bluuebunny/crossref_metadata_2025 huggingface dataset:
The Topological Entropy for an Inclined Billiard in a Gravitational Field
Authors: Vollmer Jürgen
Published: February 2015

A new parameterization for an inclined billiard initially discussed by Hénon is presented. This parameterization expresses the time evolution of the scattering system by a family of pruned baker transformations. This allows to make contact with recent work on these mappings. As an applica­tion, the topological entropy is analytically derived in a very good approximation and it is indicated how to systematically improve the result. The result which contains no free parameter, agrees excellently with numerical data for the whole parameter range from strongly chaotic scattering described by a complete symbolic dynamics to a bounded system with trivial scattering behavior. 05.45. + b, 03.20. + i, 05.90. + m
The ‘Triptych Fractal’ -A New Feature of the Logistic M ap
Authors: Richter R. , Kruelle C. A. , Kittel A. , Rössler O. E.
Published: February 2015

The recently introduced path length method for nondissipative systems is generalized to dissipa­tive systems, specifically, the logistic map. A new prototype fractal is found to underlie the resulting nowhere-differentiable structure ("triptych principle").
β-Radiation Detected NMR in Solid and Liquid Neon
Authors: Hilmer F. , Schirmer A. , Ackermann H. , Heitjans P. , Stöckmann H.-J.
Published: February 2015

Spin-polarized β-active 23Ne (T1/2 = 37.2s) nuclei were created by capture of polarized cold neutrons in solid and liquid neon. The angular asymmetry of the β-radiation was used to monitor the nuclear polarization. From nuclear magnetic resonance curves the value for the dipole moment |μ(23Ne)| = 1.079(1) n.m. (uncorrected) was obtained which is more precise than the literature value. Comparing the measured spin-lattice relaxation rates with those of stable 21Ne the nuclear quadru­pole moment of 23N e was determined. It agrees with a shell model calculation. The feasibility of 23Ne-β-NMR for investigations in condensed rare gases in demonstrated.
1H -14N Nuclear Quadrupole Double Resonance with Multiple Frequency Sweeps
Authors: Seliger J. , Žagar V. , Blinc R.
Published: February 2015

A new highly sensitive 1H -14N nuclear quadrupole double resonance technique is presented which is based on magnetic field cycling and on the application of multiple frequency sweeps of an r.f. magnetic field. The sensitivity and the resolution o f the new technique are estimated. Some experimental results obtained by the new technique are presented.
Theory of NQR Pulses
Authors: Sanctuary B. C. , Krishnan Mangala S.
Published: February 2015

Pulses applied to spin systems with I > 1/2 in the absence of any external fields, the NQR case, are fundamentally different from NMR pulses. In particular, both rotating and counter-rotating components of the rf field must be kept in NQR, whereas only the “in phase” component need be retained in NMR. NQR pulses are illustrated for I = 3 / 2 in an axially symmetric electric field gradient (EFG).
Numerical Simulation of Magnetic Resonance Experiments: Concepts and Applications to Static, Rotating and Double Rotating Experiments
Authors: Baldus M. , Levante T. O. , Meier B. H.
Published: February 2015

An object-oriented programming environment for numerical simulation of magnetic resonance spectra is introduced and applied to NQR and NMR of quadrupolar nuclei. Using a Floquet approach it is possible to perform simulations of spin systems that are described by explicitly time-dependent Hamiltonians in full analogy to simulations of time-independent systems. Applications to magic angle spinning and double rotation are discussed.
A Theoretical Study of the Vibrational Dependence of the Nuclear Quadrupole Coupling Constants of some Diatomic Molecules
Authors: Lucken E.A.C.
Published: February 2015

The nuclear quadrupole coupling constant was calculated as a function of inter nuclear distance for nine quadrupolar nuclei in eight diatomic molecules by the STO 321G method. From the value of the field-gradient and its first and second derivatives the vibrational dependence of the coupling constants were calculated and shown to com pare satisfactorily with experiment. The behaviour of the field-gradient as a function of inter nuclear distance can in most cases be rationalized in terms of the field-gradient that will arise for the infinitely separated atoms.
Crystal Structure and NQR of Two Copper (I) Complexes of 4,6-Dimethylpyrimidine-2-thione
Authors: Ramaprabhu Sundara , Lucken Edwin A. C. , Bernardinelli Gérald
Published: February 2015

The crystal structure and 63Cu NQR spectra of two neutral hexanuclear Cu(I) complexes of 4,6-dimethylpyrimidine-2-thione, (Hdmpt); [dmptCu]66CHCl3 (l) and [dmptCu]6C2H4Cl2 (2), are reported. The number and relative intensities of the NQR resonances are in agreement with the results of the crystallographic study. The temperature-dependence of the resonances reveals that both compounds undergo a phase-change in the temperature range 77 K -300 K, both of which may be associated with the loss of a symmetry-element present in the high-temperature phase. The 35Cl resonances of CHCl3 in 1 could be observed in the low-temperature phase but the corresponding resonances for C2H4Cl2 in 2 were not detected.
63,65Cu and 79,81Br NQR Studies of Halogenocuprate Complexes of Triphenylphosphine
Authors: Ramaprabhu Sundara , Amstutz Nahid , Lucken Edwin A. C.
Published: February 2015

63,65Cu and 79,81Br spectra of halogenocuprate (I) complexes containing [CuPPh3 X2]- (X = Cl, Br, I) anions with different cations were recorded in the range 77 K -300 K. The results confirm the previous trend that, for a given ligand, 63Cu NQR frequencies are in the order Cl> Br > I. 63Cu NQR frequencies in [CuPPh3 X2]- are compared with those in neutral Cu(Ph3)2 X(X = Cl, Br) complexes and with the [CuX2]- (X = Cl, Br) anions, other three-coordinate Cu(I) complexes.
Tetraguanidium Hexabromocadmate, [C(NH2)3]4[CdBr6]. Crystal Structure and Bromine Nuclear Quadrupole Resonance
Authors: Krishnan V.G. , Dou Shi-qi , Weiss Alarich
Published: February 2015

The 79, 81Br NQR spectra of tetraguanidinium hexabromocadmate, [C(NH2)3]4[CdBr6] have been studied as a function of temperature from 77 K to 390 K and the crystal structure of the compound was determined at room temperature. The title compound crystallizes monoclinic, P21/c, with four formula units in the unit cell, a = 839.2(3) pm, b = 1895.8(6) pm, c= 1527.4(5) pm, β= 108.14(1)°. The anion [CdBr6]4⊖ is an isolated octahedron, with bond lengths 275≤d(Cd-Br)/pm ≤ 281, and bond angles 88 ≤(Br-Cd-Br)/° ≤95, slightly distorted by hydrogen bonds N -H ··· Br. The 81Br NQR sextet, in dependence from temperature, shows positive and negative temperature coefficients. At 77 K the 81Br NQR frequencies have been found between 42.42 MHz and 31.99 MHz; the 79Br NQR at the frequencies expected from the nuclear quadrupole moment ratio Q(79Br)/Q(81Br). Relations between the 81Br NQR spectrum, the crystal structure, and the hydrogen bonds are discussed.
Ionic Dynamics in Plastic Crystal KNO2 Studied by 39K and 15N NMR
Authors: Kenmotsu Motoko , Honda Hisashi , Ohki Hiroshi , Ikeda Ryuichi , Erata Tomoki , Tasaki Akira , Furukawa Yoshihiro
Published: February 2015

The spin-lattice relaxation time of 39K NMR observed in the low-temperature phase (T<264.1 K) of KNO2 is explained by the quadrupole mechanism contributed from a newly found NO2
- motion. The in-plane C3 reorientation and the overvall NO2 rotation as well as the self-diffusion were shown in the intermediate phase (T ≤ 314.7 K) and the high-temperature plastic phase (T < melting point: 710 K), respectively, by observing 39K and 15N NMR relaxation times and 15N lineshapes.
Successive Phase Transitions and High Ionic Conductivity of Trichlorogermanate (II) Salts as Studied by 35C1 NQR and Powder X-Ray Diffraction
Authors: Yamada K. , Isobe K. , Okuda T. , Furukawa Y.
Published: February 2015

A series of trichlorogermanate(II) salts (AGeCl3, A = Rb, Cs, CH3N H3, and (CH3)4N) have been synthesized and characterized by 35Cl NQR , 35Cl NMR , AC conductivity, DTA, and X-ray diffraction techniques. In the temperature range studied two, two, five, and four phases were confirmed for the Rb, Cs, CH3NH3, and (CH3)4N salts, respectively. From the 35Cl NQR and structural data, isolated pyramidal GeCl3 anions were recognized in the low temperature phases. With increasing temperature the relaxation times of the 35Cl NQR decreased exponentially and the signals disappeared far below the melting point. This suggests that the reorientation of the anion about the pseudo three-fold axis is excited. With further increase in temperature, the ionic conductivity of CH3NH3GeCl3 and (CH3)4NGeCl3 increased drastically at the phase transitions to their cubic perovskite phases (CH3NH3GeCl3:σ= 10-1 Sm-1 at 400 K, (CH3)4NGeCl3: σ = 5 x 10-2 Sm-1 at 420 K). The mobile ion was confirmed to be the chloride ion by means of 35Cl NMR and X-ray diffraction.
Phase Transitions in 4,4´-Dichlorobenzophenone as Studied by 35Cl FT-NQR
Authors: Nakayama Hirokazu , Eguchi Taro , Nakamura Nobuo
Published: February 2015

The temperature dependence of 35Cl NQR frequencies in 4,4´-dichlorobenzophenone was measured between 9.3 and 372 K by the pulse Fourier-transform method. Successive phase transitions were observed at 189 and 194 K. Concerning these phase transitions, the curious thermal hysteresis phenomenon found in a previous NQR experiment was not reproduced in the present study. It also follow s that NQR indicates another phase transition around 220 K, although no thermal anomaly was detected there by DTA. Tentative explanations for these three phase transitions are presented in relation to the incommensurability between 189 and 220 K. In addition, a novel phase transition was found to occur at 331 K according to both DTA and 35Cl NQR. A single NQR line observed at room temperature splits into two components above 331 K, suggesting that the symmetry above 331 K is lower than that at room temperature. This is the behavior of re-entrant phase transition, and it reveals the quasi-continuous nature.
Inequivalent Reorientation of the Trichloromethyl Groups in 1,4-Bis(TrichloromethyI) Benzene as Studied by Pulsed 35Cl NQR
Authors: Niki Haruo , Odahara Hirotaka , Tamaki Katsuji , Hashimoto Masao
Published: February 2015

The temperature dependence of T1 of 35Cl NQR of the title com pound evidenced that the three crystallographically inequivalent CCl3 groups have different potential barriers against reorientation (about 30, 36, and 42 kJ/mol). An intramolecular interaction between π-electrons on the benzene ring and the C -Cl bond is proposed to interpret the characteristic frequency splitting common to the 35Cl NQR spectrum of each of the three inequivalent CCl3 groups. The magnitude of T2 of each Cl atom is interpreted by intra-and intermolecular H ··· Cl interactions. It was found that only part of the temperature dependence of the NQR frequency can be interpreted by reorientation.
35Cl NQR Relaxation and Hydrogen Bond in Some Chloral Hemiacetals
Authors: Hashimoto Masao , Matsumoto Shuji , Kunitomo Masakazu , Niki Haruo , Odahara Hirotaka , Tamaki Katsuji
Published: February 2015

The crystal structure of chloral ethylhemiacetal has been determined at 291 K: monoclinic, space group C2
2 - P21, Z = 2, a = 854.5(1), b = 594.0(3), c = 853.3(1) pm, β = 108.30(2)°, R = 0.0962. A sharp decrease of the spin lattice relaxation time T1 found for the 35Cl NQR of the CCl3 groups in chloral methyl-, ethyl-and n-heptylhemiacetals is attributed to the onset of reorientation of the group over a potential barrier o f ca. 39, 37, and 32 kJ/mol, respectively. An unusual T1 vs. 1/T curve with a T1 minimum superimposed on the sharp decrease of T1 due to the reorientation was observed for each of the three 35Cl NQR lines of nHp-CH . This phenomenon is tentatively ascribed to a fluctuation of EFG caused by jumping motion of the hydrogen atom s in the OH groups.
Ionic motion and Disordered Structure in the Rotator Phase of Butylammonium Chloride Studied by Temperature Dependences of 35Cl and 2H NMR
Authors: Hattori Mineyuki , Onoda Yoshito , Erata Tomoki , Smith M.E. , Hattori Masakazu , Ohki Hiroshi , Ikeda Ryuichi
Published: February 2015

Temperature dependences of 35Cl and 2H quadrupole coupling constants and 35Cl NMR spin-lat­tice relaxation times in polycrystalline samples were measured in the rotator phase of the butylammonium chlorides C4H9NH3C1 and C4H9ND3C1, obtainable above the phase transition temperature of 241 K. A rapid decrease o f the quadrupole coupling constants of both nuclei upon heating is attributed to increasing dynamic disorder formed around the polar head. The presence of self-diffussion of Cl- ions was revealed from the spin-spin relaxation time and resonance line-width in single crystals, and confirmed by measuring the dc electrical conductivity.
NQR Spin-Lattice Relaxation of Re in Perrhenates
Authors: Szabo A.J. , Brown R. J. C.
Published: February 2015

The temperature dependence of the spin-lattice relaxation time T1 for the Re NQR in KReO4 , NH4ReO4 and ND4ReO4 has been measured between 77 K and 323 K. The relaxation is electric quadrupolar in all cases, and because of the large quadrupole moment of Re, T1 is short. In KReO4 T1 follows a T2 dependence. In NH4ReO4 , T1 decreases more rapidly than T-2 above about 100 K; between 170 K and 250 K T1 is smaller than 100 (is and could not be measured, but above 250 K, T1 increases to about 140 μs, and the measured data near room temperature lie close to the T-2 extrapolation from the T1 values below 100 K. These results are interpreted as normal anharmonic Raman quadrupolar relaxation, with a T-2 dependence on temperature, combined with an additional relaxation process due to switching of the ammonium ion between two possible orientations.
Nuclear Quadrupole Interaction and Ionic Dynamics in Sodium Superionic Conductors
Authors: Nakamura Nobuo
Published: February 2015

Recent work on the 23N a quadrupole interaction in the NASICON family is reviewed. The applicability and the limitation of the two-dimensional nutation NMR to complex systems with more than one quadrupolar nuclear sites is discussed and the possibility of sodium ion exchange in some of the NASICON-type com pounds is pointed out. The microscopic mechanism of the site exchange is examined by molecular dynamics simulation. A model potential energy function for the site exchange and /or hopping transport o f the sodium ions is proposed. It interprets qualitatively the difference between the activation energies deduced by NMR and by conductivity measurement.
The Energy Dispersion of the Chain Band in YBa2Cu3O6+x and Its Effect on the Cu(2) NQR Frequency
Authors: Eremin M. V. , Markendorf R. , Solovjanov S. G.
Published: February 2015

The energy dispersion of the chain band has been determined in the framework of the Hubbard model. The results are in agreement along the ⌈-S and ⌈ -Y lines of the Brillouin zone with photoemission data. The amount of d3z
2
-r
2 states is zero at y = 0 and increases to 10% at y = 1. The admixture is due to the hybridization of C u (l) dy
2
-z
2 states with Cu(2) d3z
2
-r
2 states via apical oxygen. The effect of this admixture on the NQR frequency of Cu(2) is discussed.
Local Magnetic Fields in some Bismuth Compounds. A Survey of Experimental Evidences
Authors: Kravchenko E. A. , Orlov V. G.
Published: February 2015

The splittings observed in the 209Bi nuclear quadrupole resonances of α-Bi2O3, in zero magnetic field, follow the typical pattern of a Zeeman perturbed NQR spectrum. The lineshapes in Bi3O4Br also indicate a poorly resolved splitting that points to the presence of an internal magnetic field in the order of 200 G. This exceeds notably the dipole nuclear magnetic fields (about several G), but is orders of magnitude smaller than paramagnetic fields produced by unpaired electron spins.

The results obtained using a SQUID and μSR-technique can also be interpreted as indicative of magnetic properties not conventionally expected in such compounds.
The Influence of Reverse Nonradiative Excitation Energy Transfer on the Fluorescence Spectra of Two-component Fluorescent Solutions
Authors: Bojarski  , Kawski A. , Kukliński B. , Diehl H.
Published: February 2015

The reverse non-radiative excitation energy transfer (RNEET) in the system of rhodamine 6G (R6G, donor) and rhodamine B (RB, acceptor) is investigated. The presence of RNEET from the energy acceptors to the energy donors is dem onstrated using steady-state fluorescence and fluorescence anisotropy techniques. The spectra are deconvoluted and obtained results are analysed.
Photoselection of Luminescent Molecules in Anisotropic Media in the Case of Two-Photon Excitation. Part I. Theoretical Considerations
Authors: Kawski A. , Piszczek G.
Published: February 2015

Photoselection of elongated luminescent molecules oriented in a stretched polymer film is considered theoretically for the case of two- and three-photon excitation, having in mind the employment of this phenomenon for determining the angle between the absorption and emission transition moments. Two-photon photoselection provides information on electronic excited states which are not detectable by conventional one-photon spectroscopy due to selection principles.
ESR of Gamma Irradiation Damage Centers in Single Crystals of Thriethanolamine Hydrochloride
Authors: Birey Mehmet , Aktas Huseyin , Zengin D. Mehmet
Published: February 2015

We have observed two radicals in the ESR spectra of y-irradiated single crystals of thriethanolamine hydrochloride: R -ṄH and HN = Ċ - R .
Dielectric Properties of 4-Cyanobiphenyl in 1,4-Dioxane Solution
Authors: v. Homhardt S. , Stockhausen M. , Jadżyn J. , Kędziora P. , Ghoneim A. , Turky G.
Published: February 2015

The static and dynamic dielectric properties o f the title system are reported for a concentration series from about 8 mmol/1 up to 2.3 mol/I at 20 °C. The apparent moment (4.2 D , extrapolated to infinite dilution) decreases with increasing concentration, the relaxation time increases proportional to viscosity, that is, somewhat steeper than usually observed. Com parison with other molecules suggests that these features are mainly due to the high dipole moment rather than being specifically related to the prolate shape o f the molecule. The broadening o f the spectrum toward the high frequency side, on the other hand, may be due to the molecular shape.
Relation between NMR Properties and Electrical Resistivity in Li-Ge, Li-Sn and Li-Pb Liquid Alloys
Authors: Xu R. , van der Lugt W.
Published: February 2015

Recent measurements of the electrical resistivity of liquid Li-Ge alloys enable us to check relations between NMR properties and resistivity in non-metallic alloys derived by Warren in 1971. It is shown that the predicted linear relationships hold, but that the proportionality between the square root of the conductivity and the Knight shift is violated to some degree. A possible cause is the neglect of quadrupole interactions. Also, the relations only hold if the composition rather than the temperature is taken as the implicit parameter.
Electron Paramagnetic Resonance of some Irradiated Ammonium Compounds
Authors: Köksal Fevzi , Yavuz Metin
Published: February 2015

Gamma irradiation damage centres in (NH4)2SiF6, (NH4)2SnCl6, (NH4)2PtCl6, [(CH3)2NH2]2SnCl6, (NH4)2PdCl6 and ultraviolet irradiation damage centres in (CH3)4NCH3COO and (CH3)4NBr have been investigated by electron paramagnetic resonance spectroscopy. It has been found that the radicals produced in (NH4)2SiF6 and (NH4)2SnCl6 is N2H4
+ , and those in (NH4)2PtCl6 are NH3
+ and (PtCl6)3-. In [(CH3)2NH2]2SnCl6 the species is (CH3)2NH+ , and in (NH4)2PdCl6 the species is (PdCl6)3 -. Furthermore, it has been shown that the ultraviolet irradia­ tion produces ĊH3 and CO2
- radicals in (CH3)4NCH3COO and ĊH3 radical in (CH3)4NBr. The EPR parameters of the observed radicals have been determined.
On the Enclathration of NaB(OH)4 in the β-Cages of Sodalite: Crystallization Kinetics and Crystal Structure
Authors: Buhl J.-Ch. , Mundus C. , Löns J. , Hoffmann W.
Published: February 2015

The hydrothermal formation of sodium hydroxyborate enclathrated sodalite synthesized from an initial ternary mixture of mullite, cristobalite and corundum has been investigated. Depending on temperature and pressure the compound Na7.5[AlSiO4]6[B(OH)4]1.5 · 2H2O could be synthesized in form of polycrystalline powder as well as in form of single crystals. The kinetics of the sodalite growth could be determined at 423 K and 473 K. 29Si-and 27Al MAS NMR was shown to be the preferred method to describe the conversion into sodalite quantitatively. Evidence for the first formation of polycrystalline sodalite has been found after the total dissolution of mullite and cristobalite.

Single crystal X-ray diffraction data were used for the structure determination and refinement. The position and orientation of the hydroxyborate anions within the sodalite's /β-cages could only be found in the course of a "rigid body" refinement with constraints for the B(OH)4 tetrahedron. The boron atoms are located in an off-centre position within the sodalite cages. One out of the four oxygen atoms of the hydroxyborate group is positioned near the centre of a face of the sodium tetrahedron, whereas the three remaining oxygen atoms are near to the middle of its edges.
Mössbauer Studies of Nickel-Iron Hydrotalcites
Authors: Pegelow U. , Winterer M. , Mosel B. D. , Schmalzb M. , Schöllhorn R.
Published: February 2015

Hydrotalcite-like Fe-Ni-hydroxides [Ni2/3
IIFe1/3
III(OH)2](CO3)1/6(H2O)y , [Ni3/4
IIFe1/4
III(OH)2]-(CO3)1/8(H2O)y and [Ni3/4
II/IIIFe1/4
III(OH)2](CO3)0.14(H20)y as well as the ternary oxide NaNi2/3Fe1/3O2 have been studied by 57Fe-Mössbauer spectroscopy. All samples contain Fe3+ in a high spin state. The quadrupole interaction is smaller if a magnetic splitting is present, which may indicate a non-parallel arrangement of the principal axis of the EFG and the hyperfine field. The temperature dependence of the spectra has been understood in terms of collective cluster excitations. In this model the magnetic energy of a single domain depends on the direction of the total magnetic moment and on magnetic interaction with the neighbourhood. The spectral lineshape could be fitted assum­ing uniaxial relaxation.
Bifurcations in Globally Coupled Shift Maps
Authors: Just W.
Published: February 2015

A map lattice of globally coupled shift maps is investigated by analytical methods. The breakdown of the well known space time mixing regime at weak coupling strength is accompanied by a global synchronization of the maps. Furthermore a Cantor set like repeller survives which produces chaotic transients.
The Influence of Noise on Fractals
Authors: Hamm Andreas
Published: February 2015

The weak-noise asymptotics of the blurring effect of noise on fractals can be described by scaling laws. It does not only depend on the geometric properties of the fractals but also on their generating dynamics. This is illustrated with the example of the Feigenbaum attractor.
From Dispersion to Laminarity in Dynamical Systems
Authors: Zumofen G. , Klafter J.
Published: February 2015

We study transport in dynamical systems characterized by intermittent chaotic behavior with coexistence of dispersive motion due to periods of localization, and of enhanced diffusion due to periods of laminar motion. This transport is discussed within the continuous-time random walk approach which applies to both dispersive and enhanced motions. We analyze the coexistence for the standard map and for a one-dimensional map.
Theory of linear response applied to the lithium isotope effects on the mobilities in molten LiCl
Authors: Schäfer Lutz , Klemm Alfred
Published: February 2015

Expressions in terms of group-velocity time-correlation functions for the ionic mobilities of molten 6LiCl,7 LiCl and (6Li,7 Li)Cl are derived, taking the time-averaged zero momentum of inertia of each of the three groups of ions into account. MD-simulations have been performed for 6LiCl and 7LiCl, yielding agreement between the simulated and the published experimental reduced isotope effect, although the temperature -volume conditions of the simulations did not conform with natural LiCl.
No Decelerated β-Decay of Tritium Solved in Titanium
Authors: Wicke Ewald
Published: February 2015

Experimental results on the interaction of tritium with fine

particles of titanium, published in Phys. Lett. A and attributed

to decelerated β-decay of tritium solved in titanium, are

instead explained by adsorption of tritium on the surface of

the particles, formation of tritium oxide when oxygen is present,

and normal β-decay.
Finite Larmor Radius and Hall Effects on Thermal Instability of a Plasma in Porous Medium
Authors: Sharma R. C. , Bhardwaj V. K.
Published: February 2015

The thermal instability of a plasma in a porous medium in the presence of a finite Larmor radius (FLR) and Hall effects is considered. Oscillatory m odes due to the presence of a magnetic field (and hence the presence of FLR and Hall effects) are introduced. For stationary convection, the FLR may have a stabilizing or destabilizing effect, but a completely stabilizing one for a certain wave-number range. Similarly, the Hall currents may have a stabilizing or destabilizing effect but a completely stabilizing one for the same wave-number range under certain condition, whereas the medium permeability always has a destabilizing effect for stationary convection.
Einfluß des Silberkations auf das Fluoreszenzverhalten polyzyklischer aromatischer Kohlenwasserstoffe
Authors: Komfort Michael , Küster Jörn , Dreeskamp Herbert
Published: February 2015

Combining the results of fluorescence and triplet-triplet absorption measurements, the influence of silver perchlorate on the excited states of pyrene, phenanthrene, 9-cyanophenanthrene, 9,10-diphenylanthracene and 9,10-dicyanoanthracene in fluid solutions has been investigated. In corre­ spondence with a small energy gap between the lowest excited singlet state and the nearest lower triplet state an external heavy atom effect has been found to be responsible for the fluorescence quenching in the case of pyrene, phenanthrene and 9-cyanophenanthrene. In the case of 9,10-diphenylanthracene and 9,10-dicyanoanthracene, where this energy gap is large, an exciplex emission is observed with no significant increase of triplet state formation. Furthermore, 9-cyanophenanthrene and 9,10-dicyanoanthracene under similar experimental conditions form ground state complexes with AgCIO4 with a red-shifted fluorescence. From time-resolved fluorescence measurements a dynamic equilibrium of association in the excited state is deduced.
Kinetics and Mechanism of Nd2CuO4 Synthesis
Authors: Ghigna Paolo , Scavini Marco
Published: February 2015

The reaction Nd2O3 + CuO → Nd2CuO4 was investigated on the basis of the Wagner-Schmalzried theory of diffusion-driven reactions between crystalline solids, with the help of monodimen­sional chemical diffusion measurements. It was found that the kinetics of the process is governed by Cu2+ diffusion, and the chemical diffusion coefficient D̃(Cu2+) in the Nd2CuO4 matrix was obtained (9.9 · 10-13, 1.97 · 10-12 and 1.98 · 10-11 cm2 s-1 at 1223, 1273 and 1323 K, respectively). The relatively low value of D̃(Cu2+) was interpreted on the basis of the crystal structures of the compound and related materials, which in addition may suggest an alternative rationale for the interpretation of neodymium immobility.
121Sb and 35Cl NQR in RCN · SbCl5 Complexes
Authors: Semin G. K. , Kuznetsov S. I. , Raevsky A. M. , Bryukhova E. V.
Published: February 2015

35Cl and 121Sb NQR spectra of RCN · SbCl5 complexes with R = Et, n-Pr, i-Pr, n-Bu, n-C5H11 , Cl(CH2)2, C6H4CH2, Ph, Cl, Me, CCl3 were measured and /or refined at 77 K. Redistribution of the "transferred charge" in the SbCl5 fragment of the complexes under study was investigated. The existence of a specific region of dispersion of the electron-nuclear motions (DENM) in RCN · SbCl5 complexes was established.
79,81Br NQR Spectra of Alkyl(4-Bromophenyl)Sulphides
Authors: Feshin Valentin P. , Nikitin Peter A. , Aliev Ismail A.
Published: February 2015

The 79,81Br NQR spectra of compounds of the series 4-BrC6H4SR with R = (CH2)nH (n = 1, 2, 4-9), (CH2)nCH(CH3)2 (n = 0-2) and CHm(CH3)3-m were obtained at 77 K. The halogen atom electron densities in these compounds and chlorine-containing analogs are compared. The ratio of the amplitudes of the NQR frequency oscillations in chlorine-and bromine-containing compounds with R = (CH2)nH corresponds to the ratio of the polarizabilities of 35Cl and 79Br. The variation of the alkyl groups R influences the electron distribution of the halogen atom.
Notizen: On the Sign of the Off-Diagonal Elements of the Nuclear Quadrupole Coupling Tensor
Authors: Spoerel U. , Dreizler H. , Stahl W.
Published: February 2015

If off-diagonal elements of the nuclear quadrupole coupling tensor are determined from the rotational spectrum of only one isotopomer, the magnitude of the off-diagonal elements and the sign of the product χabχbcχac can be obtained but not the individual signs of the off-diagonal elements. In this article we give two proofs for this fact. A determination of the individual signs of the off-diagonal elements is only possible by analysing the spectra of more isotopomers.
Non-Strange Baryon Resonances in the Isgur-Karl Model Including the N=3 Oscillator Shell
Authors: Querbach Stefan , Kretzschmar Martin
Published: February 2015

The nonrelativistic constituent quark model for excited baryon states in the version proposed by Isgur and Karl is extended toward higher energies by including all states containing up to three oscillator excitation quanta. At high energies baryon resonances with spins up to 9/2 become accessible. At all energies and in particular for lower spins strong configuration mixing is obtained. Model predictions are compared to the empirical resonance energies derived in the Karlsruhe-Helsinki pion nucleon phase shift analysis. A search is made for parameter sets that apply simultaneously to the positive parity and the negative parity states. Numerical results are presented and discussed in relation to experimental data and to other theoretical works.
Provenance Study of Famous Chinese Greenware Bodies Using Principal Component Analysis
Authors: Yap C. T. , Hua Younan
Published: February 2015

This work is based on published analytical data of 69 pieces of Chinese greenware bodies from seven famous wares: Yue, Longquan, Southern Song Guan, Ru, Jun, Yaozhou, and Ge. It is possible to do provenance studies of these wares by the application of principal component analysis using major and minor chemical constituents (Si02, Al2O3, Fe2O3, CaO, MgO, K2O , Na2O , and TiO2). The results show that not only are northern and southern greenwares completely distinct in the raw materials used, but in addition the southern greenwares are reasonably well segreated into groups belonging to Yue ware, Longquan ware (white body), Longquan ware (black body) and Southern Song Guan ware. Our analysis also confirms the production of Ge ware in the Longquan area.
Intraionic Structure of HS04
- and Alkali Cation Configuration in Molten NaHS04 and KHS04
Authors: Fukushima K. , Murofushi M. , Oki M . , Igarashi K. , Mochinaga J. , Iwadate Y.
Published: February 2015

The short range structure of molten NaHSO4(I) and KHSO4(II) was estimated by X-ray diffraction. The polyatomic anion, HSO4
-, in both molten salts was found to have a distorted tetrahedral structure in which the bond lengths of S-O and S-OH were 1.45 Å and 1.53 Å in (I) and 1.46 Å and 1.56 Å in (II), respectively. The coordination number of the Na+ or K+ around the HSO4
- was evaluated to be about unity. The semi-empirical molecular orbital calculations by the MNDO-MOPAC method were applied to the determination of the intraionic structure of the H S 0 4 and the bond lengths of S-O and S -OH were computed to be 1.528 Å and 1.666 Å, respectively, supporting qualitatively that the HSO4
- forms a rather distorted tetrahedron.
Photoionization of C60 and C70 in Liquid Alkanes
Authors: Katoh Ryuzi , Lacmann Klaus , Schmidt Werner F.
Published: February 2015

Single photon ionization of C60 in 2,2-dimethylpropane (neopentane, NP), 2,2,4,4-tetramethylpentane (TMP), 2,2-dimethylbutane (neohexane, DMB), and 2,2,4-trimethylpentane (isooctane, iso-OCT), and of C70 in TMP was studied by photoconductivity measurement. Threshold energies of the photoconductivity were determined. From these results, the polarization energies and the ionic radii of the cations were obtained by application of Born's formula. The ionic radii turned out to be smaller than the van der Waals radii of the molecules.
On Biharmonic Fractals Displaying a Structural Transition
Authors: Canessa Enrique , Wang Wei
Published: February 2015

A new class of fractal structures displaying a structural transition on growing is studied by considering the morphology selection mechanism under the biharmonic field V̄2(V̄2u) = 0 as recently proposed by the authors [Phys. Rev. E 47, 476 (1993)]. By relating the growth probability for each site to the local ("potential") field as (V̄2u)n , the effects of the surrounding medium and of geometrical constraints for the seed particles are numerically calculated and discussed. A theoretical estimation of the transition point is given anew by solving the biharmonic equation with the boundary conditions used in simulations.
Isomerization of Diphenyl Polyenes. Part VIII. Absorption and Fluorescence Properties of l-Phenyl-4-diphenylthiophosphinyl Butadiene in Poly (vinyl alcohol) Film
Authors: Kawski A. , Piszczek G. , Kukliński B. , Nowosielski T.
Published: February 2015

The effect of temperature (from 296 to 423 K) upon the absorption and fluorescence of l-phenyl-4-diphenylthiophosphinyl butadiene (PDPB) and of the direct irradiation on the absorbance were investigated in poly(vinyl alcohol) film. It was found that for PDPB in PVA film the transition from cis to trans configuration is only possible as a result of thermal isomerization due to the softening of PVA polymer, whereas photoisomerization results in both cis-to-trans and trans-to-cis transitions. Similar as with 1,4-diphenyl-1,3-butadiene in PVA, the luminescence is due to two, trans-trans and cis-trans, PDPB conformers.
Missing Link Between Probability Theory and Quantum Mechanics: the Riesz-Fejer Theorem
Authors: Fröhner F. H.
Published: February 2015

Quantum mechanics is spectacularly successful on the technical level but the meaning of its rules remains shrouded in mystery even more than seventy years after its inception. Quantum-mechanical probabilities are often considered as fundamentally different from classical probabilities, in disre-gard of the work of Cox (1946) -and of Schrödinger (1947) -on the foundations of probability theory. One central question concerns the superposition principle, i. e. the need to work with inter-fering wave functions, the absolute squares of which are probabilities. Other questions concern the relationship between spin and statistics or the collapse of the wave function when new data become available. These questions are reconsidered from the Bayesian point of view. The superposition principle is found to be a consequence of an apparently little-loiown mathematical theorem for non-negative Fourier polynomials published by Fejer in 1915 that implies wave-mechanical inter-ference already for classical probabilities. Combined with the classical Hamiltonian equations for free and accelerated motion, gauge invariance and particle indistinguishability, it yields all basic quantum features -wave-particle duality, operator calculus, uncertainty relations, Schrödinger equation, CPT invariance and even the spin-statistics relationship -which demystifies quantum mechanics to quite some extent.
Determination of the Absolute Configuration of Bis(tetrahydropyran2-yl)methane by Comparison of Measured and Calculated CD-spectra
Authors: Fleischhauer Jörg , Jansen Christoph , Koslowski Axel , Raabe Gerhard , Schiffer Jan , Wollmer Axel
Published: February 2015

The absolute configuration of bis(tetrahydropyran-2-yl)methane (1) was determined by comparison of measured and calculated CD spectra. The theoretical CD spectra were obtained by means of the CNDO/2S method. The five presumably lowest local minima on the energy hypersurface of the title compound were used to describe the conformer equilibrium mixture. The geometries of these conformers were calculated employing the MM3 force field, the semiempirical AM1 method and one-determinant ab initio calculations employing the 6-31G* basis set. Boltzmann factors were then obtained using relative energies calculated with three different basis sets and including correlation- and zero point vibrational energy. Based on the sign of the observed and calculated longest wavelength Cotton effect we assign an absolute configuration to the compound which is in keeping with the chirality expected from the assumed reaction mechanism. The results of force field and ab initio calculations converge to the point that the conformer equilibrium is dominated (85 -96%) by one single conformer which is energetically separated from the other conformers by about 2-3 kcal/mol. This result agrees with previous experimental data.
Control of a Chaotic Relay System Using the OGY Method
Authors: Holzhüter Th. , Klinker Th.
Published: February 2015

The control method of Ott, Grebogi, and Yorke (OGY) is used to stabilize the unstable periodic orbits of a chaotic relay system. Small variations in the height of the relay output are used as control input. The influence of the control activation bound is studied in detail via the one-dimensional Poincare map of the controlled system. The reduced sensitivity of the multi-step OGY method for higher period orbits can thus directly be verified.
Double Resonance Detection Using Zero Field Level Crossing
Authors: Stephenson David , Smith John A. S.
Published: February 2015

Double resonance level crossing detection cannot normally be used to record transitions between the quadrupole Zeeman levels. Neither can it be used if the quadrupole resonance frequency is larger than the proton NMR frequency in high field. A simple variation of the level crossing experiment is demonstrated which allows energy to be efficiently transferred from quadrupole to proton system and hence lead to detection in these two cases. In the case of the quadrupole Zeeman levels it allows transitions between the ±½ levels to be detected in a small magnetic field, allowing measurement of the asymmetry parameter (ƞ) for spin 3/2 systems. This is demonstrated for the 11B nucleus in triethanolamine borate. Detection of high frequency quadrupole transitions is demonstrated from which relaxation information is obtained.
Ionic Size Induced Defects in Lead Titanate-Zirconate Perovskite Studied by TDPAC Method
Authors: Filho J. Mestnik , Carbonari A. W. , Motta E. F. , Moralles M. , Saxena R. N. , Olzon-Dionysio M. , de Souza S. D.
Published: February 2015

Time differential perturbed angular correlation (TDPAC) measurements were carried-out on PbZr0.8Ti0.2 O3 as a function of temperature. A broad distribution of electric field gradient (EFG) was observed in all cases with a second site for 181Hf-181 Ta probes in the R3c phase. The results were analyzed in terms of a model which simulates an attraction of the ions by the smaller Ti ions. The EFG was calculated within the point charge approximation, by averaging over a large number of configurations generated by random distribution of the Ti ions in an ensemble of lattice cells. It was verified that the model reproduces qualitatively the broadening of the TDPAC frequencies as well as explains the second component EFG observed experimentally.
Calculation of Electric Field Gradients in Isolated Molecules Using the FPLAPW-Code WIEN95
Authors: Soldner Torsten , Tröger Wolfgang , Butz Tilman , Blaha Peter , Schwarz Karlheinz
Published: February 2015

The full potential linearized augmented plane wave method as embodied in the program package WIEN95 was originally developed for crystalline solids and is based on crystal periodicity. The present work demonstrates that it is applicable to isolated molecules with the examples of CdCl2 , HgF2 , and HgCl2 by investigating the required size of artificially enlarged unit cells and by calculating bond distances and vibrational frequencies in excellent agreement with experimental data. The dependence of electric field gradients at Cd and Hg, respectively, on bond angle is investigated. A point charge like behaviour of energetically low lying states is found, whereas large discrepancies from the point charge model occurred for the energetically high lying valence states.
23Na Nuclear Spin-Lattice Relaxation in Dehydrated Zeolite NaY
Authors: Igarashi Mutsuo , Okubob Noriaki , Yoshizaki Ryozo
Published: February 2015

The spin-lattice relaxation time T1 of 23Na-NMR in dehydrated zeolite NaY has been measured from 26 to 300 K. The magnetization recovery curve is not single-exponential at all measured temperatures and T1
-1 increases in proportion to the square of temperature above 200 K. The result is analyzed with a theory of the Raman process based on covalency. The value of T1 is compared with that of NaX in which the concentration of Na is about 2 times larger than in NaY.
35Cl NQR and 1H NMR Studies of Molecular Motions in Guanidinium Salt of Chloroacetic Acid
Authors: Zdanowska-Fnjczek Maria , Grottel Małgorzata , Jakubas Ryszard
Published: February 2015

Multinuclear NQR and NMR techniques have been applied in order to study the molecular dynamics in [C(NH2)3](ClH2CCOO). The 35Cl NQR frequency was measured over a wide range of temperature. The experimental results were described by using the theories of Bayer and Brown which take into account the torsional oscillations of the CClH2 -group of the anion.

A study of the proton NMR second moment as well as relaxation times T1, and T1p performed in a wide temperature range revealed an onset of the guanidinium cation reorientation around its two-fold symmetry axis. Activation parameters for this motion were determined.
Hyperfine Interactions of 57Fe Nuclei in the Study of Interdiffusion Phenomena and Phase Formation
Authors: Carbucicchio M. , Palombarini G. , Rateo M.
Published: February 2015

The effects of interdiffusion phenomena and reactions occurring in the early stages of the interaction at 1273 K between iron and chromium monoborides were studied by transmission Mössbauer and X-ray diffraction techniques, and modifications occurring in Fe/Al multilayers during both deposition and subsequent thermal aging at 400 K in vacuum or air were studied by conversion electron Mössbauer and Auger electron depth profiling techniques. In both cases the main objective of the work was to obtain a better understanding of the mechanisms of modification of the materials under examination with a view towards improving the properties of materials and coatings for specific applications.
NMR of 51V in VRuP: Possible Onset of Charge-Density-Waves
Authors: Nishihara H. , Kanomata T. , Sato K. , Suzuki N. , Harada T.
Published: February 2015

NMR experiments are reported for VRuP which has an orthorhombic TiNiSi structure and shows anomalies in the temperature dependence of the electric conductivity and static susceptibility. A field-swept spectrum of 51V perturbed by a quadrupole interaction has been observed, which shows no anomalous temperature dependence. However, the metallic spin-lattice relaxation rate decreases in a stepwise fashion with decreasing temperature at around 200 K, in accordance with the resistivity and the susceptibility data, suggesting a possible CDW formation in this material.
Investigation of Some New Nonlinear Optical Crystals by Means of NQR, IR and X-Ray Diffraction Methods
Authors: Petrosyan A. M. , Terzyan S. S. , Burbelo V. M. , Sukiasyan R. P.
Published: February 2015

Some new analogues of the nonlinear optical crystal L-arginine phosphate monohydrate (LAP) (Arg • HIO3 , Arg • 2HIO3 , Lys • HIO3 , Lys • 2HIO3 , Lys • 3HIO3 , Bet • 3HIO3) were obtained and investigated by means of IR, NQR, X-ray diffraction and SHG methods. The importance of this class of crystals for revealing new nonlinear optical crystals is pointed out.
NQR View of Solid Phases of NOCl
Authors: Pirnat J. , Trontelj Z. , Borrmann H.
Published: February 2015

Chlorine NQR studies of solid nitrosyl chloride NOC1 between 110 and 212 K are reported. In the temperature dependence an order-disorder phase transition near 145 K, found by X-ray diffraction, is confirmed. Unusual hysteretic NQR signal behaviour indirectly proves also the low temperature phase transition below 100 K. In the measured temperature region fast relaxing mechanisms are present. The upper limit of the expected 14N NQR frequency is estimated using the Townes-Dailey approach.
Phase Transformation and Structure of N-chlorocarbonylisocyanide Dichloride
Authors: Romanenko Evgenii A.
Published: February 2015

The 35Cl nuclear quadrupole resonances in N-chlorocarbonylisocyanide dichloride show that it exists in two polymorphic forms. The metastable a phase has six 35Cl NQR lines and the stable β phase has three. The latter is obtained irreversibly by annealing the α phase at 179 K. The temperature dependences of the 35Cl NQR frequencies, spin-lattice and spin-spin relaxation times are obtained in both phases. The results of the 35Cl NQR studies are discussed together with calculated MNDO level data and other physical properties (IR frequencies, dipole moments) of this compound.
63Cu NQR Studies of Three-coordinated Complexes of Cu(I) with an Isocyanide Ligand
Authors: Khajenouri Fereidoun , Motallebi Shahrokh , Lucken E. A. C.
Published: February 2015

The 63Cu NQR spectra of five three-coordinated complexes of Cu(I) containing an isocyanide ligand are reported. The resonance frequencies are compared with those of other three-coordinated Cu(I) complexes using a partial coupling constant model to describe the effects of the various ligands and to take into account the effects of variations in the molecular geometries. The partial coupling constant of the isocyanide ligand is much higher than that of any other ligand studied so far and leads to the order of donor atom partial field gradients for terminal ligands C>N>Cl>P ≈ S ≈ Br>I>O.
Experimental Gas-phase Halogen Nuclear Quadrupole Coupling Constants; A Review
Authors: Palmer Michael H.
Published: February 2015

As a preclude to a theoretical study of nuclear quadrupole coupling constants (NQCC), via the electric field gradients at equilibrium, we review the current state of knowledge of gas-phase data for a diverse set of axially symmetric inorganic and organic molecules with symmetries C3v , C∞v , D∞h in particular, where the heavy elements are CI, Br and I with C, Si and Ge hydrides. In most of the cases, the latter elements are in an approximately tetrahedral environment.
Metalltetrahydridoborate und Tetrahydridometallate, 11 [1] Zur Kristall- und Molekülstruktur von Magnesiumtetrahydridoborat Mg(BH4)2 • 3 THF / Metal Tetrahydridoborates and Tetrahydridoborato Metallates, 11 [1] The Crystal and Molecular Structure of Magnesium Tetrahydridoborate Mg(BH4)2 • 3 THF
Authors: Nöth Heinrich
Published: February 2015

Mg(BH4)2 • 3 THF was prepared from MgHo and B2H6 in tetrahydrofuran. It crystallizes monoclinically, space group C2/c, Z = 4. The crystal structure reveals that the molecule contains a seven-coordinate Mg center. Its BH4 groups form double hydrogen bridges to magnesium. The geometry at Mg corresponds to a slightly distorted trigonal bipyramid for the O 3 B 2 (Mg)-coordination polyhedron, with two THF molecules in apical and one in equatorial position. A two-fold crystallographic axis passes through Mg and the equatorial oxygen atom thus posing C2 symmetry on the molecule