bluuebunny/crossref_metadata_2025_split huggingface dataset:
Two-dimensional Exchange Spectroscopy Using Pure NQR
Authors: Rommel E. , Nickel P. , Rohmer F. , Kimmich R. 
Published: February 2015

Abstract
Exchange between positions with different resonance frequencies can be studied by two-dimensional spectroscopy originally developed for the NMR case. Cross intensity reflects changes of the resonance frequency due to different line shifts or anisotropic interactions. We now present analogous experiments carried out with pure NQR of polycrystalline samples. The specific requirements are discussed in comparison to 2D exchange NMR spectroscopy. The method has been demonstrated with chloroform and p-chlorobenzotrichloride, where the resonances of the 35Cl nuclei were investigated. Isomeric changes taking place in these compounds reveal themselves as cross-peaks provided the right ranges of the temperature and the mixing time are chosen. The corresponding dependences were recorded and are discussed.
Zeeman NQR Studies on Polycrystals of Copper Compounds, Arsenic Compounds, and Chlorine Compounds
Authors: Ege Osamu , Hamai Sanyo , Negita Hisao 
Published: February 2015

Abstract
Powder Zeeman NQR (PZNQR) spectra of 63Cu,75As, and 35Cl in various compounds have been observed at 77 K. On the basis of the types of simulated integral curves of PZNQR absorption, the estimated asymmetry parameters of the electric field gradients have been divided into three classes; (1) measurable, (2) small (smaller than about 0.05), and (3) very small (probably zero). The asymmetry parameters have been found to be very small ( Cu, NQR frequency = 26.704 MHz) in Cu,0;0.40 (63Cu, 32.617 MHz) in KCu(CN)2; very small (75As, 116.820 MHz) in As2O3 ; very small (75As, 78.950 ; 35Cl, 25.0567 and 25.4036 MHz) and small ( 35Cl, 24.9581 MHz) in ASCl3 ; very small (75As, 98.501 and 99.046 MHz) in As(C6H5)3; small (38.389 MHz), 0.15 (38.464 MHz), and 0.14 ( 38.503 MHz) for 35Cl in hexachlorobenzene; small ( 35.847 MHz) and very small ( 39.154,39.603 , and 39.615 MHz) for 35Cl in l-chloro-2-(trichloromethyl)-benzene; small ( 32.619 MHz) and very small ( 32.878 MHz) for 35Cl in 1,4-dichlorobutane; very small ( 37.828 and 38.051 MHz) for 35Cl in 1,1,1 -trichloroethane.
Experimental Investigations of the Strong Off-Resonant Comb (SORC) Pulse Sequence in 14N NQR
Authors: Kim S. S. , Jayakody J. R. P. , Marino R. A. 
Published: February 2015

Abstract
The behavior of induction signals during steady-state pulse irradiations in 14N NQR was investigated experimentally. It has long been known that the signal response to a long sequence of η pulses will dramatically increase for pulse spacings less than T2. This increase is exponential, and can result in signals comparable to optimally prepared Free Induction Decays. Because these "SORC" signals recur as long as the pulsing continues, very efficient signal-averaging can result. The dependence of these quasi steady-state signals on pulse parameters and on frequency offset are presented, together with a discussion of the applicability of the method.
Recent Development of Nuclear Quadrupole Resonance Spectra Database
Authors: Chihara Hideaki , Mano Koichi 
Published: February 2015

Abstract
The Nuclear Quadrupole Resonance Spectra (NQRS) Database contains all the numerical data of resonance frequencies that have been published since 1950, the year NQR was discovered, through the end of 1989. The total number of records compiled is 10,155 as of May, 1991. One record usually covers data of a particular polymorphic modification of a crystalline substance. About 3/4 of all the records deal with organic or organometallic substances. Recent changes in the data content and format, development of online and stand-alone search software, statistics of the database, and updating problems are described. A personal computer version of the database with load/search software was prepared and is described in the Appendix
Feynman-Kleinert's Treatment of a Class of Harmonic-Oscillators
Authors: Bentaiba M. , Chetouani L. , Hammann T. F. 
Published: February 2015

Abstract
The Feynman-Kleinert method is applied to the harmonic oscillator class of potentials obtained through the factorization method. It is found that the free energy is in good agreement with the exact energy of the harmonic oscillator
1H NMR Studies on Cationic Motions in Solid tert-Butylammonium Hexachlorostannate (IV)
Authors: Ishida Hiroyuki , Higashiyama Tatsuo , Hayama Naomi , Ikeda Ryuichi 
Published: February 2015

Abstract
The temperature dependences of the 1H spin-lattice relaxation time (T1) and the second moment (M2) of NMR absorptions were measured for anhydrous tert-butylammonium hexachlorostannate(IV) and its partially deuterated analogs [(CD3)3CNH3]2SnCl6 and [(CH3)3CND3]2SnCl6. Three kinds of cationic motions were revealed: the reorientations of the CH3 group about their C - C bonds, the NH+
3 group about its C - N bond, and the tert-butyl group about the C - N bond. Their motional parameters were determined. Among the three motions, the NH+
3 motion occurs at the lowest temperature with quite a small activation energy (9.9-10.0 kJ mol-1 ) .
Differential Thermal Analysis and Dielectric Studies on Neopentanol under Pressure
Authors: Kreul H. G. , Waldinger R. , Würflinger A. 
Published: February 2015

Abstract
Differential thermal analysis (DTA) and dielectric measurements have been performed on 2,2-dimethyl- 1-propanol (neopentanol) up to 200 MPa. Neopentanol exhibits at least one orientationally disordered (ODIC) phase (solid I) that transforms at lower temperatures to a non-plastic phase (solid II). There is evidence of a further ODIC phase denoted as solid I'. The pressure dependence of the phase transitions and the dielectric behaviour up to frequencies of 13 MHz are described. Activation enthalpies and volumes are derived from the dielectric relaxation time and compared with results for other alcohols
Lattice Vibration Spectra. LXXV. IR Single Crystal Reflection Spectra of Sr(ClO3)2
Authors: Lutz H. D. , Schmidt M. 
Published: February 2015

Abstract
Polarized infrared reflection spectra of Sr(ClO3)2 single-crystal plates are recorded and analysed for the frequencies of the transversal and longitudinal optical zone-centre phonon modes and other oscillator parameters by Kramers-Kronig analyses and both the classical 3 parameter (dielectric sum-function) and the 4 parameter (factorized form) oscillator-fit methods. The frequencies computed are compared with the results of previous single-crystal Raman studies. Because of the great distortion of the ClO3
- ions (site symmetry C1, no intraionic coupling of the CIO vibrations to symmetric ( ν 1) and asymmetric (ν3) stretching modes occurs. The TO/LO splittings of respective CIO unit-cell group modes rank like the vector elements of the corresponding CIO bonds with respect to the crystal axe
FTIR Study of the v12 and the v12 + v14 — v14 Bands of 1,3,5-Triazine Near 740 cm-1
Authors: Bodenmüller Wolfram , Ruoff Andreas , Manceron Laurent 
Published: February 2015

Abstract
The infrared spectrum of the v12 fundamental and its accompanying hot band v12 + v14 - v14 of triazine has been measured by means of a Fourier transform spectrometer with a resolution of about 0.0023 cm-1 . A total of about 2779 rovibrational transitions has been assigned. The ground state constants have been considerably improved whilst the parameters for the excited states v12 = 1, v14 = 1 and v12 = v14 = 1 have been obtained for the first time. The standard deviations were 2.92 • 10-4 cm-1 for the ground state constants and 1.53 • 10-4 cm -1 for the excited state parameters of v12 showing the latter to be unperturbed. The upper state of the hot band v12 + v14 - v14 was found to be perturbed by an accidental resonance.
Rayleigh-Taylor Instability of a Partially Ionized Plasma in a Porous Medium in Presence of a Variable Magnetic Field
Authors: Sharma R. C. , Sunil  
Published: February 2015

Abstract
The Rayleigh-Taylor instability of a partially ionized plasma in a porous medium is considered in the presence of a variable magnetic field perpendicular to gravity. The cases of two uniform partially ionized plasmas separated by a horizontal boundary and exponentially varying density, viscosity, magnetic field and neutral particle number density are considered. In each case, the magnetic field succeeds in stabilizing waves in a certain wave-number range which were unstable in the absence of the magnetic field, whereas the system is found to be stable for potentially stable configuration/stable stratifications. The growth rates both increase (for certain wave numbers) and decrease (for different wave numbers) with the increase in kinematic viscosity, medium permeability and collisional frequency. The medium permeability and collisions do not have any qualitative effect on the nature of stability or instability.
An Effect of Deuteration on Ion Motions and Hydrogen Bondings in Guanidinium Tetrafluoroborate
Authors: Wąsicki J. , Grottel M. , Kozak A. , Pająk Z. 
Published: February 2015

Abstract
The fluorine spin-lattice relaxation time as well as NMR second moment for perdeuterated guanidinium tetrafluoroborate were studied over a wide range of temperature.
An analytical solution of a set of coupled differential equations describing the time variation of nuclear magnetisations for four unlike spin systems was applied to analyse all cross-relaxation effects in the compound. Activation parameters EF
a = 19.3 kJ/mole and τF
U= 9 • 10"14 s for the isotropic anion reorientation were derived.
A coupling of rotational modes of cation and anion was found. Significant lowering of the melting point explained by a weakening of the hydrogen bonds involves diminishing of the ion activation energies due to the large positive isotope effect
Phase Transitions of Scaling Functions Derived from Experimental Time Series
Authors: Stoop R. , Parisi J. 
Published: February 2015

Abstract
The occurrence of phase transitions in dynamical systems is intimately related to the analyticity properties of the thermodynamical functions. Such effects are believed to be of generic nature (for example, homoclinic tangency points). For one-dimensional maps, their existence has been proven for both the probabilistic and the dynamical scaling functions (that is, the / (a) and <P (A) spectra, respectively). With the help of simple model systems, we elucidate the different combinations in which the two types of phase transitions (namely, in the f(x) and <ϕ(λ) spectra) can appear. Moreover, we demonstrate the numerical evidence of phase-transition-like behavior in both spectra derived from experimental time series of laser and semiconductor systems. Finally, we discuss new aspects for the evaluation of the thermodynamic functions from time series
The Electric Field Gradient at the Site of the Halogen Ion and Structure of Amino Acid Hydrobromides and Hydroiodides
Authors: Kehrer Armin , Dou Shi-qi , Weiss Alarieh 
Published: February 2015

Abstract
The 79,81Br and 127I NQR spectra of several hydrobromides, respectively hydroiodides, of amino acides and dipeptides were studied, mostly as functions of temperature in the range 77 < T/K <420. The investigated compounds are: L-Arg • HBr • H2O, L-Cys • HBr • H2O , L - Cys - S - S - L - Cys • 2HBr, ethanolamine • HBr, L-Glu • HBr, L-His • HBr, L-His • 2HBr, L-Ile HBr • H2O , Sar • HBr, (Sar)2 • HBr, L-Val • HBr • H2O , Gly • LiBr, Gly-Gly • LiBr, ethanolamine HI, Sar • HI, (Sar)2 • HI, (Gly)2 • HI, (L-Val)2 • HI, Gly-L-Leu • HI • H2O . A phase transition with hysteresis was observed for L-Val • HBr • H2O (Tc.up = 318 K, Tc.down = 242 K). Two solid phases of Sar • HI have been studied by NQR, one crystallized from melt, the other one from aqueous solution.
For three of the title compounds the crystal structure was determined at room temperature: L-His - 2HBr, P212121 , Z = 4, aj pm = 1652, b/pm = 916, c/pm = 721; L-Cys HBr H2O , P212121 , Z = 4, a/pm = 1955, b/pm = 746, c/pm = 550; Gly-L-Leu • HI • H2O , P2X, Z = 2, a / p m = 1289, b/pm = 914, c/pm = 615, ß/° = 99.

In most cases the halogen ion in the studied hydrohalides is polycoordinated by hydrogen bonds of the type N - H • • • X⊖ and O - H • • • X⊖ , X = Br, I. The NQR frequencies and, for iodine, the nuclear quadrupole coupling constants depend on this coordination. A low frequency (coupling constant) region is found for pure N - H • • • X⊖ coordination. Replacing one N - H • • • X⊖ bond by O - H • • • X⊖ rises the electric field gradient, EFG, respectively the resonance frequencies.
The dependence of the EFG on the hydrogen bond coordination N - H • • • X⊖ plus O - H • • • X⊖ is discussed for the title compounds including information from literature
On Heisenberg's Uncertainty Principle and the CCR
Authors: Honegger Reinhard 
Published: February 2015

Abstract
Realizing the canonical commutation relations (CCR) [N, Θ] = - i as N = - i d/dϑ and Θ to be the multiplication by ϑ on the Hilbert space of square integrable functions on [0, 2π], in the physical literature there seems to be some contradictions concerning the Heisenberg uncertainty principle ⟨ΔN⟨ ⟨ΔΘ⟨ ≥ 1/4. The difficulties may be overcome by a rigorous mathematical analysis of the domain of state vectors, for which Heisenberg's inequality is valid. It is shown that the exponentials exp {i t N} and exp{i sΘ} satisfy some commutation relations, which are not the Weyl relations. Finally, the present work aims at a better understanding of the phase and number operators in non-Fock representations.
On Classical Representations of Convex Descriptions
Authors: Bugajski Slawomir 
Published: February 2015

Abstract
It is demonstrated that if V* is not a vector lattice, where V is a base norm Banach space, then there is no commutative observable providing a classical representation for V. This observation generalizes a similar result of Busch and Lahti, obtained for V - the trace class of operators on a separable complex Hilbert space.
Frequency-and Temperature-Dependence of Second Refractivity Virial Coefficients
Authors: Hohm Uwe 
Published: February 2015

Abstract
A reasonable heuristic extrapolation of a theory given by Buckingham is used to estimate the frequency-and temperature-dependence of the second refractivity virial coefficient. The calculations are carried out for the atoms He, Ne, Ar, Kr, Xe and the small molecules H2 , N2 , O2 , HCl, CO2 , N2O, NH3 , CH4 , C2H4 , and SF6 . In some cases the frequency-dependence of BR (ω, T) is compared with experimental values, showing sometimes considerable deviations between experiment and the heuristic approach used in this work.
The Centimeter and Millimeter Microwave Spectrum of 1,1-Difluoro-2-Chloroethylene
Authors: Leal Luis A. , López J. C. , Alonso J. L. , Guarnieri A. 
Published: February 2015

Abstract
The rotational spectra of both 35Cl and 37Cl 1,1-difluoro-2-chloroethylene isotopomers have been measured in the frequency range 12-225 GHz. A first order quadrupole coupling analysis has been performed for both isotopic species. The calculated quadrupole coupling constants for the 37Cl species not previously reported are χaa = - 49.2 (2), χbb = 14.2 (1), and χcc = 28.7 (1). Accurate rotational constants, quartic and some sextic centrifugal distortion constants have also been determined for both isotopomers from the fit to the observed central frequencies.
A Proton NMR Study of n-Decylammonium Chain Dynamics in the Perovskite-type Layered Compound (C10H21NH3)2CdCl4
Authors: Jurga Stefan , Jurga Kazimierz , Reynhardt Eduard C. , Katowski Piotr 
Published: February 2015

Abstract
A detailed proton second moment and spin-lattice relaxation time investigation of the bilayered compound (C10H21NH3)2 CdCl4 is reported. In the low temperature phase the methyl group exe-cutes a classical threefold reorientation, while the NH3 group is involved in a similar reorientation in an asymmetric potential well. Evidence for defect chain motions in this phase has been found, and infomation regarding the potential wells associated with these motions has been extracted from the data. In the high temperature phase, slow chain defect motions and fast fourfold reorientations of chains about their long axes, parallel to the normal to the bilayer, have been observed.
Effect of Cooling Rate on the Structure of Sodium Borate Glasses
Authors: Ennas G. , Musinu A. , Piccaluga G. , Pinna G. 
Published: February 2015

Abstract
Sodium borate glasses with two different compositions have been prepared using cooling rates in the range 7 • 10-3 ◦C/s-2 • 102 °C/s. Structural characterization has been carried out by X-ray diffraction, and glass transition temperatures have been measured by Differential Scanning Calorimetry. The samples exhibit slightly different density values and glass transition temperatures. However, radial distribution functions appear extremely similar and the sodium coordination shell does not change in going from fast to slowly quenched glasses, showing that the short and medium range order is not affected by thermal treatment.
X-Ray and Neutron Diffraction with Amorphous Ti67Si33, V67Si33, and Cr67Si33
Authors: Präffcke A. , Lamparter P. , Steeb S. 
Published: February 2015

Abstract
The amorphous alloys Ti67Si33 , V67Si33 , and Cr67Si33 were produced by sputtering. Their structure was investigated by X-ray and neutron diffraction. X-ray diffraction showed that the structure of the three metallic glasses is not isomorphous. Neutron diffraction showed that Si-Si atomic pairs occur preferentially with distances distinctly larger than the atomic diameter of the Si atoms. For T67Si33 partial pair correlation functions could be evaluated from combination of the X-ray and the neutron data.
The structural results are compared with the structure of amorphous Mn74Si23P3 .
p, T-Dependence of the Molecular Dynamics in a Hydrophobic Model System: 2,2-Dimethyl-1-propanol/D2O
Authors: Has M. , Lüdemann H.-D. 
Published: February 2015

Abstract
Aqueous solutions of 2,2-dimethyl-1-propanol were studied as a model system for the p, T-dependence of the hydrophobic interaction at pressures up to 200 MPa and between 273 K and 403 K. The liquid/liquid phase separation of this alcohol in light and heavy water is described. As expected for aqueous solutions of hydrophobic substances, the solubility of the alcohol is larger in light than in heavy water.
The p, T, c-dependence of the self diffusion coefficients and of the rotatoric mobility, as given by the deuteron spin lattice relaxation times, of the water and alcohol molecules are studied in the one phase region.
The translational and the rotational mobility of the water molecules in the binary solution show at low temperatures the anomalous pressure dependence typical for neat water.
Simplified Non-Empirical Unrestricted Hartree-Fock Approximation (SUHF) for the Calculation of Electronic Ground State Properties of Molecules with Closed and Open Valence Shells. II. Diatomic Molecules
Authors: Koch Wolfhard , Neymeyr Klaus , Pernpointner Markus , Schaper Barbara , Strecker Klaus 
Published: February 2015

Abstract
A comparison of numerical Simplified Unrestricted Hartree-Fock (SUHF) results (electronic ground state configurations, total energies, first ionization potentials, atomic charges, atomic spin densities of diatomic molecules) with those of equivalent standard calculations suggests the applicability of the non-empirical but drastically simplified procedure. SUHF may even approach ab initio quality obtained with simple (STO-3G) contracted Gaussian basis sets.
Anomeric Effect and Charge Density of Dioxane and Dichlorodioxane
Authors: Buschmann Jürgen , Strümpel Marianna , Luger Peter 
Published: February 2015

Abstract
The low-temperature molecular structure and electron density (ED) distribution of dioxane and trans-2,5-dichloro-l,4-dioxane were determined near 100 K from X-ray data. Deformation electron density maps were calculated by Fourier and multipole expansion techniques. The multipole model charge distribution of dioxane determined from experimental data was taken as a reference state, relative to which the ED of the substituted ring was analyzed. These fragment deformation density maps show quadrupolar deformations on atoms O, CI, and anomeric C only. The highly correlated orientation of the lobes at these atomic sites seems to indicate that the observed charge rearrange-ment is caused by three-center interactions.
Electrostatic Potential from High-Resolution X-Ray Diffraction. Application to a Pseudo-Peptide Molecule
Authors: Ghermani N. , Lecomte C. , Bouhmaida N. 
Published: February 2015

Abstract
The calculation of the electrostatic potential of a molecule removed from the crystal lattice is derived from the parameters obtained by a kappa refinement and by a Hansen-Coppens electron density model. These calculations in direct space are applied to N-acetyl-α,β-dehydrophenylalanine; deformation potentials calculated by Fourier transformation are compared to those obtained in direct space.
Electrostatic Properties of 3-(p-Ethoxyphenyl) sydnone
Authors: Fan Jumn-Min , Wang Yu , Ueng Chuen-Her 
Published: February 2015

Abstract
The bonding type and characteristic chemical reactions of the sydnone ring have been rationalized by examination of the deformation electron density distribution and electrostatic potential from both experiment and theory. The net atomic charges, bond lengths and bond orders of the title compound confirm the semiaromatic bonding type for the sydnone ring. The highly negative net atomic charge of C4 suggests its susceptibility to electrophilic substitution at this position. The well known 1,3-dipolar cycloaddition reaction of the sydnone ring can be understood by the analysis of the 7 t -o r b i t a l wavefunctions, which give rise to similar deformation densities as the experimental ones. The good agreement between the experimental and theoretical (ab initio calculation using 3-21G basis sets) deformation density distribution of the title compound justifies the use of the same basis set to derive the electrostatic potential. The electrostatic potential map reveals all the possible protonation sites of the sydnone ring at O1, N2 and O6 with the deepest hole at 06 (84.6 kcal/mole).
Ab initio Study of the Spin Density of Nitroxide Radicals
Authors: Wang Jiahu , Smith, Jr. Vedene H. 
Published: February 2015

Abstract
The spin densities of the nitroxides H2NO, (CH3)HNO and (CH3)2 NO have been studied by iterative CI methods. Calculations at different geometries with various basis sets were performed. It is found that the spin distribution is delocalized within the N-O group, and substitution of the hydrogen atoms on the nitroxyl group by methyl groups changes the spin distribution significantly. Electron correlation, as well as the basis-set quality, plays an important role for the fluctuation of spin populations in the nitroxide radicals. It has been found that the spin density map can be predicted fairly well when correlation was included at certain levels and reasonable quality basis sets were employed. The spin polarization mechanism has been studied through a core excitation method. The superiority of local-spin-density (LSD) theory over the unrestricted Hartree-Fock (UHF) method in spin property studies is discussed.
Visualization of Shapes of Molecular Anions
Authors: Gadre Shridhar R. , Kölmel Christoph , Ehrig Michael , Ahlrichs Reinhart 
Published: February 2015

Abstract
A recently formulated strict definition of the boundary surface of molecular anions has been employed for the visualization of some simple systems. The examples included are CN-, N-
3 , NO -
3 , ClO-
4, ClO-
3 , and BrO-
3 ions. A discussion on the anisotropy of electrostatic interaction of these anions is also presented.