bluuebunny/crossref_metadata_2025 huggingface dataset:
Notizen: Fluoreszenzlöschung von protonierten Aza-arenen durch äußere Schweratomstörer (Methyliodid und Silberperchlorat)
Authors: Zander M.
Published: February 2015

In contrast to arenes, the fluorescence of protonated azaarenes in fluid solution is more readily quenched by methyl iodide than by silver Perchlorate. This is probably due to the Coulomb repulsion between the fluorescent ion and the silver ion, thus inhibiting the formation of a non-fluorescent complex.
109Ag and 29Si NMR Investigations of Scalar Couplings and Relaxation on Cyclo-tetrakis[tri-tert-butoxysilanethiolatosiIver(I)],[(t-C4H9O)3SiSAg]4
Authors: Schwenk A. , Piantini U. , Wojnowski W.
Published: February 2015

From the 29Si NMR spectrum of [(t-BuO)3SiSAg]4 with a partly resolved fine structure recorded at 9.4 T, the coupling constants |J(29Si,109Ag)| = (4.49 ±0.04) Hz and | J(29Si, 107Ag)| = (3.90 + 0.03) Hz were derived. The 109Ag spectra at 9.4 T and at 2.1 T are single lines without fine structure shifted to higher frequency by δ = (725.8 ± 1.5) ppm relative to the resonance of the Ag + ion in aqueous solution at infinite dilution. No hint of any {Ag, Ag}-coupling can be derived from these spectra and from a comparison of the FID- and steady-state-signal intensities, i.e. | J (Ag, Ag) | < 1 Hz. This result is in contrast to the assumption of an Ag-Ag bond to explain the spatial shift of the Ag atoms towards the centre of the alternating Ag4S4-eight-membered central ring of the molecule. For the first time silver relaxation was investigated in a molecule. T1(109Ag) was determined at 9.4 T and at 2.1 T and at different temperatures to separate the contributions of different mechanisms: chemical shift anisotropy is the dominating one. T1=20.2 s at 2.1 T and at 301 K in this molecule is shorter by nearly two orders of magnitude than T1 of the Ag+ ion in aqueous solution
Self-Organized Critical Dynamics and Phase Transition Behavior During Avalanche Breakdown in p-Germanium
Authors: Knoop M. , Parisi J. , Clauß W. , Rau U. , Peinke J.
Published: February 2015

We give experimental evidence that self-organized criticality takes place during the formation of low-temperature semiconductor breakdown. Quantitative evaluation of the characteristic scaling properties together with the appropriate parameter ranges of validity further support the applicability of the model conjectured
Some Aspects of Minimally Relativistic Newtonian Gravity
Authors: Nandi Kamal K.
Published: February 2015

This paper aims to examine if the classical tests of General Relativity (GR) can be predicted by a simpler approach based on minimal changes in the Newtonian gravity. The approach yields a precession of the perihelion of Mercury by an amount 39.4"/century which is very close to the observed Dicke-Goldenberg value (39.6"/century), but less than the popularly accepted value (43"/ century). The other tests exactly coincide with those of GR. Our analysis also displays the genesis as well as the role of geometry in the description of gravitational processes. The time dependent spherically symmetric equations, which are mathematically interesting, call for a further study. The model also allows unambiguous formulation of conservation laws. On the whole, the paper illustrates the limited extent to which a second rank tensor analogy (nonlinear) with flat background Faraday-Maxwell electrodynamics can be pushed in describing gravitation
Lattice Vibration Spectra. LXX. Evaluation of IR Reflection Spectra. Model Calculations and Experimental Data of MnCr2O4 Single Crystals
Authors: Himmrich J. , Schneider G. , Zwinscher J. , Lutz H. D.
Published: February 2015

The various evaluation procedures of IR reflection spectra, viz. Kramer-Kronig analyses (KKA), 3 parameter (coTO, g, y) (3 PM), and 4 parameter (ωro, ωLO yro yLO) oscillator-model calculations (4 PM), are compared. For the zone-centre phonon energies, the oscillator parameters ωro and ωLO of 4 PM as well as the frequencies of the dielectric functions ε" and - Im(l/ε), respectively (KKA, 3 PM), are recommended. The pole frequencies of the |ε| functions yield too large TO/LO splittings, especially in the case of large damping of the phonons. In the case of asymmetric reststrahlen bands, the use of 4 PM with different damping constants y for the TO and LO phonons is recommended. Computer simulations of the influence of the various oscillator parameters on the reflection spectra as well as the phonon frequencies of spinel-type MnCr2O4 are included
X-ray Emission Wavelengths of Argon, Krypton, Xenon, and Curium
Authors: Kleykamp H.
Published: February 2015

The wavelengths of the L series of argon, krypton and xenon, the K series of argon, and the M series of curium were measured by means of wavelength dispersive X-ray microanalysis. The specimens for the investigations were TiC layers which had been HF sputtered under reduced argon pressure by the PVD method, krypton and xenon implanted zeolites, and a curium doped borosilicate glass. The obtained relative intensities of the X-ray emission lines were normalized to the maximum intensity of the line of the respective series
The Role of Singlet Oxygen in the Lyoluminescence of Saccharides
Authors: Pitt E. , Scharmann A. , Suprihadi T.
Published: February 2015

Lyoluminescence, the radiation induced light emission during the dissolution of irradiated solid substances like alkali halides, saccharides, amino acids etc. was proposed as a method of dosimetry. It is established that lyoluminescence is a consequence of a reaction of radicals from radiolysis with oxygen dissolved in the solvent. The role of oxygen in the lyoluminescence of saccharides has been investigated. It has been proved that oxygen is not only necessary for the chemical reaction preceeding the lyoluminescence process, but that it is also the emission centre itself. Singlet oxygen is released from the disproportionation of peroxyl radicals produced during solution. The lyoluminescence emission peaks may be attributed to the simultaneous transitions [ 1Σ g
+ ] [ 1Σ g
+ ] , [ 1Δg ] [1 Δg ] and [1Σg
+] [ 1Δg ] to [3Σg
+] [3Σg
-] of collisional pairs of singlet oxygen molecules
The Effect of Temperature on the Fluorescence Quenching of Perylene by Tetrachloromethane in Mixtures with Cyclohexane and Benzene
Authors: Wiczk Wieslaw M. , Latowski Tadeusz
Published: February 2015

The effect of temperature on the fluorescence quenching of perylene has been studied in a variety of two-component mixtures of CCl4 with cyclohexane and benzene. Results of these studies are explained in terms of specific interactions between the components of the mixtures
On the Problem of a Finitistic Quantum Field Theory
Authors: Winterberg F.
Published: February 2015

A finitistic quantum field theory, as a model for a unified theory of elementary particles is proposed, making the assumption that all spatial and temporal distances can only assume integer values of a fundamental length and time, for which we have chosen the Planck length and Planck time. To satisfy the condition of causality in its quantized version, the theory must be exactly nonrelativistic, because only then can the concept that points in space are separated by multiples of a fundamental length be formulated in an invariant way. The theory is formulated as a partial finite difference equation, invariant under translations and rotations in space, and translations in time, and can be expressed as a partial differential equation of infinite order. The theory is free of all divergencies, has a positive definite metric in Hilbert space and therefore no ghost states. Possessing a fundamental length, chosen to be equal the Planck length, the theory has an inbuilt cut-off at the Planck energy. For energies sufficiently below the Planck energy, the theory can be approximated by the previously described Planck aether model, which can be viewed as a superfluid consisting of Planck masses, leading to special relativity as a dynamic symmetry in the asymptotic limit of low energies.
Onset of Thermosolutal Convection in a Liquid Layer Having Deformable Free Surface – II. Overstability
Authors: Dandapat B. S. , Kumar B. P.
Published: February 2015

The onset of thermosolutal convection driven by a temperature and concentration dependent surface tension is investigated for a thin layer of fluid having a deformable free surface. It is shown that there exist two Crispation numbers (Cr) for oscillatory modes of instability. It is further shown that Cr and the frequency of the oscillatory mode are strongly coupled for large values of Cr. It is found that Cr destabilizes the system for both cases, salted from below and salted from above
The 14N Nuclear Quadrupole Coupling in E- and Z-C-Cyanomethanimine; its Prediction from Restricted Hartree-Fock Wave Functions and its Experimental Determination by High Resolution Microwave Spectroscopy
Authors: Krause H. , Sutter D. H.
Published: February 2015

The 14N hyperfine multiplets of low-7 rotational transitions of the E and Z isomers of HN = CH - C ≡ N, produced by flash pyrolysis from (CH3)2N -C ≡ N as precursor, were observed and analysed. The quadrupole coupling constants determined are (c-axis perpendicular to the molecular plane):

The observed hfs multiplets were predicted with reasonable accuracy from RHF/6-311G** field gradients, once the latter had been scaled appropriately to compensate partly for the typical errors in the RHF-wave functions. The hitherto unmeasured 14N hyperfine multiplets of the related pyruvonitriles, H - N = C(CH3) - C ≡ N, are predicted.
Preparation of Octabromoditechnetate(III,II), [Tc2Br8]3- and the Vibronic Structure of the δ → δ* Transition
Authors: Peters G. , Skowronek J. , Preetz W.
Published: February 2015

The dinstinct vibronic structure of the δ → δ* transition of Cs3[Tc2Br8] with its mixed valence is well resolved at 6 K. The electronic origin at about 5970 cm-1 is split into four components, each giving rise to progressions entirely assignable in terms of nν1 and nν1 + ν2 up to n = 9, utilizing the totally symmetric stretching modes ν1(TcTc) and ν2(TcBr) exclusively.
Hydrogen in Electrodynamics. VIII The Half-Integer Spin
Authors: Sallhofer Hans
Published: February 2015

After a discussion of the one-component Schrödinger (1926) and the four-component Dirac(1928) representation of hydrogen it is shown that the six-component electrodyamic picture turns out to be considerably simpler and clearer. The computational effort is reduced to a fraction.
Far-Infrared Laser Magnetic Resonance Detection of CH2Cl
Authors: Temps F. , Wagner H. Gg. , Wolf M.
Published: February 2015

New Far Infrared Laser Magnetic Resonance (LMR) spectra have been detected in the reaction of Cl atoms with CH2CO. Based on chemical and kinetic evidence they were assigned to CH2Cl radicals. The assignment was substantiated by subsequent experiments which employed the reactions of F atoms with CH3Cl and Na atoms with CH2Cl2, respectively. The three different sources yielded identical spectra
NMR Characterization of Half-integer Quadrupolar Nuclei in Solids
Authors: Amoureux J. P.
Published: February 2015

This article describes a few aspects of NMR characterization of half-integer quadrupolar nuclei in powder samples which are either static or rotating around one fixed axis (M.A.S. and V.A.S. techniques). The simultaneous occurence of C.S.A. and quadrupole interactions with possible noncoincident tensors is discussed. Two experimental limitations are taken into accout: the sample spinning speed and the RF-amplifier power
Presparking Effect in Spark Source Mass Spectrometry
Authors: Harfoush A. , Soulayman S. Sh.
Published: February 2015

The Relative Sensitivity Factor (RSF) in Spark Source Mass Spectrometry analysis was found to be dependent on the number and duration of previous sparking periods. This dependency becomes very strong when dealing with volatile elements. By statistical analysis of experimental RSF values it was found that there is a linear correlation between In (RSF) of some trace elements and their boiling temperature. This correlation fails when dealing with volatile elements and carbon. It was found that elements with a large diffusion coefficient have a large RSF.
Theoretical Melting Curves of Alkali Halides
Authors: Soulayman S. Sh.
Published: February 2015

An analysis of the melting curves of alkali halides is given. The study is based on the Improved Unsymmetrized Self-Consistent Field Method (IUSCFM) for strongly anharmonic crystals with complex lattice and the energy, entropy and Ross’s criterions in calculating the melting curves of alkali halides. The anharmonicities up to sixth order have been taken into consideration. The energy criterion was proven to be the most correct one along the melting curves of the high pressure modification (CsCl structure) while the entropy and Ross's criterions lead to a little better agreement with experiment than the energy criterion when dealing with rocksalt structure. Calculations of the melting curves of KCl and CsCl are compared with the experimental results.
Quantum-Mechanical Concepts in the Waveguides Theory
Authors: Marinescu N. , Apostol M.
Published: February 2015

A Klein-Gordon-type equation is derived for the wave propagation in an ideal, uniform waveguide, and its quantum-mechanical interpretation is given. The "cross-section" concept is introduced for a waveguide and the power transmission factor is obtained by using standard methods of quantum mechanics. The spinorial formalism is also employed for deriving the equivalent Dirac-type equation, and the perturbation theory is applied for computing the frequency shifts. The general applicability of the quantum-mechanical concepts to the waveguides theory is discussed
ENDOR Studies of X-Irradiated Single Crystals of Sulphamethoxazole
Authors: Krzyminiewski R. , Lund A.
Published: February 2015

Single crystals of sulphamethoxazole were X-irradiated at 273 K. ESR and ENDOR spectra were obtained at 100 K. The free radicals stable at room temperature are formally formed by abstraction of a hydrogen atom from the methyl group of the molecule. The unpaired electron is delocalized in the isoxazole ring. The assignment is supported by comparisons of spin densities obtained experimentally and by semiempirical molecular orbital calculations
Thermodynamic Study of Ce4+ /Ce3+ Redox Reaction in Aqueous Solutions at Elevated Temperatures: 1. Reduction Potential and Hydrolysis Equilibria of Ce4+ in HCIO4 Solutions
Authors: Bilal B. A. , Müller E.
Published: February 2015

The redox potential (E) of the couple Ce4+/Ce3+ has been determined up to 368 K by means of cyclic voltammetric measurement in aqueous HClO4 solutions with cHClO4 decreasing from 7.45 to 0.023 mol kg-1 . A constant potential of (1.741 V)298 K, resp. (1.836 V)368K, indicating the existence of pure unhydrolysed Ce4+ was obtained at cHClO4 ≥ 6.05 m. At lower HClO4 concentration, the potential as a function of the HClO4 molality, as well as of the pH shows 4 further distinct steps. At 298 K, for instance, the potential became nearly constant at pH values of 0.103, 0.735,1.115, after which it drastically decreased, respectively at 1.679, just before the precipitation of Ce(OH)4 occurred. The curves indicate obviously the stepwise formation of the Ce(IV) mono-, di-, tri- and tetrahydroxo complexes. The slope of the curves E vs. pH increased gradually with increasing temperature. ΔS and ΔH of the redox reaction were determined as functions of T at the different HClO4 concentrations. ΔSis positive at cHClO4 > 1.85 m and turns to be negative at lower concentrations. ΔHis negative at all HClO4 concentrations studied. The cumulative formation constants ßi, of the Ce(IV) hydroxo complexes and the corresponding hydrolysis constants (Kh)i were calculated. An unusual decrease of ßi with increasing temperature has been discussed
Cu NQR Study in a High-Jc Superconductor YBa2Cu3O6.1Ix
Authors: Ossipyan Yu. A. , Zharikov O. V. , Matukhin V. L. , Anashkin V. N. , Safin I. A. , Pogorelcev A. I. , Teitelbaum G. B.
Published: February 2015

NQR-spectra and nuclear relaxation of 63Cu in ceramic samples of the Y - Ba - Cu -O system with various oxygen content have been compared with those in iodinated YBa2Cu3O6.1.
Cu-NQR Frequencies and Linewidths in High- Tc Superconductors
Authors: Gärtner S. , Riesemeier H. , Kitaokab Y. , Müller V. , Lüders K. , Kaldis E. , Rusiecki S.
Published: February 2015

The Cu-NQR lines of various high-Tc superconductors at the Cu(2) site appear between 15 and 40 MHz. There exists an experimental correlation showing that the NQR frequency increases with decreasing Tc. By comparison, it can be concluded from these results that a formal valence state of the Cu ion around 2 + is favourable for superconductivity. All lines exhibit a strong broadening compared to CuO2 crystals, which is attributed to lattice modulations within the CuO2 layers. This effect also influences the temperature dependence of the linewidth in YBa2Cu3O7-δ .
The 111mCd Nuclear Quadrupole Interaction in CdCl2 and its Monohydrate
Authors: Fraenzke Th. , Butz T. , Lerf A.
Published: February 2015

The 111mCd nuclear quadrupole interaction in CdCl2 and CdCl2 • H2O was determined in the temperature range from 77 K to 783 K and 363 K, respectively, by time differential perturbed angular correlation. In addition, both the crystallization of the monohydrate from solution and its dehydration were monitored in situ.
A63,65Cu and 127I Nuclear Quadrupole Resonance and X-Ray Crystallographic Study of a Low-Temperature Phase of the (2-picoline) Copper (I) Iodide Dimer
Authors: Habiyakare Augustin , Lücken Edwin A. C. , Bernardinelli Gerald
Published: February 2015

The temperature-dependence of the 63Cu and 127I NQR spectra of bis(2-picoline) Copper(I) Iodide reveals the existence of a phase change at 250 K. An X-ray crystallographic study of the low-temperature phase reveals that the iodine-bridged dimeric structure, which was observed at room-temperature, is retained in the low temperature phase but that the bond-lengths and, particularly, the bond-angles of the central four-membered ring are considerably modified.
Dioxin Precursors: NQR Studies of Group 1 and Related 2,6-Dichlorophenolate and 2,4,6-Trichlorophenolate Salts
Authors: Wulfsberg G. , Shadid K. , Farris B. , Monn J. , Bonner T. , Yanisch J. , Weiss Al.
Published: February 2015

The 81Br and 35Cl NQR spectra of anhydrous Group 1, tetraalkylammonium, and thallium(I) 2,6-dichlorophenolates, 2,4,6-trichlorophenolates, and 4-bromo-2,6-dichlorophenolates were searched for evidence of solid-state cation-organochlorine interactions that might, for example, be (in part) responsible for the difference in the thermal decomposition reactions of these salts (to give the supertoxic environmental pollutants, the polychlorinated dibenzodioxins) versus those of the corresponding Group 11 chlorophenolate complexes, which do not decompose to dioxins.

For cations ranging in size from tetraethylammonium to potassium, the total range of 35Cl NQR frequencies in 2,6-dichlorophenolate and 2,4,6-trichlorophenolate salts is only 1.401 MHz, which, although larger than the 0.7 MHz range likely in molecular chlorocarbons, is smaller than in individual chlorophenolates of copper(I) and silver(I) (up to 2.0 MHz). In sodium and thallium(I) 2,4,6-trichlorophenolates substantially large frequency shifts (ca. 2.0 MHz) occur, to higher frequencies for the para-chlorines and lower frequencies for the ortho-chlorines (Na only). These disappear even in closely related compounds and show a pattern that seems unrelated to the decomposition products of the chlorophenolates.
79Br and 127I NQR of tert-Butylammonium Halides and Crystal Structure of (CH3)3CNH3
⊕ Br⊖
Authors: Shabazi Morteza , Dou Shi-qi , Weiss Alarich
Published: February 2015

The 79Br and the 127 I NQR spectrum of tert-butylammonium bromide and iodide, respectively, was studied as a function of temperature. No phase transition was observed for the bromide in the temperature range covered. The 79Br NQR frequency is 9.056 MHz at 113 K and increases with increasing temperature (10.040 MHz at 293 K).

The NQR spectrum reveals a phase transition of ( CH3 ) 3 CNH⊕
3I⊖ around 360 K with pronounced hysteresis. The nuclear quadrupole coupling constant of 127 I is 69.335 MHz with an asymmetry parameter of 0.154 for the high temperature phase at T = 370 K. For the low temperature phase the corresponding values are 67.136 MHz and 0.081 at 300 K.

The crystal structure of tert-butylammonium bromide was studied at room temperature. The compound crystallizes orthorhombic, space group D152hPbca, with 4 formula units in the unit cell, a = 1832.1 pm, b = 918.5 pm, c = 899.8 pm. The crystal structure and hydrogen bond system are discussed in connection with the NQR results.
35Cl NQR and Crystal Structure Studies of Salts of Chlorodifluoro- and Dichloroacetic Acid
Authors: Basaran Reha , Dou Shi-qi , Weiss Alarich
Published: February 2015

The 35Cl NQR spectra of several chlorodifluoroacetates were studied as a function of temperature, including the acid ClF2CCOOH. The cations were: Ammonium, guanidinium, paramethylanilinium. Also some acid salts M⊕ClF2CCOO⊖ • n - ClF2CCOOH ( n > l ) were studied by 35Cl NQR. The bleaching temperatures of the NQR signals were determined. In the para-methylanilinium salt and in the guanidinium salt a phase transition has been observed. The crystal structure of guanidinium chlorodifluoroacetate has been determined at room temperature (a = 1089 pm, 6 = 845 pm, c = 832 pm, space group Pnma, Z = 4). For comparison, guanidinium dichloroacetate was studied by 35Cl NQR and by X-ray diffraction, too: P21/c, Z = 4 , a = 804pm, b = 1202 pm, c = 1080 pm, ß = 131.58°. For guanidinium chlorodifluoroacetate and chlorodifluoroacetic acid, the 35Cl spin lattice relaxation time T1 and the line width have been followed up as a function of temperature. Therefrom, the activation energies of the reorientation motion of the group -CF2C1 have been determined to be 14 kJ • mol-1 (from T1) and 12.5 kJ • mol- 1 (from Δv) for the pure acid and 9.2 kJ • mol-1 and 8.8 kJ • mol-1 , respectively, for the guanidinium salt.
High Pressure Studies of Tetrachloro-o-benzoquinone by NQR Spectroscopy
Authors: Koziol Piotr
Published: February 2015

Tetrachloro-o-benzoquione (TOB) crystallizes in two different forms. The two forms, Sample I and Sample II, show different phases and NQR spectra. When subjected to pressures higher than about 40 MPa the a phase is converted to the y phase. X-ray powder patterns studies as well as DTA measurements have confirmed this result. Heating the y phase above 310 K reverses this process.
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

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

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

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

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

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

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

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.
Zeeman Effect of Pure NQR in a Rotating Frame (CW and Pulsed Excitation)
Authors: Furman G. B. , Kadzhaya I. M.
Published: February 2015

The Zeeman effect in a rotating frame is considered for the case when the quadrupolar nuclear spin system is acted on by two radio-frequency fields.
14N Fourier Transform Nuclear Quadrupole Resonance. Instrumentation: Measurements on Cyanuric Chloride
Authors: Ambrosetti Roberto , Forte Claudia , Ricci Domenico
Published: February 2015

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

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

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

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

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

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

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

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

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

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

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

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.
Photochemical Properties of 2-Aryl-3-imino-1-indones
Authors: Timtcheva I. , Getoff N. , Nikolov P. , Quint R. M.
Published: February 2015

Steady state as well as flash photolysis experiments of 2-aryl-3-imino-1-indones (2-AIID) have been carried out with the aim to learn more about their photochemical properties. It was established that in ethanol these substances exist solely in the keto-enamine-form and are rather photostable under the influence of uv-light. Illumination in dichloroethane, acetonitrile and dioxane is leading to stable photoproducts. A typical transient absorption spectrum of 2-AIID is presented. Probable reaction mechanisms are given.
Structural Parameters and Internal Rotational Barriers of tert-Butylammonium Ion: AM1 and ab initio Calculations
Authors: Ishida Hiroyuki , Kubozono Yoshihiro , Kashino Setsuo , Ikeda Ryuichi
Published: February 2015

Semiempirical and ab initio MO calculations were performed to estimate the structural parameters of tert-butylammonium ion and its potential energies for the internal rotation of the CH3 and NH3
+ groups. The barrier height for the rotation of NH3
+ was found to be lower than for that of CH3 , corresponding to the C - N bond being longer than the C - C bond.
Zeitaufgelöstes Fluoreszenz-Löschen in ultradünnen Coronen-Schichten auf Silizium-Substraten
Authors: Fischer P. , Port H. , Wolf H. C.
Published: February 2015

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

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

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

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

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.