crystal of [OsFPy5][BF4] · H2O CH2Cl2 (orthorhombic, space group Pbca, a = 18.774(5), b = 16.833(3), c = 20.924(6) Å. Z = 8). Due to theo stronger trans influence of pyridine as compared to fluorine the Os-N' bond length of 2.06 Å in the F•-Os-N' axis is shorter than the Os-N distances of the OsPy4 base ranging from 2.07 to 2.10 Å.
Metallkomplexe mit biologisch wichtigen Liganden, CXI. Phosphan-Gold(I), -Nickel(II) und -Platin(II) Komplexe mit dem Anion von Hydantoin und 3,4-Pyridindicarbonsäureimid/Metal Complexes of Biologically Important Ligands, CXI. Phosphine Gold(I), Nickel(II) and Platinum(II) Complexes with the Anion of Hydantoin and of 3,4 Pyridine Dicarboxylic Imide
Authors: Koch Daniela , Sünkel Karlheinz , Beck Wolfgang
Published: February 2015

The anions of hydantoin (L1) and of the imide of 3,4-pyridine dicarboxylic acid (L2) form the complexes Ph3PAu(L1-H+) (1), Ph3PAu(L2-H+) (2), (nBu3P)2Ni(L1-H+)2 (3) and the ligand bridged compounds Ph3PAu(L2-H+)M(PEt3)Cl2 (M = Pd, Pt, 4, 5). With the neutral ligand L2 the complexes Cp*Ir(Cl)2(L2) (6), (ρ-cymene)Ru(Cl)2 (L2) (7) and (Et3P)(Cl)2Pd(L2) (8) were obtained. Complexes 1, 2 and 6 were characterized by X-ray diffraction.
Zu den Phasenbeziehungen im System V/Nb/O, IV. Die Festelektrolyt-Coulometrie (FEC) als Methode zur Aufklärung ternärer Zustandsgebiete am Beispiel des Systems V/Nb/O/The Phase Relations in the System V/Nb/O, IV. Solid Electrolytic Coulometry (SEC) as a Method to Investigate Ternary Systems: V/Nb/O
Authors: Kirsten L. , Woedtke F. von , Oppermann H.
Published: February 2015

The observation of reductive decomposition with SEC-current-time-temperature curves on the binary line V2O5-Nb2O5 is a useful method to determine qualitatively and quantitatively (“quasi in situ”) the known ternary coexistence regions. By reduction of VO2 the Magneli-Phases VnO2n-1 are generated. The method is generally applicable and allows rapid information by reductive decompositon or oxidative formation in coexistence regions.

The conditions of decomposition can be optimized for a given system. Slow solid-gas equilibria are not detectable by this method.