bluuebunny/crossref_metadata_2025_split huggingface dataset:
Lattice Vibration Spectra. LX. Lattice Dynamical Calculations on Spinel Type MCr2S4 (M = Mn, Fe, Cd)
Authors: Lutz H. D. , Himmrich J. , Haeuseler H. 
Published: February 2015

Abstract
Lattice dynamical calculations of the spinel type MCr2S4 (M = Mn, Fe, Cd) have been done using various potential models (short-range, rigid-ion, polarizable-ion). The main results are that (i) the vibrational modes (eigenvectors) and potential energy distributions of the Raman and IR allowed phonon modes of the three chromium sulfides are very similar, (ii) the A-X and B-X short-range force constants (referring to AB2X4) strongly depend on the structural parameter u, i.e., the tetrahedral A-X force constants are smaller than the respective octahedral B-X ones opposite to previous calculations on the basis of an ideal spinel structure with u = 0.25, (iii) bending force constants (X-A-X and X-B-X), but not X-X and B-B repulsive forces, are negligible, (iv) in the case of the breathing mode of the tetrahedral AX4 unit (species A1g) the demand on B-X and X-X (stretching and repulsion) forces is larger than that on the A-X force, and (v) the effective dynamic charges of the bivalent metal ions are nearly zero.
Electric field Gradient Modulation by Motion of Lone-Pair Electrons in [(CH3)3S]2MCl6 (M = Pt, Sn) as a Possible Relaxation Mechanism of Chlorine Nuclear Quadrupole Resonance
Authors: Kaga Makoto , Koziol Piotr , Asaji Tetsuo , Nakamura Daiyu 
Published: February 2015

Abstract
The temperature dependence of the chlorine NQR spin-lattice relaxation time T1Q was observed for trimethylsulfonium hexachlorometallates(IV), [(CH3)3S]2MCl6 (M = Pt, Sn), trimethylammonium hexachlorostannate(IV), [(CH3)3NH]2SnCl6, and tetramethylphosphonium hexachlorostannate(IV), [(CH3)4P]2SnCl6. The quadrupolar relaxation in [(CH3)3NH]2SnCl6 and [(CH3)4P]2SnCl6 can be described by the usual librational and reorientational motion of the complex anion at lower and higher temperatures, respectively. Besides T1Q due to these two mechanisms, T1Q minimum was observed at ca. 90 and 120 K for [(CH3)3S]2PtCl6 and [(CH3)3S]2SnCl6, respectively, which is attributable to the electric field gradient modulation by the motion of the [(CH3)3S]+ cation having lone-pair electrons. The activation energies for the isotropic reorientation of the complex anion were determined as 46, 65, 59, and 60 kJ mol -1 for [(CH3)4P]2SnCl6, [(CH3)2NH]2SnCl6, [(CH3)3S]2PtCl6, and [(CH3)3S]2SnCl6, respectively
Partially Invariant Solutions for Two-dimensional Ideal MHD Equations
Authors: Becker D.-A. , Richter E. W. 
Published: February 2015

Abstract
A generalization of the usual method of similarity analysis of differential equations, the method of partially invariant solutions, was introduced by Ovsiannikov. The degree of non-invariance of these solutions is characterized by the defect of invariance d. We develop an algorithm leading to partially invariant solutions of quasilinear systems of first-order partial differential equations. We apply the algorithm to the non-linear equations of the two-dimensional non-stationary ideal MHD with a magnetic field perpendicular to the plane of motion.
Reinvestigation of the Reaction of (NH4)2[Ce(N03)6] with Triphenylphosphine Oxide; the Crystal Structure and Magnetic Properties of mer-Ce(NO3)3(OPPh3)3 • 2 (CH3)2CO
Authors: Lin Jianhua , Hey-Hawkins Evamarie , von Schnering Hans Georg 
Published: February 2015

Abstract
The reaction of (NH4)2[Ce(NO3)6 ] with two equivalents of OPPh3(Ph = C6H5 ) in acetonitrile yields Ce(NO3 ) 4(OPPh3 )2 (1) in high yield, whereas using acetone as solvent affords mer- Ce(NO3 )3(OPPh3)3 • 2(CH3)2CO (2), the yield of which is dependent on the reaction time. A crystal structure determination of 2 shows that the Ce atom is coordinated with three bidentate nitrato groups and three OPPh3 ligands, thus achieving a coordination number of nine. Eight non-coordinating acetone molecules are present in the unit cell. Crystal data (292 K): space group P21/n (no. 14), 0=12.438(2), b = 25.532(4), c = 20.379 (4) Å, β = 96.33(2)°, V = 6432(1) , Z = 4, dcalc = 1.318 g em 3. Due to poor crystal quality the refinement converges at R = 0.11, Rw = 0.09. 2 is paramagnetic, but it does not follow the Curie-Weiss law at low temperature. Therefore crystal field theory was used in order to explain these findings.
Quadrupole Hyperfine Structure in the Rotational Spectra of 1,2- and 1,3-Dichlorobenzene
Authors: Keussen Ch. , Dreizler H. , Merke I. 
Published: February 2015

Abstract
The high resolution of microwave Fourier transform spectroscopy was used to investigate the 35chlorine hyperfine structure of 1,2- and 1,3-dichlorobenzene, C6H4
35Cl2 , very accurately in the rotational spectrum of their ground vibrational state. The careful analysis with a new evaluation program also yielded the off-diagonal element of the coupling tensor. The tensor elements are χaa= -41.1153(35) MHz,χbb = 8.3415(96) MHz, χcc = 32.7738(61) MHz, and χab = ±52.41 (58) MHz for 1,2-dichlorobenzene and χaa= -44.174(12) MHz, χbb= 10.876(12) MHz, χcc = 33.298(12) MHz, and χab= ±48.181(39) MHz for 1,3-dichlorobenzene.
127I-NQR, 119 Sn Mössbauer Effect, and Electrical Conductivity of MSnI3 (M = K, NH4 , Rb, Cs, and CH3NH3 )
Authors: Yamada Koji , Matsui Takashi , Tsuritani Tomoko , Okuda Tsutomu , Ichiba Sumio 
Published: February 2015

Abstract
In a series of MSnI3 compounds (M = K, NH4 , Rb, Cs, CH3NH3) two types of coordination around the central Sn(II) were found by 127I-NQR and powder X-ray diffraction techniques. They are square pyramidal (for M = NH4 , Rb) and octahedral (for M = CH3NH3). CsSnI3 , on the other hand, showed a drastic structural change of the anion at 425 K from a square pyramid to a regular octahedron. Associated with this phase transition, the electrical conductivity increased from 4 x 10-3 S cm-1 to about 102 S cm-1 . This metallic modification was characterized by 127I-NQR and 119Sn Mössbauer spectroscopy.
Narrowing of the 35Cl NQR Lines of Trichloroacetamide Caused by Its Ferroelectric Phase Transition
Authors: Hashimoto Masao , Shono Akiko , Mido Yoshiyuki , Niki Haruo , Hentona Hiroshi , Mano Koichi 
Published: February 2015

Abstract
Dielectric measurements on single crystals and DSC of the title compound (monoclinic, space group P21) revealed a ferroelectric transition at ca. 355 K (ΔH ≈ 0.5 kJ mol-1) Powder x-ray diffraction indicated that the high temperature phase is also monoclinic and the change in volume at the transition is very small. A displacement of hydrogen atoms is considered as responsible for the appearance of ferroelectricity. The 35Cl NQR signals at ca. 77 K were considerably broad, but a drastic narrowing took place after the compound had once experienced the phase transition. A tentative assignment of the NQR spectrum was made from a calculation of the NQR frequencies based on the CNDO/2 method. Another phase transition was evidenced by a small drift of the DSC curve and a slight anomaly of the dielectric behavior around 358 K. The present 1H NMR experiments gave no indication of the onset of torsional motion of the NH2 group reported to occur at ca. 210 K.
NQR and Phase Transitions in Hexachlorocyclopropane Crystal
Authors: Suhara Masahiko , Mano Koichi 
Published: February 2015

Abstract

35Cl NQR and DSC studies on phase transitions in hexachlorocyclopropane (HCCP), C3Cl6 , are reported. It is found that HCCP has three solid phases: A high temperature disordered phase (Phase I) above 301 K (no NQR spectrum was observed); a metastable phase (Phase II), which exhibited 6 NQR lines from 77 to 270 K; a low temperature phase (Phase III) in which a 24-multiplet of 35Cl NQR lines at 77 K, the most complex multiplet spectrum ever reported was observed.
DSC measurement shows a A-type transition at 301 K and a broad transition of very slow rate at 285 K. The structure and mechanism of phase transitions in HCCP crystal are discussed.
Iodine NQR and Phase Transitions in [N(CH3)4]2 ZnI4
Authors: Pirnat J. , Lužnik J. , Trontelj Z. 
Published: February 2015

Abstract
Using a superregenerative NQR spectrometer, the temperature dependence of 127I NQR spectra in [N(CH3)4]2ZnI4 was measured between 167 and 335 K. The measurements confirm two known structural phase transitions at 219 and 257.5 K. The correspondence between the distinct regions of iodine NQR spectra and the crystal structure is discussed. The relation of [N(CH3)4]2ZnI4 to the incommensurate family with the general formula X2YZ4 and the high temperature (paraphase) crystal space group D16
2h (Pmcn) is studied.
Improvement of Bertaut's Method for Calculating Electric Field Gradient
Authors: Nakayama Hirokazu , Saitoa Kazuya , Kishita Michihiko 
Published: February 2015

Abstract
Bertaut's method for calculating the electric field and its gradient is analyzed. The formula for the electric field is always valid, whereas that for the electric field gradient holds only for an infinitely large unit cell. We present a practical method to use the formulae.
Chlorine Nuclear Quadrupole Relaxation Studies on Ionic Dynamics and Phase Transition in NH4AUCl4
Authors: Ishikawa Atsushi , Asaji Tetsuo , Nakamura Daiyu 
Published: February 2015

Abstract
Chlorine NQR frequencies, and NQR spin-lattice and spin-spin relaxation times (T1Q and T2Q) were measured for NH4AuCl4 crystals at various temperatures between 4.2 and 337 K. Each of the two resonance lines observed at room temperature is split into a doublet below Tc = 29 K, indicating a phase transition. A rapid decrease of T1Q above ca. 290 K is attributable to 90° reorientational jumps of the complex anion about its pseudo C4 axis. An activation energy of 80 kJ mol -1 was obtained for this motion. 35Cl T1Q exhibits a minimum at Tc . The T1Q isotope ratio T1Q (37Cl)/ T1Q (35Cl) becomes 1.6 and 1.0 on the high-and low-temperature sides of this minimum, respectively. These results were explained by fluctuations of the electric field gradient produced at the chlorine nuclei by the reorientational jumps of the NH+
4 ions. The motion of the cations is much faster and much slower than the resonance frequencies on the high-and low-temperature sides, respectively. This suggests that the phase transition is of the order-disorder type relating to the orientation of the NH+
4 ion.
Temperature Dependences of NQR Frequencies and Nuclear Quadrupole Relaxation Times of Chlorine in 2,6-Lutidinium Hexachlorotellurate (IV) as Studied by Pulsed NQR Techniques
Authors: Horiuchi Keizo , Shimizu Takashige , Iwafune Hitomi , Asaji Tetsuo , Nakamura Daiyu 
Published: February 2015

Abstract
The temperature dependences of the 35Cl NQR frequencies vQ and the nuclear quadrupole spin-lattice relaxation times T1Q in 2,6-lutidinium hexachlorotellurate (IV) was observed at various temperatures between 80 and 343 K. This crystal undergoes a phase transition at Tc = 229 K. A single and three pairs of 35Cl NQR frequencies were observed above and below Tc , respectively. The hysteresis of the phase transition and a discontinuity in the temperature dependence of the resonance frequencies at Tc indicate that this phase transition is of first order. Although the resonance frequencies of the pairs in the low temperature phase are very close to one another, T1Q and below Tc could be accurately determined by measuring the Fourier transform spectra of each line. Above ca. 250 K, T1Q showed an exponential decrease which is attributable to the overall reorientational motion of [TeCl6]2- with an activation energy of 82 kJ mol-1
Maxwell's Equations and Einstein-Gravity in the Planck Aether Model of a Unified Field Theory
Authors: Winterberg F. 
Published: February 2015

Abstract
In the Planck aether substratum model it is assumed that space is densely filled with both positive and negative Planck masses described by a nonlinear nonrelativistic operator field equation. With-out expenditure of energy this substratum can form a lattice of vortex rings, with the vortex core radius equal the Planck length. The vortex ring radius is determined by a universal minimum energy quantum Reynolds number, making the ring radius and lattice spacing about 10 3 -10 4 times larger than the Planck length. The zero point fluctuations of the Planck masses bound in the vortex filaments become the source of virtual compression waves, which if quantized lead to Newton's law of gravitation, including the correct value for the gravitational constant. This scalar gravitational force couples the vortex rings, which thereby can transmit two types of transverse waves through the vortex lattice. The first type involves the tilting of the vortex rings and can be described by Maxwell's electromagnetic field equations. The second type involves the elliptic deformation of the rings and can be described by Einstein's gravitational field equations. Einstein gravity is therefore explained as resulting from the symmetric, and Maxwell's electromagnetism from the antisymmetric distor-tions of the Planck aether.
Special relativity follows as a dynamic symmetry for objects held together by electromagnetic forces, and general relativity if these objects are placed in a gravitational field. Both special and general relativity, though, turn out to be low energy approximations, breaking down near the Planck scale, eliminating all divergences and singularities.
Finally, the large difference between the electromagnetic and gravitational coupling constants is quantitatively explained to result from the negative masses in the Planck aether.
Investigation of the Microwave Spectrum of cis-Cyclopropyl Carbonyl Chloride-(35Cl); Determination of the Quadrupole Coupling Tensor in its Principal Axes System
Authors: Heldmann C. , Dreizler H. , Schwarz R. 
Published: February 2015

Abstract
The vibrational ground state microwave spectrum of cis-cyclopropyl carbonyl chloride-(35Cl) was investigated in the region from 4 to 40 GHz by microwave Fourier transform (MWFT) spectroscopy. The rotational and fourth order centrifugal distortion constants were determined. The quadrupole hyperfine structure was assigned and the quadrupole coupling constants including the off-diagonal element i ab were evaluated. This leads to a transformation of the quadrupole coupling tensor into its principal axes system.
The Structure of Lithiated Aminonitriles in Solution: Interpretation of their Experimental IR Spectra by Means of ab initio Calculations
Authors: Raabe Gerhard , Zobel Elke , Fleischhauer Jörg , Gerdes Pete , Mannes Dietrich , Müller Edwin , Enders Dieter 
Published: February 2015

Abstract
Quantum chemical calculations of relative energies and vibrational frequencies have been performed in order to elucidate the structure of metalated aminonitriles (1R2RN)3RC2NLi formed upon lithiation of (1R2RN)3RCH-CN in tetrahydrofuran at -78 °C. For the sake of feasibility the calculations have been performed on model compounds where the heavy substituents 1R, 2R and 3R and in some cases even the complete amino group (1R2RN) and 3R have been replaced by hydrogen atoms. In the gasphase a lithium-bridged (nonclassical) monomer, whose lithium atom is within bonding distance to the atoms of the cyano group and the adjacent carbon atom, was found to be about 9 kcal/mol lower in energy than the most stable isomer of the corresponding nitrogen metalated ketenimine with amost linear CNLi moiety. However, the relative stability of the two structures will most likely be reversed under the influence of a solvent (modeled by H20). Dimerization of H2C2NLi, yielding a product of D2h symmetry with a four-membered (LiN)2 ring, turned out to be exothermic by about 41 kcal/mol in the gasphase and 15 kcal/mol when the model solvent is present. While in the case of the lithiated amino ketenimine with almost linear CNLi segment the structure obtained with the semiempirical MNDO method widely parallels the ab initio results, the semiempirical method seems to perform less reliably for the nonclassical monomer. Formation of the trapping products obtained with methyl iodide and acetyl chloride is explained in terms of orbital- and charge control, respectively. According to this analysis, the results of trapping experiments are compatible with presence of a dimer, of a monomer with almost linear CNLi moiety, or of a monomer with lithium in a bridging position. However, comparison of observed and computed vibrational frequencies and of the calculated energies of classical and nonclassical structures led to the conclusion that the observed IR spectra are not due to nonclassical molecules with lithium in a bridging position. Taking into account the results of recent cryoscopic measurements we assign the characteristic absorptions in the experimental IR spectra to keteniminelike monomers and their dimers
Lorentz Transformation of Electromagnetic Systems and the 4/3 Problem
Authors: Comay E. 
Published: February 2015

Abstract
Lorentz transformations of two macroscopic devices are discussed. In each case, the overall momentum flux into every static element of matter vanishes. It is shown that a Lorentz transformation of the energy-momentum 4-vector of each system agrees with special relativity. In particular, using the ordinary definition of 4-momentum of electromagnetic fields, it is proved by means of a particular form of Poincare's stress tensor, that there is no 4/3 factor in the transformation of the entire momentum of a uniformly charged spherical shell
Exchange Forces of Composite Particles in Quantum Field Theory
Authors: Pfister W. , Stumpf H. 
Published: February 2015

Abstract
Quantum fields can be characterized by state functionals and corresponding functional equations. Within this functional representation exchange forces of composite particles are discussed for the case of composite bosons which are bound states of two constituent fermions. The dynamics of these bosons is formulated by means of a weak mapping theorem which establishes a map between the functional equations for the composite boson quantum field and the constituent original fermion quantum field. Evaluation of this theorem leads to expressions which can be identified as quantum field theoretic "direct" forces and exchange forces for or between composite particles. By some theorems the exchange forces are evaluated and an estimate for them is given. The expressions for the direct forces correspond to those which were already derived in previous papers to discuss composite particle dynamics.
Polarization Studies of the Electronic Minority Charge Carriers in Ag+ -ß"-Alumina
Authors: Weppner Werner , Liu Jun 
Published: February 2015

Abstract
The partial electronic conductivity of Ag+-ß"-alumina was determined in the temperature range 180-200 °C, using Wagner's asymmetric galvanic polarization cell Ag| Ag+-ß"-alumina | Pt. The electron conductivity is 4.5 x 10-8 Ω-1cm-1, while the hole conductivity is about seven orders of magnitude lower at the silver activity aAg =1at 200 °C. These results are compared with earlier data on ß/ß"-alumina. The conduction mechanism and the effect of the electronic conductivity on the application of Ag+-ß"-alumina are discussed
Disturbances in Pipe Flow Excited by Magnetic Fields
Authors: Brösa U. 
Published: February 2015

Abstract
Defined disturbances of laminar flow in a pipe can be excited by magnetic fields. This is important for investigations concerning the onset of turbulence in a pipe. A theory of these disturbances is derived and thus a criterion established to discriminate the induction of the so-called mothers from the excitation of daughters. The conditions to optimize the effects and the inferences for the experimental setup are discussed
Heteroclinic Bifurcations and Invariant Manifolds in Rocking Block Dynamics
Authors: Bruhn B. , Koch B. P. 
Published: February 2015

Abstract
A simple model of rigid block motion under the influence of external perturbations is discussed. For periodic forcings we prove the existence of Smale horseshoe chaos in the dynamics. For slender blocks a heteroclinic bifurcation condition is calculated exactly, i.e. without using perturbation methods. That means that our results are valid for arbitrary excitation amplitudes. Furthermore, analytical formulas for the first pieces of the stable and unstable manifolds are derived not only for periodically but also for transiently driven systems. In the case of small excitation and damping the Melnikov method is used to treat the full nonlinear problem
Determination of Unstable Limit Cycles in Chaotic Systems by the Method of Unrestricted Harmonic Balance
Authors: Neymeyr Klaus , Seelig Friedrich Franz 
Published: February 2015

Abstract
The method of unrestricted harmonic balance (UHB) which is a generalization of the old method of harmonic balance and that was developed in preceding papers, is mathematically refined and applied to the evaluation of unstable limit cycles. The method is demonstrated for the case of the best investigated chaotic system, namely the Lorenz system. Some representative results are given
Molecular g-Values, Magnetic Susceptibility, Anisotropics, Second Moments of the Electronic Charge Distribution. Molecular Electric Quadrupole Moment, and 14N Nuclear Quadrupole Coupling of Nitroethylene, CH2 = CH - N02
Authors: Spiekermann J. , Sutter D. H. 
Published: February 2015

Abstract
The high-field linear and quadratic Zeeman effect has been observed in nitroethylene. The spectrum is complicated by the presence of 14N nuclear quadrupole coupling which was reanalyzed from low-J zero-field transitions observed under high resolution. Our 14N quadrupole coupling constants are Xaa = -0.8887(18) MHz, Xbb = +0.0429(29) MHz, Xcc = +0.8458(29) MHz (c-axis perpendicular to the molecular plane). Our g-values and magnetic susceptibility anisotropics, fitted to the observed high-field Zeeman multiplets, are gaa = -0.15 985(39), -0.07197(31), gcc= -0.01080(32), 2ξaa-ξbb-ξcc= + 19.07(43) * 10-6 erg * G-2 * mole-1 and 2ξbb- ξcc- ξaa = + 29.67(53) -10-6 erg * G-2 * mole-1 . From them, the anisotropics in the second moments of the electronic charge distribution and the components of the molecular electric quadrupole moment with respect to the principal inertia axes system follow as <a2> -<b2> = +36.55(7)Å2 , <b2> - <c2>= +23.58(9) Å2, <c2>-<a2> = -60.14(8) Å2, Qaa= -0.59(29) D * Å, Qbb = +0.07(36) D * Å, and Qcc = +0.52(46) D * Å. The 14N quadrupole coupling constants, the anisotropics in the second electronic moments and the quadrupole moments are compared to the corresponding Hartree-Fock SCF values calculated with the Gaussian 88 program. The discrepancy between the experimental values and the ab initio values is considerably larger than found earlier in a similar investigation of a group of imines
Photophysical Properties of Some Quindoline Bases and their Salts
Authors: Nikolov Peter , Stoyanov Stefan , Jezerskaite Angele 
Published: February 2015

Abstract
The title compounds are used as sensitizers in electrophotography. The dependence of their absorption and luminescence characteristics on the substituent, medium and temperature is investigated. The influence of various factors on the equilibrium base - salt in solution is elucidated. On the basis of changes in the absorption spectra with concentration the equilibrium constants Kq are determined
Hydration of the Ammonium Ion: Monte Carlo Simulation
Authors: Noto R. , Martorana V. , Migliore M. , Fornili S. L. 
Published: February 2015

Abstract
A Monte Carlo simulation of ammonium aqueous solution at infinite dilution shows that this ion is on the average rather loosely bonded to three of the fourteen water molecules present in its first hydration shell. This result agrees with conclusions suggested by recent experiments on the rotational mobility of ammonium in liquid water.