bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dissolution of Alkali Fluoride and Chloride Crystals in Water Studied by Molecular Dynamics Simulations
Authors: Fukushima N. , Tamura Y. , Ohtaki H. 
Published: February 2015

Abstract
The dissolution of cubic crystals of NaF, KF, CsF, LiCl, NaCl, and KCl consisting of 32 cations and 32 anions in an isolated box containing 216 water molecules was studied at 298 K by molecular dynamics simulations. The ion-ion, ion-water and water-water interactions were described in terms of the Tosi-Fumi, Kistenmacher-Popkie-Clementi, and Matsuoka-Clementi-Yoshimine potentials, respectively. During the simulation periods of 12 ps for NaF, CsF and LiCl and 20 ps for KF, NaCl and KCl cations did not dissolve, while anions dissolved from the CsF, LiCl and NaCl crystals but not from the NaF, KF and KCl crystals. The mass effect in the dissolution of CsF was examined by giving the ceasium ions the atomic weight of the fluoride ion (18.998). In case of the "light" caesium ions in the crystal fluctuated less far and again fluoride ions but no caesium ions were dissolved.
The Sites of Premelting in Organic Compounds
Authors: Dosseh Gilberte , Fuchs Alain H. 
Published: February 2015

Abstract
Bartis recently proposed a theory which should allow to determine whether impurities or defects are responsible for the premelting phenomena in crystalline solids. We have tested this model on several orientationally disordered molecular crystals studied by proton NMR spectroscopy. This showed that extended defects, and more likely grain boundaries are at the origin of the premelting phenomena in these crystals.
Hyperfine Structure and Relaxation Times of 4-Oxo-TEMPO/Methyl Alcohol Solutions in Weak and Strong Fields
Authors: Sünnetçioğlu M. , Bingöl G. , Sungur R. 
Published: February 2015

Abstract
The hyperfine structure of the 4-Oxo-TEMPO (2,2,6,6-tetramethyl-4-oxopiperidin-oxyl-l) free radical was investigated. Theoretical investigation includes four methyl groups protons close to the unpaired electron. Energy levels and transition probabilities were found by using second order and first order perturbation theory, respectively, and from these data theoretical spectra of the free radical were obtained. Diluted solutions in CH3-OH were prepared and the spectra were recorded with a double resonance spectrometer (1.53 mT) and Varian E-9X-band ESR spectrometer (~0.3 T). In order to understand the influence of time dependent phenomena on the linewidths, electronic relaxation times of 4-Oxo-TEMPO and its perdeuterated form (PDT) were measured at two different fields by using cw saturation method.
Anomalous Behaviour of the Mean Dipole Polarizability α of Neopentane C(CH3)4 in the Temperature Range between 250 K and 360 K
Authors: Hohm Uwe , Kerl Klaus 
Published: February 2015

Abstract
The temperature dependence of the dynamic dipole polarizability α(λ) of gaseous neopentane has been re-examined in the temperature range between T = 250 K and T - 360 K at the four HeNelaser wavelengths λ = 543.51 nm, 594.11 nm, 611.97 nm, and 632.99 nm. These interferometric measurements are compared with former determinations of the dynamic as well as the static dipole polarizability in the solid, liquid and gaseous state. In all cases, a shape of α(T) in the range between 290 K and 310 K has been observed which is similar to the shape of α (λ) in an absorption band. This observation is connected with other physico-chemical quantities of neopentane.
Influence of Hydrogen on the Structure of Amorphous Sputtered Fe-Co-Tb Films by Means of Wide- and Small Angle Neutron Scattering
Authors: Heckele M. , Bellissent R. , Brunseh A. , Lamparter P. , Steeb S. 
Published: February 2015

Abstract
Sputtered amorphous Fe-Co Tb-films with perpendicular and in-plane magnetic anisotropy were investigated by wide- and small angle neutron scattering. By combination with X-ray data the maxima in the pair correlation function could be attributed to the individual atomic pairs. Thus also partial coordination numbers and a short range order parameter could be determined.
Wide angle diffraction revealed that the film with magnetic in-plane anisotropy contained 13 atomic percent hydrogen. The hydrogen incorporation causes substantial changes in the short range order, associated with enhanced formation of Tb-rich clusters, and the in-plane anisotropy. The clustering effect was confirmed by results from small angle scattering with polarized neutrons
Transit Times in Lltra-Relativistic Heavy-Ion Collisions
Authors: Wolschin G. 
Published: February 2015

Abstract
Mean transit times in heavy-ion collisions are calculated as functions of the relativistic incident energy and the impact parameter. As a consequence of special relativity, they become constant in a central collision of O with Pb at T~0.15TeV. Together with a geometrical estimate of the maximum energy densities in the interaction region, it is argued that heavy ions in a large hadron collider may produce a quark-gluon plasma due to the plateau in the transit times at ultra-relativistic energies
An MD Simulation of Concentrated Aqueous Solutions of Caesium Iodide
Authors: Tamura Y. , Ohtaki H. , Okada I. 
Published: February 2015

Abstract
Molecular dynamics simulations of concentrated aqueous Csl solutions have been performed for Csl: H2O = 1:20 (2.78 molal) at 298 K and 341 K and 1:10 (5.56 molal) at 349 K. Effects of temperature and concentration on the structures of the hydrated ions, the ion pairs, and ionic aggregates are discussed by comparing the results with X-ray diffraction data obtained under similar conditions [1]
Bromine Spin-Rotation Coupling Constants of Cyclopropylbromide-79Br and -81Br
Authors: Heineking N. , Gripp J. , Dreizler H 
Published: February 2015

Abstract
We reinvestigated the microwave spectrum of cyclopropylbromide with the increased resolution of pulsed microwave Fourier transform spectroscopy. Because of the higher frequency precision, it was possible to determine the spin-rotation coupling constants of bromine. Global fits of rotational constants, quartic centrifugal distortion constants, quadrupole coupling constants including the off-diagonal component χac , and spin-rotation coupling constants simultaneously to almost one hundred hyperfine components for each of the two bromine isotopomers resulted in overall standard deviations of well below 5 kHz
Nuclear Quadrupole Hyperfine Structure in the Rotational 2Q1-Subbranch of Deuteroisothiocyanic Acid, DNCS
Authors: Heineking N. , Dreizler H. 
Published: February 2015

Abstract
The two-nuclei quadrupole hyperfine structure of four 2Q1-subbranch transitions of deuteroisothiocyanic acid, DNCS, has been resolved and analyzed by use of a waveguide microwave Fourier transform spectrometer. The analysis yielded one previously unknown quadrupole coupling constant ( χ- ≡ χbb-χcc) for both nitrogen ( χ-
N = +27.6(11) kHz) and deuterium X-
D = +175.8(11) kHz). Taking into account the results from earlier work on HNCS, DNCS, HNCO, and DNCO, the orientations of the principal axis systems of the two quadrupole coupling tensors could be calculated. It appears that while the deuterium tensor is aligned to the D-N internuclear axis as expected, the nitrogen tensor is tilted away from the bisector of the DNC angle by 13° towards the NCS chain
Static and Dynamic Properties of Ferroelectric Liquid Crystals in the Vicinity of a First-Order SmA-SmC* Phase Transition
Authors: Netz Roland R. , Hess Siegfried 
Published: February 2015

Abstract
A unified theoretical description of static and dynamic properties of ferroelectric liquid crystals in terms of a Landau free energy is presented. The shear deformation tensor is used as principal order parameter. Results for the stationary case for tilt angle variation and dielectric properties are compared with experiments on a compound with a pronounced first-order SmA-SmC* phase transition for various strengths of the applied electric field
Solvation Structure of the Ti(III) Ion in Methanol Solutions and in Perfluorinated Ionomers Swollen by Water and Methanol. A Study by ESR and ENDOR
Authors: Schlick Shulamith , Myers Brian E. , Sjöqvist Lars , Lund Anders 
Published: February 2015

Abstract
The local environment of Ti3+ cations in methanol solutions and in Nafion perfluorinated ionomers swollen by water and methanol has been studied by electron spin resonance (ESR) and by 1H and 2H electron nuclear double resonance (ENDOR) spectroscopies. The two major sites reflecting the ligation of the cations as a function of solvent structure and cation concentration have been analyzed, using whenever possible the method of orientation selection for the ENDOR transitions. The distance RN of the protons from the central cation, and the angle ΘN between the symmetry axis of Ti3+ and the Ti3+ -proton vector have been deduced by evaluating the dipolar interaction tensor and by simulating the orientation dependence of the ENDOR signal. For site 1 of Ti3+ in methanol (g॥
= 1.986 and g⊥
= 1.894) no orientation selection was possible, and RN
values in the range 4.1 to 4.6 Å are suggested from the ENDOR splittings. For site 2 of Ti3+ in methanol (g॥ = 1.943 and g⊥
= 1.960) equatorial and axial methyl protons have been detected; the RN values deduced from the simulations are 3.95 and 4.35 Å, respectively. For Ti3+ in Nafion swollen by water (g
|| = 1.997 and g⊥
= 1.907), equatorial and axial protons from OH groups have been detected, and the ENDOR spectra were simulated with RN values of 2.60 and 3.10 Å respectively for these protons
Dependence of Potential Energy on Inter-bond Angles in Simple Molecules
Authors: Indira K. , Warier M. K. Rudra , Ananthakrishnan T. R. , Paul C. M. 
Published: February 2015

Abstract
A method is developed to investigate the variation of potential energy contributions (Vstretch, Vbend, Vstretch-bend and Vstretch-stretch) in simple molecules when their inter-bond angles θ are varied arbitrarily. Applied to XY2 bend symmetric systems, the V - θ plots suggest that the actual equilibrium configuration in these molecules lies in the premises of minimum Vbend and zero Vstretch-bend.
An NQR Study of Tetrachloride Complexes of Group IVA Elements
Authors: Feshin Valentin P. , Voronkov Mikhail G. 
Published: February 2015

Abstract
The results of an NQR study on the MCl4 complexes (M = Si, Ge, Sn) with organic heteroatom ligands (including those containing several coordination centers) are summarized: chloroanhydrides of unsaturated, aromatic and heteroaromatic carboxylic acids; alkylarylethers, ketones, aryldichlorophosphates, nitrogen-containing compounds, etc. The octahedral or trigonal-bipyramidal structure of these complexes has been established, and the factors influencing the formation and structure of such complexes (component ratio, character of ligand and M atom) have been analyzed. The structure of several complexes may vary with time or depend on the crystallization condition of the system. Some of these results indicate coordination isomerism. The quantitative ratios between the 35Cl NQR frequency shifts of ligand and axial Sn-Cl bonds in trigonal-bipyramidal RCOCl • SnCl4 complexes relative to the initial component frequencies have been found
NQR Studies of Organic Compounds Containing Tetra- or Pentacoordinated Atoms of Elements of Groups IVA and VIA
Authors: Feshin Valentin P. 
Published: February 2015

Abstract
The 35Cl and 79Br NQR spectra of halogen-containing organic compounds of Si, Ge, Sn and Te, in which these atoms may be tetra- or pentacoordinated, have been compared to the results of their X-ray diffraction analysis. The NQR technique was also used to study a large number of such compounds for which X-ray investigations were found to be impossible. It has been shown that the NQR technique may be considered as a rapid method for the determination of the electronic and spatial structure of these compounds. The conditions for pentacoordination of atoms of IVA group elements have been also formulated.
Theoretical Study of the Electric Field Gradient in Silver Iodide
Authors: Frantz G. , Leiberich R. , Schmidt P. C. 
Published: February 2015

Abstract
The electric field gradient (EFG) in hexagonal Agl at the iodine site is studied theoretically by three different procedures, namely the point charge model, the Hartree-Fock cluster approach, and the augmented plane wave band structure procedure. A comparison is made for the electronic charge distribution and the sizes of the various contributions to the EFG obtained by the different procedures. From the point charge model and the Hartree-Fock cluster approach one gets almost the same result for the EFG, q = +0.743 • 1021 V/m2 and +0.816 • 1021 V/m2 respectively. Only a rather preliminary result of q = +0.393 • 1021 V/m2 is found by the band structure calculation to be compared with the experimental value of qexp= ±0.415 • 1021 V/m2 .
The confidence limits of the theoretical results are discussed, including possible ways to bridge the gap between the theoretical results by different methods and experiment. Both the cluster and the band structure calculations are shown to support an ionic model for hexagonal Agl with some overlap between the charge distributions on neighboring ions.
14N NQR and the Molecular Charge Topology in Coordinated Ammonia
Authors: Murgich Juan , Aray Yosslen , Ospina Edgar 
Published: February 2015

Abstract

14N NQR spectra of [Co(NH3 ) 6 ] • 3Cl, [Co(NH3 ) 5CO3 ] • NO 3 , [Zn(NH3 ) 4 ] • 2Cl, [Zn(NH3 ) 4 ] •(BF4)2, and [Ag(NH3) 4 ] • NO 3 were obtained at 77 K. The results, analyzed by means of the topology of the charge distribution obtained from ab-initio MO calculations of free and of a model of coordinated NH3 , showed that bonding to the metal-ion produces a strong decrease (Co ≫ Zn ≈Ag) in the N nonbonded density ("lone pair") and an increase in the bonded maxima found in the N - H bond direction of the N valence shell.
Chlorine-NQR Relaxation Near the Structural Transitions of Natural and Deuterated (NH4)2TeCl6
Authors: Dimitropoulos C. , Borsa F. , Pelzl J. 
Published: February 2015

Abstract
The temperature and isotope dependence of the 35,37Cl-NQR spin-lattice relaxation rate near the cubic to trigonal phase transition at Tc1 ≌ 87 K has been investigated in both (NH4) 2TeCl6 and (ND4)2TeCl6 salts. In the temperature range of ~ 20 K above and ~ 10 K below TCl, the relaxation obeys the relation (T1 • T)2 ∞(T-TCl). This behaviour corresponds to a direct relaxation mechanism in presence of a strongly damped rotational soft mode of the TeCl2
6- tetrahedra and is discussed on the basis of cation-anion coupling near the critical region. Below TCl we observe an extra contribution to the 35,37Cl relaxation rate which is tentatively ascribed to the dynamics of the NH4+ tetrahedra.
Chlorine Nuclear Quadrupole Relaxation and Cationic Motion in Trimethylsulfonium Hexachloroselenate(IV): [(CH3)3S]2SeCl6
Authors: Kaga Makoto , Asaji Tetsuo , Ikeda Ryuichi , Nakamurab Daiyu 
Published: February 2015

Abstract
The 35Cl NQR spin-lattice and spin-spin relaxation times, T1Q and T2Q, respectively, and the 1HNMR spin-lattice relaxation time T1H at 32 and 60 MHz were determined for [(CH3)3S]2SeCl6 as functions of temperature. The rapid decrease of observed above ca. 250 K with increasing temperature was attributed to the onset of reorientation of the [SeCl6 ]2- complex anion with the activation energy Ea = 42 + 5 kJ mol -1 . When cooled from ca. 250 K, T1Q showed an anomalous decrease. This T1Q decrease was explained by electric field gradient modulation related to some cationic motion. Possible origins of the cationic motion are discussed
35Cl NQR Relaxation in Chloral Cyclohexylhemiacetal
Authors: Niki Haruo , Igei Ryokan , Kyan Hiroshi , Hamagawa Takeshi , Isono Takahiro , Hashimoto Masao 
Published: February 2015

Abstract
The crystal structure of cyclohexylhemiacetal (cycHx-CH) was determined at 296 K : monoclinic, space group P21/c, a =1028.7 (9), b = 609.5 (1), c = 1811.9 (4) pm, and ß = 99.79 (3)°, Z = 4, R = 0.0552. The three 35Cl NQR lines in cycHx-CH, T1, T2, and T2*, were measured by a pulsed method at 80-300 K. Below 200 K T1
-1 obeyed the T law well, indicating that the spin lattice relaxation is governed by lattice vibrations. The reorientation of CCl3 seems to be responsible for the sharp T: drop observed above 250 K. Shoulders in the T1 vs. 1/T curves indicate the presence of T1 minima at about 240 K. A fluctuation of the EFG due to a dynamic disorder of hydrogen atoms in the OH groups is assumed to explain the T1 minima.
NQR and Neutron Diffraction in Scheelites
Authors: Brown R. Julian C. , Shortreed E. , Szabo Andrew J. , Powell Brian M. , Stuart Stephen N. 
Published: February 2015

Abstract
Measurements of the spin-lattice relaxation time for rhenium in KReO4 and NH4ReO4 are reported; relaxation rates are extremely fast due to the large quadrupole moment of Re. Calculations of the electric field gradient in KReO4 show that the EFG is a very sensitive function of the orientation of the anion in the unit cell as well as of the unit cell dimensions, and that geometrical effects make a major contribution to the temperature dependence. Neutron diffraction in these two salts has been employed to determine the temperature dependence of structural parameters over a wide range of temperature, and preliminary results are reported.
Temperature dependence of the Spin-Lattice Relaxation Time of the 23Na-NMR Line in NaNO2
Authors: Igarashi M. , Kitagawa H. , Takahashi S. , Yoshizaki R. , Abe Y. 
Published: February 2015

Abstract
The spin-lattice relaxation time, T1, of the 23Na-NMR line in NaNO2 is measured between 25 K and 160 K at two magnetic field strengths, 1.1 T and 6.9 T. The temperature dependence of T1 for the center line, observed on a polycrystalline sample prepared by precipitation from aqueous solution, is given by a monotonous curve. T1 increases gradually as the temperature decreases. On the other hand for a single crystal, which is made by a modified Bridgman method, the temperature dependence of T1 shows two deep dips below 150 K and a frequency dependence which cannot be explained by ordinary BPP theory.
The dominant relaxation mechanism above and below 150 K is also investigated.
Isomerization of Diphenyl Polyenes. Part II. Fluorescence Properties of 1,8-Diphenyl-1,3>5,7-octatetraene in Poly (vinyl alcohol) Film
Authors: Kawski A. , Kubicki A. , Kukliński B. , Gryczyński I. , Gryczyński Z. 
Published: February 2015

Abstract
The effect of temperature on the fluorescence properties of 1,8-diphenyl-1,3,5,7-octatetraene (DPO) in polyvinyl alcohol) film (PVA) was investigated in the range from 295 to 428 K. Upon heating above 353 K, the quantum yield of D PO increases rapidly. This effect is irreversible, similarly as the optical density in the long wavelength absorption band (320-440 nm). It has its origin in the cis-trans conversion of DPO molecules in PVA film at high temperatures. The behaviour of the fluorescence anisotropy in the same temperature range was also investigated. The emission anisotropy was found to be a viscosity indicator in the microenvironment of the DPO molecules in PVA film.
Principal Component Analysis of Chinese Porcelains from the Five Dynasties to the Qing Dynasty
Authors: Yap C. T. , Hua Younan 
Published: February 2015

Abstract
This is a study of the possibility of identifying antique Chinese porcelains according to the period or dynasty, using major and minor chemical components (SiO2 , Al2O3 , Fe2O3 , K2O, Na2O, CaO and MgO) from the body of the porcelain. Principal component analysis is applied to published data on 66 pieces of Chinese procelains made in Jingdezhen during the Five Dynasties and the Song, Yuan, Ming and Qing Dynasties. It is shown that porcelains made during the Five Dynasties and the Yuan (or Ming) and Qing Dynasties can be segregated completely without any overlap. However, there is appreciable overlap between the Five Dynasties and the Song Dynasty, some overlap between the Song and Ming Dynasties and also between the Yuan and Ming Dynasties. Interestingly, Qing procelains are well separated from all the others. The percentage of silica in the porcelain body decreases and that of alumina increases with recentness with the exception of the Yuan and Ming Dynasties, where this trend is reversed.
Potentiometrie Study of Magnesium Fluoro Complexes in Aqueous Solutions up to 473 K and 1 kbar
Authors: Bilal B. A. , Müller E. 
Published: February 2015

Abstract
The formation of magnesium fluoro complexes in a hydrothermal fluorite-bearing model solution has been potentiometrically studied up to 473 K and 1 kbar at the ionic strength I = 1 m (NaCl), in order to estimate the competition with the formation of the lanthanide fluoro and fluorohydroxo complexes in such systems. No evidence of difluoro complex was found at p, T, [F- ] and pH conditions which are relevant to fluorite formation. The apparent formation constant Q, as well as the apparent thermodynamic data ΔG, ΔS and ΔH of MgF+ have been determined. The effect of pressure was found to be negligible. The competition with the lanthanide complexes becomes increasingly negligible with increasing T and in particular with increasing pH.
The Phase Transition of Potassium Sulfate
Authors: Kurtz Wolfgang 
Published: February 2015

Abstract
The discontinuous phase transition of K2SO4 is described by a semi-empirical model that uses the elastic stiffnesses ci,i and the changes in volume and entropy associated with the order-disorder transition. Consideration of the elastic anomaly (existence of soft, damped longitudinal acoustic phonons) in K2SO4 removes the disagreement between transition enthalpies ΔHtr measured calorimetrically and ΔHtr derived from the p-T phase diagram via the Clausius-Clapeyron equation. The model used requires the knowledge of the cu (i = 1, 2, 3) which in many cases is not available in the literature. It is demonstrated that these values can be calculated with sufficient accuracy from the anisotropic displacement (Debye-Waller) factors which are routinely determined in crystal structure analyses and which, therefore, are available for many substances. There is fair agreement between the calculated strain energy and ΔHtr also for K2SeO4 . In the case of K2CrO4 , use of published expansion data resulted in disagreement between calculated strain energy values and published, measured ΔHtr data.
Methyl Internal Rotation and 14N Nuclear Quadrupole Coupling from the Rotational Spectra of Ethyl Isocyanide, iso-Propyl Isocyanide and gauche- and trans-n-Propyl Isocyanide
Authors: Krüger Michael , Dreizler Helmut 
Published: February 2015

Abstract
The barrier heights (V3) hindering methyl internal rotation were determined with microwave Fourier transform spectroscopy from the ground vibrational state for the title molecules and found to be V3 = 3.336(52) kcal/mol for ethyl isocyanide, V3 > 3.1 kcal/mol for iso-propyl isocyanide, V3 = 2.894(23) kcal/mol for gauche-n-propyl isocyanide and V3 = 2.954(22) kcal/mol for transn- propyl isocyanide. The quadrupole coupling constants of iso-propyl isocyanide are χaa = 179.3(31) kHz, χbb = -140(15) kHz and χcc - 39(15) kHz; the constants of trans-n-propyl isocyanide were determined to be χaa = 268.1 (71) kHz, χbb = - 108(23) kHz and χcc = - 160(23) kHz.
Rotational Spectrum of cis-HS3D
Authors: Liedtke M. , Saleck A. H. , Behrend J. , Winnewisser G. , Klünsch R. , Hahn J. 
Published: February 2015

Abstract
The rotational spectrum of HS3D in the vibrational ground state has been measured in the frequency range between 75 and 293 GHz. Up to now, about 180 Q-, 30 P-, and 70 R-branch c-type transitions have been identified. The preliminary rotational constants of the species observed support the cis-conformation established earlier from the H2S3 rotational spectrum.