bluuebunny/crossref_metadata_2025 huggingface dataset:
Internal Cation Mobilities in the Molten Systems (Li-Na)NO3 and (Na-Cs)NO3
Authors: Yang Chao-cheng' , Takagi Ryuzo , Okada Isao
Published: February 2015

For the molten salt systems (Li-Na)NO3 and (Na-Cs)NO3, relative differences of internal mobilities have been measured with the Klemm method. The internal mobilities, b, are calculated from these data and the available conductivity data. In the mixtures of the former system, bNa is always greater than bLi. In the latter system, the Chemla crossing point occurs. It is found that bLi and bNa in the binary alkali nitrate systems so far investigated are well expressed, except at small molar volumes, by b = {A/(V - V0)} exp(- E/RT) with constant A and E, where V is the molar volume and F° a constant for bu and nearly a constant for The values of bCs at equal concentrations of CsNO3 in the systems (Li-Cs)NO3 and (Na-Cs)NO3 are practically equal. The internal mobilities obtained are discussed in terms of free space, mutual ionic attraction and thermal agitation.
Einfluß von Substituenten auf die Fluoreszenzquantenausbeute bei Donator-Akzeptor-substituierten trans-Stilbenen
Authors: Gloyna D. , Kawski A. , Gryczyński I.
Published: February 2015

For 4'-acceptor substituted 4-dimethylaminostilbenes 1 the fluorescence quantum yield φf increases in n-heptane and toluene with decreasing acceptor interaction (i.e. with decreasing polarity in the S1-state). At the same time, the lifetimes τf
w change with φf so that kf
n remains approximately constant. Changes in φf for compounds 1 result from a strong change of the rate constant ktp of radiationless deactivation. This is interpreted in terms of the decreased stabilization of the Si-state occurring with the increase in the polarity of the investigated compounds in non-polar solvents, and remains in good agreement with the calculations carried out previously.
Reaction of the Ground and Metastable Excited C+ and N+ Ions with C2H4, CH3Cl and SO2 Gases at 300 K
Authors: Rakshit Asit B.
Published: February 2015

Rate coefficients and product distributions were measured for the reactions of C+ and X+ ions with C2H4, CH3Cl and SO2. The reactant ions were produced by electron impact using electron energies of 30 V and 100 V and then injected into a flow tube. The product ion distributions for these reactions depend significantly on the electron energy at which the reactant ions are formed. Reactions with CH3Cl and SO2 of ions formed at 100 V yield product ion distributions with a preference for fragmentation channels. In the case of C2H4, the simple charge transfer channel is favoured at high energy. Various new product ions have been identified from these studies, some of which having not been observed previously 7 . Rate coefficients for these reactions at 30 V agree closely with the calculated values using Langevin and ADO theory.
A Contribution to the Microwave Spectrum of Dimethyl Selenide
Authors: Dreizler H. , Fliege E. , Pandey G. K.
Published: February 2015

The microwave spectra of five isotopic species of dimethyl selenide have been measured and analysed for centrifugal distortion and internal rotation by PAM and IAM.
Collision Broadening and Shift of the 535.0 nm Tl Line Accompanying the Photodissociation of Thallium Iodide Perturbed by Noble Gases
Authors: Lisicki E. , Bielski A. , Szudy J.
Published: February 2015

The shape and shift of the 535.0 nm thallium line resulting from the photodissociation of thallium iodide perturbed by krypton and xenon were investigated at low densities. The Doppler and collision broadening components of the line shape have been determined. The linear dependence of both the Lorentzian half-width and the shift on the perturbing gas density was found and interpreted in terms of Van der Waals and Lennard-Jones potentials.
Rotational Motions of Synthetized Yt-Base, Free or Bounded to Adenine, in Solvents of Various Viscosities
Authors: Gryczyński I. , Kawski A. , Paszyc S. , Skalski B.
Published: February 2015

Mean lifetimes in the singlet excited state and emission anisotropics of Yt base and Yt (CH2) 5-adenine were measured as a function of solvent viscosity. Effective volumes of the molecules studied and the cor-responding radii were determined. The fluorescence depolarization of Yt-base in solutions was found to be due to the rotational motion, for the most part about the main x-axis.
Magnetic Field Dependence of Molecular Quantum Beat: Biacetyl
Authors: Henke W. , Selzle H. L. , Hays T. R. , Schlag E. W.
Published: February 2015

The effect of an external magnetic field on the decay of an excited single rotational state of the 1Au electronic state of biacetyl is observed in a hypersonic jet experiment after narrow bandwidth laser excitation. The lifetime of the ex-cited state decreases already at low magnetic fields and the molecular quantum beat vanishes.
Host Spin-Lattice Relaxation Narrowing in Pr2Co3(NO3)12 · 24 H2O: Mn2+ \ Gd3+ Single Crystals
Authors: Jain Vimal Kumar
Published: February 2015

Electron paramagnetic resonance of Mn2+ and Gd3+ in single crystals of Pr2Co3(NO3)12 · 24 H2O has been studied at X-band at 305 and 77 K. Mn2+ substitutes at two types of Co2+ sites whereas Gd3 substitutes at the single type of Pr3+ site in the lattice. The spin-Hamiltonian parameters have been evaluated. Observation of resolved Mn2+ and Gd3+ spectra at 305 K and their broadening on lowering the temperature are discussed in terms of host spin-lattice relaxation narrowing.
The Spectrum of Lanthanum Oxide: A Reanalysis of the Rotational Data
Authors: Bernard A. , Sibaï A. M.
Published: February 2015

A consistent set of improved rotational constants is derived for the X2Σ+, A′2⊿r, A2Πr, B2Σ+,and C2Πr electronic states of lanthanum oxide from the reanalysis of all available data. These constants are obtained from a global fit of the respective bands by a "Direct Approach" technique using complete Hamiltonian matrices for the description of Π and ⊿ states. In order to fit the lines accurately it is shown necessary to include centrifugal distortion effects in the spin-orbit interactions (AJ, AJ and AJJ respectively in A′, and A and C states) as well as in Λ-doubling (PJ pJJ,qJ in C state) and spin-rotation interactions (γJ in B state).

More reliable values for the internal partition function and dissociation equilibrium constant of La O are computed for temperatures between 1000 and 8000 K, by taking account of all the known electronic states and using present or recent values for the molecular parameters and dissociation energy.
Some Luminescence Properties of the Laser Dye Stilbene 3
Authors: Bauer R. K. , Balter A. , Kowalczyk A.
Published: February 2015

Absorption and emission spectra of stilbene 3 (Na-bis-ortho-stilbene-sulphonate) were measured and discussed on the basis of quantum-chemical calculations. The decay of the polarized fluorescence was investigated, yielding information about the rotational behaviour of stilbene 3 in solutions.
Raman-spektroskopische Untersuchungen an PCl5
Authors: Brockner Wolfgang , Demircan Bülent
Published: February 2015

Raman spectra of some solid and molten AuCl3-PCl5 mixtures have been recorded. In the system investigated only the compound AuCl3 · PCl5 is found. This adduct is built up by ionic PCl4
+ and AuCl4- units and it should be formulated as PCl4AuCl4. These complex ions are present in the melt too. The thermal stability of AuCl4- is noteworthy, and it is explained by pressure influenced equilibria. Only PCl4AuCl4, besides excess PCl5 or AUCl3, is present in the mixtures.
Einfluß von Substituenten und polaren Lösungsmitteln auf die Deaktivierung des S1Zustandes bei Donator-Akzeptor-substituierten trans-Stilbenen/Influence of Substituents and Polar Solvents on the Deactivation of the First Excited Singlet of Donor-acceptor Substituted Trans-stilbenes
Authors: Gloyna D. , Kawski A. , Gryczyński I.
Published: February 2015

The effect of substituents on the fluorescence quantum yield φf of trans-stilbenes (1) in dimethylformamide, acetonitrile, and n-propanol, as well as in n-heptane, is mainly due to radiationless deactivation. Contrary to n-heptane, the rate kd of radiationless deactivation in the above mentioned polar solvents for compounds 1 of similar structure is not a monotoneous function of the polarity of the first excited singlet state. The maximum of kd corresponds to compounds with medium polarity (1h, 1i). The effect of substituents on the fluorescence rate kf
n in polar and nonpolar solvents is small compared to that on kd. In all solvents kf
n drops with increasing polarity of the first excited singlet state.
Notizen: The Electrical Conductivity of Molten Lead Iodide
Authors: Easteal A. J. , Khoo P. H.
Published: February 2015

The electrical conductivity of molten PbI2 has been determined in the temperature range 798-978 K. The data have been fitted to the equation

χ= -0.8167 + 1.5668 x10-3T + 3.810 x10-7 T2.

The data are compared with previously published data for PbI2.
Notizen: Anthracene and its Argon Complexes, Spectra and Lifetimes
Authors: Hays T. R. , Henke W. , Selzle H. L.
Published: February 2015

Fluorescence excitation spectra and fluorescence lifetimes at specific wavelengths are reported for anthracene and anthracene-argon complexes in a supersonic jet. At low argon pressures, complexes are observed with lifetimes and transition energies which are not dependent on the argon pressure.

At high pressures, the lifetimes reach a limiting value while the wavelength maximum continues to red shift within the pressure range observed. The possible relationship to solvent or matrix effects on a central ion are discussed.
Stabile Radikalanionen von Aromaten: Strahlenchemische Erzeugung in Gegenwart von Natrium-dihydridobis( 2-methoxyethoxy) aluminat
Authors: Getoff Nikola , Haenel Matthias W. , Hildenbrand Knut , Richter Udo-Burckhard , Solar Sonja
Published: February 2015

Arenes are reduced at room temperature to their very long-lived radical anions by exposing the solution of the arene and NaAlH2(OCH2CH2OCH3 )2 (1) in dimethoxyethane (DME) to an ionizing radiation (electrons, gamma- or X-rays) for few minutes:

Thereby 1 is acting as a scavenger for the solvent counter ions which are produced concomitantly to solvated electrons by the radiolysis. The method is very convenient for the ESR and UV-VIS spectroscopy of aromatic radical anions.
Self-Similar Statistics in MHD Turbulence
Authors: Camargo S. J. , Tasso H.
Published: February 2015

The fully developed decaying turbulence of 3-d resistive, viscous, incompressible magnetohydrodynamics is investigated using Elsasser variables and Hopf equation for probability distributions. The method is an extension of a previous work for Navier Stokes equations done by Foias et al. based on a suggestion by Hopf. It uses essentially self-similar properties of the statistics, which "almost" determine the turbulence spectrum up to a mild assumption on an unknown function. This spectrum is the well known Kolmogorov spectrum
Compressibility and Resistive Ballooning Modes
Authors: Correa-Restrepo D.
Published: February 2015

For equilibria stable with respect to ideal ballooning modes it is shown by means of a simple argument that, owing to plasma compressibility, resistive ballooning modes with small growth rates can only exist if they are extended along a field line. In particular, a small region of bad curvature along a field line is not sufficient for the existence of unstable modes
Molecular Graphs with Equal Z-Counting and Independence Polynomials
Authors: Gutman Ivan , Hosoya Haruo
Published: February 2015

It is demonstrated that the cycle graphs corresponding to the carbon atom skeletons of cycloalkanes and annulenes are the only graphs having the same Z-counting and independence polynomials.
The Millimeter and Submillimeter-Wave Spectrum of Dimethylether
Authors: Neustock W. , Guarnieri A. , Demaison J. , Wlodarczak G.
Published: February 2015

We report the analysis of the rotational spectrum of dimethylether measured between 60 and 400 GHz. Rotational and quartic centrifugal distortion constants are given. Internal rotation splittings are analysed with the I AM method. The value of is compared to the values obtained for similar molecules
Fluorescence, Phosphorescence, and E-Type Delayed Fluorescence of Hexabenzo [bc,ef,hi,kl,no,qr] coronene
Authors: Fetzera John C. , Zander Maximilian
Published: February 2015

The luminescence of hexabenzo [be,ef,hi,kl,no,qr] coronene (I) has been studied in a perhydrocoronene matrix at temperatures from 77 to 353 K. I exhibits phosphorescence and prompt and E-type delayed fluorescence. The phosphorescence transition is symmetry-forbidden. The luminescence behaviour of I is closely related to that of coronene (II)
Electrical Instability in CuO1-x: Possible Correlations with the CuO-based High Temperature Superconductors
Authors: Azzoni C. B. , Parravicini G. B. , Samoggia G. , Parmigiani F.
Published: February 2015

Physical properties of stoichiometric and non stoichiometric CuO are reported. The electrical conductivity has been measured on CuO pellets, sintered with the usual procedure for the preparation of Y Ba-Cu O superconductors and then deoxygenated under a nitrogen flow. It is shown that oxygen deficient CuO pellets present abrupt and large resistivity drops as the temperature decreases below 230-200 K. Possible correlations between the electrical instability of oxygen deficient CuO and the high temperature superconductivity problem are discussed
A Theoretical Study of Monosubstituted Fulvenes
Authors: Jarjis Hayfa M. , Khalil Salim M.
Published: February 2015

MINDO-forces calculations have been done after complete optimization of geometry on X-monosubstituted fulvenes, where X is OH, NH2 , CH3, NO2, CN, F, dimethyl and cyclopropyl. It was found that all the substituents are stabilizing. The electron releasing substituents increase the dipole moment at the exocyclic double bond while the electron withdrawing ones increase the dipole moment at the endocyclic diene. Geometrical parameters, heats of formation, orbital energies and electron densities are reported.
On the Use of Perhydrocoronene as a Matrix in the Luminescence Spectroscopy of Polycyclic Aromatic Hydrocarbons
Authors: Fetzer John C. , Zander Maximilian
Published: February 2015

Higher molecular polycyclic aromatic hydrocarbons (PAH) form supersaturated solid solutions in perhydrocoronene. With coronene as the solute, concentration-dependent P-type delayed fluorescence is observed at 77 K. Even very small amounts of coronene, present as an impurity in the perhydrocoronene matrix, can lead to quenching of the phosphorescence of an added guest PAH by intermolecular triplet-triplet energy transfer and to sensitized coronene phosphorescence when the lowest triplet state of the added guest molecule lies higher in energy than that of coronene. Thermal band broadening of guest molecule phosphorescence has been studied in the temperature range from 77 to 433 K.
Nonlinear Instabilities, Negative Energy Modes and Generalized Cherry Oscillators
Authors: Pfirsch D.
Published: February 2015

In 1925 Cherry [1] discussed two oscillators of positive and negative energy that are nonlinearly coupled in a special way, and presented a class of exact solutions of the nonlinear equations showing explosive instability independent of the strength of the nonlinearity and the initial amplitudes. In this paper Cherry's Hamiltonian is transformed into a form which allows a simple physical interpretation. The new Hamiltonian is generalized to three nonlinearly coupled oscillators; it corresponds to three-wave interaction in a continuum theory, like the Vlasov-Maxwell theory, if there exist linear negative energy waves [2-4, 5, 6], Cherry was able to present a two-parameter solution set for his example which would, however, allow a four-parameter solution set, and, as a first result, an analogous three-parameter solution set for the resonant three-oscillator case is obtained here which, however, would allow a six-parameter solution set. Nonlinear instability is therefore proven so far only for a very small part of the phase space of the oscillators. This paper gives in addition the complete solution for the three-oscillator case and shows that, except for a singular case, all initial conditions, especially those with arbitrarily small amplitudes, lead to explosive behaviour. This is true of the resonant case. The non-resonant oscillators can sometimes also become explosively unstable, but the initial amplitudes must not be infinitesimally small. A few examples are presented for illustration.
Onsager's Relation and Other Results for Relativistic Electrons in Magnetic Fields
Authors: Holas A. , Olszewski S. , Pftrsch D.
Published: February 2015

Onsager's result concerning the quantization of the magnetic flux enclosed by the orbit of an electron moving in a static uniform magnetic field is shown to hold also in the relativistic case, and not to be restricted to the regime considered by Onsager in which the correspondence principle can be applied. The results obtained via the correspondence principle and via expectation values differ, however, in the deails. It is shown also that the eigenenergies and eigenfunctions of Dirac's relativistic equation for an electron in a static non-uniform and arbitrarily strong magnetic field may be obtained directly from the solutions of Schrödinger's non-relativistic equation. In this case the expectation value of an observable depending on coordinates only equals the one calculated directly with the non-relativistic eigenfunctions.
A Laser Limit Cycle - An Analytical Study
Authors: Yao Demin , Großmann Siegfried
Published: February 2015

The limit cycle behaviour of the intensity and of the polarization of a monochromatic two-polarization- mode laser with an intensity coupling asymmetry and a linear phase anisotropy is studied analytically. In a previous paper we found such limit cycle oscillations numerically. Explicit formulae are derived by perturbation methods for the case of small intensity coupling asymmetry and for the case of large pumping, respectively, which describe the dependence on the laser parameters of the limit cycle period as well as of its amplitude.
Motions of Methylammonium Ions in (CH3NH3)2ZnBr4 Crystals Studied by 1H NMR and Thermal Measurements
Authors: Ishida Hiroyuki , Takagi Kentaro , Iwachido Tadashi
Published: February 2015

Measurements of the 1H spin-lattice relaxation time T1, the linewidth parameter T*2
the second moment of 1H NMR absorption, differential thermal analysis, and differential scanning calorimetry were performed on methylammonium tetrabromozincate(II) crystals from 58 to above 500 K. A solid-solid phase transition was located at 456 K. In the room temperature phase, 120° reorientational jumps of CH3 and NH3
+ groups in the cation about its C -N bond axis were detected. In the high-temperature phase, the cations undergo overall reorientation as well as translational self-diffusion. The activation energy for the cationic self-diffusion was evaluated to be 18 kJ mol-1 .
Absorption and Luminescence Studies of Some Highly Fluorescent Derivatives of Vitamin B1; Solvent and pH Effects
Authors: Marciniak B. , Koput J. , Kozubek H.
Published: February 2015

The influence of solvent on the UV-visible absorption and luminescence spectra of some highly fluorescent vitamin B1 derivatives, the products of the reaction of N-methylated vitamin B1 with cytidine (I), adenosine (II) and 2-amino-4-methylpyridine (III) is studied. Spectroscopic manifestations of protonation of I and II are also investigated using a semiempirical INDO/S CI method. Singlet and triplet energy levels of the free ion and several protonated species are calculated, and transition energies and oscillator strengths are compared with the experimental spectra. Calculated charge densities on heteroatoms in the ground and excited singlet and triplet states are correlated with changes of the experimental pKa values with excitation. The results for I and II are compared with those for the trimethylated pyrichrominium ion (III) previously studied
Notizen: Pressure Dependence of the Melting of RbHS04
Authors: Friesel Milan , Baranowski Bogdan , Lunden Arnold
Published: February 2015

The temperature and enthalpy of melting have been studied in the range up to 0.55 GPa by means of differential scanning calorimetry. In the range below a triple point at (498 ± 5) K and (0.27 ±0.02) GPa the results can be expressed by means of linear relations: 7 = 476 + 80 p, and AH = 22.4- 29.8 p, where the corresponding units are K, kJ/mol and GPa. Above the triple point the correlation between pressure and temperature corresponds to Simon's equation, p = 0.27 +1.57 x 10-3 (T-498)1.28, and the enthalpy of melting decreases linearly with the pressure: ΔH = 9.50-10.65 (p-0.28). Comparison is made with a recent study by Sinitsyn et al
Molecular Dynamics Study of the Structural and Dynamical Properties of Liquid Tetrahydrofuran
Authors: Drabowicz W.
Published: February 2015

A molecular dynamics simulation has been performed to investigate the structural and dynamical properties of liquid tetrahydrofuran. In particular, we have calculated six radial distribution functions, translational and rotational autocorrelation functions and their associated frequency spectra.
Flüssigkristalle mit monosubstituierten alicyclischen und heteroalicyclischen Ringen
Authors: Vill V. , Thiem J.
Published: February 2015

Twenty two liquid crystalline mono-substituted cyclopentanes and cyclohexanes including their oxygen analogues were prepard and studied. Smectic phases with clearing temperatures ≦ 80 °C were observed, and these do not differ considerably between the esters of the more flexible five-membered ring derivatives and those of the conformationally more rigid six-membered rings. In case of the latter, decreasing clearing points are observed with increasing ratios of the axial conformation (static conformational effect). Altogether rather low clearing points are observed, which may be interpreted by a dynamic conformational effect owing to which fast ring inversion causes the compounds to appear in a bulkier shape, and this results in a disadvantageous packing in the mesophase.
Rotational Depolarization of Fluorescence of Prolate Molecules
Authors: Kawski A. , Kojro Z. , Bojarski P. , Lichacz J.
Published: February 2015

The theory of rotational depolarization of fluorescence, taking into account the inertial effect, has been verified experimentally for two angular velocity autocorrelation functions obtained for both the approximate and the exact Langevin equation. To this end, the emission anisotropy was investigated as a function of viscosity for PPO, POPOP, and α-NOPON in liquid n-paraffins (from « = 5 to n = 11) at 304.5 K. For these three luminescent molecules with mean lifetimes of about 1 ns, and the viscosities ranging from 0.22 to 0.9 cP, no essential difference was found between the experiment and the theory for the angular velocity autocorrelation functions employed.
The Bond Sn-Cl in SnIV Complex Salts A2 [(C2H5 )SnCl 5]. A Single Crystal 35Cl NQR Study of Bis(methylammonium)- pentachloroethylstannate, (CH3NH3 )2](C2H5 )SnCl5]
Authors: Storck Peter , Weiden Norbert , Weiss Alarich
Published: February 2015

Zeeman 35Cl NQR spectroscopy has been applied to determine the magnitude and orientation of the EFG tensors at the chlorine sites in a single crystal of(CH3NH3)2[(C2H5)SnCl5] at 293 K. The assignment of the NQR frequencies vi(35Cl), the corresponding quadrupole coupling constants eQΦ(i)
zz h-1 , and the asymmetry parameters ηi(35Cl) to certain Cl(k) atoms is discussed. The most probable assignment is (no. i of vi(35Cl), vi(35Cl)/MHz, eQΦ(i)
zz h-1 / MHz ηi, (35Cl), no. k of assigned Cl(k), d(Sn-Cl(k) )/pm, ∢ (Φ(i)
zz , d(Sn-Cl(k) )) :i = 1,17.032, 34.046,0.056, k= 1, 242.6, 3.1°; i = 2, 12.072, 24.089, 0.117, k = 3, 250.7, 1.9°; i = 3, 11.537, 22.992, 0.146, k = 2, 253.1, 2.8°; i = 4, 10.770, 21.455, 0.154, k = 4, 249.7, 2.9 °; i = 5,9.969,19.842,0.171, k=5,254.9,1.7°. The orientation of the tensor axes Φ(i)
jj , j = x, y, z,i= 1 - 5 , in space is mainly determined by the geometry of the [(C2H5)SnCl5]2⊖ anion. The Φ(i)
zz are nearly parallel to the assigned bond directions Sn-Cl(k) · η (35CI) is low, increasing with decreasing v(35Cl). The reason for the asymmetry seems not to be a π-character in the Sn-Cl bond, but the charge distribution within the anion. The rule that a longer bond corresponds to a lower NQR frequency is valid as a general tendency, but not strict.
NQR Studies of Atomic Arrangements and Chemical Bonding in Glasses
Authors: Lee Donghoon , Gravina S. J. , Bray P. J.
Published: February 2015

A very high sensitivity continuous wave NQR spectrometer was developed to detect pure NQR transitions at low frequencies (down to 200 kHz). A signal-to-noise ratio of more than 100 to 1 has been achieved at about 1.36 MHz for crystalline B 2 0 3 . Two large n B responses have been found in vitreous B 2 0 3 (NMR detected only one site) with linewidths of less than 30 kHz. 27 A1 NQR spectra were obtained for OC-A1203 (Corundum), the mineral andalusite (a form of A1203 • Si0 2), and a glass having the composition of anorthite (CaO • A1203 • 2Si0 2).
NQR in Dipolar and Quadrupolar Glasses
Authors: Blinc R.
Published: February 2015

It is shown that nuclear quadrupole resonance and quadrupole perturbed magnetic resonance represent a powerful technique to determine the local polarization distribution and its second moment, the Edwards-Anderson order parameter, in proton and deuteron glasses. For quadrupolar glasses the local orientational distribution function can be determined from the inhomogeneous NMR or NQR lineshape, thus allowing for a measurement of the quadrupolar Edwards-Anderson order parameter. The comparison of the temperature dependences of the thus obtained order parameters with theoretical predictions then allows for a discrimination between the different possible models of the glassy transition.
35Cl NQR Study of 4,4 , -Dichlorobenzophenone
Authors: Wolfenson A. E. , Pusiol D. J. , Brunetti A. H.
Published: February 2015

Pulsed NQR has been used to get information about the two phase transitions (PT) in 4,4'-di-chlorobenzophenone. The measurements of the NQR spectrum and spin-lattice relaxation suggest that the PT's correspond to a normal-incommensurate and to the lock-in of a commensurate structure at lower temperature. Strong hysteresis has been observed, which could be assigned to memory effects produced by defect migrations.
NQR and NMR Studies of Spin Dynamics in High Tc Superconducting Cuprates
Authors: Warren W. W. , Walstedt R. E.
Published: February 2015

Recent NQR and NMR studies of Cu spin dynamics in metallic YBa2Cu3O6+x are reviewed. The Cu nuclear relaxation rates are shown to be inconsistent with weak correlation (band) theory and the Korringa relation, but the Cu spins retain important characteristics of itinerancy. These include pairing of the Cu d-spins in the superconducting state and strong sensitivity of the Cu spin dynamics to changes in carrier concentration associated with variation of the oxygen content. Samples of reduced oxygen content (Tc = 60 K) are found to contain a high concentration of Cu+ Cu(1) sites associated with "full chain-empty chain" vacancy ordering. These samples also exhibit remarkable precursive suppression of planar Cu(2) nuclear relaxation above Tc .
Cu NQR Studies of the Superconductors YBa2Cu3Ox and YBa2Cu4O8
Authors: Brinkmann D.
Published: February 2015

The paper reviews some copper NQR studies in the superconductors YBa2Cu3Ox and YBa2Cu4O8 performed at the University of Zürich. The following topics are discussed: the temperature and pressure dependence of the NQR frequencies; relation between linewidths and oxygen deficiency; the determination of the electric field gradients (EFG) and Knight shifts at the copper sites; discussion of some calculations of the EFG tensors; measurements of the various relaxation times in all phases. The results obtained in both structures are compared; possible interpretations are discussed.
NQR and Low-Field NMR of 181Ta in the Low-Temperature CDW State of 2 H-TaS2
Authors: Nishihara H. , Hayashi K. , Naito M. , Butz T. , Lerf A. , Saibene S.
Published: February 2015

NQR and low-field NMR spectra of 181 Ta are reported to probe the electronic environment of inequivalent tantalum sites in the low-temperature CDW state of a layered compound 2H-TaS2 . The overall features are found to be consistent with the structure consisting of nine-atom snowflake clusters in a locally commensurate CDW state.
Cu NQR Study on Transverse Relaxation Rate below T c in YBa2Cu3O7
Authors: Tei M. , Takai H. , Mizoguchi K. , Kume K.
Published: February 2015

The transverse relaxation rate T2
-1 was measured in YBa2Cu3O7 from 4.2 to 100 K in zero magnetic field. It showed a sudden drop just below T c down to 1/3 of that above Tc . A cusp-shaped sharp peak of T2
-1 was found at 35 K for Cu(2) (plane) site, but not for Cu(l) (chain) site. Except the peak, all the behavior can be interpreted by the model of Pennington et al. that the origin of T2
-1 at 100 K is mainly the local field fluctuation by the Cu d-electron and secondly the indirect nuclear spin-spin coupling via superexchange interaction between Cu-ions. Below Tc the former is sup-pressed.
Anomalous Temperature Dependence of NQR Frequencies
Authors: Brown R. J. C.
Published: February 2015

The anomalous temperature dependence of NQR frequencies which is often observed in crystals in which there is reorientational motion of ions or molecules is considered. Two theories of the phenomena, the jump rotation theory and the pseudo-spin theory, are described, and their successes and failures are discussed. The importance of considering other properties such as pressure dependence of NQR, heat capacity, and elastic constants is emphasized, and it is shown that neither theory is entirely satisfactory at present.
A Study of Complex Anionic Motions in (Me2NH2)2ZnCl4 Crystals by Means of Chlorine Nuclear Quadrupole Resonance Techniques
Authors: Yamamoto Hiroshi , Ishikawa Atsushi , Asaji Tetsuo , Nakamura Daiyu
Published: February 2015

Three 35Cl NQR frequencies were observed for (Me2NH2)2ZnCl4 at room temperature, indicating the existence of three crystallographically nonequivalent chlorines in the crystal. With decreasing temperature, the frequency of the lines increased almost linearly and disappeared below ca. 220 K near the reported phase transition temperature (ca. 215 K) detected on cooling. The three NQR lines faded out above room temperature because of the occurrence of rapid anionic reorientational motions disclosed from measurements of the 35Cl NQR spin-lattice relaxation time.
Bloch-Siegert Effect in Pure Nuclear Quadrupole Resonance
Authors: Furman G. B.
Published: February 2015

The Bloch-Siegert shift of the NQR frequency is calculated for the case when more than one resonance transition are excited by radiofrequency fields.
Proton Spin Relaxation of a Liquid Crystal with a Glassy Cholesteric State
Authors: Pusiol D. , Noack F. , Aguilera C.
Published: February 2015

Field-cycling and standard pulsed NMR techniques have been used to study the frequency dependence of the longitudinal proton spin relaxation time T x in the crystalline estradiol compound (+)3,1,7-ß-bis-(4n-butoxybenzoyloxy)-estra-1,3,5-(10)-trien or BET, which is a mesogenic material with a chiral molecular structure. From the measured Larmor frequency and temperature depen-dences we conclude that, at low NMR frequencies in the cholesteric phase, T1 reflects in addition to the relaxation process familiar from nematic liquid crystals (director fluctuation modes) another slow mechanism theoretically predicted for cholesteric systems, namely diffusion induced rotational molecular reorientation. These relaxation processes are not or much less effective in the crystalline and glassy state, where they are frozen. Also the high NMR frequency relaxation dispersion strongly differs between the cholesteric mesophase and the not liquid crystalline samples. This is interpreted by a change from essentially translational self-diffusion to rotational diffusion controlled proton relaxation.
Structural Study of Amorphous Co-Ferrite Film by Anomalous X-Ray Scattering
Authors: Matsubara E. , Okuda K. , Waseda Y. , Okuno S. N. , Inomata K.
Published: February 2015

The structure of amorphous Co-ferrite film grown on a glass substrate was studied by anomalous X-ray scattering (AXS). Co atoms cannot be distinguished from Fe atoms with the usual X-ray diffraction technique. Therefore the AXS method at the Fe and Co K-absorption edges was adopted. In the previous AXS studies only the lower energy side of the absorption edges was adopted. In the previous AXS studies only the lower energy side of the absorption edge was used. In the present case, the lower energy side of the Co K-absorption edge corresponds to the higher energy side of the Fe K-absorption edge. Therefore, in order to overcome this inconvenience, the scattering was measured on both sides of the absorption edge, thus enabling the independent determination of the oxygen coordination numbers around Co and Fe in the ferrite film from the environmental RDFs estimated from the energy differential profiles by coupling with the linear least squares technique.
Cross-Section for Proton Transfer from a Large Peptide Ion to Ammonia in the Gas Phase
Authors: Davis Stephen C. , Derrick Peter J. , Ottinger Christoph
Published: February 2015

Proton transfer between ions of the cyclic peptide valinomycin (relative molecular mass 1110.6) and ammonia molecules has been studied over a range of ion energies from 50 eV to 8 keV. Valinomycin ions were produced by field desorption. Collisions of valinomycin ions with ammonia molecules at controlled energies were carried out using an ion-optical lens system situated in the source region of a large research mass spectrometer. The maximum cross-section for proton transfer occurred when the valinomycin ion possessed 1500 eV of kinetic energy. This maximum cross-sec-tion for proton transfer was 3 orders of magnitude smaller than the cross-section for collision-in-duced dissociation of the valinomycin ion at the same ion energy (2.4 • 10-17 cm2 molecule-1 as compared to 2 • 10-14 cm2 molecule-1). A stereospecific stripping model can explain the observa-tions.
Millimeter Wave Spectrum and Centrifugal Distortion Analysis of Difluorochloromethane CHF2Cl in the Ground State
Authors: Spiehl R. , Guarnieri A.
Published: February 2015

The rotational spectra of CHF2
35Cl and CHF2
37Cl (CFC22) in the vibrational ground state between 42 and 214 GHz are reported. A centrifugal distortion analysis up to the sixth order is carried out.
A Highly Disordered New Solid Phase Containing Isotropically Reorienting Cations in (CH3NH3 )2CdBr4 Studied by 1H NMR and Thermal Measurements
Authors: Ishida Hiroyuki , Takagi Kentaro , Terashima Mifune , Nakamura Daiyu
Published: February 2015

The 1H spin-lattice relaxation time, linewidth, second moment of 1H NMR absorption, differen-tial thermal analysis, and differential scanning calorimetry of methylammonium tetrabromocado-mate(II) crystals were studied. A new solid phase was found between 482 K and the melting point (493 K). The 1H NMR measurements revealed the presence of overall reorientation of methyl-ammonium cations in this phase. In the room temperature phase, 120° reorientational jumps of the CH3 and NH3
+ groups were detected.
A Theoretical Analysis of the Contributions to the Internal Rotation Barrier in N-Benzylideneanilines
Authors: Figueroa K. , Campos-Vallette M. , Contreras R. R.
Published: February 2015

An analysis, using CNDO wave functions, has been carried out on the different contributions to the internal rotation barrier in N-benzylideneaniline (1) and p-dimethylaminobenzylidene-p-nitro-aniline (2) in several conformations. The stability of the different structures has been expressed in terms of a partition of the total energy into electronic, net charges and steric hindrance contributions. Based on the shape of the total energy surface it appears that the barrier composition may be reasonably well described without approaching the absolute minimum. Rotation of the aniline group in both molecules is mainly governed by steric hindrance. Rotation of the benzylidene group shows a prevalent destabilizing electronic effect. The donor strength of the substituent in the benzylidene ring seems to play an important role in stabilizing a less nonplanar structure.
Calculation of Energy Characteristics of Point Defects in bcc Iron by Molecular Dynamic Technique
Authors: Melker A. I. , Mizandrontzev D. B. , Sirotinkin V. V.
Published: February 2015

The influence of the calculation procedure on the energy characteristics of vacancies and helium impurities in α-iron is considered. Calculations are performed with the help of long-range oscillating interatomic pair potentials found on the basis of a model pseudopotential approach. It is shown that for improving the convergence of the lattice sums one must introduce space windows. The best results were obtained with the Vashista-Singwi local-field correction and the modified windowmodulation interatomic potential based on the Heine-Abarenkov pseudopotential with the Animalu formfactors
An 1H NMR Study on the Cationic Motion in Solid tert-Butylammonium Chloride and Bromide
Authors: Ishida Hiroyuki , Inada Syuichi , Hayama Naomi , Nakamura Daiyu , Ikeda Ryuichi
Published: February 2015

The 1H spin-lattice relaxation time (T1) in solid (CD3)3CNH3Cl and (CD3)3CNH3Br was measured above room temperature and the motional parameters for the reorientation of the NH3
+ groups were determined. The 1H NMR absorptions measured in the same temperature range for (CH3)3CNH3Cl and (CH3)3CNH3Br indicate the presence of superimposed several cationic motions commonly taking place in both compounds. From X-ray powder patterns taken at room temperature, the bromide was found to be isomorphous with the chloride
Time Scale and its Application in Perturbation Theory
Authors: Olszewski S.
Published: February 2015

A circular scale of time is proposed and applied to the calculation of the Rayleigh-Schrödinger perturbation energy for a non-degenerate state
Structural and Defect Study of Naß''-Gallatc by X-Ray Powder Diffraction Analysis
Authors: Massarotti V. , Capsoni D. , Marini A. , Berbenni V. , Flor G. , Margheritis C.
Published: February 2015

The Rietveld profile refinement has been applied to X-ray powder diffraction data on Naß''-gallate, a solid electrolyte isostructural with Naß''-alumina and characterized by different types of lattice defect. Several structural models have been refined and discussed in order to understand if a statistical comparison of the structure discrepancy factors can be used as a reliable criterion to retain or reject structural changes from one model to the other. It is shown that, due to the correlation between structural parameters and to the poor sensitivity of the structure discrepancy factors to chemical composition, some care is necessary to direct correctly the refinement and to obtain a reliable structural model
Space-time Transformations in Ether Theories
Authors: Selleri F.
Published: February 2015

By assuming the validity of the principle of inertia and the existence of a privileged frame, the transformation laws (TL) between inertial frames are investigated in ether theories. For onedimensional space the TL's are fixed up to two undetermined functions of absolute velocity, Δ (v) and E(v). If the principle of relativity is finally assumed, these functions acquire their well known Lorentzian expressions ΔL and EL. It is concluded that special relativity theory is "unstable", in the sense that any shift, however small, of Δ away from ΔL and/or of E away from EL leads to an ether theory. In Earth-based experiments one can expect deviations from c of the two-way and one-way velocity of light of the order of 10-12 and 10 -9 respectively
Monte Carlo Simulations of Water under Supercritical Conditions. I. Thermodynamic and Structural
Authors: Kalinichev A. G.
Published: February 2015

The thermodynamic and structural properties of water along two supercritical isotherms at 673 and 773 K in the pressure range from 0.3 to 30 kbar have been studied by the NPT-ensemble Monte Carlo method using a TIP4P intermolecular pair potential. Simulated values of the configurational enthalpy, molar volume, isobaric heat capacity, isothermal compressibility, and thermal expansion coefficient are found to be in a rather good agreement with experimental data, although the critical point of the TIP4P water model is supposed to lie about 50 degrees lower than observed experimentally. The analysis of simulated atom-atom radial distribution functions as well as the dimerization energy distributions clearly shows that hydrogen bonding persists under the conditions studied, despite the fact that the water structure may be considered as "argon-like" in terms of oxygen-oxygen distribution functions (i.e. close to that of a simple liquid)
A Microwave Fourier Transform Spectrometer in the Range from 18 to 26.4 GHz Increased Sensitivity Using Circular Waveguides. Measurements of Isotopomeres of Carbonylsulfide and of Methane
Authors: Meyer V. , Jäger W. , Schwarz R. , Dreizler H.
Published: February 2015

We present a microwave Fourier transform spectrometer in the region of 18 to 26.4 GHz with an increase in sensitivity roughly by a factor of ten in comparison to a former set up. Measurements of rotational transitions of isotopomers of carbonylsulfide, OCS, in natural abundance and of rovibrational transitions of methane, CH4, illustrate the improvement
Paramagnetic Defects in Benitoite
Authors: Vassilikou-Dova A. B. , Eftaxias K.
Published: February 2015

In clear, blue, transparent bipyramidal crystals of the rare mineral benitoite, BaTiSi3O9, para­ magnetic defects have been investigated by electron paramagnetic resonance at room temperature and 9.43 GHz. They are attributed to Sn3+ and Fe3+ . A pair of satellites recorded for a wide angular rage around B0 || c (~40°) and a relative intensity of ~ 13% to the central signal is most likely due to hyperfine interaction with 117Sn and 119Sn isotopes. Attempts to bleach the colour of the crystal were unsuccessful.
Specific Interactions of CH2
- and CH3-Groups of n-Paraffins with PFTB
Authors: Luck Werner A. P. , Peil Stephan
Published: February 2015

The OH stretching frequency νOH of perfluoro-tert.-butanol (PFTB) dissolved in different liquid n-paraffins decreases with increasing chain length n of the solvent. This observation is explained by an overlapping of two different vOH absorption bands induced by interactions between CH2- resp. CHj-groups and the OH-oscillators of PFTB. The decrease of vOH demonstrates an increase of the intermolecular interaction energies. These mean interaction energies between the OH-groups and the solvent molecules increase with n in a similar way as the densities q of the paraffins. The frequency shifts zh'OH (^vOH = vOH(Gas, -vOH) of PFTB as well as the specific volumes V of the paraffins can be described by a sum of CH2- and CH3-group contributions. In this way the role of the cohesion energy for zlvOH is demonstrated. The OH ··· CH2-interaction has been found as 2.5 times larger than OH ··· CH3-interactions. The I ··· CH2 Lennard-Jones parameter £ has been found too as 2.5 times larger than the value of I ··· CH3 interactions. This agreement demonstrates the efficiency of the intermolecular IR spectroscopy.

The sum of group contributions for interactions of linear molecules seems to have some advan- tages and may be more intuitive by its simplicity in comparison to explanations with parameter for “non-central forces” as e.g. the acentric factors ω of Pitzer et al.
Course of the Melting Transition in Organic Compounds
Authors: Bartis Francis J.
Published: February 2015

This problem is reconsidered in the light of the mounting evidence that dislocations act as the centres of nucleation and growth. A new relation between the fraction of the sample in liquid form and the equilibrium temperature is derived and found to fit well the data on succinonitrile and N-p-ethoxybcnzylidcne-p´-butylanilinc (EBBA). It is argued that the additional dislocations in a cyclopentyl-l-thiaethane sample after rapid crystallization are responsible for the greater breadth of its melting transition compared to that of the same sample following slow crystallization. Past studies of the fractional melting process are criticized for their failure to include the early stages of the transition in their comparison of theory and experiment.
A New Method for Numerical Abel-Inversion
Authors: Pretzier Georg
Published: February 2015

A new numerical solution of Abel-type integral equations is presented which is based on the principle of Fourier-analysis. The unknown radial distribution is expanded in a series of cosine-functions. the amplitudes of which are calculated by least-squares-fitting of the Abel-transformed series to the measured data. Advantages and applications of the new method are discussed, followed by a short comparison with methods, commonly used for Abel-inversion.
Geometric Formulation of Gauge Theories
Authors: Drechsler W.
Published: February 2015

The development of gauge theories is reviewed beginning with Weyl's theory of 1918 and with the changes introduced by London in the context of quantum mechanics. After a discussion of the Yang-Mills theory and Utiyama's work in the fifties the translation to the modern geometric formulation of gauge theories in terms of fiber bundles is presented
The Occurrence of a Finite Number of Particle Families in the Planck Aether Model of a Unified Field Theory
Authors: Winterberg F.
Published: February 2015

The Planck aether substratum model explains Dirac spinors as excitons made up from vortex resonances of the positive and negative mass substratum. In the framework of this model it is conjectured that the higher particle families arise from excited states due to radial oscillations. The characteristic feature of quantum mechanics involving negative masses leads to a finite number of such excited states. Without the knowledge of the mass distribution in the excitons, a maximum number of four families can be predicted from the known mass spectrum of the leptons. Finally, it is conjectured that the small neutrino-electron mass ratio results from a compensating gravimagnetic effect, leading to a value for this ratio equal to (m(GUT)/m (Planck))2
Stability Properties of Nonlinear Delay Systems and the Breakdown of the Adiabatic Approximation
Authors: Hawdon Brendan J. , O'Gorman James , Heffernan Daniel M.
Published: February 2015

We consider the adiabatic approximation as it is applied to a familiar class of infinite-dimensional equations. We show how this approximation may be directly invalidated by analyzing a statistical form of the eigenvalue equation before and after the adiabatic approximation is made. We introduce a statistical quantity which can be used to predict the existence of periodic windows in the chaotic regime
Surface Induced Spin-Lattice Relaxation of Water in Tricalcium Silicate Gels
Authors: Milia F. , Bakopoulos Y. , Miljkovic Lj.
Published: February 2015

The water proton spin-lattice relaxation time and recovery function of exchangeable water was measured in tricalcium silicate (C3S) gels. The measurements were carried out as a function of the hydration time and grain size. Results show that the hydration of (C3S) is a two stage process. A model is developped
Fluorescence Quantum Yields of 2-Substituted 3-Methylquinoxalines in Liquid Solutions at Room Temperature
Authors: Kawski A. , Nowaczyk K. , Kuklinski B.
Published: February 2015

A sensitivity modulation method was employed to measure the fluorescence spectra and quantum yields of weakly fluorescent 2-substituted (NH2, O, OCH3, CI, Br) 3-methylquinoxalines in n-hexane and methanol at room temperature. A strong decrease in the quantum yield with increasing atomic weight of the substituents was observed in n-hexane. In polar solvents, the CI substituent is the strongest quencher although its atomic weight is 2.254 times smaller than that of Br