bluuebunny/crossref_metadata_2025_split huggingface dataset:
Appearance Potentials of Field Desorbed Silver Ions
Authors: Hummel E. , Domke M. , Block J. H. 
Published: February 2015

Abstract
The onset, eδ0, in the energy distribution of field desorbed silver ions (from Ag deposit on a W-tip) has been measured at T > 400 K. With increasing field strength (0.5 < 1010 V/m < F < 1·1010 V/m) or with decreasing temperature (800 K > T > 500 K)
eδ0 increases up to 1.5 eV. For a comparison with the eδ0-values, activation energies, Q, for field desorption have been determined from Arrhenius plots (0.5 eV < Q < 2 eV). Two different kinetic regimes (desorption and diffusion) were identified. For field desorption, the sum eδ0 + Q is constant, irrespective of F-values.
In the frame of "image hump" or "charge exchange" models, field dependent activation barriers are discussed. Temperature dependencies are related to (i) the Fermi distribution of the emitter, (ii) the distribution of F and (iii) the distribution of surface bond energies. Results are consistently explained in a three-dimensional model with directionally distinguished desorption steps.
Hochtemperatur-Festkörperchemie von Verbindungen der seltenen Erden mit Valenzinstabilität: Nichtstöchiometrisches TmSe und Mischkristalle / High Temperature Solid State Chemistry of Rare Earth Compounds with Valence Instability: Nonstoichiometric TmSe and Alloys
Authors: Kaldis Emanuel , Fritzler Benno , Peteler Winfried 
Published: February 2015

Abstract
The phase diagram of TmSe has been measured in the composition range 0.6 ≦ x ≦ 1.2 (x = mole Tm/mole Se) up to 2300 °C. Both phase diagram and lattice constants show the existence of a gross homogeneity range at 0.90 < x < 1.05. X-ray and electron diffraction at room temperature confirm the homogeneity of this phase and show no superstructures in this range but only a correlation of vacancies. A dramatic change of the lattice constant (1.7%) with nonstoichiometry shows that the latter controls the valence of Tm between 3 + and 2.71+. Density measurements indicate that both the solution of excess Tm or Se in the lattice leads to the formation of vacancies in the other sublattice. The experimental results can be explained by the existence of approx. 1% Schottky defects for all samples and nonstoichiometric vacancies increasing with deviations from stoichiometry up to 10% for the Se-rich phase boundary (each tenth lattice site vacant!). With increasing temperature the nonstoichiometric samples show two phase transitions: the first at approx. 1100°C for Tm-rich samples or approx. 1700°C for Se rich samples (the stoichiometric sample shows both transitions); the second for all samples at 2003°. At 2020 °C a eutectic appears at the composition of x = 1.00, its components melting at 2032 °C and 2028 °C. This shows that in the temperature range between the phase transitions and the eutectic temperature a decomposition of the homogeneity range must take place. This decomposition might be due to a valence segregation, the two components of the eutectic possibly being Tm2,71+Se and Tm3+Se. Various measurements indicate changes of the lattice stability in TmSe as a function of stoichiometry. Thus stoichiometric samples show a minimum melting point and solution-reaction calorimetry (with 4N HCl) indicates that the composition with the highest melting point (Tm3+Se) has the highest stability. As it is briefly discussed the unstable states may have important implications as active states for surface phenomena and catalysis. Further change of the Tm-valence in a TmSe-containing compound exceeding the range Tm3+↔Tm2,71+ may be achieved by mixed-crystal formation. The lattice pressure in TmSe is changed by chemical substitution leading among others to the interesting mixed crystal systems TmSe1-xTex and Tm1-xEuxSe. The first shows two pressure-induced phase transitions accompanied by a change of the Tm-valence from 2.25+ → 2.52+ and 2.52+ → 2.93+. Density measurements show that when the lattice collapses the number of vacancies nears 10%.
Solutions of Partial Differential Equations for Mean Molar Functions
Authors: Wittig F. E. 
Published: February 2015

Abstract
The well known formulas for computing the partial molar functions from a given mean molar function are treated as deferential equations for computing the mean molar function from any given partial molar function. Solutions do not depend on the number of components, but only on the choice of three indices: the index d of the dependent mole fraction xa to be eliminated prior to any computations, the index j of a pivot mole fraction xj and the index i of the partial molar function yi. An arbitrary number of additional mole fractions of the other components safe xd may be linked to the pivot mole fraction xj. The simple solution: y = (xj - δij) Iij, yi = (xj - δij)2 Xij and Xij = d Iij/dxj holds for an arbitrary number of components, if the (c - 2) mole fractions xj safe xd and xj are transformed to new variables found from the auxiliary equations. Three different cases arise if either i = d, i = j or i ≠ d, i ≠ j is chosen. Formulas for the three sets are provided. As an example a simple interpolation formula for ternary systems is discussed.
Boltzmann Equation Approach to Fröhlich’s Vibrational Model of Bose Condensation-Like Excitations of Coherent Modes in Biological Systems
Authors: Kaiser Fr. 
Published: February 2015

Abstract
A modified Peierls-Boltzmann transport equation formalism for phonons is applied to Fröhlich’s vibrational model. In this model a set of oscillators it nonlinearly coupled to the rest of the system, which can be taken as a heatbath. An external energy supply leads to an additional excitation of the modes. The Hamiltonian for the model is presented and the kinetic equations are derived. The steady state solutions show that under certain conditions the lowest mode be-comes strongly excited, when the phonon flux increases. The resulting excitation far above the thermal value corresponds to a preferred channeling of energy into a single mode (Bose condensation-like excitation). Correspondence with Fröhlich’s rate equation approach is established and the quasi phase transition-like behaviour is discussed
Ortho and Parahydrogen in Interstellar Material
Authors: Reeves Robert R. , Harteck Paul 
Published: February 2015

Abstract
Since H2 is the most abundant molecule in the universe, the ratio of orthohydrogen molecules to parahydrogen in interstellar space is of interest. H2, formed by any exothermic reaction will be in the ratio of 3: 1 according to their statistical weight. This corresponds to the high temperature equilibrium. At the low prevailing temperatures of interstellar space, the thermo-dynamic equilibrium should be shifted to the parahydrogen side. In the gas phase this shift can occur only over chemical reactions which are close to thermally neutral. In addition, it can be concluded that two ion scrambling reactions dominate the process and these both involve positive hydrogen ions. In special cases, surface catalysis on interstellar dust particles may add to the equilibrating process. The highly forbidden process of transition by radiation J = 1(ortho) → J = O(para) + hv can only play a minor role in this catalysis
Structure and Properties of Vacuum-Deposited Cadmium Thin Films
Authors: Halder N. C. 
Published: February 2015

Abstract
Thin films of Cd were prepared by vacuum deposition onto glass plates at temperature of 45 °C and pressure of about 10-6 torr. Several good quality films of various thicknesses (15,000 ~ 28,000 Å) were made. The films were characterized by strong preferred orientation along the 002 planes parallel to the surface of the substrate, which were found to be thickness dependent. In particular, the 002, 100 and 004 peaks were many times stronger than their corresponding diffraction peaks obtained from powder specimens. Both the real and imaginary parts of the Fourier coefficients were considered for line broadening analysis. The particle size (which is also called the average size of the coherently diffracting domains in a direction perpendicular to the diffracting planes), microstrain (which is usually called the mean strain in a given direction) and faulting were determined. A systematic study for all the diffraction peaks indicates an increase of average particle size D̅ from 546 to 620 Å in the above thickness range with no apparent anisotropy for the 100, 002 and 004 directions. The microstrain, however, decreased as much as 50% in this thickness range and showed a considerable amount of anisotropy. The fault parameters α (deformation fault probability) and β (growth fault probability) decreased rather rapidly for all directions
Lattice Dynamics and Thermal Expansion of Thulium
Authors: Rao R. Ramji , Rajput A. 
Published: February 2015

Abstract
The lattice dynamics, lattice specific heat and thermal expansion of the rare-earth metal thulium are worked out applying a model based on Keating’s method. A frequency distribution function involving 50,880 frequencies has been employed. Using the calculated lattice heat capacity, the experimental Cp data of thulium are analysed to get the magnetic contribution to the specific heat in this metal. The energy of magnetic ordering and the magnetic entropy increase involved in the transition from the ordered antiferromagnetic phase to the disordered paramagnetic phase are evaluated. The lattice parameters and volume of thulium are also calculated as a function of hydrostatic pressure and compared with the experimental results
Investigation of the H1 Spin-Lattice Relaxation Times of Some Ammonium Compounds
Authors: Köksal F. 
Published: February 2015

Abstract
The temperature dependence of the proton spin-lattice relaxation times of (NH4)2Al(SO4)2, (NH4)2 MoO4, NH4NH2SO3 and (NH4)2SnCl6 has been investigated in the temperature range 100- 500 K. The experimental results indicate that intra H-H dipolar interaction, modulated by reorientational motion of the ammonium ion, is the dominant relaxation mechanism between 100 and 200 K. The activation energies for the reorientational motion of the ammonium ions were found to be 1.54, 1.56, 0.99, and 0.91 kcal/mole, respectively. Furthermore, it has been detected that above 200 K the spin-rotational interactions of the ammonium ions contribute to the spin-lattice relaxation. The average value of the mean-square spin-rotational interaction constant for NH4
+ was found to be C2 = 1.42 × 1010 s-2
Evidence of a New Decay Mode of 9
ΛB
Authors: Mandal P. , Bhattacharya D. K. , Saha M. , Sen P. K. 
Published: February 2015

Abstract
In a sample of about 200 hyperfragments produced in the interactions of 1.8 GeV/C K--mesons in nuclear emulsions, one example of the hitherto unobserved decay 9
ΛB →π- + 1H + 1H + 7Be has been established. The value of the Λ-hyperon binding energy (BΛ) obtained is 7.37 ± 0.42 MeV
Boundary Conditions for the Distribution Function and for the Moments of a Gas at a Moving Wall
Authors: Vestner H. , Waldmann L. 
Published: February 2015

Abstract
As a slight generalization of previous work [1], boundary conditions for the distribution function of a monatomic gas at a moving solid or liquid wall are derived from the interfacial entropy production. The new scheme is compared with the conventional one. Boundary conditions for a set of moments of the distribution function are obtained by taking the corresponding moments of the new kinetic boundary condition. With a special set, the details are worked out. Finally, a simple two-parameter model for the interfacial kernel is designed and discussed.
Blackbody Radiation in the Rectangular Wave Guide
Authors: Eckhardt W. 
Published: February 2015

Abstract
Electromagnetic (EM-)fluctuations in the rectangular wave guide are considered. In the limit of the empty (lossless) wave guide the partial mode densities, the volume averaged correlations and the internal energy are discussed in both, the high and the low temperature representation. The results are compared with the corresponding quantities in the cube, the slab resonator and the infinite isotropic space.
Proton Magnetic Resonance Study of Molecular Motion in Solid Silver Sulfate Tetrammine, Ag2SO4 · 4NH3
Authors: Kummer Norbert , Ragle John L. , Weiden Norbert , Weiss Alarich 
Published: February 2015

Abstract
The spin lattice relaxation time T1 and the second moment of the proton magnetic resonance were studied on polycrystalline samples of Ag2SO4 · 4NH3. The wideline NMR measurements show a rapid reorientation of the NH3 groups around their threefold axes in the temperature range 250 K ≦ T ≦ 380 K. Below T ≈ 250 K, the rotation of the NH3 starts freezing-in. From Ti measurements an activation energy of 27.5 kJ mol -1 for the rotation was found for temperatures above 210 K. Around 330 K a phase transition has been observed by T1 measurements which is not recognized by wideline NMR measurements in the range 77 K ≦ T ≦ 375 K. The results are discussed and compared with other NMR studies on solids containing NH3 groups.
Influence of Relaxing Defects on the Paraelectric-Ferroelectric Phase Transitions of Rochelle Salt
Authors: Petersson J. 
Published: February 2015

Abstract
It is well known that different types of crystal defects influence the static and dynamic behaviour of the dielectric polarization of Rochelle salt crystals. Particularly strong effects appear near the paraelectric-ferroelectric phase transitions. In this paper it is shown that a slightly modified relaxing defect cell model which has been developed [1] in order to explain the narrow central peaks observed near structural phase transitions adequately describes the interaction between the strongly temperature dependent relaxational motion of the order parameter and the relaxational motions of the various defect modes. This theory is shown to be equivalent to a phenomenological Landau Khalatnikov approach, which so far has only been used to characterize the macroscopic dielectric behaviour of Rochelle salt crystals with defects near the phase transitions, and which in a previous work [16], has been developed in order to give a general description of central peak phenomena caused by defects. For instance the so called very fast after effect and its influence on the phase transitions is discussed in more detail.
Further Study on the Forms of Umbelliferone in Excited State. Part II
Authors: Taszner Stanislawa , Grzywacz Jerzy 
Published: February 2015

Abstract
The assumption [1] that there exist two excited tautomeric forms of umbelliferone in ethanolaqueous solutions is compared with experimental results. Agreement is achived by assuming that the equilibrium between the two forms is dependent on the polarity of the solvent.
Die Schwingungsstruktur der Shpolskii-Spektren von Anthracen, 9-Methyl-und 9.10-Dimethylanthracen in n-Hexan bei 77 K II.Absorption / The Vibronic Structure of Shpolskii Spectra of Anthracene, 9-Methyl- and 9,10-Dimethyl - anthracene in n-Hexane at 77 K II.Absorption
Authors: Jung Ch. , Kawski A. , Zukowska M. I. 
Published: February 2015

Abstract
The absorption spectra of 9-methyl- and 9,10-dimethylanthracene in n-hexane and of anthracene in n-heptane at 77 K were measured spectrographically. From the comparison with calculated frequencies and intensities it can be shown that the observed intense vibronic lines correspond to the same totally symmetric vibrations as in the earlier measured fluorescence spectra. Compared with the fluorescence spectra deviations from the mirror symmetry were observed. In the case of anthracene and 9,10-dimenthylanthracene they result first of all from different intensities of the corresponding vibronic lines, and it can be shown that these differences are mainly due to the Duschinsky-Effect. For 9-methylanthracene the great frequency difference of one totally symmetric vibrations perturbs the mirror symmetry also.
Solid State Transitions in Alkali Alkanoates: Diffractometric and Conductometric Measurements on Lithium, Sodium and Potassium Propanoates
Authors: Cingolani A. , Spinolo G. , Sanesi M. 
Published: February 2015

Abstract
Conductometric measurements on solid lithium, sodium and potassium propanoates and X-ray powder diffraction measurements on the sodium and potassium salts have been performed over temperature ranges including solid state transitions. The temperature dependence of the transport and lattice parameters of the different crystalline phases and the changes of the same parameters in correspondence with phase transitions have been put into evidence.
Time-resolved Microwave Double Resonance in Four Level Systems: H2CO
Authors: Glorieux Pierre 
Published: February 2015

Abstract
Experiments have been performed using time-resolved spectroscopy techniques in a four-level double resonance scheme. The time-resolved variations of radiation probing the populations of a K-type doublet of H2CO have been studied as pump radiation suddenly switched on and off induces population changes between levels of another K-doublet. Non-exponential behavior with characteristic times longer than the relaxation time associated with pressure broadening has been exhibited. A theoretical treatment of this effect, using a generalized density matrix equation, is proposed. It gives reasonable agreement with the observed time dependences.
Mössbauer Studies on some Europium(III) β-Diketonate Complexes
Authors: Medhi O. K. , Agarwala U. 
Published: February 2015

Abstract
Some Europium(III) dibenzoylmethide and benzoylacetonate complexes have been subjected to Mössbauer studies at liquid nitrogen temperature. An attempt is made to discuss covalency in these complexes in terms of 6s, 4f and/or 5d orbital participation in the bond formation. Small linewidths are correlated to less symmetric structures. Resonance effects reflect the polymeric nature of these chelates.
Silicon Über die strahlende Rekombinationswahrscheinlichkeit B von eigenleitendem Silizium / On the Radiative Recombination Probability B in Intrinsic
Authors: Wasserrab Th. 
Published: February 2015

Abstract
In 1974 a theory of the radiative recombination including the Coulomb interaction and the exciton recombination was published by Schlangenotto et al. Now, a quantitative evaluation of this theory was carried out for Si: it shows a strong enhancement of the recombination probability, compared with the theory of van Roosbroeck and Shockley, and yields a remarkable agreement with the measurements.
An Application of Karman’s Energy Transfer Process in Hydromagnetic Turbulence
Authors: Pramanik G. C. 
Published: February 2015

Abstract
A modified version of Chandrasekhar’s equation is derived with the aid of Karman’s energy transfer process for the decay of hydromagnetic turbulence in the limiting case of zero viscosity and infinite electrical conductivity. It is found that the asymptotic behaviour of self-preserving solutions of the aforesaid equations leads to F(k, t)≈k4 , (c = 2/7), G(k, t)≈k6 , (c = 2/9) as k→0 and F(k,t)≈k-5/3 ,G(k,t)≈k-5/3 for k→∞.
Energy Transfer in Competition to Charge Transfer as a Method to Determine the Rate Constant for Charge Carrier Injection in the Sandwich System: Cyanine Dye Monolayer/p-Chloranil Crystal
Authors: Killesreiter Hermann 
Published: February 2015

Abstract
A new method is described to calculate the rate constant for charge transfer (CT) from an excited dye to a molecular crystal by taking into account competing energy transfer to a metal electrode. For the system oxacarbocyanine dye/p-chloranil single crystal in a sandwich arrangement with additional arachidic acid monolayers and evaporated aluminium electrodes, based on photocurrent and fluorescence measurements kCT - (1.5 ± 0.7) 109 sec-1 has been calculated.
This overall rate constant is discussed in terms of a detailed but simple reaction scheme for charge carrier injection. It turned out to be equal to the dissociation rate constant of the excited dye times the quantum efficiency ΦCT for dissociation of an intermediate “charge transfer” state. Dissociation occurs from a vibrationally relaxed excited state of the dye.
Finally, comparison is made with a straightforward calculation using the well-known unipolar current density. Nearly quantitative agreement of estimations emphasizes the use of the mono-layer technique to build "dry" electrochemical cells in order to study the principles of photo-electrochemical reactions.
Gas Electron Diffraction Study of the Molecular Structure of Di-2-pyridyl Sulphide
Authors: Rozsondai B. , Hargittai I. , Pappalardo G. C. 
Published: February 2015

Abstract
The gas-phase electron diffraction study of di-2-pyridyl sulphide has yielded rg(S-C) 1.786 ± 0.004 Å and ∢ C-S-C 104.4 ± 1.7°. The dimensions of the pyridyl groups were found to be consistent with those of free pyridine molecules. Models with various conformational properties could be used to approximate the experimental data.
Group Electronegativities: as Empirically Estimated from Geometrical and Vibrational Data on Sulphones
Authors: Hargittai Istvàn 
Published: February 2015

Abstract
The S=O bond lengths and the S=O bond stretching frequencies characteristically change with changing ligand electronegativities in the XSO2Y sulphone series. Empirical relationships have been established between the S=0 bond length and the sum of the ligand electronegativities (χX+ χY) and also between the mean stretching frequency and (χX + χY)-These relationships may be used for estimating group electronegativities from geometrical and vibrational data or to predict bond lengths, bond angles and stretching frequencies from ligand electro-negativities.
Condensed Aromatics. Part III. In-Plane Molecular Vibrations of Pyrene
Authors: Cyvin S. J. , Cyvin B. N. , Brunvoll J. , Whitmer J. C. , Klaeboe P. , Gustavsen J. E. 
Published: February 2015

A new force field is developed for the in-plane vibrations of condensed aromatics using pyrene as a test molecule. Only five parameters are employed in this force field, which improves a four- parameter approximation previously investigated. Still the simple five-parameter approximation gives calculated vibrational frequencies in good agreement with those from the more elaborate Califano-Neto force field.
In the course of the normal coordinate analysis the Hüekel molecular orbitals have been de­duced. The CC stretching parameters were modified by means of the calculated bond orders. A complete set of independent symmetry coordinates (both in-plane and out-of-plane) for the pyrene molecular model was developed.
New experimental data from infrared and Raman spectra for pyrene are reported.
Also the mean amplitudes of vibration are studied in detail. It is concluded that the simple five-parameter approximation gives reliable mean amplitudes, which undoubtedly are accurate enough for the interpretation of gas electron diffraction data.
Finally the calculated frequencies and mean amplitudes of benzene are given. The mean amplitudes are again found to be very accurate in spite of some substantial inaccuracies in the frequencies.
Deuterium Relaxation in Specifically Labeled Lecithin-Bilayers
Authors: Peters Andrew , Kimmich Rainer 
Published: February 2015

Abstract
Deuterium magnetic relaxation measurements are reported for two samples of specifically labeled dipalmitoyl lecithin bilayers in the temperature range 0° to 60 °C. While the liquid-crystalline phase shows a "dynamic gradient" along the alkane chains, which is already known from 13C-investigations, there is no such gradient in the gel phase at least between the second and tenth methylene group. Moreover there is a common T1-minimum compatible with that observed in studies of the (non-specific) proton relaxation.
Deuterium signals from the gel phase could only be detected by a combined spin-locking / echo method allowing to substract spurious signals arising from magneto-acoustic ringing typical for low-frequency / high-field pulse experiments in iron magnets.