bluuebunny/crossref_metadata_2025_split huggingface dataset:
NQR Investigation of the Temperature-Induced Neutral-to-Ionic Phase Transition in the Mixed-Stack Charge-Transfer Complex TTF-CA
Authors: Gourdji M. , Guibé L. , Péneau A. , Gallier J. , Toudic B. , Cailleau H. 
Published: February 2015

Abstract
The chlorine-35 NQR has been investigated in the mixed-stack charge-transfer complex tetrathiafluvalene- chloranil. The neutral-to-ionic (N-I) phase transition is clearly seen on the NQR spectrum. Among several features of the spectra recorded and their counterpart in the sample behaviour, the evidence for the change in the crystal symmetry and the quite likely existence of neutral domains in the ionic phase below the N - I transition temperature are the most striking ones.
Uniaxial Reorientation of Octahedral Complex Anions Excited in Triethylammonium Hexachlorostannate (IV) Crystals
Authors: Shimizu Takashige , Asaji Tetsuo , Nakamura Daiyu , Ikeda Ryuichi 
Published: February 2015

Abstract
The temperature dependence of the 35Cl NQR spin-latticew relaxation time T1Q has been determined for the three resonance lines observed in [ ( C2H5 ) 3NH]2SnCl6 . The higher frequency lines fade out around 150 K upon heating, whereas the lowest line shows up to room temperature no anomaly, although these three lines are assigned to chlorines belonging to the same complex anion. The T1Q values of the higher two lines decrease exponentially around the fade-out temperature, where T1q of the lowest line shows no such behavior. These results are explained by the onset of uniaxial reorientations of the octahedral complex ions by 90° about the Cl -Sn -Cl axis containing the lowest frequency chlorines. The activation energy ( Ea)of this reorientation (22-24 kJ mol-1 ) is the lowest so far reportd for [SnCl6 ] 2 - ions. Ea about the other axes is 67 kJ mol-1 , indicating a remarkable anisotropic reorientation.
Sodium Ion Exchange in Na1+xZr2SixP3-xO12 as Studied by 23Na Nutation NMR
Authors: Ohki Hiroshi , Nakamura Nobuo 
Published: February 2015

Abstract

23Na two-dimensional nutation NMR was applied to Na1+x* Zr2SxP3-xO12 with x = 0, 1, and 2. The nutation spectrum in each compound consists of two clearly separated peaks corresponding to the two crystallographically inequivalent sodium sites. In the compound with x = 2 the nuclear quadrupole coupling constants (e2 Qq/h) and the asymmetry parameters (η) were by spectral simulation estimated to be 1.0 MHz and 0 for one site, and 1.5 MHz and 0.8 for the other site. The spectrum varies considerably on heating; the two peaks merge into a single peak at high temperatures due to fast ion exchange between the two different sites. For x = 0 and x = 1 the nutation spectra did not show any significant temperature dependence, suggesting that the rates of the sodium ion exchange are negligibly low.
Quadrupole Nutation NMR in Solids
Authors: Veeman W. S. 
Published: February 2015

Abstract
The nutation frequency of a quadrupolar spin I depends on the quadrupole interaction. From nutation spectra, therefore, one obtains information about the direct surrounding of the atom. The theory of the straightforward and of more complicated nutation NMR experiments is outlined. Two applications of nutation NMR, to 23Na in zeolites and 27Al in alumina, are shown. In this way in CaO • 6 Al2O3 penta-coordinated aluminum has been detected
NQR Imaging
Authors: Kimmich Rainer , Rommel Eberhard , Nickel Peter 
Published: February 2015

Abstract
A rotating-frame NQR imaging (ᵨNQRI) procedure based on pure NQR is reported. The technique is suitable for powdery or crystalline solid materials containing quadrupole nuclei. The spatial information is encoded by gradients of the radio frequency amplitude of the excitation pulse. A special deconvolution procedure has been developed for the analysis of the spatial information encoded in the pseudo-FID of the NQR signal in the case of powder geometry. The technique is applicable to rotationally symmetric as well as to asymmetric electric field gradient tensors. The RF gradients are suitably produced by surface coils. The prominent advantage of surface-coil NQR is that objects larger than the coil diameter can be investigated. The imaging procedure then provides depth resolution in a range of the order of the coil radius. The technique is particularly suitable for the detection of gradients of physical parameters influencing the NQR line shift and of spatial distributions of the chemical composition. Examples are stress or temperature gradients. Twodimensional images have been produced by rotating the sample step by step. For each orientation a profile across the sample is evaluated as the projection on the direction of the radio-frequency gradient. A projection-reconstruction formalism then permits the rendering of two-dimensional NQR images.
Detection of Quadrupole Interactions by Muon Level Crossing Resonance
Authors: Cox S. F. J. 
Published: February 2015

Abstract
The positive muon proves to be a very versatile and sensitive magnetic resonance probe: implanted in virtually any material its polarisation may be monitored via the asymmetry in its radioactive decay, giving information on the sites occupied by the muon in lattices or molecules, and the local fields experienced at these sites. The scope of these experiments has been greatly extended by the development of a technique of cross relaxation or level crossing resonance which allows quadrupole splittings on nuclei adjacent to the muon to be measured. The principles of the technique and the conditions necessary for detection of the spectra are described, together with a number of applications. Of especial interest is the manner in which muons mimic the behaviour of protons in matter. In metal lattices, for instance, muons invariably adopt the same interstitial sites as do protons in the dilute hydride phases, so that they can be used to study problems of localisation and diffusion common to those of hydrogen in metals. Studies of the muon level crossing resonance in copper have given valuable information on the crystallographic site, electronic structure and low temperature mobility of the interstitial defect. In semiconductors, muons are expected to trap at other impurities - notably acceptors - in processes analogous to the passivation of dopants by hydrogen. Muon resonance offers the exciting prospect of spectroscopic study of these passivation complexes. In molecular materials, substitution of protons by muons can be thought of rather like deuteration. Muons implanted in ice produce a significant change in the quadrupole coupling constant of adjacent 17O nuclei which may be traced to the effects of the large muon zero point energy; the resonance spectrum also exhibits temperature dependent features which may be informative on the nature and lifetime of defects in the ice structure. Muon level crossing resonance has already been studied in an oxide superconductor and this relatively young field is now wide open for quadrupole interaction studies in other materials, using a variety of nuclei.
A Simple Model to Explain 19F-TDPAD Amplitude Characteristics
Authors: Blank H.-R. , Frank M. , Heindl J. , Kaltenhäuser M. , Köchner H. , Kreische W. , Müller N. , Porscher S. , Wagner T. 
Published: February 2015

Abstract
Since many years the 19F-TDPAD method (TDPAD = time differential perturbed angular distribution) has been used to investigate electric field gradients in fluorine compounds. In these experiments always a strong reduction of the observed interaction amplitudes is observed. To explain these characteristics, a simple kinematic model is suggested.
14N Fourier Transform Nuclear Quadrupole Resonance. Instrumentation: Measurements on Cyanuric Chloride
Authors: Ambrosetti Roberto , Forte Claudia , Ricci Domenico 
Published: February 2015

Abstract
A Matec pulsed instrument, already equipped with a laboratory-built data system, has been considerably improved by adding new capabilities, such as versatile pulse sequence programming. Among other things, this allows automated T1 relaxation measurements. The instrument has been employed to record the 14N NQR FT spectrum of cyanuric chloride and measure its T1 relaxation time from 77 K to the melting point at 418 K. The four-line 14N spectrum indicates the presence of two chemically inequivalent sites. The intensity ratio of the lines identifies the site pertaining to a couple of symmetry-related 14N nuclei. The lines smoothly decrease in frequency up to the melting point, where they remain narrow and almost equally spaced. Considering previous results at 4.2 K, this indicates that a single phase is stable over the entire accessible temperature range. The relaxation time T1 decreases smoothly with increasing temperature, with a T-2 law, from nearly 180 s at 77 K to about 1 s near the melting point, where a precipitous decrease starts. The high T1 values found are consistent with the lack of nuclei having high magnetic moment.
Two-dimensional Two-frequency NQR Spectroscopy
Authors: Grechishkin V. S. , Sinjavsky N. Ja. 
Published: February 2015

Abstract
Two-dimensional NQR spectroscopy is experimentally accomplished by direct detection; forbidden transitions are also recorded. Two-dimensional spectra with cross-peaks are used in assigning lines in complex spectra.
A method is described of increasing the 14N NQR sensitivity by saturating the line v0 whilst observing the NQR at a frequency v_. The presence of a low magnetic field is shown to improve the conditions for localised NQR observations.
Surface Structure of Nanometer-Sized Zinc Ferrite Particles by the Anomalous X-ray Scattering (AXS) Method
Authors: Matsubara Eiichiro , Okuda Kaneharu , Waseda Yoshio , Saito Toshihiko 
Published: February 2015

Abstract
The atomic structure of nanometer-sized zinc ferrite particles has been studied with the anomalous x-ray scattering (AXS) method as well as the ordinary x-ray diffraction. The analysis of the peak broadening indicated that little microstrain exists in these nanometer-sized particles, and the average size of the particles is estimated to be 4 nm. Since the ratio of atoms located on the surface increases extremely in such fine particles, the contribution of these surface atoms to the x-ray scattering intensity was evaluated. The interference function Qi (Q) for the surface atoms appears to be similar to that of the zinc-ferrite glass. The experimental intensity is successfully explained by using a simple particle model consisting of the about 0.2 nm thick surface layer having a glass-like structure and the internal atoms having the ferrite crystalline structure.
Self-Diffusion in Molten Lithium Nitrate
Authors: Herdlicka C. , Richter J. , Zeidler M. D. 
Published: February 2015

Abstract
Self-diffusion coefficients of 7Li+ ions have been measured in molten LiNO3 with several compositions of 6Li+ and 7Li+ over a temperature range from 537 to 615 K. The NMR spin-echo method with pulsed field gradients was applied. It was found that the self-diffusion coefficient depends on the isotopic composition and shows a maximum at equimolar ratio. At temperatures above 600 K this behaviour disappears.
Molecular Motion in Phenpropylammonium Chloride Studied by Deuterium NMR
Authors: Gruwel Marco L. H. , Wasylishen Roderick E. 
Published: February 2015

Abstract
Cation dynamics in phenpropylammonium chloride, C6H5(CH2)3NH3Cr, were studied in three different solid phases by means of 2H nmr. Both 2H nmr line shapes and spin-lattice relaxation studies were performed on the ammonium head group, the adjacent methylene group and the phenyl-ring. In the low temperature phase, solid III, the - ND3 group dynamics were dominated by C3 jumps about the C - N axis. From the observed minima in T1Z and T1Q a quadrupole coupling constant of 165 ± 5 kHz was obtained. The 2H nmr line shapes of the methylene group indicate that this group does not execute any large amplitude motion in the low temperature phase. In contrast, the phenyl ring deuterium nuclei give rise to line shapes characteristic of C2 ring flips about the Cpara - Cipso axis.
In the solid II phase the 2H nmr line shapes of both the - ND3 and - CD2 - groups are characterized by asymmetric Pake powder patterns. Since one of the principal components of the electric field gradient tensor remains temperature independent for both groups, it was concluded that these groups perform planar large-amplitude motions between two sites. Axially symmetric spectra were obtained for all three groups in the high temperature phase, solid I. The 2H nmr line shapes indicate the presence of whole ion reorientation about a molecular axis. In addition, the - ND3 groups perform C3 jumps about the C - N axis and the - C6D5 group display line shapes characteristic for rotational diffusion about the Cpara - Cipso axis.
Molecular Motion in Solid Tetrapropylammonium Bromide and Iodide
Authors: Lewicki S. , Szafranska B. , Pajak Z. 
Published: February 2015

Abstract
The proton NMR second moment and spin-lattice relaxation time for tetrapropylammonium bromide and iodide have been measured over a wide temperature range. A solid-solid phase transition related to the onset of cation tumbling was found for both salts and confirmed by DTA. In the low temperature phases methyl group reorientation was evidenced. For iodide a dynamic nonequivalence of the methyl groups and the onset of ethyl groups motion was also discovered
A Modification of the Free-Electron Model for Cyclic Polyenes
Authors: Taubmann Gerhard 
Published: February 2015

Abstract
In the free-electron model (FE) of cyclic polyenes the π-electrons are allowed to move freely in a ring. A modification of the FE-model (the MFE-model) is discussed in which the N-fold symmetry due to the N C-atoms of the ring is taken into account by an appropriate potential. The results of the MFE-model are compared with HMO-theory. The sequence of degenerate and non-degenerate levels which determines the chemical properties (aromaticity and anti-aromaticity) of the annulenes is the same for both models
Dielectric Relaxation of Liquid Alicyclic Alcohols
Authors: Stockhausen M. , Hornhardt S. v. 
Published: February 2015

Abstract
The dielectric spectra of liquid cyclopentanol, cyclohexanol, cycloheptanol and cyclooctanol are reported for frequencies up to 72 GHz and temperature 20 (cyclohexanol solid), 30 and 40 °C. The absorption spectra are peculiar in exhibiting a remarkably developed high frequency shoulder which is attributed to single molecule and internal motion, while the principal absorption is due to association as with other alcohols
A Technique to Classify the Similarity Solutions of Nonlinear Partial (Integro-)Differential Equations. I. Optimal Systems of Solvable Lie Subalgebras
Authors: Kötz H. 
Published: February 2015

Abstract
Lie group analysis is a powerful tool for obtaining exact similarity solutions of nonlinear (integro-) differential equations. In order to calculate the group-invariant solutions one first has to find the full Lie point symmetry group admitted by the given (integro-)differential equations and to determine all the subgroups of this Lie group. An effective, systematic means to classify the similarity solutions afterwards is an "optimal system", i.e. a list of group-invariant solutions from which every other such solution can be derived. The problem to find optimal systems of similarity solutions leads to that to "construct" the optimal systems of subalgebras for the Lie algebra of the known Lie point symmetry group. Our aim is to demonstrate a practicable technique for determining these optimal subalgebraic systems using the invariants relative to the group of the inner automorphisms of the Lie algebra in case of a finite-dimensional Lie point symmetry group. Here, we restrict our attention to optimal subsystems of solvable Lie subalgebras. This technique is applied to the nine-dimensional real Lie point symmetry group admitted by the two-dimensional non-stationary ideal magnetohydrodynamic equations
Surrealistic Bohm Trajectories
Authors: Englert Berthold-Georg , Scully Marian O. , Süssmann Georg , Walther Herbert 
Published: February 2015

Abstract
A study of interferometers with one-bit which-way detectors demonstrates that the trajectories, which David Bohm invented in his attempt at a realistic interpretation of quantum mechanics, are in fact surrealistic, because they may be macroscopically at variance with the observed track of the particle. We consider a two-slit interferometer and an incomplete Stern-Gerlach interferometer, and propose an experimentum crucis based on the latter.
Reconstructed Au (100) Surface Imaged with Scanning Tunneling Microscopy in Air
Authors: Schilling T. , Tesche B. , Lehmpfuhl G. 
Published: February 2015

Abstract
Scanning tunneling microscopy (STM) of Au(100) was performed in air with a NanoScope II. Regions of 150 x 150 nm with atomatically flat areas fragmented by atomic steps were observed. The reconstructed (100) surface, deformed to a twisted hexagon with an interatomic distance of 0.27 μ ± 0.02 nm, could be seen and a corrugation of about 0.05 nm depth was measured. These results are in good agreement with Reflection Electron Microscopy measurements and STM investigations in UHV.
Cosmological Implications of the Planck Aether Model for a Unified Field Theory
Authors: Winterberg F. 
Published: February 2015

Abstract
In the previously proposed Planck aether model of a unified theory, the vacuum ground state consists of a dense assembly of positive and negative Planck masses obeying an exactly nonrelativistic law of motion. The Planck aether is superfluid, and it can without expenditure of energy form a tangle of quantized vortex filamants permitting the transmission of two types of waves: One associated with a symmetric displacement of the vortex lattice leading to gravitational waves, and one associated with an antisymmetric displacement leading to electromagnetic waves. Dirac spinors are explained in this model as excitons made up from positive and negative energy resonances of the vortex lattice.
Because the number of positive and negative Planck masses is assumed to be equal, the cosmological constant is equal to zero. With the Dirac spinors formed as bound states from the Planck aether, the sum of the positive kinetic energy and negative gravitational energy must remain exactly equal to zero, resulting in ß = l as the exact value for the cosmological mass parameter.
To make up for the unobserved missing mass, estimated to be about 10 times larger than the baryonic mass, it is conjectured that this mass consists of rotons, which in the superfluid Planck aether would come from the cut-off of the energy spectrum near the Planck energy. Because of their unusual dispersion relation, rotons possess a large momentum, even if their velocity vanishes. They are, for this reason, a promising candidate for the nonbaryonic dark matter, combining properties of hot and cold dark matter. The critical value Ω = 1 requires that the number density of the rotons is equal to nr ≃ 2 x 10-25 cm-3 . This value corresponds to an average distance of separation between the rotons of the order nr
-1/3 ≃ 6000 km. The small number of rotons per unit volume combined with their weak gravitational coupling constant would make it difficult to detect them directly, but the gravitational field these roton masses generate in the vicinity of galaxies could explain the observed flat rotation curves of disc galaxies.
Finally, because the gravitational waves have a cut-off at the vortex lattice scale at 1015 -1016 GeV, there can be no singularity in the course of a gravitational collapse, as it happens for solutions of Einstein's gravitational field equations. A generalization of Einstein's gravitational field Lagrangian, taking into account the existence of a smallest wave length, rather predicts a conversion of all mass into electromagnetic (or gravitational) radiation in approaching the singularity. The predicted conversion of mass into radiation in the course of gravitational collapse may provide an explanation for the large energy release of quasars.
Zeitaufgelöstes Fluoreszenz-Löschen in ultradünnen Coronen-Schichten auf Silizium-Substraten
Authors: Fischer P. , Port H. , Wolf H. C. 
Published: February 2015

Abstract
The fluorescence decay from thin coronene films deposited on Si (100) and Si/SiO2 substrates are measured as a function of coronene coverage at helium temperature. As the film thickness is decreased (1000 Å-10 Å) the decays are shortened and increasingly deviate from monoexponential. Excellent fits to the experimental curves are achieved by superimposing the monoexponential decay by an empirical function of the Kohlrausch type. Possible quenching processes are modeled in terms of energy transport through the layer followed by trapping in surface states and direct energy transfer from the excited molecules to the substrate
Absorption Spectrum of Ni(II) Ions Doped in Magnesium Thallium Sulphate Hexahydrate
Authors: Subbaiah A. Venkata , Rao J. Lakshmana , Krishna R. Murali , Lakshman S. V. J. 
Published: February 2015

Abstract
The optical absorption spectrum of Ni(II) ions doped in magnesium thallium sulphate hexahydrate has been studied at room- and liquid nitrogen-temperature. The crystal shows characteristic absorption of Ni(II) ion in the visible and near infrared region. The observed bands are assigned as transitions from the ground state 3A2g(F) to various excited triplet and singlet levels of the Ni(II) ion in octahedral symmetry. The splitting in one of the bands at liquid nitrogen temperature has been explained to be due to spin-orbit splitting. All the observed band positions have been fitted with the parameters B, C, Dq, and ξ
Structure Investigation on Liquid Tellurium by X-Ray and Neutron Scattering
Authors: Hoyer Walter , Neumann Hartmut , Wobst Manfred 
Published: February 2015

Abstract
We present the results of neutron and X-ray scattering experiments on liquid tellurium. No dependence on temperature of the radius and the coordination number of the first neighbour shell has been found in the temperature range between 460 °C and 550 °C. We investigate the influence of the truncation of the Fourier transformation on the determined coordination number of nearest neighbours and on the shape of the second coordination maximum at both, the lower and upper integration limit. The structure of liquid tellurium can be described in terms of a chain-like atomic arrangement with two bonds per atom
Supplement to "Some Aspects of Minimally Relativistic Newtonian Gravity"
Authors: Nandi Kamal K. 
Published: February 2015

Abstract
This supplement to Z. Naturforsch. 46 a, 1026 (1991) provides additional material that should be combined with the contents of that paper. The combined content then provides a model of gravitation which is complete in essential details. Its main features are that it (i) predicts all the local GR tests accurately but (ii) does not exhibit Schwarzschild singularity, (iii) allows the wellknown Birkhoff's theorem to hold and (iv) has well defined conservation laws in virtue of the maximal group of motions admissible on the flat background spacetime
ENDOR Spectra of 2-Methyl-Naphthalene-TCNB Triplet Trap in Naphthalene-TCNB Single Crystals
Authors: Maniero Anna Lisa , Toffoletti Antonio , Corvaja Carlo 
Published: February 2015

Abstract
Naphthalene-TCNB charge transfer crystals doped with 2-methyl naphthalene illuminated by visible light give rise to triplet traps which have been identified by EPR and ENDOR spectroscopy as 2-methyl naphthalene-TCNB CT complexes in their first excited triplet state. The complete hyperfine tensors of all the 2-methyl naphthalene protons have been obtained by analysis of the variation of the ENDOR frequencies with the crystal orientation in the magnetic field. The structure of the CT complex, the spin distribution and the CT character are discussed.