bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ro-inversional Spectrum of Ammonia
Authors: Winnewisser G. , Belov S. P. , Klaus Th. , Urban S. 
Published: February 2015

The ground state J = 2 ←1 , K = 0 and K = 1 ro-inversional spectrum of 14NH3 and 15NH3 at 1.2 THz has been measured with an accuracy of 20 kHz using the Cologne terahertz spectrometer. The measured frequencies for the K = 0 components are:

14NH3 (J, K) = a(2, 0) - s( 1,0): 1 214 852.942(20) MHz,

15NH3 (J, K) = a(2, 0 ) - s( 1,0) : 1 210 889.556(20) MHz.
In addition we have determined from saturation dip measurements of the J = 1 - 0 transition the spin-rotation constant CN = 6.7(3) kHz and the unsplit line center frequency:

14NH3 (J, K) = s( 1, 0) - a(0, 0): 572 498.163( 10) MHz.
The new results are in excellent agreement with existing high resolution Fourier transform data. The terahertz line frequencies are of considerably higher accuracy than the FT-data. by about two orders of magnitude. They will serve as future calibration lines. The ro-inversional transitions are of astrophysical interest
Energy Surfaces of Ellipsoidal Billiards
Authors: Wiersig Jan , Richter Peter H. 
Published: February 2015

Abstract
Energy surfaces in the space of action variables are calculated and graphically presented for general triaxial ellipsoidal billiards. As was demonstrated by Jacobi in 1838, the system may be integrated in terms of hyperelliptic functions. The actual computation, however, has never been done. It is found that generic energy surfaces consist of seven pieces, representing topologically different types of invariant tori. The character of the corresponding motion is discussed. Frequencies, winding numbers, and the location of resonances are also determined. The results may serve as a basis for perturbation theory of slightly modified systems, and for semi-classical quantization.
EPR of VO2+ in ZnTiF6 · 6H2O
Authors: Jayaram Geetha , Krishnan V. G. 
Published: February 2015

Abstract
Electron Paramagnetic Resonance (EPR) studies have been carried out on the vanadyl (VO2) ion doped in single crystals of ZnTiF6 • 6H2O. The spectra indicate the presence of one set of eight lines characteristic of only one occupation site. The V-O bond orientation is along one of the three Zn-H2O bond directions in the trigonally distorted [Zn(H2O)6] octahedra. This behaviour is unlike that reported for vanadyl ion substituting for the M(H2O)6 sites in the Tutton salts, alums and AlCl3 • 6H2O. The Spin-Hamiltonian and bonding parameters for the [VO(H2O)5] complex have been evaluated. The hyperfine linewidths are 0.8 mT at 300 K and 77 K. No proton superhyperfine structure was observed at both these temperatures.
Calculation of the Partition Function of a Double Minimum Oscillator from a Modified Variation Perturbation Method
Authors: Taubmann Gerhard 
Published: February 2015

Abstract
The partition function of a double minimum oscillator is evaluated by means of variation perturbation theory. For low temperatures, the method cannot be applied in the usual way. Even for a symmetric double minimum potential VDM(x), the shift of the harmonic reference oscillator is not always zero as expected, but its minimum is near one of the minima of VDM(x) at low temperatures. The partition function thus calculated is only half the correct value. For sufficiently high temperature, the method works normally. The anomaly in the low temperature region is investigated in detail, and a modification of the variation perturbation method is suggested which eliminates most of the problems.
Die Lösung der Schrödinger-Gleichung als eindimensionales Problem. III. Einelektronsysteme mit verbesserten Diskretisierungsmethoden
Authors: Preuß H. , Pernpointner M. 
Published: February 2015

Abstract
After the calculations on one-electron atoms with simple discretization methods in part II of this work, more powerful techniques are presented here. The method of ARICKX was transferred to our one-dimensional calculations, and a fast „energy profile method" is used with which the excited states of one-electron atoms can be reproduced with high accuracy. The simplest polyatomic particle, H+
2, can be integrated into the formalism without any difficulties because of the general applicability of the integral kernel. Good results are available for this system, and a geometry optimization yields the same core distance as given in the literature.
Structural and Defect Study of LiMn2O4 Formation
Authors: Massarotti V. , Bini M. , Capsoni D. 
Published: February 2015

Abstract
The LiMn2O4 formation from MnO and Li2CO3 mixtures with lithium cationic fraction 0.31 <̲ x <̲ 0.40 was studied by structural profile refinement from X-ray data, thermal (TGA and DSC) measurements and scanning electron microscopy (SEM) observations. Quantitative phase analysis, structural and microstructural parameters and composition of the coexisting phases were obtained. Different behaviours were observed in the composition ranges 0.33 <̲ x <̲ 0.35 and x >̲ 0.37. In the former range only the stoichiometric spinel phase was obtained, in the latter, in addition to the Li2MnO3 compound, two spinel phases could be considered: I) LiMn2O4 stoichiometric spinel; II) Li1 + yMn2-yO4 (0.11 <̲ y <̲ 0.23), a non-stoichiometric phase whose small particle size resulted practically independent of the initial composition and annealing temperature. Such a conclusion was supported also by SEM observations. The relative abundance of phase II increased with increasing lithium content and with decreasing temperature.
Relaxation of 27Al NMR in Aluminium Tribromide due to Raman Process
Authors: Okubo Noriaki , Igarashi Mutsuo , Yoshizaki Ryozo 
Published: February 2015

Abstract
The nuclear spin-lattice relaxation of 27Al NMR in AlBr3 has been examined from 25 to 320 K. The result is analyzed using a theory of the Raman process based on covalency. A Debye temper-ature of 118 K is obtained together with a covalency larger than that obtained from the relaxation in the 81Br NQR.
Electronic Structure of the C60 Fragment in Alkali- and Alkaline-earth-doped Fullerides
Authors: Böhm Michael C. , Schedel-Niedrig Thomas , Werner Hartmut , Schlögl Robert , Schulte Joachim , Schütt Johannes 
Published: February 2015

Abstract
The electronic structure of the C50 fragment in alkali-and alkaline-earth-doped fullerides is studied theoretically. With increasing metal-to-C 60 charge transfer (CT) the n electronic properties of the soccerball are changed. In the undoped solid and for not too high a concentration of doping atoms the hexagon-hexagon (6-6) bonds show sizeable double bond character while the hexagon-pentagon (6-5) bonds are essentially of single bond type. In systems with a high concentration of doping atoms this relative ordering is changed. Now the 6-5 bonds have partial double bond character and the 6-6 bonds are essentially single bonds. The high ability of the C 60 unit to accomodate excess electrons prevents any sizeable weakening of the overall n bonding in systems with up to 12 excess electrons on the soccerball. A crystal orbital (CO) formalism on the basis of an INDO (intermediate neglect of differential overlap) Hamiltonian has been employed to derive solid state results for potassium-and barium-doped C 60 fullerides. For both types of doping atoms an incomplete metal-to-C 60 CT is predicted. In the potassium-doped fullerides the magnitude of the CT depends on the interstitial site of the dopant. The solid state data have been supplemented by INDO and ab initio calculations on molecular C 60 , and C^, 2 , -. The calculated bondlength alternation in the neutral molecule is changed in C 6 ö~ where the length of the 6-6 bonds exceeds the length of the 6-5 bonds. The geometries of the three molecular species have been optimized with a 3-21 G* basis. The theoretically derived modification of the C 60 (7r) electronic structure as a function of the electron count is explained microscopically in the framework of two quantum statistics accessible for n electronic ensembles. In the 7r ensemble of the C W) fragment so-called hard core bosonic properties are maximized where the Pauli antisymmetry principle has the character of a hidden variable only. Here the electronic degrees of freedom are attenuated only by the Pauli exclusion principle. This behaviour leads to the changes in the ir electronic structure mentioned above.
Dielectric Studies of trans,trans-4'-n-Pentyl-bicyclohexyl-4- carbonitrile (5CCH) under High Pressure
Authors: Brückert T. , Würflinger A. 
Published: February 2015

Abstract
Dielectric studies on the static and complex permittivity have been performed on trans,trans-4'-n-pentyl-bicyclohexyl-4-carbonitrile (5 CCH) in the pressure range 0.1-200 MPa, the frequency range 1 kHz-13MHz and the temperature range 300-390 K. Phase transitions between the isotropic, nematic, smectic B (metastable), and crystalline state have been recorded as steps in the static permittivity. Thus the phase diagram of 5 CCH was established. In particular the slow relaxation process in the nematic and smectic phase has been investigated. The dielectric relaxation time τ|| increases by a constant factor of 210 on passing the nematic-smectic B phase transition. From the pressure and temperature dependences of τ we have calculated the activation volumes (Δ≠ V/cm3 mol-1 = 88-65 (nematic), = 70-45 (smectic) and ≈ 32 for the isotropic phase) and activation enthalpies (Δ≠H/kJ mol-1 = 76-60 (nematic), ≈ 60 (smectic) and ≈ 37 for the isotropic phase), respectively, which are compared with previous results on similar homologous series. The activation parameters increase significantly, when the rigid phenyl ring is replaced by the more flexible cyclohexyl ring.
The Influence Of Matter And Black-Body Radiation Photons On The Dipole Polarizabilities A And γ Of Atoms
Authors: Hohm Uwe 
Published: February 2015

Abstract
The influence of the surroundings on the linear dipole polarizability α and second hyperpo-larizability γ is discussed in terms of the density ϱM of isotropically distributed matter as well as the density ϱp of thermal black-body radiation photons, α and γ of the rare gas atoms are studied as examples. At standard conditions, both effects are of comparable size for the rare gases. Possible consequences for ion-molecule reaction rate constants in astronomical environments are suggested.
Solid State Reaction Study Of The System Co-Li2CO3
Authors: Marini A. , Berbenni V. , Massarotti V. , Capsoni D. , Bruni G. 
Published: February 2015

Abstract
A detailed analysis of the reactive processes taking place in Co-Li2CO3 was performed by use of thermogravimetry and X-ray diffraction. A reaction model is proposed which accounts for the nature, stoichiometry, and amount of the phases present, at room temperature, in samples subjected to different thermal treatments. In particular it is shown that the thermal treatment influences substantially the final lithium content and the relative amount of the Li-containing phases. The results obtained for powdered samples are compared with those obtained in a previous work for plaques.
Effect of Rotation on Thermal Instability in Rivlin-Ericksen Elastico-Viscous Fluid
Authors: Sharma R. C. , Kumar P. 
Published: February 2015

Abstract
The thermal instability of a layer of Rivlin-Ericksen elastico-viscous fluid acted on by a uniform rotation is considered. For stationary convection, a Rivlin-Ericksen elastico-viscous fluid behaves like a Newtonian fluid. It is found that rotation has a stabilizing effect and introduces oscillatory modes in the system. The visco-elasticity also introduces oscillatory modes in the system. A suffi-cient condition for the non-existence of overstability is also obtained.
A Theoretical Modeling of the Static and Dynamic Polarizability of O2- in Large and Complex Oxides
Authors: Ray D. , Anton H. , Schmidt P. C. , Weiss Al. 
Published: February 2015

Abstract
A time-dependent approach is employed in conjunction with a crystal potential model to study the environment-specific optical linear response of the O2- ions in a number of cubic oxides with varying number of constituents, unit-cell dimension and degree of complexity. It is shown that the static polarizability of the anion may vary significantly depending on the position of the anion within the unit-cell. Due to neglect of overlap compression, our method has limited success in predicting the refractive indices of large crystals of complex structures. For small binary oxides the frequency-dependent polarizability of the O2- ion is found to exhibit the first poles close to the ultraviolet absorption edges ascribed to the lowest excitonic transitions in these crystals.
Perylene-like Dyes in Liquid Crystalline Media
Authors: Mykowska Ewa , Bauman Danuta 
Published: February 2015

Abstract
The spectral and electrooptical properties of some dichroic fluorescent dyes (derivatives of 3.4,9,10-perylenetetracorboxylic acid and of 3,4,9-perylenetricarboxylic acid) in isotropic solvents and nematic liquid crystals have been studied. The order parameter of the dyes in the anisotropic matrices has been determined by means of optical spectroscopy methods. Moreover, the influence of the dye addition on the nematic-isotropic phase transition temperature of the pure host has been investigated. It was found that some of the dyes studied can be utilized in guest-host liquid crystal display devices.
Investigation of the Structure of Liquid Pyridine: a Molecular Dynamics Simulation, an RISM, and an X-ray Diffraction Study
Authors: Bakó Imre , Radnai Tamás , Pálinkás Gábor 
Published: February 2015

Abstract
The structure of liquid pyridine is investigated by molecular dynamics simulation and the RISM integral equation methods. The calculated total radial distribution functions (RDF) are compared with the experimental RDF’s, obtained by X-ray diffraction measurement. It is shown that the local structure of liquid pyridine is mainly determined by the dipole-dipole interaction between the molecules. The local order is characterized by the pair distribution functions, angular correlation functions and orientational distributions. Dynamical properties (self-diffusion coefficients, rotational correlation times and reorientational correlation times) calculated on the basis of MD results are in good agreement with experimental data.
Liquid Crystals and Glasses in Binary Systems from Sodium and Alkali-Earth Metal Butyrates
Authors: Mirnaya T. A. , Bereznitski Y. V. , Volkov S. V. 
Published: February 2015

Abstract
The temperature and composition ranges of liquid crystal and glass formation have been established for the binary mixtures of mesogenic sodium butyrate with non-mesogenic magnesium, calcium and strontium butyrates by means of differential thermal analysis and hot stage polarization microscopy. The formation of a vitreous optically anisotropic mesophase has been found for binaries of sodium butyrate with calcium and strontium butyrates.
EPR Studies of Tb 4+ in Single Crystals of Zircon and Scheelite Structure Silicates and Germanates
Authors: Hansen S. , Mosel B. D. , Müller-Warmuth W. , Fielding P. E. 
Published: February 2015

Abstract
Electron paramagnetic resonance spectra of tetravalent terbium ions have been observed in host crystals of ZrSiO4 , HfSiO4 , ThSiO4 , ThGeO4 (zircon structure) and ZrGeO4 , HfGeO4 (scheelite structure) at X band and Q band and various temperatures. The spin Hamiltonian parameters have been determined from the rotational diagrams; the zero field splittings turned out to be extremely large, so that complex spectra far from the strong magnetic field limit had to be analyzed. In all the compounds Tb4+ substitutes for the tetragonal metal lattice sites. The incorporation of terbium, the origin of the large second-order parameters and comparisons with the spectra of trivalent gadolinium in similar systems are discussed.
ESR of Gamma Irradiation Damage Centers in Single Crystals of Some Glutamic Acid Derivatives
Authors: Zengin D. Mehmet , Birey Mehmet , Aktas Huseyin , Hancer Ahmet , Murathan Atilla M. 
Published: February 2015

Abstract
We have observed four radicals in the ESR spectra of y-irradiated single crystals of some glutamic acid derivatives. These radicals, produced by gamma-irradiation, in single crystals of N-Acetyl-L-Glutamic acid, L-Glutamic acid and DL-Glutamic acid hydrochloride were identified as CH3CONH, -C3H5 , -CH, and -NH2 radicals respectively.
THz Rotational Spectra of HBr Isotopomers in their υ = 0,1 States
Authors: Saleck Axel H. , Klaus Thomas , Belov Sergei P. , Winnewisser Gisbert 
Published: February 2015

Abstract
We have observed the pure rotational spectra of HBr isotopomers in their υ = 0 and υ = 1 states between 0.97 and 1.02 THz. i. e. the HBr Ј = 2-1 and the DBr Ј =4 - 3 transitions, respectively. In the analysis, all presently available rotational transitions of all isotopomers have been fitted to a Dunham-type Hamiltonian to obtain the isotopically invariant parameters, including vibrational and rotational expansion coefficients for the hyperfine constants. In the analysis, the vibrational expansion coefficients of the nuclear quadrupole interaction are determined up to second order, and up to first order for the nuclear spin-rotation interaction.
Fluorescence Properties of p-Quaterphenyl and p-Quinquephenyl Derivatives in Liquid Solvents
Authors: Kawski A. , Piszczek G. , Kubicki A. 
Published: February 2015

Abstract
Absorption, fluorescence and emission anisotropy spectra, as well as quantum yields and fluores-cence decay times of p-quaterphenyl (PQP), 4,4"'-bis-(2-butyloctyloxy)-p-quaterphenyl (BBQ), 2,5,2"",5""-tetramethyl-p-quinquephenyl (TMI) and 3,5,3"",5""-tetra-f-butyl-p-quinquephenyl (QUI) were investigated in several nonpolar and polar solvents. It was found that high quantum yield is accompanied by a short (not exceeding 1 ns) lifetime and considerable emission anisotropy in low viscosity solvents. For TMI and QUI, which incorporate as many as 5 phenyl groups, the quantum yield in dioxane is 0.98 and 0.97, respectively. In the case of molecules with 4 phenyl groups, the quantum yield is slightly lower, amounting to 0.91. Rotational motions of terminal phenyl groups cause a lower deactivation of the excitation energy of the singlet state S p the longer the linear molecule.
13C CP/MAS NMR Study of the Layered Compounds [C6H5CH2CH2NH3]2[CH3NH3]n - 1Pbnl3n+1 (n = 1, 2)
Authors: Ueda T. , Shimizu K. , Ohki H. , Okuda T. 
Published: February 2015

Abstract

13C CP/MAS NMR spectra were measured on the layered compounds [C6H5CH2CH2NH3]2[CH3NH3]n - 1PbnI3n + 1 (w = 1, 2). The linewidth of the resonance peak corresponding to the phenyl carbons changed with temperature. The maximum broadening took place at 363 K for both com-pounds. The activation energy E a for the reorientation of the phenyl group was determined to be 25 kJ mol- 1 for n = 1 and 26 kJ mol- 1 for n = 2. The frequency factor τ 0 was evaluated from the linewidth at 363 K. The value of the second moment, estimated from the maximum linewidth, was interpreted by assuming a 180° flip of the phenyl group around its two-fold axis. The similarity of the activation energies for the reorientation of the phenyl group suggested that the local structure and the molecular motion of the organic cations is little affected by the difference in the sub-structure of the inorganic layer in those compounds.
Magnetic Solitons in the 1-D Antiferromagnetic Chains of Li2Mn0.98Fe0.02F5 and Na2Mn0.98Fe0.02F5
Authors: Frommen Ch. , Mangold M. , Pebler J. 
Published: February 2015

Abstract
Measurements of the 57Fe Mössbauer effect and magnetic susceptibility have been performed on 57Fe-doped quasi-1-d antiferromagnetic chains of Li2MnF5 and Na2MnF5 as a function of temperature. The Mössbauer spectra, fitted by the Blume-Tjon model, show definite relaxation effects near the Neel temperature, which are attributed to short-range order with temperature-dependent relax-ation times. The soliton model of non-linear excitations was applied. Experimental data confirm the predicted exponential temperature dependence of the thermal excitation of moving domain walls. From the activation energies E2
A/k2 as a function of 1-d exchange energies J/k the local anisotropy energy D/k of -3.7(2) K was derived on the basis of sine-Gordon theory. This result is in fair agreement with -3.5(1) K previously derived from magnetic susceptibility measurements. In the light of our results there is some evidence that at low bridging angle ß ≈ 102(5)° a phase-transition from antiferromagnetic to ferromagnetic ordering occurs.
Phase Diagrams of Binary Alkanoate Systems with Common Cation: Potassium Isobutyrate-Propionate, and Sodium Butyrate-Isobutyrate
Authors: Mirnaya T.A. , Yaremchuk G.G. , Volkov S.V. 
Published: February 2015

Abstract
The phase diagrams of the binary mixtures of mesogenic potassium isobutyrate with non-mesogenic potassium propionate and mesogenic sodium butyrate with non-mesogenic sodium isobutyrate have been investigated by differential thermal analysis and hot stage polarization microscopy. Both systems have one eutectic and one metatectic phase equilibriums. Pecularities of liquid crystal formation in binary alkanoate systems with common alkali metal cation are discussed and compared with those of systems with common anion.
Time Reversibility and the Logical Structure of the Universe
Authors: Diebner Hans H. , Kirner Thomas , Rössler Otto E. 
Published: February 2015

Abstract
Both Fredkin's findings on the reversibility of logical operations and the novel capability to integrate Newton's equation of motion in an exactly reversible manner enables one to perform a gedankenexperiment in the form of a molecular dynamics simulation of the universe. This leads to a new validation of the reversible structure of the universe. Alternatively, the role of information needs to be upgraded in accordance with a recent proposal by Stonier.
Structure of Metallic Glasses: Experiments and Models
Authors: Lamparter P. , Steeb S. 
Published: February 2015

Abstract
The topological and the chemical short range order in metallic glasses is discussed by means of representative examples from the systems Ni-P, Ni-B, Nb-Ni, and Dy-Ni. The characterization of the chemical short range order, e.g. in terms of a short range order parameter, depends on the definition of an appropriate hypothetic statistical reference system. The consideration of the size effect is essential. Some structural features of metallic glasses point to relationships with the related individual crystalline phases, whereas other features show that the different types of metallic glasses have certain construction principles in common. Small angle scattering with hydrogenated metallic glasses suggests the presence of extended two-dimensional structures. Reverse Monte Carlo models reveal rather broad distributions of the local structural properties and show that metallic glasses are not built as assemblies of defined structural units.
1H and 19 F NMR Study of Cation and Anion Motions in Guanidinium Hexafluorozirconate
Authors: Grottel M. , Kozak A. , Pająk Z. 
Published: February 2015

Abstract
Proton and fluorine NMR second moments and spin-lattice relaxation times of polycrystalline guanidinium hexafluorozirconate and its deuterated analogue were studied in laboratory (60 MHz) and rotating (H1 = 20 G) frames over a wide range of temperature. An analysis of the experimental results enabled us to reveal a dynamical inequivalence of two crystallographically independent cations and an unexpected high mobility of nonspherical anion dimers. A comparison of the ions dynamics in 2:1 complex studied with the guanidinium 1:1 and 3:1 complexes has shown a significant contribution of the hydrogen bonds to the potential barriers hindering the anion reorientations. At low temperatures a proton motion in the hydrogen bond and at 400 K a solid-solid phase transition have been discerned.