bluuebunny/crossref_metadata_2025 huggingface dataset:
On the Intensity Distribution within Photoluminescence Bands in Rigid and Liquid Solutions
Authors: Kawski A. , Stoń M. , Janić I.
Published: February 2015

The effect of the excitation light frequency on the intensity distribution within the fluorescence band and the band position of non-polar and strongly polar luminescent substances is investigated in pure and mixed liquid and glassy solvents. An interpretation concerning the intensity distribution in the emission band and the local temperatures determined by the method of Stepanov is given.
Brillouin-Streuung an dichten Fluiden/ On Brillouin Scattering in Dense Fluids
Authors: Asenbaum A.
Published: February 2015

It has been shown analytically that Mountain's theory of the spectral distribution of density fluctuations in fluids having an external degree of freedom (MOUXI) is equivalent to the translational hydrodynamics theory (TH) of Desai and Kapral at liquid state densities where selfdiffusion can be neglected. On the other hand, comparing TH and Mountain’s second theory of Brillouin scattering on thermal relaxing fluids involving a frequency dependent volume viscosity (MOUETA), differences are found in several spectral components, especially the intensity of the Rayleigh line, of the Brillouin spectra of CCl4 , C6H12 and C6H6 at large values of the wave vector k. This theoretical effect can be demonstrated experimentally by fitting TH and MOUETA to experimental Brillouin spectra of CCl4 at high values of k, resulting in small changes of the corresponding relaxation times.
Structure of Molten Bi-Zn-Alloys by Means of Neutron Diffraction
Authors: Knoll W. , Lamparter P. , Steeb S.
Published: February 2015

Neutron diffraction experiments were performed with five molten Bi-Zn-alloys and the two molten elements Bi and Zn. The total structure factors and the pair correlation functions are given. The concentration dependence of the experimental nearest neighbour distances and the experimental coordination numbers is in accordance with the segregation behaviour prevailing in these melts.
On the Cholesteric-Nematic Phase-Change Transition in Layers with Homeotropically Orienting Surfaces
Authors: Gerber Paul R.
Published: February 2015

Lattice-model calculations of the energies of surface director-configurations are presented. These configurations mediate between the homeotropic surface conditions and the bulk fingerprint texture of cholesteric layers. Their energy determines the asymptotic behaviour of the cholesteric-nematic threshold field in the limit of thick layers. The dependence of their energies on the elastic constant ratios could be brought into a simple scaling form. This form is in agreement with existing and newly presented measurements.
Investigation of Some Sulphur Halides — An Application of the Pseudopotential Method
Authors: Krüger T. , Preuß H.
Published: February 2015

Semilocal pseudopotentials are used in combination with a density-functional approximation for the correlation energy and special optimized basis sets to investigate the sulphur halides SF, SF2, SF3, FSSF, SSF2, SCl, SCl2, ClSSCl and SSCl2. It turns out that the inclusion of d-orbitals in the basis set playes a significant role with respect to the quality of the calculated molecular parameters. Properties of SF3 are calculated for the first time, and the differences between the disulphur difluorides and the disulphur dichlorides are explained.
Some Features of Excited States Density Matrix Calculation and Their Pairing Relations in Conjugated Systems
Authors: Segre de Giambiagi Myriam , Giambiagi Mario
Published: February 2015

Direct PPP-type calculations of self-consistent (SC) density matrices for excited states are described and the corresponding “thawn” molecular orbitals (MO) are discussed. Special atten­tion is addressed to particular solutions arising in conjugated systems of a certain symmetry, and to their chemical implications. The U(2) and U(3) algebras are applied, respectively, to the 4- electron and 6-electron cases; a natural separation of excited states in different cases follows. A simple approach to the convergence problem for excited states is given. The complementarity relations, an alternative formulation of the pairing theorem valid for heteromolecules and non-alternant systems, allow some fruitful experimental applications. Together with the extended pairing relations shown here, they may help to rationalize general trends.
Lagrangian Formulation of a Consistent Relativistic Guiding Center Theory
Authors: Wimmel H. K.
Published: February 2015

A new relativistic guiding center mechanics is presented that conserves energy (in timeindpendent Fields) and satisfies a Liouville's theorem. The theory reduces to Littlejohn's theory in the non-relativistic limit and agrees to leading orders in ε ≡ rg/L with the relativistic theory by Morozov and Solov'ev (which generally lacks a Liouville's theorem). The new theory is developed from an appropriate Lagrangian and is supplemented by a collisionless relativistic kinetic equation for the guiding centers. Moment equations for guiding center density and energy density are also derived
Theoretische Untersuchungen zum Absorptionsverhalten von Benzopyrrol-und Benzodipyrrolderivaten / Theoretical Investigation.'! on the Absorption Characteristics of Benzopyrrole-and Benzodipyrrole Derivatives
Authors: Fabian Walter
Published: February 2015

In order to explain the unusual absorption characteristics of derivatives of benzopyrrole and benzodipyrrole, PPP-calculations were carried out. By means of configuration analysis the results of these calculations were interpreted in terms of molecular subunits. On the basis of this method the long wavelength absorption of this class of compounds can mainly be ascribed to the large contribution of charge transfer configurations as well as to excitonic interactions. The effect of twisting the N-phenyl bond is discussed
Spectroscopic Studies of the Dark Space ahead of a Shock Wave in an Argon Plasma Flow
Authors: Nishida Michio , Nakajima Akihiko
Published: February 2015

Spectroscopic studies of the dark space ahead of a detached shock wave caused by a blunt body were made in a partially ionized argon flow. From emission measurements, spatially resolved population densities of states 5p[3/2], 5p[5/2] and 4p[3/2] were determined at 20 stations in the flow, for both cases when the blunt body is placed in the flow and when it is withdrawn. The result shows that the population densities of the above mentioned states ahead of the shock wave are reduced when the body is placed in the flow. A prediction was obtained by assuming a steady state population for all levels higher than level 4 s. In the prediction the measured electron temperatures and densities were employed to determine collisional transition probabilities. From a comparison of the experiment with the prediction, it is considered that the dark space is caused by the elevation in the electron temperature ahead of the shock wave.
Kristallstruktur und Schwingungsspektren des Di-Blei-Hexathiohypodiphosphates Pb2P2S6 / Crystal Structure and Vibrational Spectra of Pb2P2S6
Authors: Becker Robert , Brockner Wolfgang , Schäfer Herbert
Published: February 2015

Pb2P2S6 crystallizes in the monoclinic system, space group Pn with the lattice constants a = 940.2(4) pm, b= 746.6(3) pm, c = 661.2(3) pm, β = 91.53(5)°. The compound is isotypic to the monoclinic modification II of Sn2P2S6 . In the structure there are discrete P2S4-
6 -anions.

Far infrared, infrared and Raman spectra of this compound have been recorded. The observed frequencies are assigned on the basis of P2S4-
6 units with C2h symmetry in the crystal. DTA-data have been determined and interpreted.
Permanent Dipole Moment and Polarizability of a Gass of Merocyanine Dyes in Their Ground and First Excited Singlet State
Authors: Baumann Wolfram
Published: February 2015

The permanent dipole moment of a class of merocyanine dyes in their ground and first excited singlet state has been determined studying the influence of an external electric field on the absorption of the compounds in various solvents. Evaluation of the experimental results on the basis of the Onsager reaction field model also gives values for the polarizability in the ground and excited state, the latter approaches the value of a respective conducting ellipsoid with the longer chainlength molecules.
Photoakustik-spektroskopische Untersuchungen an Lösungen von Farbstoffen in Polymermatrizen
Authors: Görtz W. , Perkampus H.-H.
Published: February 2015

PA-spectroscopic Investigation on Solutions of Dyes in Polymermatrixes Dyes solved in polymer matrixes are ideal systems to examine the RG theory. PVA and PVP were used as matrixes. In these polymer matrixes the thermal properties are given by the matrix molecules being present in excess. The dye molecule serves as an indicator. Thus the thermal properties, specific heat, temperature and heat conductivity of the matrix can be measured for thermally thick layers. Further investigations to examine the RG theory show, that this theory can be used for the quantitative evaluation of PA measurements of thermally thick, non scattering samples.
On the Determination of Moment of Inertia of Prolate Luminescent Molecules
Authors: Kawski A.
Published: February 2015

The possibility to determine simultaneously the effective volume and the molecular moment of inertia on the basis of the generalized equation of the rotational motion of prolate luminescent molecules in solutions is discussed.
Nitrogen Hyperfine Structure in Allvlcyanide Synperiplanar
Authors: Bestmann G. , Dreizler H.
Published: February 2015

With the help of Microwave Fourier transform Spectroscopy we were able to resolve the nitrogen hyperfine structure of allylcyanide synperiplanar (cis). As the rotational relaxation is relatively rapid this molecule is even for this technique at the limit of the present possibilities.
Effective Hamiltonians for EPR Spectroscopy of Exchange-Coupled Pairs
Authors: Buluggiu E.
Published: February 2015

The paper refers to the second-order spin-hamiltonian formalism, recently proposed by the author, describing the EPR properties of an exchange-coupled pair of orbitally not degenerate ions in the limit of strong isotropic exchange (higher-order effects such as biquadratic exchange or exchange striction are considered neglectable). Tables of numerical values for the relevant coefficients involved are given. This allows to write immediately the effective spin operators spanning each total spin multiplet which arises from the coupling between the ions. Explicit formulas for the recurrently encountered cases of pairs where S1 = S2 = 3/2 or S1 = 5/2 and S2 = 1/2 or S1 = 1 and S2 = 1/2 are deduced. Some salient features of these, concerning the second-order contributions to the zero-field splitting, are discussed in the light of available experimental data. The conclusions drawn seems to encourage a more extensive use of the model.
Quantitative Comparison of the Shape of Bio-organic Molecules
Authors: Motoc loan
Published: February 2015

The paper proposes and illustrates a new method for quantitatively comparing the degree of relatedness of the shape of bio-organic molecules which exhibit the same biological action but which may vary widely in their shape. The method is of interest for drug research in connection with the design and selection of test compounds.
Study of the Liquid Crystalline Phases in Some Compounds of 4-Trans-(4-Alkyl)Cyclo-Hexylphenyl-Alkylcarboxylate
Authors: Ibrahim I. H. , Haase W.
Published: February 2015

Three mesogenic compounds of the general formula

have been investigated by differential scanning calorimetry. thermal optical microscopy and X-ray diffraction methods/Enthalpy changes of The different phase transitions for these compounds have been determined. H33 exhibits smectic B and nematic phases, whereas H34 and H75 exhibit only smectic B phases. The thickness of the smectic layers and the average intermolecular distance have been evaluated, as well as the corresponding molecular parameters in the nematic phase.
Zur Interpretation des Substituenteneinflusses auf das UV-spektroskopische Verhalten von Benzimidazol- und Indazolderivaten
Authors: Fabian Walter
Published: February 2015

On the interpretation of the influence of substituents on the UV-spectroscopic properties of benzimidazole and indazole derivatives.

The UV spectra of a series of substituted benzimidazoles and indazoles were calculated by means of semiempirical quantum chemical methods (PPP, CNDO/S-CI). The results of the PPP calculations were subjected to a configuration analysis. Using this method, the influence of the nature and position of substituents on the absorption characteristics could be rationalized.
Thermal Expansion of Lithium Sulphate
Authors: Meilander B. E. , Nilsson L.
Published: February 2015

The thermal expansion of the α and β phases of lithium sulphate has been studied using dilatometric and X-ray diffraction techniques. In the α-phase the coefficient of linear thermal expansion is 4.6·10-5 K-1 while in the β-phase the coefficient of linear thermal expansion increases from 0.9·10-5K-1 at room temperature up to 3.4·10-5 K-1 close to the first order phase transition at 575 °C. The volume expansion at the phase transition is 3.2%. In the α-phase the thermal Grüneisen parameter has been calculated to be 0.63 at 705 °C.
Further Analyses of Infrared 1Π → 1Σ Bands of 89Y127I: New Spectroscopic Data on States up to υ"=7 and υ'=4
Authors: Bernard A. , Gravina R.
Published: February 2015

This paper deals with the extension of a recent study of the infrared 1Π → 1Σ emission system of the YI molecule (1). Thanks to the extreme regularity of the structure, rotational analyses can be completed for the previous 3-1, 2-0, 1-0, 0-0 and 0-1 bands and extended to 11 more bands detected step by step from their synthetic spectra (owing to the extremely dense structure). A unique and consistent set of accurate rotational constants is derived for both states, up to the levels υ" = 7 and υ' = 4, from the reduction of 5772 line wavenumbers in the bands 3-1, 2-0, 1-0, 0-0. 0-1. 0-2, 1-3, 2-4, 2-5, 3-6 and 4-7, the υ-connected bands being fitted simultaneously. The 57 estimated constants allow to reproduce the observed spectra with typical weighted rms errors between 4 and 5 mK. When using these constants to generate the bands 2-1, 1-2, 3-3, 1-4 and 3-5, ~1300 lines can be picked out whose experimental positions relatively to the predicted ones correspond to quite equivalent rms errors with nearly normal distributions of the residuals, therefore ensuring the reliability of the analysis. Molecular constants at equilibrium are derived; improvments are significant, particularly for vibration. Franck-Condon factors and r-centroïds appropriate to RKR potential curves are given. The observed bands correspond to those which are predicted to be the strongest ones in each υ'-progression.
An Exactly Solvable Difference Equation that Gives Pure Chaos for a Continuous Range of a Parameter
Authors: Tsuchiya Takashi
Published: February 2015

A one-dimensional first-order nonlinear difference equation which is an extended version of currently well-studied systems is presented and solved analytically. From the exact solution it is shown that for a continuous range of a parameter of the system (i.e., 0 ≦ k2 < 1) nonperiodic solutions behave in a purely chaotic fashion, whereas for k2 = 1 the exact solution converges to a unique attractor.
High Temperature NMR Study of 51V and 195Pt in the V3Pt Compound
Authors: Rünger R. , Ploumbidis D.
Published: February 2015

Measurements of both the 51V and 195Pt Knight shift in the V3Pt compound are reported for temperatures ranging from 300 K to about 1300 K. The temperature coefficients of the Knight shift and the NMR linewidth have been determined. An interpretation of the observations is given in the frame of a model which is based on the temperature dependence of the core polarization contribution to the total Knight shift.
Protonation of 4 H-Pyran-4-one and its Sulfur Analogues. MNDO Study
Authors: Eckert-Maksić Mirjana
Published: February 2015

The molecular and electronic structure of 4H-pyran-4-one and its mono- and disubstituted sulfur analogues (1-4) are studied by the MNDO method. The salient structural features are qualitatively reproduced and the trend of changes of geometric parameters is in good agreement with experiment. The charge distributions exhibit strong polarization due to the large π-electron drift toward the exo-heteroatom. The protonated conjugated acids are considered too. It is found that exo-heteroatom protonation is favoured by 60-80 kcal/mol over the attachment of the proton to the intraring heteroatom. This is in accordance with experimental evidence. It is rationalized by the higher electron density centered on the exo-heteroatom and the appreciable increase in aromatic cyclic conjugation taking place upon the exo-protonation.
Quantum Chemical Investigations on Solvated NaCl Adducts
Authors: Rode Bernd M. , Limtrakul Jumras P.
Published: February 2015

Ab initio MO calculations on solvated NaCl adducts are presented. They provide insight into effects to be expected upon oligomerisation of NaCl in aqueous solution or, vice versa, during the last step of the dissolution/solvation process in water. Extrapolation of the data obtained predict the minimal nucleation size for the formation of NaCl crystals to be represented by a (NaCl)~100 aggregate.
Spectroscopic Investigation of the High Pressure Ethylene Polymerization
Authors: Buback M.
Published: February 2015

Quantitative absorption spectroscopy in the infrared and near-infrared region enables kinetic and thermodynamic investigations to be performed on systems at high temperatures and pressures. The technique is illustrated for the ethylene polymerization. From spectroscopic experiments up to 3 kbar at maximum temperatures of 250 °C, the rate equations of the thermally, of the photochemically, and of the chemically initiated polymerization are determined.
Low-pressure Noble Gas Broadening of the Cs Resonance Lines
Authors: Siegling F. , Niemax K.
Published: February 2015

The wings of the Cs resonance line (62S1/2 - 62P1/2, 3/2) broadened by noble gases (He, Ne, Ar and Kr) at low pressures (p ≦ 700 Torr) have been measured in absorption in the range 4 up to a few hundred wavenumbers from the line centres. The far wings are compared with quasistatic wings based on the semiempirical potentials by Baylis and by Pascale and Vandeplanque. In some cases the agreement between the experimental and theoretical line wings is found to be reasonable
Association in Molten Salts and Mobility Isotherms
Authors: Klemm A.
Published: February 2015

A change with concentration in the height of the first peak of the pair distribution function g+ - of a salt in a mixture of molten salts indicates a change in the degree of association of that salt. It is shown that the changes in association observed this way from MD-simulations of binary mixtures of charge symmetric salts with a common anion are qualitatively consistent (i) with the requirements for the occurrence of the crossing of mobility isotherms (Chemla effect) and (ii) with the ideal law of mass action
On the Dependence of Stark Width and Shift on the Ionization Potential
Authors: Dimitrijević M. S. , Konjević N.
Published: February 2015

The simple relations between the Stark broadening parameters and the ionization potential derived by Purić et al. [1] are discussed, and attention is drawn to the serious limitations for their application. The periodic dependence of the Stark width and shift on nuclear charge number obtained by the same authors [2] is also explained.
On Deuling's Transition in a Nematic Liquid Crystal
Authors: Barbero G. , Strigazzi A.
Published: February 2015

We analyse Deuling's problem both in the one constant approximation and in the general case.

An explicit expression is found for the electric field threshold vs. the crossed applied magnetic field, in the strong anchoring hypothesis.
Glow Discharge Enhancement by Shock Waves
Authors: Miyashiro Seiji
Published: February 2015

The effect of shock waves on the glow discharge is investigated experimentally. A fast electric discharge is generated across a shock wave for this purpose. The lower pressure around the cathode in front of the shock wave enables electrons to strongly diffuse radially, and therefore the glow is maintained with little constriction even at high average pressures. Moreover, the glow diameter, discharge fluorescence and current are enhanced by the shock wave.
Observation of Direct Phase Transition Smectic A ↔ Blue Phase in a Liquid Crystalline Mixed System
Authors: Onusseit H. , Stegemeyer H.
Published: February 2015

Hithertoo, for all liquid-crystalline samples exhibiting Blue Phases (BP) it has been found that these phases occur between the cholesteric and the isotropic state. In the mixed system of cholesteryl myristate and an azoxybenzene derivative a phase transition from the smectic A phase directly to the BP has been observed. The phase diagram has been obtained by differential scanning calorimetry and is discussed together with the helical pitch behaviour.
Molar Heat Capacity of AgI: Evaluation of the Cationic and Anionic Contributions from Thermoelectric Power Data
Authors: Schiraldi Alberto , Baldini Primo
Published: February 2015

Thermoelectric power data provide a useful tool for the evaluation of the thermodynamic properties of ionic species of both solid and molten electrolytes in equilibrium with electrodes of thermocells; however a previous evaluation of the heat of transport of the mobile ions is necessary.

This is the case of AgI. whose standard modifications have been investigated with silver electrode thermocells some years ago. The interpretation of the thermoelectric power change at the melting point allows one to recognize that the heat of transport of the silver ions in the high conductivity bcc modification is practically the same as in molten Agl. This result has been used to evaluate the molar heat of the silver ions in the bcc phase from the corresponding thermoelectric power data reported in the literature.

The analysis of the thermoelectric power change at the transition point, from the wurtzitic to the bcc phase, as well as a more speculative interpretation of thermoelectric power data obtained with iodine electrode thermocells, allows one to evaluate the molar heat of the iodide ions in the bcc modification of AgI.

The summation of the ionic contributions so computed reproduces rather satisfactorily the trend of AgI molar heat data obtained with adiabatic calorimetry.
Relativistische Verallgemeinerung des Lenzschen Vektors (II) / Relativistic generalisation of the Lenz vector (II)
Authors: Kern Eberhard
Published: February 2015

The Lenz vector Λ= m {x′ × L + α · x/r} is a special integral of motion of the non-relativistic Kepler problem. Accordingly, there also exists a special integral of motion Λ (x, x') of the relativistic Kepler problem as pointed out in Part I of this paper. In the following Part II, the system of equations is compiled to the extent required for the relativistic generalisation of the Lenz vector and its interpretation.

Starting point are the statements of conservation for the energy and the angular momentum. From these two quantities, it is possible to derive the complete system of solutions x(t) in accordance with standardised methods. Some details and some modifications of the approach are of special importance for the purposes of this paper. In the centre of the consideration are the construction and interpretation of the standardised polar angle θ as a function of r, r'. The explicit time dependance of the functions r(t), θ(t) is not required for constructing the relativistic Lenz vector in the form Λ (x, x').

In the literature, one does Find only few, not sufficient for our purposes, data on the relativistic orbits (rosettes, spirals, hyperbola-type curves etc.). It is, therefore, necessary to discuss these orbits in detail. For this purpose, a series of relationships are derived which apparantly have not been published before.
Topological Properties of Benzenoid Systems. XXIX. On Hosoya's Topological Index
Authors: Gutman Ivan , Shalabi Ahmed
Published: February 2015

Some properties of Hosoya's topological index Z and the modified topological index Z͂ of benzenoid hydrocarbons are examined. A simple relation between Z͂ and Z has been established, namely Z͂= Z1+a, where a = 0.02.
Rayleigh-Taylor Instability of a Stratified Magnetized Medium in the Presence of Suspended Particles
Authors: Chhajlani R. K. , Sanghvi R. K. , Purohit P.
Published: February 2015

The hydromagnetric Rayleigh-Taylor instability of a composite medium has been studied in the presence of suspended particles for an exponentially varying density distribution. The prevalent horizontal magnetic field and viscosity of the medium are assumed to be variable. The dispersion relation is derived for such a medium. It is found that the stability criterion is independent of both viscosity and suspended particles. The system can be stabilized for an appropriate value of the magnetic field. It is found that the suspended particles can suppress as well as enhance the growth rate of the instability in certain regions. The growth rates are obtained for a viscid medium with the inclusion of suspended particles and without it. It has been shown analytically that the growth rate is modified by the inclusion of the relaxation frequency parameter of the suspended particles.
Luminescence of 5-Phenyltetrazole and its Derivatives Part III. Quantum Yields and Mean Lifetimes of Fluorescence
Authors: Gryczyński I. , Kawski A.
Published: February 2015

Quantum yields and mean lifetimes of fluorescence have been measured of 5-phenyltetrazole and its three methyl derivatives, para-, meta- and ortho-methyl-5-phenyltetrazole. The rate constants, kF, of the radiative transition S1 → S0 have been deduced from these measurements. The mean lifetimes, τF, the quantum yields of fluorescence and the rate constants have been found to be clearly dependent on the position of the methyl substituent in the ring and could be arranged as follows:

τp
F>τm
F>τ0
F and k0
F>km
F>kp
F
Dolomite Decomposition to (Ca,Mg)O Solid Solutions: An X-Ray Diffraction Study, Part I.
Authors: Spinolo G. , Tamburini U. Anselmi
Published: February 2015

Dolomite [CaMg(CO3)2] full decomposition has been studied by in situ powder X-ray diffraction. The primary products are Ca-rich and Mg-rich (Ca.Mg)O solid solutions with compositions different from equilibrium values. In some cases a strained form of calcite is also produced. The experimental results show that the oxides are formed in a direct process with a shear mechanism, whereas calcite formation is due to CaO recarbonation.
Carboxylic Acid-N Base Hydrogen Bonds with Large Proton Polarizability in Acetonitrile as a Function of the Basicity of the Hydrogen Bond Acceptors
Authors: Albrecht Gunnar , Zundel Georg
Published: February 2015

Carboxylic acid-N base systems are studied in acetonitrile. The association equilibrium constants Ka and the proton transfer equilibrium constants KPT in the OH···N ⇄ O-···H+N bonds formed, are determined from IR spectra. The association constants Ka increase in proportion to the basicity of the hydrogen bond acceptors. The same is true with regard to the proton transfer constants. The OH ···N ⇄ O- ···H+N equilibria are shifted with increasing basicity to the right hand side. It is discussed that this shift is caused by an intrinsic effect as well as by an extrinsic one (interaction of the dipole of the hydrogen bond with its environment). A linear relation exists between log KPT and ⊿pKa (pKa of the protonated base minus pKa of the acid). 50% transfer of the protons to the N base is found at ⊿pKa = 2.6. As indicated by intense continua. these hydrogen bonds show large proton polarizability if the degree of asymmetry of their proton potentials is not too large.
On the Infrared A2Πi - X2∑+ System of Aluminium Monoxide in Relation with the Spectra of M Giant- and Mira-Type Stars
Authors: Bernard A. , Gravina R.
Published: February 2015

From combinations between known ultraviolet transitions of the AlO molecule line positions in the A2Πi - X2∑+ system are tentatively proposed. Indeed, the available data on the C2Πr → X2∑+ and C2Πr → A2Πi transitions permit us to derive about 2400 energy level differences in the A-X system corresponding to the six ν-connected bands 0-0, 0-1, 0-2, 1-0, 1-1 and 1-2. A unique and consistent set of rovibrational constants is derived from a global fitting, allowing to reproduce the observed differences with a total standard deviation of 0.053 cm-1. A catalogue of vacuum line wavenumbers in the six bands is generated and can be made available on request. The synthetic spectra are expected to represent properly the true spectra at least up to J ~ 35.5 and can therefore be of usefulness for the detection of the system in the spectra of M giant- and Mira-type stars.

Franck-Condon factors and r-centroïds appropriate to RKR potentials and estimates of intensities in emission are given for bands up to ν′ = 5, v″ = 8.

More reliable values for the internal partition functions and dissociation constants of AlO are computed for temperatures between 1000 and 8000 K. All the known and predicted electronic states are taken into account, and present or recent values for the molecular parameters and dissociation energy are used.
NMR Behaviour of Molten 115Indium Chlorides
Authors: Margheritis Chiara
Published: February 2015

An NMR study was made of the 115In nucleus in InCl. InCl2, InCl3 and in a mixture InCl3 + NaCl. Chemical shifts and line-widths as a function of temperature were recorded in the molten state for all samples except InCl3. As regards InCl2, NMR results gave little support to the generally held view that InCl2 is InI(InIIICl4) rather than (InIICl2)2.
Note an Bond Orders
Authors: Godsil C. D. , Gutman I.
Published: February 2015

Both the Coulson bond order and the contribution of an electron to bond order are decomposed into through-path interactions. These through-path interactions are strictly additive functions of the molecular topology.
Temperature Dependence of the 127I-Nuclear Quadrupole Coupling in Tetramethylammonium-periodate(CH3)4NIO4
Authors: Klobasa Dagmar G. , Burkert Paul K.
Published: February 2015

Tetramethylammonium-periodate shows 127I-NMR second order quadrupole splitting with negative temperature coefficients α for the quadrupole coupling constants and a second order phase transition. From these measurements one can exclude the ratio (rcation/ranion) > 1 to be the origin of the anomalous temperature dependence in NH4IO4.
Some Considerations About Bond Indices in Non-orthogonal Bases and the MO Calculation of Valence and Oxidation Number
Authors: Giambiagi Myriam S. de , Giambiagi Mario , Jorge Francisco Elias
Published: February 2015

In order to guarantee the desired invariance properties of bond indices, we show the importance of expliciting the tensor character of the matrices concerned, so as to deal with a contraction in the tensor sense between a covariant index and a contravariant one. A straightforward definition of oxidation numbers is proposed. IEH calculations of valence and oxidation numbers for some appropriate examples are performed: they emphasize the role of "secondary" bonds in N and C-containing compounds; the hydrogen behaviour in half-bonds and strong H-bonds is satisfactorily accounted for; valence and oxidation number values are assigned to Fe, Co and Ni in a few complexes.
Comment on "Collective Ion Acceleration by Relativistic Electron Rings in the Magnetosphere"
Authors: Winterberg F.
Published: February 2015

A proposal by Schumacher and Boswell for the generation of an electron ring in the magnetosphere, and subsequent collective ion acceleration, by a rocket- or satelliteborne electron gun is unfeasible, because it ignores the electric field by the charged-up gun.
Pattern of Intrinsic Reaction Coordinates and Separatrices for a Symmetry-Forbidden Reaction
Authors: Fernández Ariel
Published: February 2015

The relative distribution of the basins of attraction of the chemical species and of the transition states is derived for the thermal isomerization of cyclobutene to butadiene.

It is shown that the transition states for the symmetry-allowed and symmetry-forbidden pathways are lumomers of one another. Use is made of the structural stability principle of Ariel Fernández and Oktay Sinanoglu to show that these transition states are respectively the conrotatory and disrotatory Jahn-Teller distortions of the 2-butene diradical.

The results exhibit good agreement with J. A. Berson’s conclusions in the sense that even the forbidden pathway is concerted.
Photophysical and Photochemical Studies of Polycyclic Aromatic Hydrocarbons in Solutions containing Tetrachloromethane. I. Fluorescence Quenching of Anthracene by Tetrachloromethane and its Complexes with Benzene, p-Xylene and Mesitylene
Authors: Wiczk Wiesław M. , Latowski Tadeusz
Published: February 2015

Fluorescence quenching of anthracene has been studied in two-component mixtures of CCl4 with cyclohexane, benzene, p-xylene and mesitylene. Non-typical quenching curves have been found in mixtures containing benzene and its derivatives.
The Influence of the Cell Geometry on the Signal Shape in Electron Drift Velocity Measurements
Authors: Borghesani A. F. , Bruschi L. , Santini M. , Torzo G.
Published: February 2015

An accurate determination of the “time-of-flight” in swarm experiments with a parallel plate drift chamber requires that the time evolution of the charge induced on the collector is linear. This is obtained in very large chambers where the edge effects can be neglected. However, the experimental conditions of high-mobility carriers and highly pressurized gases impose some constraints on the acceptable drift cell dimensions. We have numerically calculated the effects of the finite size of the collector by exploiting the methods of the images. The numerical results have been experimentally checked using a suitable drift cell of variable geometry. As a result, a quantitative limit on the ratio between the collector radius and the drift distance has been established in order to design drift cells for which the edge effects can be neglected.

P.A.C.S. numbers: 2940. 4110 D, 3480 B
Pressure and Temperature Dependence of Self-Diffusion in Liquid Linear Hydrocarbons
Authors: Bachl F. , Lüdemann H.-D.
Published: February 2015

The pressure and temperature dependence o f the self-diffusion coefficients D of n-butane, n-pentane, n-hexane, n-decane, trans-2-butene, cis-2-butene and 2-butyne were determined in the liquid state by NM R-techniques at pressure up to 200 MPa and temperatures up to 450 K.

The results are taken as tests for the various dynamical models and compared to results obtained by M D calculations. The activation parameters for translational transport and the parameters for the RHS-m odel are derived and discussed.
Number of Benzenoid Hydrocarbons
Authors: Gutman Ivan
Published: February 2015

The number of benzenoid hydrocarbons with h hexagons can be estimated by means of the formula Bh = 0.045-3/2 (5 .4 )h . The analogous estimate for the number of catacondensed benzenoids is Ch = 0.049 h-5/4 (4.27)h.
Notizen: A Highly Resolved Rotational Transition of Urea Measured for Radioastronomical Searches. Analysis of the Nitrogen Quadrupole Coupling
Authors: Kasten W. , Dreizler H.
Published: February 2015

We reinvestigated the 14N quadrupole hyperfine structure (hfs) of the JK-K+ = 110 - 101, transition of urea by use of microwave Fourier transform spectroscopy.

We resolved eight components of the hfs pattern to provide a precise laboratory experiment for possible radioastronomical searches.
Nuclear Quadrupole Coupling Constant and Conformational Studies
Authors: Santhanam V. , Sobhanadri J.
Published: February 2015

A molecular conformation study on three 3-monosubstituted derivatives of propene has been

carried out by evaluating the EFG at the site of the halogen nucleus using a semi-empirical
LCAO-MO-SCF method. Calculations are performed on several conformers at INDO and
CNDO level, using “sp” and “spd” valence basis sets, with Slater type orbitals as the basis
functions. The results obtained for various conformers indicate that the nuclear quadrupole
coupling constant is practically independent of the orientation of the CH2X group (X = Cl, Br
and I) (Figure 1). The mean value of e2 Qqzz/h (averaged over all conformers) in each system
matches favourably with the experimental value, despite the severe approximations that are
inherent in the semi-empirical theory as well as in its application in the evaluation of the EFG.
81Br and 127I NQR of Rare Earth Trihalogenides REX3, X = Br, I
Authors: Babushkina T. A. , Boguslavsky A. A. , Dudareva A. G.
Published: February 2015

The 81Br NQR spectra of REBr3, RE = Dy, Ho, Yb, Sm, and the 127I NQR spectra of REI3, RE = Dy, Ho, Sm. are reported. Additionally 127I NQR data of RbHoL4, KSml4*, and Rb3Sm2l9 are given. The line shape of the 127I NQR of HoI3 was studied in external magnetic fields up to 300 Gauss.
Nuclear Quadrupole Double Resonance of Compounds with Transannular Boron—Nitrogen Bonds
Authors: Lötz A. , Voitländer J. , Stephenson D. , Smith J. A. S.
Published: February 2015

The boron and nitrogen nuclear quadrupole double resonance spectra of several ring compounds with transannular boron-nitrogen bonds are reported. The electron donation from nitrogen to boron as seen by their quadrupole coupling parallels the boron-nitrogen bond lengths. One of the compounds exhibits a transannular valence topomerisation between two identical boron-nitrogen pairs in solution which is frozen in the solid state but may possibly exist in a preformed state of this equilibrium from its quadrupole coupling. The oxygen-boron π-bond in boroxines, whose extent is deduced from the quadrupole coupling in one of the compounds with a boroxine-like structure at boron and in (PhBO)3, is approximately half as strong as the nitrogen-boron π-bond in borazine.
NQR Studies of Phase Transitions and Intermolecular Interactions in Crystals
Authors: Nakamura Nobuo
Published: February 2015

Simple methods to analyze the anomalous behavior of NQR parameters are presented. Unusual positive temperature coefficients of antimony resonance frequencies in (NH4)2SbF5 below the phase transition at 169 K were interpreted in terms of ordering processes of the ammonium ions. Calculation of the EFG in LaF3 revealed that the translational diffusion of Li ions brings about an anomalous decrease in η of the 139La NQR at high temperatures. The same kind of an EFG calculation was made to predict the 14N NQR frequency in Li3N . The calculation of the intermolecular potential energy was used to evaluate the potential barrier to molecular rotation in C6Cl6 and sym-C6Cl3F3. It was shown in the latter that the quadrupolar relaxation, due to a reorientational jump to a metastable site, works in the low temperature phase below 296 K. while the molecular three-fold reorientation is the dominant relaxation mechanism in the high temperature phase.
133Cs Nuclear Quadrupole Coupling in CsOH · H20 Through the 232 K Transition
Authors: Amm D. T. , Segel S. L.
Published: February 2015

The 133Cs NMR has been observed in a pseudosingle crystal of CsOH · H20 in all three solid state phases. The 133Cs quadrupole coupling constant varies almost linearly with temperature throughout the three phases (e2qQ/h = 156 ± 1 kHz at 193 K, 101 ± 1 kHz at 295 K, 36.4 ± 0.5 at 410 K). There is also a discontinuous change of (13 ± 2) kHz in the cesium coupling at the monoclinic to Hex ß transition. In contrast to previous neutron scattering experiments, which indicate significant atomic motion in the Hex α phase, the temperature dependence of the proton NMR indicates that proton diffusion occurs in the Hex ß phase.
Chlorine-35 NQR Studies on [(NH4)0.01K0.09]SnCl6 Mixed Crystals
Authors: Ishikawa A. , Sasane A. , Mori Y. , Nakamura D.
Published: February 2015

The temperature dependence of 35Cl NQR frequencies was measured on the mixed crystal [(NH4)0.01K0.99]2SnCl6. Two phase transitions have been located at Tc1 = 259K and Tc2 = 252K , which are lower by 3 K than the corresponding transition temperatures of the pure K2SnCl6 crystal. The DSC experiments showed that the NH4
+ concentration dependence of Tc2 almost parallels that of Tc1. The impurity effect resulting from the inclusion of a small amount of NH4
⊕ ions in K2SnCl6 crystals is discussed in relation to the microscopic viewpoint of the phase transitions.
Temperature Dependence of the 127I Quadrupole Coupling in Periodates with Alkyl- or Aryl-Substituted Cations of Main Group V
Authors: Klobasa Dagmar G. , Burkert Paul K. , Müller Gerhard
Published: February 2015

127I solid state NMR studies of metaperiodates with alkyl- or aryl-substituted cations of main group V revealed second order quadrupole effects with quadrupole coupling constants in the range of 2 - 7 MHz.

In (C2H5)4PIO4 and (C2H5)4AsIO4 the 127I quadrupole coupling constants show normal temperature coefficients ᾱ in the order of -10-4 K-1 for 186 K < T < 300 K.

For the metaperiodates with aryl-substituted cations (C6H5)4P+, (C6H5)4As+ and (C6H5)4Sb+ complicated temperature dependences of the 127I quadrupole interaction with phase transitions and anomalous positive temperature coefficients +0.2 · 10-2K-1 ≦ ᾱ ≦ +0.8 · 10-2K-1 were observed.

The relevance of possible mechanisms for the anomalous temperature coefficients, like breakdown of dη - pη backbonding, negative pressure coefficients, charge transfer, orientational change of the EFG-tensor axes system and influence of reorientational motions is discussed for these compounds, including results from an X-ray investigation of (C6H5)4AsIO4 and 1H-solid state NMR measurements.
NMR Investigation of the Quadrupolar Glass Na(CN)xCl1-x
Authors: Elschner S. , Petersson J.
Published: February 2015

The freezing process of the CN dumbbells in the orientational glass Na(CN)xCl1-x was studied by 23Na and 35Cl NMR for several concentrations x. The systems with x ≳ 0.7 undergo structural phase transitions, whereas systems with x ≲ 0.7 stay cubic on the average down to lowest temperatures. For concentrations x ≈ 0.65, the temperature dependences of the NMR line widths give evidence that the transition into the glass state essentially consists in a deformation of the local potential leading to a formation of preferential directions for the orientations of the CN ions. The temperature dependence of the spin lattice relaxation time T, shows that the motion of the CN ions in their deformed potentials remain fast. With decreasing concentration x, the influence of the collective interactions between the CN ions become less pronounced and a gradual transition to systems with decoupled CN ions can be observed.
Glassy Crystals VI. Nitrogen-14 Quadrupole Resonance in Glassy Crystalline Thiazole
Authors: Bessada Catherine , Fuchs Alain H. , Péneau Alain , Szwarc Henri
Published: February 2015

Crystalline thiazole has been studied by nitrogen-14 nuclear quadrupole resonance in the 77 - 206 K temperature interval that contains a glass transition at 174 K. The temperature dependences of the relaxation time T1 , of the frequencies and the amplitudes of the NQR signals have been determined for lines ν+ and ν-. No crystal-crystal phase transition has been observed, so that the glass transition at T'g can be observed on heating and on cooling. The T1 measurements have shown the existence of a large-amplitude motion which is different from that which is “frozen” at T'g: it corresponds to a secondary relaxation process which is still active in the glassy crystalline phase. Further studies will attempt to assign it to a definite molecular motion.
Orientation Dependence of the Nuclear Quadrupole Spin-lattice Relaxation of 23Na in NaNO2
Authors: Towta S. , Hughes D. G.
Published: February 2015

The nuclear quadrupole relaxation probability W1 of 23Na in a single crystal of NaNO2 has been studied by applying a selective 180° pulse to the centre line and monitoring the exponential approach to equilibrium of the satellites. The orientation dependence of W1 at 170 K is similar in form to that at 298 K, indicating that the lattice motions responsible for the relaxation are similar at both temperatures. Ratios of the M-tensor components obtained by fitting the W1 data have been compared with the results of various point charge calculations. It indicates that the relaxation is primarily caused by interaction with the four nearest oxygen atoms and confirms that the NO2 groups oscillate and reorient primarily about the c axis.
A Combined Analysis of the Cl NQR Transition Frequency and of the Specific Heat in Trichlorofluoromethane
Authors: Martin Carlos A. , Zuriaga Mariano J.
Published: February 2015

The temperature dependences of the Nuclear Quadrupole Resonance (NQR) transition frequency (νQ) and of the specific heat (Cp) in Trichlorofluoromethane (TCFM) are analyzed. In the analysis of νQ a procedure is developed and successfully applied that takes advantage of all the transition in the NQR spectrum on a simultaneous basis. An effective value of about 40 cm-1 is determined for the librational frequency of a TCFM molecule, and from the analysis of Cp the formation of defects is concluded, which are proposed to be lattice vacancies with a formation energy and entropy of 9.66kJ · mol-1 and 29.6 J mol -1 K-1 , respectively. The behaviour of νQ at the higher temperatures and the fade-out of the signals below the melting point are consistent with the presence of lattice vacancies.
Deuterium Quadrupolar Parameters from 1H and 2H NMR Spectra for Pyridine-d5, Benzonitrile-d5 and Chlorobenzene-d5 Using Liquid Crystal Solvents
Authors: Ambrosetti R. , Catalano D. , Forte C. , Veracini C. A.
Published: February 2015

T he quadrupolar coupling constants (DQCC) and the asymmetry parameters (η) for the ortho, meta and para deuterons in pyridine-d5, benzonitrile-d5 and chlorobenzene-d5 were determined by NMR spectroscopy in oriented phases. The 1H and 2H NMR spectra were recorded in the following solutions in liquid crystal solvents: pyridine + pyridine-d5 in PCH , in ZLI 1167 and in EBBA; benzonitrile + benzonitrile-d5 and chlorobenzene + chlorobenzene-d5 in the same solvents.

The order parameters of the non-deuterated solutes in the various solutions were calculated using the dipolar couplings of the proton spectra and the rα structures taken from the literature. The same order parameters were assumed to describe also the orientation of the deuterated solute in the corresponding solutions.

Each 2H spectrum yielded three quadrupolar splittings for the three different deuterated positions in the labelled solute. The splittings from the three different solutions of the same solute, together with the order parameters and the rα structure, were used to determine DQCC and η of the ortho, meta and para deuterons (Pyridine-d5: DQCCortho= 183(1) kHz, ηortho = 0.030(5), DQCCmeta = 185(1) kHz, ηmeta = 0.030(10), DQCCpara = 188(6) kHz, ηpara = 0.01(5). Benzonitrile-d5: DQCCortho = 171(12) kHz, ηortho = 0.07(3), DQCCmeta = 175(12) kHz, ηmeta = 0.05(3), DQCCpara = 176(4) kHz, ηpara = 0.10(7). Chlorobenzene-d5: DQCCortho = 180(2) kHz, ηortho = 0.06(1), DQCCmeta = 174(2) kHz, ηmeta = 0.09(3), DQCCpara= 182(4) kHz, ηPara = 0.06(4)). The results are discussed, as well as the limits and possibilities of the method used.
Computer Enhanced SRO NQR-Spectrometer
Authors: Mano Koichi , Hashimoto Masao
Published: February 2015

An automatic computer supported SRO NQR spectrometer system was constructed for the measurement of time dependent NQR signal intensities. The system has several functions: fast scanning (500 kH z/25 s), averaging, smoothing, automatic noise level estimation, automatic peak detection, etc. The process of the ß → α phase transition of p-dichlorobenzene is illustrated by the 3-dimensional spectrum .