bluuebunny/crossref_metadata_2025 huggingface dataset:
209Bi NQR Powder Spectra Influenced by Local and Applied Magnetic Fields
Authors: Ainbinder N. E. , Volgina G. A. , Kravchenko E. A. , Osipenko A. N. , Gippius A. A. , Hai Fam Suan , Bush A.A.
Published: February 2015

Several experimental techniques have shown evidence for the existence of internal magnetic fields of the order of 200 G in α-Bi2O3 [1]. The asymmetrical 209Bi NQR lineshapes in Bi3O4Br also point to a source of poorly resolved splitting present in this compound.

In order to obtain further insight into the origin of the local magnetic fields in these compounds the 209Bi NQR lineshapes of polycrystalline a-Bi2O3 and Bi3O4Br were recorded in weak (below 500 G) static magnetic fields. A calculation of the expected powder lineshapes in a-Bi2O3 under the influence of the internal and applied magnetic fields up to 1 kG was made. The results of the computer simulation are compared with the lineshapes recorded. From the 209Bi lineshapes ob­ served in the experiment, the local magnetic field at one of the two Bi-sites in Bi3O4Br was estimated.
Double Modulation Technique in Pulsed Jet Experiments with Tunable Diode Lasers
Authors: Pa I. , Hepp M. , Philipp R. , Schieder R. , Winnewisser G.
Published: February 2015

A double modulation technique was used to achieve higher sensitivity in absorption measure­ ments with a pulsed supersonic jet. The wavelength of a lead-salt diode laser was modulated at a frequency of 10 kHz and detected at twice the frequency by a lock-in amplifier, reducing significantly the influence of the low frequency excess laser noise. The output of this lock-in amplifier was measured by a boxcar integrator, driven at 80 Hz, the frequency of the pulsed jet. In case the duration of the jet pulse is long enough, a second lock-in amplifier can also be used instead of the boxcar integrator. The optical path of the diode laser radiation through the jet was increased 16 times by using White type multireflection optics. The achieved value for the minimum detectable absorption of Ar - CO complexes in the jet was 2 x 10-5 in relative absorption, limited by the excess noise of the diode laser.
Potential of the Aqueous Ag – Ag2SO4 Electrode in 1 m Na2SO4 in Contact with 1 m H2SO4 at up to 473 K and 975 bar
Authors: Bilal B. A. , Müller E.
Published: February 2015

The potential of the Ag - Ag2SO4 electrode in 1 m Na2SO4 solution in contact with 1 m H2SO4 solution has been determined up to 473 K and 975 bar. The potential of the electrode in aqueous 1 m Na2SO4 solution without accounting for any diffusion was calculated under the same p and T conditions taking the formation of NaSO-
4 into account. Small differencies ( ≤ 2%) have been found in comparison with the values given previously by the authors [1] assuming a complete dissociation of Na2SO4.
Molecular Properties of PPO Excimer Luminescence in a Binary Solvent
Authors: Burak F. , Tyrzyk J. , Polacki Z.
Published: February 2015

Time resolved emission spectra and the luminescence decay of 2,5-diphenyloxasole in dioxane-water mixtures disclose an important influence of water on the observed luminescence. We suppose that this is caused by structural changes of the solution connected with its water content.
Upper and Lower Bounds for the Number of Conjugated Patterns in Carbocyclic and Heterocyclic Compounds
Authors: Morikawa Tetsuo
Published: February 2015

It is possible to regard two polygonal skeletons as the same in a special class of carbocyclic and heterocyclic compounds, if the one is reducible to the other by means of the contraction of cyclic subskeletons, and if the numbers of conjugated patterns in them are equal to each other. In such polygonal skeletons, three forms of cyclic subskeletons are defined; the one is called “alternate”, and the others, involving the one called “inclusive”, have a path (b, b), where (b) is a conjugated vertex connecting with three vertices. Successive eliminations of the cyclic subskeletons enable to estimate the upper and lower bounds for the number of conjugated patterns in a given polygonal skeleton.
Coordination of Eu3+ Ions in a Phosphate Glass by X-ray Diffraction
Authors: Medda Maria Paola , Piccaluga Giorgio , Pinna Gabriella , Bettinelli Marco , Cormier Guy
Published: February 2015

Two vitreous samples, 0.9 Z n (PO3)2 • 0.1 Eu(PO3)3 and pure zinc metaphosphate, were examined by X-ray diffraction to determine the local environment of the Eu3+ ion. Using a difference procedure involving the radial functions of the two glasses, the results indicate that the rare-earth ion is surrounded on average by a polyhedron of about 7.4 oxygens at 2.36 A and about 1.6 oxygens at 2.68 Å. A possible different coordination of the zinc ion in the two samples, suggested by the experimental findings, is discussed.
Exact Solutions of Two Body Dirac Equations
Authors: Nag Nivedita , Roychoudhury Rajkumar
Published: February 2015

A set of exact eigen values and eigen functions for the two body Dirac problem described by the Hamiltonian

H = (α⃗1 - α⃗2)p⃗ + β1m 1+ β2m2 + ½ (β1 + β2) λr

are obtained using the properties of Supersymmetric Quantum Mechanics.
Dielectric Relaxation in Nematic and Isotropic Phases of 4-(trans-4'-n-Propylcyclohexyl) isothiocyanatobenzene
Authors: Jadżyn J. , Hellemans L. , Stockhausen M. , Legrand C. , Czechowski G.
Published: February 2015

The results o f a dielectric relaxation study (in the frequency region from about 1 kHz to 1 GHz) of the liquid crystalline title com pound (C3H7-Cyhx-Ph-NCS , 3-CHBT) in the isotropic and the nematic phase (measurements with electric field parallel to alignment) are presented. The spectra of both phases can be described by two relaxation processes of Debye-type, possibly related to rotation around the long and short molecular axes.
Fluorescence and Phosphorescence Anisotropy Spectra of Indole in Poly (Vinyl Alcohol) Film at Room Temperature
Authors: Kawski A. , Gryczyński I. , Gryczyński Z.
Published: February 2015

Excitation anisotropy spectra of indole were measured in poly (vinyl alcohol) film at room temperature. The behaviour of the phosphorescence anisotropy of indole in isotropic and anisotropic PVA film enabled a conclusion to be drawn that the T1 - S0 transition is located outside the indole ring plane, close to the perpendicular direction.
Rotational Spectra of 14N17O and 15N18O
Authors: Saleck Axel H. , Liedtke Martin , Dolgner Alexandra , Winnewisser Gisbert
Published: February 2015

The mm-wave spectra of 15N18 O and 14N 17 O in both X2 Π1/2 and X2 Π3/2 states have been measured and assigned for the first time. Improved rotational and, for the first time, 17O hyperfine coupling constants have been derived from the analysis. The 14N17 O data yield parameters of the unpaired electron spatial distribution near both nuclei. Furthermore, the deviation from the Born-Oppenheimer approximation is confirmed on the basis of the rotational constants of five isotopomers. Finally, when comparing the nuclear spin-rotation constants to the ones of other molecules containing 14N or 17O nuclei, a roughly linear proportionality with the rotational constant B is found.
Raman Scattering and X-ray Diffraction Studies on Zinc(II)Bromide Solutions in Methanol and N,N-Dimethylformamide in the Temperature Range 77-333 K
Authors: Takamuku Toshiyuki , Nakamura Keisuke , Ihara Mikito , Yamaguchi Toshio
Published: February 2015

The structure of zinc(II) bromo complexes in methanol and N,N-dimethylformamide (DMF) (molar ratio [solvent]/[ZnBr2] = 10, temperature range 77 -333 K) has been investigated by Raman scattering and X-ray diffraction. In the methanol solution symmetric Zn - Br vibrations (γ1) of the dibromo- and tribromozinc(II) complexes were observed at 209 and 184 cm-1, respectively. With decreasing temperature the intensity of the γ1 band decreased for the dibromo and increased for the tribromo complex. In addition, the γ1 band for the tetrabromo complex appeared in the supercooled and glassy methanol solutions. In the DMF solution only one band, assigned to both the dibromo-and tribromozinc(II) complexes, was observed. Its intensity did not change with temper­ature. The X-ray diffraction data revealed that the average number of Zn -Br interactions within the zinc (II) bromo complexes does not change with temperature while the number of nonbonding Br ··· Br interactions within the complexes increases from 1.5 at 298 K to 1.9 at 243 K for the methanol solution and from 1.3 at 298 K to 1.8 at 243 K for the DMF solution. These Raman and X-ray results have confirmed that in both methanol and DMF solutions at high temperatures the dibromo species is predominantly formed, whereas at low temperatures the tribromo complex is favored, the tetrabromo species being formed only in the supercooled and glassy methanol solutions. The temperature dependent equilibrium shifts of the zinc(II) bromo complexes in the methanol and DMF solutions are discussed together with previously reported results for the aqueous phase.
Point Defects and Diffusion in Paratellurite
Authors: Wegener J. , Kanert O. , Küchler R. , Watterich A.
Published: February 2015

125Te nuclear spin relaxation (NSR) and electrical conductivity measurements were performed on ultrapure single-crystalline paratellurite (α -TeO2) between about 50 K and the melting point (1007 K) at various oxygen partial pressures (1 bar -10-4 bar). At elevated temperatures the NSR rate 1 / T1 and conductivity σ are caused by the diffusive motion of point defects. From the observed p02-dependence of 1/T1 and σ a defect model is developed which is shown to be consistent with the experimental data. The model involves ionic oxygen interstitials (O″i), doubly charged oxygen vacancies (Vö) and charge-compensating electron holes (h•). The observed pressure dependence suggests that the NSR rate is induced by the motion of Vö while the conductivity is due to the mobility of h• . Evaluation of the data leads to 3.3 eV for the incorporation enthalpy of oxygen on interstitial sites and to 4.5 eV for the formation enthalpy of oxygen Frenkel pairs (O″i - Vö). Further, the chemical diffusion coefficient Dc is found to be caused by the ambipolar diffusion of O″i and h• .At 950 K we obtained from both the NSR and conductivity experiments Dc = (1 ± 0.3) • 10-5 cm2/s.
NMR Field-Cycling Study of Rotational Flow and Viscosity in Nematic Liquid Crystals
Authors: Gotzig H. , Grunenberg-Hassanein S. , Noack F.
Published: February 2015

A proton NMR method is described which enables rotational flow and viscosity measurements of low molecular weight ṉematic ḻiquid c̱rystals (NLC's). This is achieved by an extension of the common NMR field-cycling technique, namely by fast electronic switching of both the external magnetic field direction and strength. In thermodynamic equilibrium, the director of an NLC with positive diamagnetic anisotropy (Δχ > 0) orients parallel to the external magnetic field. Thus a change of this direction causes a reorientation process of the molecules to align to the new equilib­rium, which in low viscous systems in contrast to polymer liquid crystals is rather fast and hence requires fast field switching. We have studied systematically this response as a function of the initial field rotation angle 90 relative to the director for some homologous NLC's of the n-alkyl-cyano-biphenyl (nCB) series. It is shown that there exists a critical angle θcr in such a way that for θo < θcr, however (e.g. in the case of 5 CB θcr is ≈ 85 degrees) the viscoelastic behaviour is more complicated because of a coupling between flow and director gradients. The analysis of the alignment process by the changes of the proton line spectra also allows to determine the Leslie viscosities α1, α2, α3, α4 + α5, and the average Frank elastic constant K̄ by a single measurement.
Nitrogen-14 SQUID NQR of L-Ala-L-His and of Serine
Authors: Werner-Zwanziger Ulrike , Ziegeweid Marcia , Black Bruce , Pines Alexander
Published: February 2015

14N nuclear quadrupole resonance spectroscopy, detected with a Superconducting Quantum Interference Device, makes possible the study of nitrogen environments in amino acids and small peptides. The present experiments characterize: 1) the effects of intermolecular interactions upon the amino nitrogen of serine upon cocrystallization of the stereoisomers in a range of concentrations; 2) the changes of the amino and imidazole nitrogen environments brought about by combining L-Alanine and L-Histidine into the dipeptide L-Ala-L-His.
Mechanisms for Phase Transitions in the Multifractal Analysis of Invariant Densities of Correlated Random Maps
Authors: Radons Günter
Published: February 2015

Multifractal properties of the invariant densities of correlated random maps are analyzed. It is proven that within the thermodynamical formalism phase transitions for finite correlations may be due to transients. For systems with infinite correlations we show analytically that phase transitions can occur as a consequence of localization-delocalization transitions of relevant eigenfunctions.
Constrained Frobenius-Perron Operator to Analyse the Dynamics on Composed Attractors
Authors: Szabó K. G. , Tél T.
Published: February 2015

In this contribution we propose a technique to analyse arbitrary invariant subsets of chaotic dynamical systems. For this purpose we introduce the constrained Frobenius-Perron operator. We demonstrate the use of this operator by determining the geometrical multifractal spectrum of invariant chaotic subsets of one-dimensional maps which are either coexisting side by side indepen­dently or are embedded in a larger set close to a crisis configuration.
Detecting Phase Transitions in Intermittent Systems by Using the Thermodynamical Formalism
Authors: Toroczkaia Zoltán , Péntek Áron
Published: February 2015

Here we illustrate the effectiveness of the thermodynamical formalism applied to a well known chaotic phenomenon, the intermittency. This leads us to a new classification for intermittent phe­nomena from the point of view of the generated chaotic phases in the spectrum of the generalized entropies K (q). New types of intermittencies are found related to the absence or presence of phase transitions with infinite jump in K (q). This is underlined with examples. It is also shown via examples that the existence of a marginally stable fixed point in the system is neither necessary nor sufficient for intermittency.
Noisy Maps near Crises
Authors: Reimann Peter
Published: February 2015

We address the escape rate for single-humped maps near a boundary crisis multiplicatively coupled to weak uncorrelated noise. A scaling law for the rate is derived predicting a stabilization of deterministic transient chaos by noise. Generalizations to maps near interior crises and band merging points are given.
X-Ray Investigations on Molten Cu-Sb Alloys
Authors: Halm Th. , Neumann H. , Hoyer W.
Published: February 2015

Using X-ray diffraction, structure factors and pair correlation functions of several molten Cu-Sb alloys and pure antimony were determined and compared with published structural, thermodynamic and electronic properties. The eutectic concentration Cu37Sb63 was investigated in dependence on temperature, and a model structure factor was calculated applying a segregation model.
Dielectric Studies on Liquid Crystals under High Pressure: VI. Low Frequency Relaxation Process in the Nematic and Smectic A Phase of 4-n-Octyl-4'-Cyanobiphenyl (8 CB)
Authors: Urban S. , Brückert T. , Würflinger A.
Published: February 2015

Dielectric relaxation studies of 4-n-octyl-4'-cyanobiphenyl (8 CB) were performed in the pressure range 0.1 -120 MPa, the frequency range 1 kHz -13 MHz and the temperature range 295-331 K. The dielectric behaviour of 8C B in the nematic phase is similar to that of 5 CB, 6 CB and 7 CB. In particular, the activation enthalpy decreases with increasing pressure and the activation volume decreases with increasing temperature in the nematic phase. In the smectic A phase of 8 CB both these parameters are markedly lower and show opposite pressure and temperature dependencies. We tentatively interpret these effects as a result of breaking of the dipole-dipole correlations which manifests itself differently in these liquid crystalline phases.
Orientational Order-Disorder and Phase Transition in Solid Trichloromethane Sulfonic Acid Chloride, Cl3CSO2Cl
Authors: Dou Shi-qi , Fuess Hartmut , Schmahl Wolfgang , Strauss Roman , Weiss Alarich
Published: February 2015

By DTA DSC a phase transition of Cl3CSO2Cl was observed, TII,I = 227.4 K, ΔHII,I = 7.10 kJ · Mol-1; ΔSII,I/R = 3.63; Tm = 418.5 K, ΔHm = 7.46 kJ · Mol-1, ΔSm/R = 2.14. By X-ray'powder diffraction, the orientationally disordered solid phase I (plastic phase) was found to be body centered cubic, Im3m, Z = 2, a = 721.7 (5) pm at room temperature. The 35CL NQR quartet fades out at the transition temperature TII,I = Tf, and the fade out temperature Tf is identical for the four 35Cl NQR lines. The NQR spectrum shows a hysteresis in TI,II - TII,I.
Neutron Diffraction Study of 1,2,3-Trichlorobenzene-d3
Authors: Groke Dirk , Heger Gernot , Schweiss Bernd Peter , Weiss Alarich
Published: February 2015

In order to explain the observed 35Cl-NQR anomaly of the title compound, a neutron diffraction study on single crystals was carried out at 295 K and 158 K. No significant structural changes concerning phase transitions or molecular disorder between the two experiments were observed. The space group is P21/c = C2h
5 with 8 molecules per unit cell. The asymmetric unit contains 2 molecules. The cell parameters were determined to a = 1264(4) pm, b = 825(2) pm, c = 1503(3) pm, ß = 14.3(3)° at 295 K and a = 1243(2)pm, b = 815(1) pm, c = 1494(2) pm, ß = 114.3(1)° at 158 K. The molecules show rigid-body behaviour. No significant changes of the molecular geometry were observed. A strong variation of the temperature factors as function of the temperature was detected. An anharmonicity of the librational potential of the molecules was found by evaluation of the thermal parameters as function of temperature. For verifying the existence of dynamic processes which lead to a bleaching out of the 35Cl-NQR lines difference, Fourier syntheses were calculated. A reorientation or an order-disorder process as suggested by 35Cl-NQR spectroscopy above 230 K could not be confirmed within the error of the experiments. The degree of deuteration of the samples was determined by refinement of the occupation factors of the deuterium sites.
Higher Dimensional Integrable Models with Painleve Property Obtained from (1+1)-Dimensional Schwarz KdV Equation
Authors: Chen Li-li , Loua Sen-yue
Published: February 2015

Using the extended Painlevé analysis, we obtained some higher dimensional integrable models with the Painlevé property from the (1+1)-dimensional Schwarz KdV equation.
Magnetic Order in Li-Mn Spinels
Authors: Azzoni C. B. , Mozzati M. C. , Paleari A. , Massarottib V. , Capsonib D. , Binib M.
Published: February 2015

Magnetic measurements were carried out on different samples of Lithium-Manganese spinel LiMn2O4 , great care having been taken to avoid the presence of spurious magnetic phases, such as Mn3O4 . Susceptibility data, showing deviations from paramagnetic behaviour at about 40 K, were analyzed in terms of local magnetic interactions, taking into account the structural and transport properties of these com-pounds. The magnetic response of pure and stoichiometric samples suggests that the onset of a longrange magnetic ordering is hindered by the topological frustration of the antiferromagnetic octahedral sublattice of the spinel.
Topological Properties of Circumcoronenes
Authors: Gutman Ivan , Cyvina Sven J. , Ivanov-Petrović Vesna
Published: February 2015

The regular-hexagon-shaped benzenoid hydrocarbons: B1 = benzene (C6H6), B2 = coronene (C24H12), B3 = circumcoronene (C54H18), B4 = circumcircumcoronene (C150H30), etc. possess unique topological properties. General expressions for the most important of such properties (number of fun-damental structural invariants, number of Kekule and Clar structures, number of aromatic sextets, Wiener and Szeged indices, spectral moments) are given, including a number of results that are communicated here for the first time. Cyclic conjugation in circumcoronenes is analyzed by means of its energy-effect, and found to agree with the predictions of Clar's aromatic sextet theory only in the case of B1 and B2.
Relations between Nematic Potential and Order Parameters (P2) and (P4)
Authors: Würflinger A. , Urban S.
Published: February 2015

The Maier-Saupe theory is employed in order to calculate order parameters (P2) , (P4) from the nematic potential q. The relation between σ=q/(RT) and S = (P2) corresponds well with a recently established formula by Kalmykov. The relation between the order parameters is in accordance with the analytic expression (P4)=5/7 (P2)2 proposed by Zanonni, but deviates significantly from the Faber model, according to which log (P4)=(10/3) log (P2). Experimental results for 5 CB obtained from Raman measurements, however, are in better agreement with the Faber model.
Determination of the Absolute Configuration of 1,5-Diaza-cis-decalin by Comparison of Measured and Calculated CD-Spectra
Authors: Fleischhauer Jörg , Raabe Gerhard , Santos A. G. , Schiffer Jan , Wollmer Axel
Published: February 2015

The absolute configurations of both 1,5-diaza-c/s-decalin enantiomers were determined by com-parison of measured and calculated CD spectra.

CD spectra for both enantiomers were recorded. Theoretical CD spectra for one of the isomers were calculated by means of the semiempirical CNDO/2S method. Eight 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 one-determinant ab initio calculations using the split valence 6-31G* basis set. Boltzmann factors were then obtained using relative energies calculated with three different basis sets and including correlation(MP2)-and zero point vibrational energy.

Comparing the sign of the observed and calculated longest wavelength Cotton effect, we assign an absolute configuration to the compound. This assignment was verified by means of X-ray structure determination of one of the enantiomers’ α-methoxy-α-trifluoromethylphenyl aceticacid (MTPA, Mosher’s reagent) derivative.
Elastic Constants of Binary Liquid Crystalline Mixtures
Authors: Kapanowski A. , Sokalski K.
Published: February 2015

Microscopic expressions for the elastic constants of binary liquid crystalline mixtures composed of short rigid uniaxial molecules are derived in the thermodynamic limit at small distorsions and a small density. Uniaxial and biaxial nematic phases are considered. The expressions involve the one-particle distribution functions and the potential energy of two-body short-range interactions. The theory is used to calculate the phase diagram of a mixture of rigid prolate and oblate molecules. The concentration dependence of the order parameters and the elastic constants are obtained. The possibility of phase separation is not investigated.
On the Experimental Proofs of Relativistic Length Contraction and Time Dilation
Authors: Jefimenko Oleg D.
Published: February 2015

Recent advances in the theory of electromagnetic retardation have made it possible to derive the basic equations of the special relativity theory and to duplicate the most important practical results of this theory without using the concepts of relativistic length contraction and time dilation. Thus the reality of these concepts appears to be questionable. It is imperative therefore to reexamine the experimental evidence supporting these concepts. The calculations presented in this paper show that some of the experiments allegedly proving the reality of length contraction and time dilation can be unambiguously interpreted as manifestations of velocity-dependent dynamical interactions taking place within the systems involved in the experiments rather than as manifestations of length contraction or time dilation.
Dielectric Relaxation Study of Zn(NO3) 2, Cu(NO3)2 , Ni(NO3)2 , and Mg(NO3)2 Solutions in Water/DMSO Mixtures
Authors: Galstian A. , Stockhausen M.
Published: February 2015

Dielectric spectra have been measured for the title systems up to 72 GHz at 20 °C with salt concentrations ≤1 mol/1 and DMSO mole fractions of the mixed solvent in the 0.3 to 0.6 range. Results can be described by a superposition of two Debye terms (at lower frequencies) plus one Cole-Davidson term (at higher frequencies). The discussion is particularly focused on the lowest frequency term, which is related to ionic species. These are likely to consist in nonsymmetrically solvated cations rather than ion pair complexes. While Cu, Ni and Mg nitrates behave similarly, the Zn salt shows some differences which possibly are due to a change of the coordination number with increasing salt content.
63Cu Nuclear Magnetic Resonance and Viscosity Studies of Copper (I) Perchlorate in Mixed Solvents Containing Acetonitrile
Authors: Gill Dip Singh , Byrne Lindsay , Quiekenden Terry I.
Published: February 2015

63Cu nuclear magnetic resonance and viscosity studies of 0.064 M copper (I) Perchlorate solutions have been made at 298 K in binary mixtures of acetonitrile (AN) with dimethylsulphoxide (DMSO), hexamethylphosphotriamide (HMPA), N,N-dimethylacetamide (DMA), nitromethane (NM), propylene carbonate (PC) and 3-hydroxypropionitrile (3 HPN) at several compositions of the mixtures using a 500 MHz NMR Spectrometer and Ubbelohde viscometer, respectively. The chemical shift (δ), linewidth (Δ) and line intensity (I) of the 63Cu NMR signal in these mixed solvents have been measured relative to the 63Cu signal in 0.064 M copper (I) Perchlorate (CuClO4) solution in pure AN. The quadrupolar re-laxation rates (1/T2)Q, reorientational correlation times (τR) and quadrupolar coupling constants (QCC) of the copper (I) solvates have also been estimated from the data. The QCC values show a big variation in all solvent systems with the change of solvent composition, indicating the formation of mixed com-plexes. The variation of all NMR parameters with solvent composition shows strong effects of DMSO, HMPA, and DMA on the solvation behaviour of Cu + in the first three mixtures, and relatively much weaker effects of PC, NM and 3HPN in the other three mixtures.
Statistical Invariances in Artificial, Natural, and Urban Images
Authors: Ziegaus Christian , Lang Elmar W.
Published: February 2015

To answer the question about the way our visual system processes images it has to work with every day, it is necessary to investigate the statistical structure of these pictures. For this purpose we investigated several ensembles of artificial and real-world greyscale images to find different invariance properties: translation invariance by determining an average pair-correlation function, scale invariance by investigating the power spectrum and the coarse graining of the images, and a new hierarchical invariance recently proposed [D. L. Ruderman, Network 5, 517 (1994)]. The results of our work indicated that the assumption of translational invariance can be taken for granted. Our results concerning the scale invariance are qualitatively the same as those found by Ruderman and others. The deviations of the distributions of the logarithmically transformed images from a Gaussian distribution cannot be seen as clearly as stated by Ruderman. This results from the fact that for a correct determination of the deviations the non-linear transformation must be considered. Depending on the preprocessing of the images the results concerning the hierarchical invariance differed widely. It seems that this new invariance can be confirmed only for logarithmically transformed images.
NMR and NQR Studies of Borate Glasses
Authors: Bray Philip J. , Petersen Gary L.
Published: February 2015

Nuclear magnetic resonance (NMR) has been used for some 40 years to study atomic arrangements, chemical bonding, and structural groupings in borate glasses and crystalline compounds, and nuclear quadrupole resonance (NQR) has more recently increased the resolution and accuracy of the measurements. Examples are presented of the use of first-order and second-order quadrupolar effects in 11B NMR spectra to obtain structural information, and 11B and 10B NQR spectra to obtain the quadrupolar parameters Qcc (the coupling constant) and ƞ (the asymmetry parameter) with accuracies of 5 or 6 significant figures, and 3 figures, respectively. Qcc and ƞ are extremely sensitive to changes in atomic rearrangements and chemical bonds, so they are excellent monitors and provide identification of bonding configurations and structural groupings in borates: Examples are also presented in which combinations of NMR and NQR data are used to extract the desired information. NQR detection of resonances at frequencies as low as 276 kHz is discussed.
Electric Quadrupole Interactions of the Short-Lived β-Emitter 12N in Insulator Crystals (12N Implanted in Single Crystal TiO2)
Authors: Minamisono T. , Sato K. , Akai H. , Takeda S. , Maruyama Y. , Matsuta K. , Fukuda M. , Miyake T. , Morishita A. , Izumikawa T. , Nojir Y.
Published: February 2015

The electronic structure of nitrogen atoms as impurities in an ionic TiO2 crystal has been investigated by analyzing electric field gradients (EFGs) measured by use of short-lived β-emitting 12N implant-ed following nuclear reactions. Conventional β-NMR and its modification, suitable for the detection of quadrupole effects in the NMR spectra, were used for the investigation of hyperfine interactions of 12N located in substitutional sites of O atoms and interstitial sites in the crystal. In order to deduce absolute values of the EFGs from the obtained eqQ/h, the quadrupole moment of 12N has been determined from the NMR detection of 12N implanted in BN(hexagonal) crystal. Here the EFG at the N atom in BN was measured by detecting the FT-NMR of 14N in the crystal. The EFGs in TiO2 are compared with the theoretical predictions based on the ab initio band-structure calculation in the framework of the KKR method.
NMR Detection of Oxygen Isotopes in TiO2 Single Crystal
Authors: Tanigaki M. , Takeda S. , Matsuta K. , Matsumoto Y. , Minamisono T. , Akai H. , Sato K. , Miyake T. , Maruyama Y. , Morishita A. , Fukuda M. , Nojiri Y.
Published: February 2015

We studied the electric quadrupole interactions of Oxygen isotopes in a TiO2 single crystal. For 13O and 19O nuclei, quadrupole coupling constants were measured by the β-NMR technique, and for the 17O nucleus the FT-NMR technique was utilized. We synthesized a TiO2 single crystal which was enriched in 17O up to 5 atom % to observe NMR signals without any perturbations from impurities. Using the known quadrupole moment of 17O, EFGs at an O site in TiO2 and the quadrupole moments of 13O and 19O were determined.
Electric Field Gradients at the In Site in Au-In Compounds
Authors: Wodniecki P. , Kulińska A. , Wodniecka B. , Hrynkiewicz A. Z.
Published: February 2015

The quadrupole interaction in Au-In compounds of different stoichiometrics was studied with the perturbed angular correlation technique. The electric field gradients at 111Cd probes were measured and the temperature dependences of the quadrupole frequencies were determined. A new high temperature phase of Auln above 630 K and a new metastable modification of Au7In3 were found.
Halogen Nuclear Quadrupole Coupling Constants in Non-axially symmetric Molecules; Ab initio Calculations, which Include Correlation, Compared with Experiment
Authors: Palmer Michael H. , Blair-Fish John A.
Published: February 2015

Ab initio determination of the electric field gradient (EFG) tensors at halogen and other centres ena-bled determination of the nuclear quadrupole coupling constants (NQCC) for a diverse set of C2v , C3v and other symmetry molecules of general formula MH2X2 and MHX3 , where the halogen atoms (X) are Cl, Br and I, and the heavy central atoms (M) are C and Si. The study presents results at a standardised level of calculation, triple-zeta in the valence space plus polarisation functions (TZVP) for the equilib-rium geometry stage; all-electron MP2 correlation is included in all these studies. For the bromo and iodo compounds, especially the latter, it is essential to allow core polarisation, by decontraction of the p,d-functions. This is conveniently done by initial optimization of the structure with a partly contract-ed basis, followed by reestablishment of the equilibrium structure with the decontracted basis.

The NQCCs, derived from the EFGs, using the 'best' values for the atomic quadruple moments Cl, Br and I, lead to good agreement with the inertial axis (IA) data obtained from microwave spectroscopy. When the data from the present study is plotted against the values derived from the IA data, obtained by whatever approximations chosen by the MW authors, we obtain a linear regression for the data (85 points) with the slope 1.0365 and intercept -0.1737, with standard errors of 0.0042 and 0.2042, respectively; these are statistically identical results irrespective of whether the data is restricted to IA or EFG principal axis (PA) data.

Since as in the C3v MH3X compounds studied previously, a close correlation of the microwave spectral data with the calculations was observed using the 'best' current values for Qz , there seems no need to postulate that the values of QBr for both 79Br and 81Br are seriously in error. A scaling downwards of Qz by about 5% for Br and I increases the agreement with experiment, but the contributions of relativistic effects are unknown, and could lead to further reassessment.

Of the two common assumptions used in MW spectroscopy, to convert from IA to EFG-PA data, either (a) cylindrical symmetry of the NQCC along the bond direction, or (b) coincidence of the tensor principal element with the bond axis, the latter is found to be a much more realistic approximation.
NQR Relaxation Studies on Halogenomethyl Groups in Halogenoacetates
Authors: Zdanowska-Fnjczek Maria
Published: February 2015

The effect of temperature on the chlorine NQR spin-lattice relaxation times in CsH(ClH2-CCOO)2 , KH(Cl3 CCOO) 2 and N(CH3)4 H(ClF2CCOO)2 has been studied in the temperature range 77 K to room temperature. The results were discussed on the basis of NQR relaxation theory.
Spin Gap, Electronic Crossover, and Charge Density Waves in Y-Ba-Cu-O Superconductors
Authors: Brinkmann Detlef
Published: February 2015

This paper discusses recent NQR/NMR studies performed on Y-Ba-Cu-0 superconductors at the University of Zürich. The work is concerned with normal state properties which are still controversial, for instance the spin-gap effect, i.e. the opening of a pseudo gap in the electron spin excitation spectrum at a temperature T*, which lies above Tc . We will report on the detection of “anomalies” which are dis-played in the temperature dependence of several NMR and NQR quantities measured in the normal state of YBa2Cu4O8 . These anomalies are interpreted as an electronic crossover which involves a charge re-distribution in the CuO2 planes and an enhancement of the charge fluctuations. As a possible mechanism of the crossover, a charge density wave instability is proposed.
Chlorine-35 NQR Study of a Structural Phase Transition in (ND4)2PdCl6
Authors: Kume Yoshio , Asaji Tetsuo
Published: February 2015

Temperature dependences of 35Cl NQR frequencies and spin-lattice relaxation times were measured at 4.2 to 400 K for natural and deuterated ammonium hexachloropalladate. It was confirmed that only the deuterated salt undergoes a first order phase transition at 30 K. The crystal structure of the low-temperature phase is predicted to be the same as that of the deuterated ammonium hexachloroplatinate and hexachloroplumbate. The mechanism of the deuteration-induced phase transition is discussed.
Phase Transitions and Crystal Structure of Dimethylammonium Tribromomercurate(II), (CH3)2NH2HgBr3 , as Studied by 81Br NQR and Single Crystal X-ray Diffraction
Authors: Terao Hiromitsu , Hashimoto Masao , Okuda Tsutomu , Weiss Alarich
Published: February 2015

The temperature dependence of the 81Br NQR frequencies of the title compound has revealed the presence of three phases (I, II and III, in the order of decreasing temperature): Tcl (II -1) = (318 ± 10) K and Tc2 (III -II) = (202 ± 1) K. The transitions were confirmed by thermal analysis (DTA). Both of the II-I and I-II transitions exhibited strong hysteresis (i. e., superheating and supercooling, respectively). The crystal data, determined by single crystal X-ray diffraction, are: monoclinic, space group P2/a, a = 1384.8(3), b = 934.7(4), c = 1452.0(2) pm, β = 104.10(1)°, Z= 8, R = 0.076. The crystal has two crystallographically independent cations (CH3)2NH2+ and an infinite chain of anions almost in the c-direction. The anion chain is considered to consist of a HgBr2 molecule and two different HgBr4
2- anions which are interconnected via weak intermolecular Hg···Br bonds. The splitting patterns of the 81Br NQR spectra indicate that rearrangements of the Hg-Br bonds are slight at the III-II transition but serious at the II-I transition. Some of the 81Br NQR lines show anomalous temperature coefficients, attributable probably to thermal motions of cations.
A 35Cl NQR Study on Cs2[AUICl2] [AuIIICl4]
Authors: Ishikawa A. , Kurasawa M. , Kitahara S. , Sasane A. , Kojima N. , Ikeda R.
Published: February 2015

Abstract A pair of 35Cl NQR spin echo signals has been observed for the mixed valence complex Cs2 [AuICl2] [AuIIICl4] between 77 and 243 K. At 77 K, two resonance lines with the half widths ΔvQ ~ 50 kHz were located at vQ1 = 17.28 MHz for the AuI-Cl chlorine and at vQ2 = 27.10 MHz for the AuIII -Cl chlorine in accordance with the crystal structure. The chlorine ionic characters of the AuI-Cl and AuIII-Cl bonds are estimated as 0.63 and 0.42, respectively. The central gold atom carries a fractional protonic charge of 0.26 in [AuICl2]- and 0.68 in [AuIIICl4]-. The charge distributions in the complex anions differ insignificantly from those in the isolated [AuCl2]- and [AuCl4]- for ordinary complexes, indicating that the charge transfer interactions between the anions are weak in the mixed valence complex. The observed linear temperature dependencies of VQ and log TlQ are well explained by the lattice vibration. When the temperature was increased from 77 K, the resonance lines became gradually weak without changing ΔvQ and immeasurable above 215 K. ESR spectra taken at various temperatures revealed the presence of paramagnetic sites of ca. 5 x 1020 mol- 1 arising from Au(II). The small but finite concentration of Au(II) or some other reason should be responsible for the fade out phenomenon and the large ΔvQ observed.
Stability of in 111In-ligand Complexes Studied by TDPAC
Authors: Shpinkova L. G. , Kulakov V. N. , Sorokin A. A. , Ryasny G. K. , Komissarova B. A. , Nikitin S. M.
Published: February 2015

The TDPAC technique has been applied to study the stability of 111In complexes with NTA and DTPA in solutions with different concentrations of stable In at pH = 7. A sample of In-DTPA complexes attached to microspheres of albumin (MSA) has been measured at temperatures of 293 and 130 K. The results show that the products formed after 111ln → 111Cd decay and following Auger-effect are determined by the stability of In (Cd)-complexes with organic ligands. The daughter Cd behaviour depends on the In: ligand mole ratio, from 1: ∞ to 1:1. The possibility of Cd-ligand complex destruction and following Cd rechelating is discussed. The results indicate that the rechelating probability correlates with the stability of the parent and daughter complexes.
Kristall- und Molekülstruktur von „Imido-tetraphenyl-dithiophosphinsäure" und Imido - tetraphenyl- diphosphinsäure / Crystal and Molecular Structure of "Imido-tetraphenyl-dithio-phosphinic Acid" and Imido-tetraphenyl-diphosphinic Acid
Authors: Nöth Heinrich
Published: February 2015

The crystal structures of the title compounds have been investigated in order to gain information on the problem of tautomerism associated with these and related compounds. [Ph2P(S)]2NH crystallizes in the triclinic space group P 1̄. Its structure is represented by the above formula, e.g. as a disubstituted amine with its nitrogen atom being sp2-hybridized. In contrast, ,,[Ph2P(O)]2NH" in the solid state is present as its tautomer Ph2P(O)-N = PPh2OH. It is an imidodiphosphinic acid as previously suggested. The crystals are monoclinic, space group P 21/n, Z - 2. Crystallographic inversion centers are occupied by the N- and the unique H-atom. Therefore a linear PNP arrangement as well as a symmetric OH-O-hydrogen bridge are characteristic for the structure of this molecule. The short PN bonds suggest a high bond order approaching 2. A consequence of the hydrogen bonded oxygen atoms are fairly long PO distances. The crystal structure of

is made up of infinite zig-zag chains of Ph2P(0)NPPh2ÖH molecules along the crystals b-axis
δ Beiträge zur Chemie des Phosphors, 120 [1] Carbonyl-Triorganylcyclotriphosphan-Komplexe von Chrom und Wolfram / Contributions to the Chemistry of Phosphorus, 120 [1] Carbonyl-Triorganylcyclotriphosphane Complexes of Chromium and Tungsten
Authors: Baudler Marianne , Salzer Franz , Hahn Josef
Published: February 2015

The reaction of triorganylcyclotriphosphanes, (RP)3 (R = i-Pr, t-Bu), with metal carbonyl-tetrahydrofuran complexes, M(CO)5THF (M = Cr, W), yields the novel mononuclear and binuclear cyclotriphosphane-carbonylmetal complexes (RP)3M(CO)5 (R = i-Pr, t-Bu; M = Cr, W) 1-4 and (RP)3[M(CO)5]2 (R = t-Pr, M = Cr) 5, respectively. They are remarkably stable both thermally and to oxidation. Their structures have been elucidated by 31P NMR spectroscopic investigations. The cyclotriphosphane functions as a 2- or a 4-electron donor, respectively, and behaves as a Ti-acceptor comparable to Ph3P
Die Kristallstruktur des Cyano-Elpasoliths [N(CH3)4]2CsFe(CN)6 / The Crystal Structure of the Cyano Elpasolite [N(CH3)4]2CsFe(CN)6
Authors: Babel D.
Published: February 2015

The crystal structure of the cubic compound [N(CH3)4]2CsFe(CN)6 was determined by X-ray methods: a = 2527.4(6) pm, space group Fd3c, Z = 32, Rg = 0.028 (260 independent single crystal reflections). The resulting distances within the practically undistorted Fe (CN)6
3- - octahedron are Fe-C = 193.4(6) and C-N = 115.7(7) pm. Compared to the ideal elpasolite structure of space group Fm3m, Z = 4, the octahedra are rotated by 7.4° through their 3 axis. This is discussed as caused by steric requirements of the tetramethylammonium groups (N-C = 148.4(10) and 149.1(38) pm, resp.). Three quarters of them, of which also the hydrogen positions could be located, are well oriented. The remaining quarter shows orientational disorder to approach similar contact distances as the other N(CH3)4
+ ion exhibits between the methyl groups and the nitrogen ends of the anions
Eine neue Käfigverbindung mit dem Adamantangerüst C2B4S4 A New Cage Compound with the Adamantane Skeleton C2B4S4
Authors: Binder Herbert , Diamantikos Wassilios , Dermentzis Konstantinos , Hausen Hans-Dieter
Published: February 2015

Hydroboration of carbon disulfide with THF-BH3 yields the new cage compound [CH2(SBH2)2]2 which has the adamantane skeleton C2B4S4. The same compound could be prepared by the action of methane dithiole on THF • BH3 or THF • BH2C1. The crystal structure was determined from diffractometer data and refined to R = 0.027 for 2240 independent reflections. [CH2(SBH2)2]2 is monoclinic, P21/c, with a = 730.7(1), b = 911.5(2), c = 1462.6(2) pm and β = 90.84(1)°. The unit cell contains four formula units
Darstellung und spektroskopische Charakterisierung von Tetrachloro- und Tetrabromo-Oxalatoiridaten(IV) / Preparation and Spectroscopical Characterization of Tetrachloro- and Tetrabromoiridates(IV)
Authors: Schulz H. , Preetz W.
Published: February 2015

On treatment of [IrX6]2- with oxalate in aqueous solution at first [IrX4OX]3- (X = Cl, Br) is formed, which after extraction with pentylammonium ions into CH2Cl2 can be oxidised by X2 to give the corresponding pure Ir(IV) complexes [IrX4OX]2-. The IR and Raman spectra are assigned according to point group C2V- The UV/VIS absorption spectra show strong CT bands of transitions from "(π + σ)tlu"- and "πt2U"-ligand niveaus to t2g
5 (IrIV). These are split into three components by spin-orbit coupling and corresponding to the different groups of ligands: Xtr
2, Xc
2, ox. The spectrum of (TBA)2[IrBr4OX] recorded at 10 K is highly resolved, showing a splitting of the Brtr
2 → Ir(IV) and Bc
2 → Ir(IV) transitions by 1000-1400 cm-1. In the NIR-region two d-d-transitions are observed superimposed with a fine structure by coupling with vibration modes
Spektroskopische Untersuchungen an Monofluorammoniumsalzen / Spectroscopic Studies on Monofluorammonium Salts
Authors: Minkwitz Rolf , Naß Rüdiger
Published: February 2015

The NMR, IR and Raman spectra of several NH3F+X- salts are reported. The preparation of NH3F+SO3CI- and NH3F+SO3F- is described
Tetraalky lammonium - tetr achlor oantimonate (III). Struktur und Schwingungsspektren / Tetraalky lammonium Tetrachloroantimonates(III). Structure and Vibrational Spectra
Authors: Ensinger U. , Schwarz W. , Schmidt A.
Published: February 2015

The crystal and molecular structures of tetraethyl- (1), tetra-η-propyl- (2) and tetra-nbutylammonium tetrachloroantimonate(III) (3) were determined by X-ray analysis. There are discrete Sb4Cl16
4- (1) and Sb2Cl8
2- (2 and 3) anions. The Sb-Cl bond lengths vary in the range between 234 and 326 pm, and are explained as in a three centre-four electron situation. The vibrational spectra of the anions are briefly discussed
Röntgenstrukturanalyse von N-[3,3-Dimethyl-5,5-bis- (trifluormethyl) -1 -pyrazolinio] pentafluoranilid / X-ray Structure Analysis of N-[3,3-Dimethyl-5.5-bis(trifluoromethyl)- ] -pyrazoliniojpentafluoroanilid
Authors: Gieren Alfred , Lamm Viktor
Published: February 2015

The title compound crystallizes in the monoclinic space group P21/n with a - 8.761(3), b - 9.773(5), c = 18.727(7) Å, y = 100.86(3)°, V = 1574.7.Å3, Z = 4. The structure was solved by direct methods and the refinement converged for 2030 independent reflections to an JR-value of 0.060 (Rw = 0.071). The N-N distances in the mesoionic -N⊖-N⊕(R) = Nmoiety are asymmetric with 1.304 and 1.263 Å, respectively. The almost planar heterocyclic pyrazolinium ring system and the plane of the aromatic pentafluorophenyl group include an angle of 60° caused mainly by a torsion around the N-C bond to the phenyl ring. The crystal packing contains columnar stacks of parallel phenyl rings with distances of 3.30 and 3.35 Å. Also H-F contacts play a dominant role
Sterically Hindered Alkanes, II 1,1,1,3,3,3-Hexaphenylpropane
Authors: Winter Werner , Moosmayer Alfred , Rieker Anton
Published: February 2015

The structure of the title compound 3, C39H32, obtained for the first time by Schlenk and Bornhardt (1912) from triphenylmethyl (1) and diazomethane (2) has been determined by 14C-tracer technique, NMR spectroscopy and X-ray analysis. It crystallizes in the monoclinic space group C2/c with Z = 4, a = 9.943(6), b= 19.054(3), c = 14.708(2) Å and β = 101.80(2)°. The structure was solved by direct methods and refined by full-matrix least squares to R = 0.046 for all 2625 reflexions (|F0| >0). On account of steric repulsions between the phenyl rings at both termini the central propane bond angle φ is stretched to 127.2°, whereas the bond lengths are not much affected. The X-ray results are compared with those of Blount et al. (1982), obtained on a triclinic crystal modification (P1) of 3. A fair agreement of bond lengths and angles is observed, the slopes of the homochiral propellers, however, aro different in both modifications. The measurement of the N2- evolution shows that the mechanism of formation of 3 from 1 and 2 is different in the photochemical and dark reaction. A carbene respectively a one-electron transfer mechanism is suggested. In spite of the remarkably normal CC-propane bond lengths homolytic cleavage of these bonds to give 1 is observed at 200-220 °C using the ESR technique
Neue Vertreter vom Weberittyp mit der Zusammensetzung Ag2MIIMIIIF7 / New Weberite Type Members of the Composition Ag2MIIMIIIF7
Authors: Koch Jürgen , Hebecker Christoph , John Heinz
Published: February 2015

mpounds (MIII = AI, Ga, In, Sc) have been determined by X-ray-Guinier-photographs: all new members of the Weberite type crystallize according to the mineral Na2MgAlF7. The X-ray powder data are given