bluuebunny/crossref_metadata_2025 huggingface dataset:
Schwingungseigenschaften der XF6
3- Anione (mit X = AI, Ga, In, TI)
Authors: Baran Enrique J. , Lavat Araceli E.
Published: February 2015

The principal force constants for the title anions have been calculated using the GVFF. Mean amplitudes of vibration, at different temperatures are also estimated. The results are briefly discussed and some comparisons with related species are made
Kinetics of Triplet Sublevel Selective Photochemical Reactions in the Solid State
Authors: Gehrtz Manfred , Bräuchle Christoph , Voitländer Jürgen
Published: February 2015

A detailed description of the overall kinetics of photochemical reactions has to deal with photo-physical activation and de-activation rates as well as with true photochemical rates. Based on the hypothesis that for photoreactions involving the lowest excited triplet state the chemical reaction rates of the individual triplet zero-field levels have different values, a method is presented for the evaluation of these rates from bulk measurements under steady state illumination conditions. The complications arising from the detection of solid state reactions are discussed, and a simple solution is given, illustrated by a numerical example.
On the Structure in Aqueous Superconcentrated Calcium Nitrate
Authors: Caminiti R. , Musinu A. , Paschina G. , Piccaluga G. , Pinna G.
Published: February 2015

Liquid hydrous calcium nitrate of composition Ca(NO3)2 · 3.5 H2O was investigated by X-ray diffraction. Experimental data were interpreted in terms of geometrical models suggested by the structure of the crystalline hydrates Ca (NO3)2 · 3H2O and Ca(NO3)2 · 4H2O, in which calcium ions are coordinated to nine oxygen atoms, partly coming from water molecules, partly from NO3
-ions.
Untersuchungen zum Strukturaufbau von As2P2S7 und (As2P2S8)n
Authors: Wibbelmann Claus , Brockner Wolfgang
Published: February 2015

The compounds of the analytical composition AS2P2S7 and ASPS4 have been prepared by ele-mental synthesis. Vibrational spectra of both compounds have been recorded and their structure was proposed therefrom. AS2P2S7 has a cage-like structure (C2v symmetry). The compound A8PS4 is polymeric (C2V symmetry) and it will be better formulated as (As2P2Ss)n. Mass spectra of the two compounds have been reported. Some X-ray diffraction data, the melting tempera-tures and the density values have been given.
Microwave and Millimeterwave Spectrum of Chlorofluoroacetylene (Cl—C≡C—F)
Authors: Guarnieri A. , Andolfatto M.
Published: February 2015

The microwave and millimeterwave spectra of chlorofluoroacetylene 35 C1—C = C—F and 37 C1—C = C—F in natural abundance, have been investigated. The molecule has been found to be linear. The rotational constant, the centrifugal distortion constant Do and the chlorine quadrupole coupling constant have been determined. Some ro-structures have been calculated assuming different values for the C = C distance.
The Statistical Dynamics of a System Consisting of a Classical and a Quantum Subsystem
Authors: Aleksandrov I. V.
Published: February 2015

For a system consisting of a quantum and a classical subsystem, an equation of the Liouville type is obtained starting with the density matrix equation. The validity condition and the transformation properties of this quantum-classical equation as well as the application of the adiabatic approximation and the perturbation theory within the frame of this equation are discussed. Some general expressions are obtained for the probability of the transition between the quasi-equilibrium states of the system.

Special attention is given to the electron-nuclei system, as the general formalism was developed first of all in order to obtain a foundation for the theoretical analysis of elementary processes in liquids. An example is given to demonstrate that the quantum-classical approach in the range of its validity gives the same result as the corresponding quantum solution. It is also shown that both the cases of weak and strong interaction (leading to the transition) can be described by the quantum-classical equation in question.
Precision Measurements of the Lead Kαi and Kα2 X-ray Energies
Authors: Hungerford P. , Schmidt H. H. , Brissot R. , Barreau G. , Börner H. G.
Published: February 2015

The energies of the Kαi and Kα2 X-ray lines in lead have been measured with a curved crystal spectrometer. The values of 74.9720 ± 0.0010 keV (Kα1) and 72.8077 ± 0.0010 keV (Kα2) are compared to recent theoretical estimates and previous experimental results.
Three Pulse Photon Echoes on an Inhomogeneously Stark Broadened Line at 3 mm-Wavelengths
Authors: Rohart F. , Macke B.
Published: February 2015

Three pulse photon echoes are studied when the prevailing inhomogeneous damping arises from the application of an inhomogeneous Stark field. Whereas the molecular free flight through the inhomogeneous Stark field entails a strong attenuation of conventional photon echoes, this effect is shown to be eliminated for the even numbered echoes of a Carr Purcell sequence. These predictions are well supported by a detailed experimental study at a 3 mm wavelength. Velocity changing collision influence is discussed and T1 and T2 relaxation times of the (J, |KM| = 1,1 → 2,1) rotational transition of CH3F are incidentally determined.
Laser Spectroscopy of the υ3 Band of Methyl Fluoride
Authors: Herlemont F. , Lyszyk M. , Lemaire J. , Demaison J.
Published: February 2015

The υ3 fundamental of CH3F has been remeasured using a tunable diode laser and a waveguide CO2 laser. Combination of this new measurement with earlier laser and microwave results has allowed us to obtain improved spectral parameters for both the ground and the υ3 = 1 excited state.
Phosphorescence Lifetimes of [Cr(NCS)6]-3 in Frozen Alcohol Solvents
Authors: Łukowiak E. , Stręk W. , Jeżowska-Trzebiatowska B.
Published: February 2015

For [Cr(NCS)6]-3 in normal alcohols at 77 K the lifetimes of phosphorescence from the excited doublet state are reported. The lifetimes decrease in the order ethanol > methanol > n-propanol > n-butanol > n-pentanol > n-hexanol > n-heptanol, and the rate constant increases exponentially when the 0'-0 band energy of the 2Eg → 4A2g transition decreases.
Ligand Induced Spin Crossover in Penta-Coordinated Ferric Dithioearbamates
Authors: Ganguli P. , Iyer R. M.
Published: February 2015

On addition of lewis bases to Fe(dtc)2X, ligand exchange takes place through a SN2 mechanism, with a parallel spin crossover in the ferric ion. The two species (S = 3/2 and S = 5/2) formed are in dynamic chemical equilibrium, and a slow decomposition is then initiated.
Analysis of Centrifugal Distortion Effects in the Rotational Spectrum of Formyl Fluoride
Authors: Jones Harold , Typke Volker
Published: February 2015

The measurements of the ground state spectra of both HCOF and DCOF have been extended to high-J transition. The centrifugal distortion analysis clearly showed that in HCOF the inclusion of sextic terms is absolutely necessary, whereas the effects from this source in DCOF are smaller but not negligible. The planarity condition for the sextic terms was introduced to reduce the number of parameters. Spectra in the lowest vibrational state of both HCOF and DCOF were also treated.
An X-Ray Diffraction Study on an Aqueous Solution of CdSO4 at 9 and 62 °C
Authors: Caminiti Ruggero
Published: February 2015

The X-Ray scattering of a 2 M aqueous solution CdSO4 has been measured at 9 and 62 °C in a “Θ-Θ” transmission arrangement with a plane-parallel liquid sample. The experimental distribution curves show main peaks at about 1.5, 2.3, 2.8, 3.5, and 4.35 Å. The 3.5 A peak reveals the formation of inner sphere cadmium-sulphate complexes Cd(H2O)6-z(OSO3)z
+2-2z, in which oxygens from sulphate groups substitute z water molecules of the hydrated Cd(H2O)6
2+ ions. Least squares refinements of the i(s) curves are consistent with a structural unit in which the sulphate tetrahedron shares a corner with one cadmium octahedron with Cd-O-S angle of 133 deg. The average number (z) of coordinated sulphate ions increases with increasing temperature.
Molecular Orbital Calculations on the Interaction of Ni and Cu Atoms with PN
Authors: Itoh H. , Ertl G.
Published: February 2015

Ab initio MO calculations for PN predict a pronounced electron transfer from the P to the N atom. Only very weak interactions result for M-PN (M = Ni, Cu) configurations whereas bond formation is predicted if the N atom couples to the metal. The bond strength for Ni (10.5 kcal/mole) is about twice as large as for the Cu-NP complex (4.6 kcal/mole). Coupling occurs mainly with the 7 σ-level (HOMO) of the ligand whose energy is lowered below that of the 2 π-level.
Nuclear Spin-Lattice Relaxation and Knight Shift in Liquid In-Zn System
Authors: Bucklisch R. , Plourabidis D.
Published: February 2015

The nuclear spin-lattice relaxation time T1 and the Knight shift K of 115In in the liquid In-Zn system have been measured over the temperature range (450-900) K. The Korringa correction factor K(α) is found to be temperature independent. The electric quadrupolar contribution to the relaxation rate is concluded to be very small (about 6% of the measured relaxation rate).
Infrared Absorption of Concentrated Aqueous NaClO4 Solutions to High Pressures and Temperatures
Authors: Valyashko V. M. , Buback M. , Franck E. U.
Published: February 2015

The infrared absorption of the O-D stretching fundamental of HDO in concentrated aqueous (HDO/H2O)NaClO4 solutions up to 20 mole% salt has been measured. The data for the wave-number of maximum absorption, ν̅(max), and for the integrated molar absorptivity B up to pressures and temperatures of 2800 bar and 250 °C, respectively, demonstrate the importance of non-hydrogen-bonded interactions in aqueous perchlorate solutions. A non-continuous dis­tribution of the states of water molecules is clearly evident from the experimental spectra. A band separation using three Gaussian components proves the close similarity between the high-pressure high-temperature vibrational O-D infrared spectra of aqueous perchlorate solutions and the O-D Raman spectra of water and aqueous solutions.

Results of the band separation together with literature Raman data provide some evidence that a transition from “water-like” to “melt-like” behaviour occurs in a fairly narrow concentra­tion region between 10 and 15 mole% salt.
Triplett-sensibilisierte Photoreaktionen von Azobenzol in schwefelsaurer Lösung / Triplet-sensitized Photoreaction of Azobenzene in Sulphuric Acid
Authors: Rau Hermann , Crosby Alan D. , Crosby Alan D. , Frank Rudolf
Published: February 2015

The kinetics of the thermally induced cis-trans-isomerization of protonated azobenzene de­pend upon the amount of acid in a mixed H2SO4-H2O-solvent. This is rationalized by the assumption of a doubly protonated azobenzene molecule as an intermediate. Triplet sensitization of protonated azobenzene in 73% sulphuric acid (by weight) leads to cis-trans-isomerization and a photostationary state. This is similar to stilbene. With 1-aminonaphthalene as a sensitizer a photoreduction and cleavage of the azo group is an alternative reaction. It is shown that the cis-azobenzene molecule is the electron acceptor and that the photoreduction can be quenched by the addition of oxygen.
Maximum Overlap Study of Some Bridged Annulenes
Authors: Maksić Z. B. , Kovačević K. , Vampola M.
Published: February 2015

The electronic and geometrical structures of 9,10-methano[10]annulene, 11,11-dimethyl-9,10 methano[10]annulene and 9,10-ethano-9,10 dihydronaphthalene are studied by the maximum overlap method. It is found that the first two molecules have bisnorcaradiene structures possessing very weak central bonds described by sp7 hybridisation states. Bending of these hybrid orbitals is highly pronounced indicating that the most probable place for electrophilic attack is the central bond on the side opposite from the bridge. Their overlapping is, however, by no means negligible concomitant with the experimental NMR evidence which suggests the presence of a direct bond between the bridgehead atoms. The calculated bond angles are in good accordance with available experimental data. The present results provide rationalization of the unusual dihedral angle of 136° found in 9,10-methano[10]annulene by X-ray measurements. Thus the current opinion that bridged annulenes tend to achieve a planar configuration of the olefinic carbon atoms in order to maximize conjugation between the rings should be revised.
Miscibility Studies Indicating a Low Temperature Smectic A Phase in Biaromatic Liquid Crystals with Re-entrant Behaviour
Authors: Göbl-Wunsch A. , Heppke G. , Hopf R.
Published: February 2015

Recent reports [1] have shown that compounds of the homologous series of the 4(4-n-alkyloxy- benzoyloxy)-4′-cyanoazobenzenes (Cn; n = 1 - 12), all have a low temperature smectic A phase (SA″). The homologues with alkyl chain length n≧9 exhibit in addition a high temperature smectic A phase (SA′), separated from the first one by a re-entrant nematic phase (N(re)). Homol­ogues of this series were used for miscibility studies with some compounds of the biaromatic liquid crystal series of the 4-cyano-4′-n-alkyloxybiphenyls (n̄ CBP) and of the 4-cyanobenzylidene- 4′-n-alkyloxyanilines (CN · n̄). The phase diagrams studied show that the smectic A phases of biaromatic liquid crystalline nitrile compounds correspond to the high temperature smectic SA′ type and are not miscible with the low temperature SA″ phase. Moreover, the shapes of the transition temperature curves to the SA″ phase indicate a low temperature smectic A phase (SA″) for the biaromatic compounds. This suggests that for biaromatic compounds with re-entrant behaviour, the dependence of liquid crystalline phase sequences on the alkyl chain length is very similar to that of triaromatic compounds.
Der Einfluß unmagnetischer Dotierungen auf die ESR-Linienbreite von antiferromagnetischen Verbindungen / The Influence of Non-Magnetic Dopants on the ESR Line Width of Antiferromagnetic Compounds
Authors: Dräger K. , Gerling R.
Published: February 2015

ESR spectra of doped antiferromagnetic compounds exhibit a concentration-dependent line width ∆B̄(x). We have investigated polycrystalline samples of Cr2O3 doped with Ga2O3 and Al2O3. For temperatures T sufficiently high above the Néel point TN and for concentrations x≦10%, the experimental values of AB show a linear dependence on x.

This behaviour deviates from theoretical predictions based on the method of second moments. Starting with other reasonable assumptions, we have developed a statistical model of resonance that describes ∆B(x) as a linear function of x. Moreover this allows us to deduce that as far as antiferromagnetic Cr2O3 is concerned, the dopants Ga2O3 and AI2O3 are distributed homogene­ously throughout the lattice sites.
Lattice Dynamical Properties of Potassium
Authors: Gupta O. P.
Published: February 2015

The phonon dispersion, temperature dependence of the Debye temperature, Debye-Waller factor, and Grüneisen parameter of potassium are calculated using a realistic lattice dynamical model. The model considers short range pairwise forces effective upto second neighbors and an improved electron ion interaction on the lines of Bhatia. An equilibrium condition, which preserves the crystal stability, is obtained. The theoretical results are found to be in good agreement with the experimental values.
Notizen: Mapping Parts of the Electron Density Distribution from X-Ray Bragg Scattering Intensities (Lambda Technique)
Authors: Fischer Karl F.
Published: February 2015

By appropriate selection of two or three wavelengths, intensity differences can be used for obtaining directly the electron density distribution (i.e. the arrangement of atoms) for parts of a crystal structure. Application to macro­molecules and amorphous binary substances appear fea­sible.
Spin-Orbit Coupling in Tetragonal d3 Systems
Authors: Hoggard Patrick E.
Published: February 2015

The complete set of energy matrices for tetragonal d3 systems, including spin-orbit coupling, has been constructed within the framework of the Angular Overlap Model. Examples are presented of the variation in energy of the intraconfigurational (t3
2g) doublets as a function of spin-orbit coupling (appropriate to first row metal ions) and ligand field asymmetry. It is seen that asymmetry in Dq values is much less important than the relative partitioning of Dq into eσ and eπ. The use of spin-orbit matrix elements in the calculation of intensities of spin-forbidden transitions is also illustrated.
Nuclear Magnetic Resonance of 51V inV3 Si and VSi2 at High Temperatures
Authors: Ploumbidis D. , Rünger R. , Bucklisch R.
Published: February 2015

The Knight shift of the 51V resonance has been measured as a function of temperature in poly-crystalline V3Si and VSi2 samples. For the VaSi system the measurements have been extended to the temperature range from 400 K up to 1250 K, whereas for VSi2 the first NMR measurements at all have been carried out, covering the range 300 to 1250 K. The observed 51V Knight shift in VSi2 is negative (K51V (T=272 K) = -0.15%) and tends to zero with increasing temperature.
Equilibrium of EuS with Gas Mixtures of H2S,H2 and CO2
Authors: Hauck J.
Published: February 2015

EuS and EU2O3 powder samples were equilibrated with H2S-H2-CO2 gas mixtures in the temperature range 700-1500 °C. Since the sulfur and oxygen fugacities of the gas mixtures - as calculated from thermodynamic data - can vary by about 107 , EuS of different stoichiometrics may be produced. At higher oxygen and lower sulfur fugacities EuS is oxidized to EU2O2S. The border line between the two phases can be fitted by the equation log(f(S2)/atm.) = 2 log(f(O2)/ atm.) + 48300/T - 9.3 and compared to border lines of other phases of the Eu-O-S system, which can be calculated from thermodynamic data.
Fluorescence from High Vibronically Excited Benzene: a "Channel Three" Problem
Authors: Wunsch L. , Neusser H. J. , Schlag E. W.
Published: February 2015

Gas phase benzene is excited by two-photon absorption at various pressures between 4 and 80 torr. Fluorescence is observed even from states located at excess energies of 3000 cm-1 - 7000 cm-1 , i.e. well above the onset of "channel three". The nonradiative decay rates as estimated from this fluorescence intensity continue the well known shortening of lifetime with excess energy in a monotone fashion and do not show a drastic cut-off as often concluded from previous line-width measurements.
The Influence of Small Monovalent Cations on Neighbouring Hydrogen Bonds of Aquo-Protein Complexes
Authors: Sagarik Kritsana P. , Rode Bernd M.
Published: February 2015

The influence of small monovalent metal ions on hydrogen bonds of aquo-protein complexes is studied on Li+/HCONH2-OH2 as an example. Using results obtained from ab initio calculations with minimal GLO basis sets, the remarkable changes in the hydrogen bond energy and charge distribution, due to metal ion complex formation, are discussed. The metal ion seems to enhance strongly the donor-acceptor interaction of the O ... H-N-C=0 hydrogen-bonded system.
Die Kinetik des Zerfalls von tert. Butylperoxypivalat bei hohen Drücken und Temperaturen / The Kinetics of the Decomposition of tert.Butylperoxypivalate up to High Pressures and Temperatures
Authors: Buback M. , Lendle H.
Published: February 2015

The decomposition of tert. butylperoxypivalate dissolved in n-heptane has been measured ir-spectroscopically in optical high-pressure cells up to 2000 bar at temperatures between 65 °C and 105 °C. The reaction follows a first order rate law with an activation energy Ea = 122.3 ±3.0 kJ · mol-1 and an activation volume ⊿V≠ = 1.6 ± 1.0 cm3 mol-1 .
Cationization by Alkali Ion Attachment in Laser Desorption Mass Spectrometry
Authors: Stoll R. , Röllgen F. W.
Published: February 2015

The formation of quasimolecular ions by alkali ion attachment in laser desorption mass spec-trometry has been investigated by using a CW CO2 laser. For molecules such as sucrose the desorption of preformed ions could be excluded. Evidence is presented for the ionization by alkali ion attachment in the gas phase. Quasimolecular ions of organic salts were found to result from cationization reactions in the gas phase and from surface reactions. Very fast cation exchange reactions have been discovered for salts and acids impinging on alkali ion emitting surfaces.
Ion Formation from Alkali Halide Solids by High Power Pulsed Laser Irradiation
Authors: Jöst B. , Schueler B. , Krueger F. R.
Published: February 2015

Ion formation from alkali halide solids caused by the irradiation of high power (some 108 W/ cm2) pulsed lasers is investigated by means of time-of-flight mass spectrometry (LAMMA®). It is shown that the ions are formed directly from the solid state, several uppermost atomic layers being involved; gas phase interactions are negligible. The ion formation rates, however, are in-compatible with the assumption of a quasiequilibrium phase transition, but should be explained in terms of non-adiabatic rate processes discussed in some detail. The light absorption of the transparent halide crystals is assumed to be initiated by multiphoton absorption - free electron production; the further energy transfer being maintained by rapid polaron-Joule-heating. The data are compatible with this model.
Pulse Radiolysis and Simulation Computation Studies on Acridine Orange in Aqueous Solutions
Authors: Solar Sonja , Solar Wolfgang , Getoff Nikola
Published: February 2015

A combined pulse radiolysis-computer simulation method was applied for the elucidation of the complicated multiple H-attack on acridine orange in aqueous solutions at pH = 1 to 3. The simultaneous formation of three intermediates was established: semiquinone (H-addition on the N-atom of the chromophore group), R--species (reaction on the meso-C-atom) and H-adducts on the aromatic ring carbon. Their superimposed spectra were resolved, the individual extinction coefficients and the rate constants for their formation and decay were determined. The results are of importance in particular for understanding the decomposition of acridine orange applied as sensitizer in various devices for solar energy utilization.
On the Electron Drift Velocity in Solid Neon
Authors: Sakai Y. , Böttcher E.-H. , Schmidt W. F.
Published: February 2015

The electron drift velocity in solid neon is reported for the field strength range 1 to 50 kV cm -1 .
Ab Initio Calculations of the Molecular Structures and the Electronic Properties of Sulfur-containing Compounds: III. Thioacrolein (CH2=CH–CH=S) and Thioglyoxal (S = CH–CH=S)
Authors: Ha Tae-Kyu , Nguyen M. T. , Vanquickenborne L.
Published: February 2015

Results of ab initio SCF calculations on thioacrolein (CH2=CH-CH=S) and thioglyoxal (S=CH-CH=S) are reported. The geometries are optimized by the analytical gradient method using the double zeta (DZ) basis set. The trans conformers of these molecules are calculated to be more stable than the cis conformer by 2.06 and 4.31 kcal/mol, respectively.
Remarks on Concentration Quenching in Chlorophyll
Authors: Bojarski C.
Published: February 2015

A quantitative analysis of fluorescence self-quenching of chlorophylls a and b in ether as well as chlorophyll a in lipid vesicles and liposomes has been carried out. It is demonstrated that concentration changes of the fluorescence quantum yield can be correctly described by a Förster-type excitation energy transfer process between chlorophyll molecules in the monomeric form if part of the transfers leads to energy degradation.
Geometrization of the Lienard-Wiechert Field
Authors: Sorg M.
Published: February 2015

A geometric description of the Lienard-Wiechert field of a single point charge is given. The dual of the Lienard-Wiechert field can be considered as the curvature in a bundle of 2-planes distributed smoothly over space-time. This geometric construction also accounts for the Teitel-boim splitting of the total field into bound and radiative parts: The radiation field can be identified with the curvature in the normal bundle. Various questions concerning potentials and the integrability of the distributions involved are discussed.

Whereas the intrinsic symmetry group for the field is that of the 2-plane bundle, namely SO (2), the normal bundle approach leads to the group SO (1,1) as the internal symmetry group for the radiation field.
Fluorescence Quantum Yields of Laser Dyes Determined by On-Line Computer Evaluation
Authors: Gauglitz Günter , Lorch Alwin , Oelkrug Dieter
Published: February 2015

The determination of relative fluorescence quantum yields has been improved to better than 3% precision by use of a multichannel analyzer and an on-line desk-top computer. The new combined device for data acquisition and handling as well as a new correction procedure are described. Drifts of excitation source and dark current can be omitted. The yields for laser dyes, emitting at short wavelengths, are presented in dependence on excitation wavelength. These results simplify the optimal choice of the pump conditions of laser dyes, which usually are not photostable.
Turbulence Limits in Rotating Plasmas for Isotope Separation
Authors: Hora Heinrich , Hoyle Ian B.
Published: February 2015

With the aim of using rotating plasmas (driven by j x B or E x B forces) for isotope separation, several experimental configurations have been studied and theory has been developed with respect to numerical models, the Alfvén ionization limit, D'Angelo's shear instability, while turbulence was suggested qualitatively only. A more detailed study of the limit of laminar flow is presented taking into account the magnetic anisotropy of viscosity and interaction with neutrals. In all cases of experiments, the Reynold's numbers are below critical values of 10 4 by at least a factor 100. The pessimistic conclusions of Boeschoten for his experiment can there-fore not be shared with respect to the turbulence problems. The published cases of isotope separation by rotating plasmas are then discussed extensively.
Surface-Induced Flexoelectric Domains in Asymmetrically Strong-Weak Anchored MBBA Films
Authors: Hinov H. P.
Published: February 2015

The longitudinal surface-induced flexoelectric domains, previously obtained in symmetrically weak-anchored nematic layers have been further investigated in asymmetrically strong-weak anchored MBBA layers. The threshold voltages indicating the onset of the flexoelectric instabilities are high for thin cells (d = 9 μm, Uth = 10 V) and small for thick cells (d = 150 μm, Uth =1.5 V). Pronounced minima in the curves p vs. d and Uth vs. d, where p is the domain period and d is the cell thickness, were obtained.

The flexoelectric domains were replaced by electrohydrodynamic instabilities only in the case of strong azimuthal anchoring of the liquid crystal layer.

The role of the sign and the value of the dielectric anisotropy, the homogeneity of the electric field as well as the asymmetry in the surface anchoring are discussed in detail.
Potential Energy Distribution in the Presence of Redundancies
Authors: Brunvoll J. , Cyvin B. N. , Cyvin S. J.
Published: February 2015

A theory is outlined for the potential energy distribution in the presence of redundancies. Numerical examples are given for the cage-like molecules P4S3, P4Se3, As4S3, As4Se3 and PAs3S3, for which the molecular vibrations have been analysed previously.
Molecular Orbital Calculations on the Interaction of PF3 and CO with Ni and Cu Atoms
Authors: Itoh H. , Ertl G.
Published: February 2015

The interaction of Ni and Cu atoms with PF3 and CO ligands was investigated by means of ab initio MO calculations. Coupling occurs mainly through the HOMO (8a1 for PF3 and 5 a for CO) levels with the metal 4s and 3dz2 orbitals, if the 3dn-1 4s1 electronic configuration of the metal atom is considered. The estimated M-PF3 bond lengths are 2.0 Å for Ni and 2.5 Å for Cu. Calculations with Ni(3d10) revealed for PF3 a more pronounced electron transfer to the ligand than for CO. The results are consistent with experimental UPS data for mononuclear complexes as well as corresponding adsorption systems. In particular, split-off d-states observed in UPS data for adsorbed PF3 are attributed to the pronounced lowering of the 3d-orbital energy of the metal atom upon interaction with this electropositive ligand.
Investigation of Self-and Foreign Gas Collision-induced Transitions between M-resolved Rotational Levels of OCS
Authors: Mäder H.
Published: February 2015

Four-level MW-MW double resonance experiments on rotational Stark levels j = 0, 1, 2 and 3 of OCS have been performed to investigate transfer of rotational energy by collisions of OCS with OCS, He, Ne, Ar, Kr, H2, N2, O2, and CH3F. Theoretical arguments are given for the interpretation of the experimentally determined η-values by considering Bloch-type equations of an "embedded" four-level system with ±M degeneracy of the energy levels. The results indicate significant deviations from first order dipole collisional interaction.
Polycrystal Scattering Topography, Scattering Tomography and their Perspective Fields of Application
Authors: Yoneda Yasuharu , Chilcaura Yoshinori
Published: February 2015

A concept of X-ray topography for polycrystalline materials has been proposed. In this method X-rays scattered from a specimen produce the image. Various techniques for this kind of topo­graphy are described and their characteristic features are pointed out; some of these techniques offer the possibility to make tomographic observations.

The new topographic method has been applied to the observation of commercially used alu­minium sheet and of wood (cedar). The discussion is extended to mechanisms of the image forma­tion and the perspective fields of application.
X-Ray and Neutron Integrated Intensity diffracted by Perfect Crystals in Transmission
Authors: Lambert D. , Malgrange C.
Published: February 2015

The integrated reflection power for perfect crystals has been measured with neutrons and X- Rays for different crystals in a wide range of absorption coefficients and values of |μh/μ0| where μh is the h Fourier term of the absorption coefficient. The influence of Compton effect and tem­perature factor is discussed. The results are compared to Kato’s theoretical values.
Generation and Proof of Elliptically Polarized X-Rays
Authors: Brümmer O. , Eisenschmidt Ch. , Höche H. R.
Published: February 2015

Using an arrangement being analogous to optics of visible light the phase relation of the mutually perpendicularly polarized wave fields are examined in the Laue case of X-ray diffraction. Bragg reflections at an angle of reflection of about 45° are used as polarizer and analyzer. The different phase relations result from different thicknesses of a wedge-shaped silicon crystal, which is placed between the polarizer and the analyzer and adjusted for the symmetric 220-CuKαl-Laue case. The determined polarization states produced by coherent excitation of both σ-polarized and π-polarized waves in the silicon crystal coincide very well with calculations of the dynamical theory of X-ray diffraction.
Radial Distribution Function of Liquid Sodium
Authors: Reddy M. Rami
Published: February 2015

The radial distribution function of liquid sodium has been studied by considering the integral equation Perturbation Theory of Madden and Fitts for the reference part and the optimised cluster theory for the attractive part of the pair potential. Calculations were carried out for the long range oscillatory potential of Schiff. The calculated results are compared with the molecular dynamics calculations HTA, OCT and with experiment. The agreement was found to be satisfactory.
Absorption of X-rays by Coplanar Four-beam Reflections
Authors: Pacherová O. , Bubáková R.
Published: February 2015

The absorption effect in dispersion and reflection curves is shown for the a and n polarizations and for some wavelengths in the small wavelength interval in which the coplanar four-beam diffraction of x-rays exists. The investigated coplanar Ge[000, 440, 260, 2̄20] reflections appear in a Ge[440, 2̄20] monolithic monochromator working with CoKα1 radiation. It is shown that the absorption not only reduces the intensity in a complicated way but also changes the energy distribution between the participating reflections.
Curved X-ray Trajectories in Nonperfect Crystals
Authors: Dietrich B. , Härtwig J. , Hölzer G. , Kittner R.
Published: February 2015

X-ray trajectories are determined qualitatively and numerically for some one-dimensional deformation gradients by means of Katos geometrical optics. Based on these results the channelization of X-rays and the X-ray contrast are discussed and proved experimetally.
On the Linearity of Certain Coordinate Transformations Including the Lorentz Transformation
Authors: Sjödin Torgny
Published: February 2015

It is shown that, given choices of units and of synchronization in the moving systems which are independent of the time and space coordinates, the linearity of the transformation equations connecting uniformly moving reference systems is a consequence of the fact that the functions deciding the behaviour of moving bodies and clocks are independent of the time and space coordinates ("homogeneity of time and space").
Kelvin-Helmholtz Instabilities at the Interface Between an Accretion Disk and the Magnetosphere of a Neutron Star
Authors: Anzer U. , Börner G.
Published: February 2015

The material in an accretion disk moves on Kepler orbits whereas the magnetosphere of a neutron star rotates like a solid body. Therefore large velocity differences will occur at the interface between the two media. These give rise to Kelvin-Helmholtz instabilities. We present a stability analysis for a simplified geometry. The consequences of the instability for the mass flow from the disk into the magnetosphere are discussed. The resulting transfer of angular momentum to the neutron star is compared with the observed changes of the rotation periods of these stars
Numerische Simulation von Diffusionsprozessen mit nichtnegativitätserhaltenden konservativen Differenzenverfahren / Numerical Simulation of Diffusion Processes with conservative difference schemes of non-negative type
Authors: Gorenflo Rudolf , Kuban Angelika
Published: February 2015

After analyzing the general linear equation of diffusion (of a substance or of energy) with source term and given influx across the boundary we describe a method for constructing explicit and implicit conservative difference schemes which also preserve nonnegativity. We call a scheme “conservative” if via a convenient sum-analogue it does exactly imitate the conservation of a substance or energy. We concretize this method for the spatially two-dimensional heat equation in a rectangle with given influx. We also present a conservative implicit scheme with alternating directions
On the Equilibrium of a Linear Extrap Pinch
Authors: Lehnert B.
Published: February 2015

The equilibrium is studied of a pinched linear plasma column of “Extrap” type which is confined in a purely transverse magnetic field, partly arising from currents in a set of external conductor rods being introduced for stabilizing purposes. The axial and transverse losses are separated in a simplified theoretical model for which stability is assumed as a working hypothesis and anomalous transport as well as impurity radiation are neglected. Then, the reduction of the axial heat transport by the magnetic field will have a substantial effect on the over-all heat balance, thus leading to high temperatures at large axial lengths of the plasma column. Conditions near ignition should become possible at technically realistic linear dimensions and pinch currents
Nonlinear Evolution of Internal Ideal MHD Modes Near the Boundary of Marginal Stability
Authors: Rebhan E.
Published: February 2015

A family of ideal MHD equilibria is considered introducing the concept of a driving parameter λ the increase of which beyond a certain threshold λ0 drives the plasma from a linearly stable to an unstable state. Using reductive perturbation theory, the nonlinear ideal MHD equations of motion are expanded in the neighbourhood of λ0 with respect to a small parameter ε. An appropriate scaling for the expansions is derived from the linear eigenmode problem. Integrability conditions for the reduced nonlinear equations yield nonlinear amplitude equations for the marginal mode. Nonlinearly, the instabilities are either oscillations about bifurcating equilibria, or they are explosive. In the latter case, the stability limit depends on the amplitude of the perturbation and is shifted into the linearly stable regime. Generally bifurcation of dynamically connected equilibria is observed at λ0
Stellarator Expansion at Finite Aspect Ratio
Authors: Lortz D. , Nührenberg J.
Published: February 2015

A previous stellarator expansion valid for finite aspect ratio and small rotational transform ι and based on the axisymmetric toroidal vacuum field is generalized to stellarator equilibria with arbitrary closed line vacuum fields as zeroth order field. The equilibrium beta value behaves as β ~ ι2. The condition for the magnetic surfaces to be unaffected by β within this ordering is formulated
Numerical Studies of Magnetohydrostatic Finite-Beta Stellarator Equilibria
Authors: Herrnegger F.
Published: February 2015

Properties of finite-beta stellarator equilibria are investigated which are obtained as fully three-dimensional finite-beta solutions of the magnetohydrostatic boundary value problem with the help of the code by Bauer, Betancourt, and Garabedian based on the energy method. In the case of slender l = 2 stellarator equilibria the displacement of the magnetic axis as well as its helical deformation as functions of beta are found to be close to the known theoretical predictions which were derived for slender low beta l = 2 configurations of large aspect ratio. In the case of l = 2 stellarators with moderate aspect ratio the shear has a weak effect on the displacement in contradiction to results from asymptotic theories. A class of l = 0, 1, 2, 3 configurations with reduced secondary currents could be found showing axis displacements which are at least a factor of three smaller than those in pure l = 2 stellarators. A critical equilibrium beta value of βe(0) = 0.045 has been estimated in the W VII-AS stellarator for a bell-shaped pressure profile. Extensive numerical convergence studies are presented
An Algorithm for the Solution of Impurity Diffusion under Finite Reaction Rates
Authors: Lackner K. , Behringer K. , Engelhardt W. , Wunderlich R.
Published: February 2015

An algorithm allowing a fast solution of stationary and time dependent 1-d diffusion problems for the case of finite ionization and recombination rates is presented. Results of numerical computations and an analytic stability analysis show its unconditional stability. The computational effort involved rises only linearly with the number of ionization stages included. An application to the diffusion of oxygen and iron impurities in JET is described
Simulation of Space Charge Waves in Finite Length High-Current Beams with Wall Resistivity
Authors: Hofmann I.
Published: February 2015

Collective space charge effects play an important role in intense unneutralized beams of non relativistic heavy ions, which are of interest in recently proposed high-current accelerators (such as drivers for inertial confinement fusion etc.). Of particular importance is the propagation of wave-like perturbations including the destabilizing effect of dissipation due to finite electrical conductivity in the surrounding walls. The propagation characteristics of such waves are investigated by means of 2½-dimensional computer simulation, with emphasis on dispersion, steepening (leading to solitary waves), and the problem of reflection of a growing wave at the beam tail with subsequent conversion into a damped wave propagating back into the beam. The net result on beam quality is discussed
Selfsimilar Spherical Compression Waves in Gas Dynamics
Authors: Meyer-ter-Vehn J. , Schalk C.
Published: February 2015

A synopsis of different selfsimilar spherical compression waves is given pointing out their fundamental importance for the gas dynamics of inertial confinement fusion. Strong blast waves, various forms of isentropic compression waves, imploding shock waves and the solution for non-isentropic collapsing hollow spheres are included. A classification is given in terms of six singular points which characterise the different solutions and the relations between them. The presentation closely follows Guderley’s original work on imploding shock waves
On a Universal Potential Energy Function and the Importance of Ionic Structures for the Ground State of Molecules
Authors: Van Hooydonk G.
Published: February 2015

The Kratzer-Fues-Varshni-V-potential, applied to ionic dissociation energies, is shown to yield rather accurate potential energy curves in the bonding region for H2, HF, LiH, Li2 and LiF. Vibrational levels, calculated by this ionic approximation to the ground state of widely differing molecules, nearly coincide with RKR-data. At the repulsive side of the curve and up to 2re, the agreement with RKR-curves is even better than for Morse's curve, also for the "covalent" molecules H2 and Li2. Calculated spectroscopical constants αe and ωeχe are far better than those calculated with Morse's function. Even the existence of a maximum in the potential curve at larger r-values seems not in confict with an ionic approximation. From the universal character of the function used, it is concluded that a reasonable approximation for the ground state of all molecules considered is one in terms of ionic structures, even for H2 and especially for Li2. According to the present results, the term “covalent bonding” seems to be definitely superfluous, as the usually made distinction between ionic and covalent bonding is more appearant than real.
Consistent Guiding Center Drift Theories
Authors: Wimmel H. K.
Published: February 2015

Various guiding-center drift theories are presented that are optimized in respect of consistency. They satisfy exact energy conservation theorems (in time-independent fields), Liouville’s theorems and appropriate power balance equations. A theoretical framework is given that allows direct and exact derivation of associated drift-kinetic equations from the respective guiding-center drift-orbit theories. These drift-kinetic equations are listed. Northrop's non-optimized theory is dis-cussed for reference, and internal consistency relations of G.C. drift theories are presented.
The Electric Dipole Moments of Methine Dyes – Comparison of Experimental Results with Theoretical Predictions
Authors: Salamon Z. , Skibiński A. , Celnik K.
Published: February 2015

Absorption and emission spectra of methine dyes in polar and nonpolar solvents were measured. From the Stokes shift as a function of solvent polarity the dipole moments of excited singlet states have been estimated and compared with the quantum chemical predictions. Also the π-electronic charge distribution in the ground and first excited singlet electronic states and bond orders of the dyes were calculated. All investigated methines showed an increase in dipole moment upon excitation to the first excited emitting state.
Orientation of the Absorption and Emission Transition Moments of Methine Dyes
Authors: Salamon Z. , Skibiński A. , Celnik K.
Published: February 2015

The emission anisotropics of the fluorescence of the prolate molecules 2[4(N,N-dimethyloamino)-α styrylo]benzothiazol and 2[4(N,N-dimethyloamino)α styrylojbenzoksazol in solvents of different viscosities were measured, yielding information about the rotational motion of the molecules.

The non-linear dependence of 1/r on T/η was confirmed. On the basis of a comparison of experimental and quantum chemical calculations the orientation of the transition moments of the dye molecules is proposed.
Hydration Shell Structures in an MgCl2 Solution from X-Ray and MD Studies
Authors: Pálinkás G. , Radnai T.
Published: February 2015

The results of a molecular dynamics simulation of a 1.1 molal aqueous MgCl2 solution are com-pared with newly performed x-ray measurements. The structural properties of the solution are evaluated from the scattering data by a model fit to the experimental structure function. The comparison on the basis of fit parameters and partial structure functions shows an overall good agreement between experiment and simulation.

Detailed information on the structure of the hydration shells is deduced from the simulation and shown in form of density maps and angular distributions. It is demonstrated that the octahedral arrangement of the water molecules in the first hydration shell of Mg++ is strongly pronounced while it is only indicated in the case of Cl-. A preferential arrangement in tetrahedral directions has been found for the nearest neighbor water molecules around a central water molecule with an asymmetry in respect to lone pair and hydrogen atom directions. In addition, the probability of finding water molecules at a given number of symmetry sites at the same time has been calculated.
The Molecular and Electronic Structure of Tetrasulphur-dinitride; a Study by ab initio Molecular Orbital Methods and Photoelectron Spectroscopy
Authors: Palmer Michael H. , Lau Woon Ming , Westwood Nicholas P. C.
Published: February 2015

The He (I) photoelectron spectrum of gaseous S4N2 is reported, and an assignment is made on the basis of the correlation with ab initio molecular orbital calculations. The latter, based upon the recently optimised geometry of Cѕ symmetry, used both a large basis set of greater than double zeta quality, together with configuration for both the ground state and the ionised states. The Koopmans’ Theorem order gives a reasonable prediction of the order of states for most of the low energy ionised states; beyond IP5 additional states involving excitation processes in conjunction with ionisation were computed. The numerical agreement between the observed IP’s and the CI value is reasonable.
Differential Orbital Expansion in Tetragonal d3 Systems
Authors: Hoggard Patrick E.
Published: February 2015

Matrix elements for interelectronic repulsion, including differential orbital expansion, have been calculated for d3 complexes with tetragonal symmetry. The expansion parameter e influences the overall positions of the five components of the 2Eg and 2T1g states and the separation between 2Eg and 2T1g, but is relatively unimportant with respect to the splittings within those states.
The Rotational Zeeman Effect in Fluorobenzene and the Molecular Quadrupole Moment in Benzene
Authors: Stolze W. H. , Stolze M. , Hübner D. , Sutter D. H.
Published: February 2015

The rotational Zeeman effect in fluorobenzene is reinvestigated with a resolution improved by a factor of almost five to give more accurate g-tensor elements, magnetic susceptibility anisotropics and molecular electric quadrupole moments. The results fit into the pictures of a linear dependence of the out of plane molecular electric quadrupole moment, Qcc, on the number of fluorine substituents and of a linear correlation between the nonlocal (ring current) susceptibility, Χcc
nonlocal, and the CNDO/2-π-electron density alternation. They lead to a gasphase molecular electric quadrupole moment in benzene, Qcc,benzene = - (28.4 ± 4.7) · 10-40 Cm2 which is slightly less negative than the value deduced from electric field-gradient birefringence experiments on dilute benzene solutions with carbon tetrachloride as solvent. A detailed description of the high resolution microwave spectrometer is given in the appendix.
X-ray Diffraction Study of Aqueous Solutions of ZnSO4
Authors: Licheri G. , Paschina G. , Piccaluga G. , Pinna G.
Published: February 2015

Five aqueous solutions of ZnSO4 of concentrations ranging from 0.6M to 3.1 M were examined by X-ray diffraction. In the correlation functions no concentration effect on structural phenomena is detectable. The same model was then successfuly used for all cases, attributing two hydration shells to Zn2+ and one hydration shell to SO42+ . The reliability of the structural parameters obtained is discussed.