bluuebunny/crossref_metadata_2025_split huggingface dataset:
Investigation of Intrinsic Point Defects in Metals by Nuclear Quadrupole Double Resonance
Authors: Notter M. , Konzelmann K. , Majer G. , Seeger A. 
Published: February 2015

Abstract
The paper reviews the principal features of the Nuclear Quadrupole Double Resonance (NQDOR ) technique, with particular emphasis on its application to the investigation of imperfections in cubic metals. NQDOR permits measurements of the electric field gradients (EFG) at quadrupole-moment-carrying nuclei in the neighbourhood of point defects and thus to obtain “fingerprints” of these defects. An NQDOR facility set-up at the M ax-Planck-Institut für Metallforschung in Stuttgart is described. It has been used to study the intrinsic defects introduced into Cu and dilute Cu/Be alloys by low-temperature irradiation with electrons or protons or by cold-work. It is shown that all well-resolved irradiation-induced EFG observed in the present work are due to one kind of defect only, which is identified as the <100> dumbbell self-interstitial. When considered together with measurements of the electrical resistivity on the same specimens, the annealing behaviour of the NQDOR lines supports the so-called two-interstitial model of radiation damage in face-centred cubic metals rather than the one-interstitial model.
A New Pulsed Nuclear Quadrupole Resonance Spectrometer
Authors: Petersen G. L. , Bray P. J. , Marino R. A. 
Published: February 2015

Abstract
A new pulsed nuclear quadrupole resonance spectrometer is described and a number of Nitrogen-14 spectra are shown and discussed. The spectrometer is computer interfaced and both data acquisition and all adjustments other than the matching network tuning are automatic. Spectra may be produced using fast Fourier transforms or by the Clark Method. The latter is particularly valuable when very wide line widths are encountered.
The Breathing Mode of BaBiO3: Electric Field Gradient and Total Energy Calculations
Authors: Blaha P. , Schwarz K. , Dufek P. , Vielsack G. , Weber W. 
Published: February 2015

Abstract
We present ab initio full-potential linearized augmented plane wave (LAPW) band structure calculations for BaBiO3. We focus on total energies and electric field gradients at the oxygen site and present results for the breathing mode in the experimentally observed cubic and monoclinic structures of doped and undoped Ba1-xKxBiO3.
Halogen NQR and Crystal Structure of Ammonium Halides (R-NH3)+X- and (X–) (+H3NR´­NH3
+) (X–). R = (HOCH2)3C, R´ = CH2C(CH3)2CH2; X = I,Br
Authors: Dou Shi-qi , Fuess Hartmut , Paulus Helmut , Weiss Alarich 
Published: February 2015

Abstract
The 127I-NQR of(HOCH2)3CNH3
+ I- was determined in the range 77 ≤ T/K ≤ 310. At T = 310 K the NQR signal fades out (Tm = 463 K). The 127I spectrum ( T =77 K.): v1 =29.195 MHz, v2 = 14.597 MHz, η(121l)=0, e QΦzz h-1 (127I) = 97.315 MHz, is in agreement with the crystal structure.
The 127I NQR spectrum of 1,3-diammonium-2,2-dimethylpropane diiodide, (H3NCH2C(CH3)2CH2NH3)2+ ·2I- , is a quartet within the whole temperature range investigated, and the lines correspond to two crystallographically independent iodines: Space group P21/c, Z = 4, a = 731.2(3) pm, b = 689.0(3) pm, c = 2255.1(8) pm, β = 104.90(1)°. At 7 = 7 7 K the 127I NQR quartet is (MHz): v1 = 34.145, v2 = 32.805, v3 = 22.113, v4 = 16.787; at 295 K (same order, MHz): 30.559, 29.729, 19.810, 15.651. There are two combinations of the NQR frequencies. Considering the coordination of I-, the hydrogen bonds N -H ··· I, eQΦzzQ h-1 and η, we choose for I(1) v1 and v3, for I(2) v2 and v4. At 77 K eQΦzzQ h-1 (I(1))= 118.86 MHz,η (127I(1)) = 0.498, eQΦzzQ h-1 (I(2)) = 109.75 MHz, η(127I(2)) = 0.135 follow for the two iodine atoms. Both, eQΦzzQ h-1 (I(1)) and e eΦzzQ h-1(I(2)) decrease smoothly with increasing T: η I(2)) increases with increasing T whereas η(127I(1)) is almost constant within 77 ≤ T /K ≤ 4 0 6 .
The 79,81Br NQR spectrum of l,3-diamino-2,2-dimethylpropane dihydrobromide is also a quartet, showing two crystallographic inequivalent Br atoms in the unit cell. The frequencies are (T =273 K, MHz): v1 (79Br)= 14.303, v2 (79Br)= 12.884, (81Br)= 11.951, v2(81Br) = 10.781; space group C2/c, Z = 8 , a = 2136.4(6) pm, b = 854.6(3) pm, c = 1125.8(3) pm, β = 93.23(1)°.
Crystal structures and NQR results are discussed.
Structure and Bonding of Bromoantimonate (III) Complexes with Unusual Valency by Means of NQR and Powder X-Ray Diffraction
Authors: Okuda Tsutomu , Kinoshita Yoshihiro , Terao Hiromitsu , Yamada Koji 
Published: February 2015

Abstract
NQR and powder X-ray diffraction were observed for several bromoantimonate (III) complexes which contain CnH2n+1NH3 (n = 1 -3) or (CnH2n+1)2NH2(n = 1 -4) as a cation. The bond character, anion structure, crystal structure, and phase transition are discussed on the basis of the three-center-four-electron bond. A good correlation was found between the halogen NQR frequency and the Sb-X bond length.
81Br NQR and Crystal Structure of Ethylammonium Tribromomercurate(II), CH3CH2NH3HgBr3
Authors: Terao Hiromitsu , Okuda Tsutomu , Koto Kichiro , Dou Shi-qi , Weiss Alarich 
Published: February 2015

Abstract
The 81Br NQR triplet spectrum of (CH3CH2NH)3
⊕(HgBr3)⊖ was measured in the range 77 K to near the m.p. (99~106°C) v1 decreases strongly with increasing temperature, exhibiting 136.784 MHz at 77 K and 128.129 MHz at 298 K. v2 decreases from 82.060 MHz at 77 K to 76.322 MHz at 298 K. v3 increases with temperature, showing v3 = 81.292 MHz at 77 K and 84.903 MHz at 298 K. Replacement of the ammonium hydrogens by deuterium produces a negative shift of v1 and positive ones of v2 and v3 at high temperatures. These shifts change with temperature from |~ 0| up to |~ 200| kHz.
The crystal structure of the title compound was determined at room temperature: P 21/m, Z = 2, a = 1021.6(8) pm, b = 643.0(6) pm, c = 691.8(6) pm, β = 96.96 (4)°. The coordination of the mercury atom by the bromines is trigonal bipyramidal; by formation of bridges Hg··· Br··· Hg by one of the three bromines (Br(2)) of the planar HgBr⊖ ions a double chain of trigonal bipyramids is formed, running along the b-axis of the crystal. Br(1) and Br(3) are single bonded to Hg. The hydrogen bonds N -H···Br(1) and N -H ··· Br(3) (twice), connect the Hg-Br chains to planes lying parallel to the be plane at x = 0. The relations between the Br-NQR spectrum and the structure are discussed.
The Zeeman Effect in Quadrupole Double Resonance Spectra: Dependence of the Line Shapes on the Orientation of the Electric Field Gradient Tensor
Authors: Stephenson David , Smith John A. S. 
Published: February 2015

Abstract
The solid effect spectrum of 1,4-dichlorobenzene was recorded at magnetic field strengths in excess of 50 G; at these field strengths Zeeman structure is seen on the 35Cl resonance. Unlike in single resonance experiments, peaks are asymmetric, and the high frequency and low frequency solid effect peaks have not the same shape. Computer calculation o f the solid effect spectrum gives peaks which show the same asymmetry as the experimental spectrum. The simulated line shapes are found to depend on the direction the principal components of the electric field gradient in the crystal framework and indicate that qyy lies in the plane o f the benzene ring.
Internal Magnetic Field at Ba Site in Antiferromagnetic YBa2Cu3O6 Determined by 137Ba NQR
Authors: Roos J. , Mali M. , Brinkmann D. 
Published: February 2015

Abstract
By measuring the beat frequency of the spin-echo amplitude modulation of pulsed 137Ba NQR , the internal magnetic field of 14.8 mT perpendicular to the tetragonal c-axis at the Ba site in the antiferromagnetic YBa2Cu3O6 at 80 K was determined. Calculation of the dipole field at the Ba site due to localized antiferromagnetically ordered 0.66 μB magnetic moments at Cu(2) sites yields 47 mT.
Hydrogen-doped Antiferromagnetic YBa2Cu3O7-δHx as Studied by Proton NMR and Cu NQR
Authors: Niki Haruo , Tomiyoshi Shoichi , Shinohara Takeshi , Omori Mamoru , Kajitani Tsuyoshi , Kyan Hiroshi , Hamagawa Takeshi , Odahara Hirotaka 
Published: February 2015

Abstract
of the C u(l) site have been measured on the antiferromagnetic phase of a powdered sample of hydrogen-doped tetragonal YBa2Cu3O6.1H0.14 between 5 and 300 K. The line width, Δω, of 1H NMR increases abruptly below 20 K. The enhancement of T2
-1 and that of T1
-1 of 63Cu (1) NQR occurs around 20 K and 40 K, respectively. The nuclear magnetization does not recover in a simple exponential manner below 80 K. The predominant mechanism governing T1 below 80 K was found to be the fluctuating magnetic field which originates from the staggered Cu2+ moments in either the Cu(l) oxygen-deficient layer or the Cu(2)O2 plane induced by the hole doping effect. These enhancements and the abrupt increase in Δω are attributed to this fluctuating magnetic field.
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract

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

Abstract
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

Abstract

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

Abstract
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

Abstract
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

Abstract
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.
X-Ray Investigations on Molten Cu-Sb Alloys
Authors: Halm Th. , Neumann H. , Hoyer W. 
Published: February 2015

Abstract
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.