bluuebunny/crossref_metadata_2025_split huggingface dataset:
Old Tools Updated for New Problems: RAMAN Spectroscopic Studies on the Structure of Inorganic Compounds
Authors: Eysel Hans H. 
Published: July 2012

AbstractThe present paper gives a survey over applications of vibrational spectroscopy — especially RAMAN methods — in inorganic chemistry. The following topics are covered: analytical application for the characterisation of molecular compounds, their symmetry and structure, discussion of bond properties by means of Valence Force Field methods, effects of intermolecular interactions on the spectra of liquids and solids. The importance of intensity calculations for the check and improvement of force field calculations is briefly referred to. These different aspects of RAMAN spectroscopy are introduced using examples from recent literature and from the current work of the author.
Surface Enhanced Raman Scattering from Pyridine, Water, and Halide Ions on Au, Ag, and Cu Electrodes
Authors: Pettinger Bruno , Wetzel Herbert 
Published: July 2012

AbstractThe enhancement of Raman scattering for pyridine molecules on Au, Ag, and Cu and for water and halide ions on Ag and Cu electrodes has been investigated. — An enhancement has been found only in that spectral region where relative undamped surface plasmon polaritons (SPP) can be excited, showing a general increase for long wavelength excitation. — The electrochemical pretreatment of the metal surfaces. consisting in an oxidation/reduction cycle creates large scale roughness and adatom‐adsorbate complexes, both of which are necessary simultaneously in order to obtain intense SER scattering. — It is infered that the enhancement results from high density of SPP quanta created at rough or particularly shaped metal surfaces and the SPP scattering cross section being significant larger than that of photons.
Raman Spectra of Mercurimethanes CH4‐n (HgX)n at High Pressures
Authors: Kress Wolfram , Emmert Leonhard , Breitinger Dietrich K. 
Published: July 2012

AbstractRaman spectra of the mercurimethanes C (HgX)4 (X = Cl, Br, and I), CH (HgCl)3, and CH2 (HgX)2 (X = Cl and Br) at high pressures up to about 6 GPa were studied. v (CH) and v (CHg) valence vibrations show strong and medium pressure dependences in the ranges (13.8 ± 2.7) and (7.6 ± 1.7) cm−1 · GPa−1, respectively. It is concluded that obviously anharmonic vibrations of light atoms with large vibrational amplitudes should exhibit high pressure sensitivities.
High‐Pressure Raman Studies of Scheelites and Related Solids
Authors: Breitinger Dietrich K. , Emmert Leonhard , Kress Wolfram 
Published: July 2012

AbstractHigh‐pressure effects (up to 6.5 GPa) in Raman spectra of spinels Na2MO4 (M = Mo and W) and Ag2MoO4, of scheelites M″ MO4 (M″ = Ca, Sr, Ba, and Pb) and of scheelite‐type rhenates M'ReO4 (M' = Na, K, Rb, Ag, and NH4) were compared. For rhenates with high force constants f(ReO) the internal modes show small or medium pressure dependences, in contrast to the highly dependent lattice modes. The pressure dependences are correlated to vibrational amplitudes and anharmonicities.
Heterocyclic Ring Vibrations as Diagnostic Tools for the Differentiation of Metal Coordination Sites
Authors: Lippert B. 
Published: July 2012

AbstractRing stretching and ring breathing modes of (uracilato)ethylenediamineplatium (II) complexes have been examined by means of Raman spectroscopy at different pH values and compared with related complexes in order to establish typical Raman frequencies for the various binding modes possible.
Kinetic and Equilibrium Isotope Effects of Proton Exchange and Autoprotolysis of Pure Methanol Studied by Dynamic NMR Spectroscopy
Authors: Gerritzen Detlef , Limbach Hans Heinrich 
Published: July 2012

AbstractThe rate constants of the intermolecular proton exchange in pure methanol, i.e. the reciprocal proton lifetimes, τ0−1, have been determined as a function of the temperature by total lineshape analysis of the1H‐NMR spectra. Since CH3OH is an AB3spin system of high order the quantum mechanical density matrix formalism was employed for the simulation of the spectra. The neglect of high order effects as well as the presence of impurities had led to inconsistencies in previous studies. For the first time, the primary kinetic isotope effects were determined indirectly by simulation of the1H‐NMR spectra of CH3OD samples containing 1 vol‐% CH3OH. The results are given byfor CH3OH, andfor CH3OD, with a kinetic isotope effect of 3.2 ± 0.4 at 298 K. ‐ The data cannot be explained by a cyclic exchange mechanism. However, they can be quantitatively related to the autoprotolysis constant of methanol and to Grunwald's kinetic data on proton transfer in buffered methanol solutions. It is concluded that the proton lifetimes in pure methanol are determined by the natural amount of free solvated CH3OH2+and CH3O−ions generated by autoprotolysis. The observed energy of activation is then the sum of two terms, namely the energy of activation of the proton jumps between the ions and a methanol molecule, and half the enthalpy of methanol selfdissociation. In the presence of acid or basic impurities the second term becomes negligible. We propose a method for the quantitative determination of these impurities in the 10−9to 10−7mol 1−1range. From our results we derive an equilibrium isotrope effect of (KH/KD)298K = 6 ± 3 for the autoprotolysis of pure methanol, which has not been reported before. It is shown that the literature data on proton exchange in pure water and other protoc systems can be explained in a similar way. The mechanism of the neutralisation in water and methanol is discussed. For the neutralisation of solutions containing 1 mol of each ion it is found that the mean number of proton transfer steps necessary is 5.3 for water and 2.5 for methanol. These data correlate well with the molar solvent density.
Influence of Ion Pair Formation Kinetics in Diffusional Transport of Symmetrical Electrolytes
Authors: Turq Pierre , Orcil Louisiane , Chemla Marius , Barthel Josef 
Published: July 2012

AbstractThe diffusional properties of an associated electrolyte are calculated accounting for the kinetics of pair formation. Chemical rate constants as well as individual particle diffusion coefficients are the fundamental parameters introduced in the calculation. Comparison with other transport coefficients such as mutual diffusion coefficients shows the specificity of the fluctuating mode and the importance of the departures from local equilibrium condition.
Radiation Emitted by a Slightly Ionized Nonideal High‐Pressure Plasma
Authors: Uchtmann H. , Popielawski J. , Hensel F. 
Published: July 2012

AbstractThe paper presents first measurements of the optical emissivity of a slightly ionized mercury plasma at a temperature T of 1600 °C in the pressure range from p = 400 bar to p = 1925 bar corresponding to a density range from d = 0.45 g/cm3 to about d = 4.1 g/cm3. For densities smaller than about 3 g/cm3 where a broad featureless emission band is observed in the visible spectral range the results can be explained in terms of absorption by excitonic states of large randomly distributed Hg‐clusters. The experimental data above 3 g/cm3 show additional strongly density dependent emission tails in the infrared spectral range. A comparison of these results with a recent computer study leads to the conclusion that the infrared emissivity is due to electrons localized in clusters of high atomic densities.
High Temperature Ultraviolet Absorption Spectra of Polyatomic Molecules in Shock Waves
Authors: Astholz D. C. , Brouwer L. , Troe J. 
Published: July 2012

AbstractThe ultraviolet absorption spectra of substituted cycloheptatrienes, toluene, p‐xylene, and of benzyl and methyl‐benzyl radicals have been measured in shock waves at temperatures between 700 and 1650 K. The temperature dependence of the spectra is compared with an analysis based on the deltafunction method in various approximations. The measurements allow for the prediction of the shape of microcanonically hot spectra of laser excited molecules.
Activities in Solid and Liquid Fe  Ni and Fe  Co Alloys Determined by Knudsen Cell Mass Spectrometry
Authors: Rammensee W. , Fraser Donald G. 
Published: July 2012

AbstractThe thermodynamic activities and heats of mixing of liquid and solid solutions in the systems Fe‐Ni and Fe‐Co have been measured by Knudsen‐Cell mass spectrometry using a newly designed molecular beam apparatus. The data obtained for the system Fe‐Ni agree very closely with previous results and confirm negative deviations over the whole concentration range. Results for Fe ‐ Co indicate negative deviations from ideality for all composition between XCo = 0.05 – 1.00 and positive deviations below XCo = 0.05. This supports calorimetric measurements and is in conflict with a previous mass‐spectrometric investigation reporting positive deviations from ideality.
Theoretical Equation of State for n‐Paraffin Liquids
Authors: Jain R. K. , Simha R. 
Published: July 2012

AbstractPrevious theoretical analyses of several n‐paraffins are extended to recent PVT measurements for n = 11 and 12. The results are combined with the earlier ones to obtain interpolation equations for the characteristic scaling and other parameters of the theory as functions of chainlength. This makes it possible to predict the complete equation of state of a n‐paraffin fluid. Finally we discuss the extension of these considerations to mixtures.
PVT Data for Water in the Ranges 20 to 600°C and 100 to 4000 bar
Authors: Hilbert R. , Tödheide K. , Franck E. U. 
Published: July 2012

AbstractPVT data for pure water have been measured between 20°C. and 600°C. for pressures between 100 and 4000 bar using an internally healed pressure vessel. The accuracy of the measured specific volumes is 0.2 percent or better. The volume isotherms were fitted by the Tait equation with an average absolute deviation of the experimental points from the smoothed curves of 0.02% below and of 0.05% above 200°C.
Role of Solvation and Desolvation in Polymer “Catalysis” III. The Influence of High Pressures on the Alkaline Fading Reactions of Triphenylmethane Dyes Catalyzed by Macroions
Authors: Maruno Tohru , Okubo Tsuneo , Ise Norio 
Published: July 2012

AbstractAlkaline fading reactions of ethyl violet and crystal violet were studied in the presence of polyelectrolytes under high pressure, and the significant role of the hydrophobic hydration effect in polyelectrolyte “catalysis” was demonstrated in terms of the volume of activation (ΔV#). Polyelectrolytes used are poly‐4‐vinylpyridine quaternized with n‐cetylbromide (5 mol‐%) and benzylchloride (95 mol‐%) (C16BzPVP), 3‐6 ionen polymer (polybrene), sodium polyethylenesulfonate (NaPES), and sodium polystyrenesulfonate (NaPSS). These four samples, respectively, enhanced, slightly retarded, retarded and strongly impeded the reactions. The influence of a cationic surfactant, cetyltrimethylammonium bromide, on the rates and the activation parameters was similar to that of C16BzPVP. These experimental findings indicate that the hydrophobic macrocations such as C16BzPVP facilitated the formation of the “ice‐berg” structure of water around the activated complex so that the complex and the macrocations are incorporated in the ice‐berg structure causing decrease in ΔV≠. On the other hand, the hydrophobic macroanions (NaPSS, for example) enhanced the ice‐berg formation around the reactants with resulting increase in ΔV≠. Correspondingly, addition of C16BzPVP decreased the enthalpy and entropy of activation (ΔH≠ and ΔS≠) whereas NaPSS increased both ΔH≠ and ΔS≠. These results can be reasonably accepted if we assume that the contribution of the electrostatic hydration term is much less important than that from the hydrophobic hydration.
The Influence of Crystallographic Anisotropy on Photocurrents at GaSe‐Electrodes
Authors: Gerischer Heinz , Lübke Margot 
Published: July 2012

AbstractPhotocurrents have been measured at single crystalline p‐type GaSe electrodes under cathodic polarization where a Schottky barrier is formed at the contact to a suitable electrolyte. By using polarized light and varying the orientation between the c‐axis of the crystal and the light beam, the influence of the optical anisotropy and the anisotropic mobility of the electrons is exemplified by a varying quantum yield. The results can be explained by a theoretical model for the generation of the photocurrent at such a hetero‐junction, using two different values for the absorption coefficients and the diffusion lengths in the directions ∥c and ⟂c.
Entropieerzeugende Prozesse an Phasengrenzflächen
Authors: Hampe Manfred J. 
Published: July 2012

AbstractA thermodynamic theory for the treatment of transport phenomena in multiphase and multicomponent systems is presented. Starting point is a field theoretical description of interfacial systems. The interface in its three dimensional structure is described by new thermodynamic variables, namely the structure vectors ak of the components k. This offers the possibility to analyse processes related with a change of the three dimensional structure by means of the methods of irreversible thermodynamics. Compared to the well known theory of irreversible processes in single phase and membrane systems there are differences regarding the balance equations for component masses and momentum; additionally a balance equation for the structure vector has to be introduced to treat changes of the interfacial structure. The linear constitutive equations obtained from the production term of the entropy balance equation describe transport processes at every point of a multiphase system.—It is shown that in the interfacial region of multiphase systems there are other processes producing entropy than in the bulk of a single phase system. E. g. in the region of an interface Fickian diffusion is not allowed to occur due to a stability criterion. Instead of this a tensorial transport phenomenon due to the structural change of the interface sets in which is possible only at interfaces. By means of a thermodynamic coupling of this tensorial process with the tensorial momentum transport a thermodynamic explanation and description of the Marangoni‐effect is obtained.—New expressions for entropy producing processes are also derived for generalized chemical reactions and transport of momentum. A discussion of potential interactions between fluxes shows that the same cross‐effects occurring in single phase systems cannot be supposed to occur in an interfacial region roo. This results in new aspects for the thermodynamic explanation of active transport.
Ellipsometrie—Eine Methode zur Charakterisierung dünner Filme
Authors: Haller W. 
Published: July 2012

AbstractEllipsometry is an optical non‐destructive method used to examine a surface or a thin film. The principle of measurement is a characteristic change in the state of polarization of elliptic polarized light reflected at a clean or a film‐covered surface. This surface may be on a solid or on a liquid. Normally the evaluation takes place with the aid of a computer. The results are the optical properties of the surface: refractive index and extinction coefficient, or thickness and refractive index of the film.
The Treatment of Ionic Solutions over the Entire Miscibility Range
Authors: Pitzer Kenneth S. 
Published: July 2012

AbstractConductance and thermodynamic properties are considered for several ionic systems continuously miscible from the fused salt to dilute solution in water or another polar solvent. Over most of the composition range, the activities of the respective components of the ionic systems show the same patterns of behavior and can be represented by the same equations that were developed for nonelectrolytes. Consideration is also given to ionic systems of large but finite solubility, including mixed electrolytes. The dominant factor in the behavior of these systems is the strength of ion solvation in competition with intermolecular forces in the solvent and direct interionic forces. Strong ion solvation yields negative deviations from ideal solution behavior and vice versa.
Mikrodynamische Vorgänge in Flüssigkeiten
Authors: Bertagnolli H. , Hertz H. G. , Posch H. A. 
Published: July 2012

AbstractAfter a brief introduction with a discussion of the concept of the correlation function needed for the formulation of the problem, a progress report is given concerning our knowledge of microdynamic processes in liquids covering the fields of neutron scattering, IR‐absorption and light‐scattering, dielectric and nuclear magnetic relaxation as well as studies of diffusion and electric conductance.
Abweichungen im Konzentrationsverlauf scheinbarer Molvolumina und Viskositäten bei hochverdünnten Elektrolytlösungen
Authors: Härtling Christiane , Mecklenburg Thomas , Seidel Wolfhart 
Published: July 2012

AbstractWith the assumption of different subsystems in a liquid model can be shown that a perturbation of the molecular distribution in the liquid, caused by ions, may give rise to deviations in the concentration course of apparent molar volumes and of viscosities of very dilute solutions. Results of the qualitative model discussion are confirmed by some experiments.
The Blue‐Shift of the FIR‐Absorption Bands of Hydrogen Halides due to the Phase Transition Gas/Solution: A Quantum Statistical Interpretation
Authors: Chatzidimitriou‐Dreismann C. A. , Lippert E. 
Published: July 2012

AbstractThe physical principles concerning the far‐infrared absorption process in liquids are discussed. It is shown that the adiabatic approximation cannot be justified in this physical context. The basic ideas of the Kubo‐van Vliet linear response theory are discussed in connection with the FIR‐absorption process. As an application, the blue‐shift of FIR‐absorption bands of dipolar molecules due to the transition gas/solution is interpreted.
Theory of Cyclic Voltammetry at Microdisk Electrodes
Authors: Heinze Jürgen 
Published: July 2012

AbstractThe cyclic voltammetric response, which is obtained by measurements at microdisk electrodes (R ± 1 mm), may deviate strongly from theoretical predictions. The cause of such effects is due to nonlinear diffusion processes, which, in principle, are present at unshielded disk electrodes. They increase with diminishing electrode radii and slow scan rates in accordance with the value of the dimensionless parameter = (D/aR2)1/2. A quantitative description of nonlinear mass transport to microdisk electrodes can be achieved with the aid of a two‐dimensional simulation based on an implicit difference approximation. The agreement with experimental data is very close. The reversible and the quasi‐reversible charge transfer is discussed. To facilitate the interpretation of cyclic voltammograms, working‐curves and diagnostic criteria are presented.
Vapour Pressure of Ternary LiClNaClAlCl3 Melts
Authors: Knapstad Børge , Linga Hogne , Øye Harald A. 
Published: July 2012

AbstractThe vapour pressure and vapour composition have been determined for ternary LiClNaClAlCl3 melts, dilute in AlCl3. Three experimental methods have been employed in order to obtain unambiguous results; a) total pressure of the boiling liquid, b) vapour composition by direct condensation of the boiled‐off vapour, c) mean molecular weight from inert gas transportation. The major gas molecules are NaAlCl4, LiAlCl4, and AlCl3. NaAlCl4 is found to be the major gas species over most of the composition range even though the total pressure of the binary LiClAlCl3 system is considerable higher than that for the corresponding NaClAlCl3 system. The results are described in terms of a semiempirical thermo‐dynamic model.
Untersuchung von Trübungserscheinungen im Einphasengebiet wäßriger Lösungen nichtionogener Tenside
Authors: Platz G. 
Published: July 2012

AbstractSolutions containing Triton‐X‐100 (p‐octylphenoxydecaethyleneglycol), potassiumchloride and water were investigated by dynamic light scattering and temperature jump measurements. It could be shown that the strong turbidity effects in the one phase region near the cloud point depend on increasing concentration fluctuations and not on statistical distributions of isolated large micellar aggregates. In the limit of small q‐values the same expression is valid as well for the intensity correlation function as for the T‐jump relaxation of the scattered light: 1/r = 2Dq2 · (qζ << 1). D is the mutual diffusion coefficient, q is the length of the scattering vector: q = sin (v/2). ζ is the correlation length. The change Δα of the turbidity α with time is given by the following expression which is valid for q ζ <<1:magnified imageFrom dynamic light scattering measurements on solutions of micellar aggregates diffusion coefficients of the micelles are obtained. If the increasing scattering intensity depends on increasing molecular weights T‐jump experiments will yield the two relaxation times for micelle formation and redistribution. With this investigation method it is therefore possible to distinguish between changes of the fluctuation term or structure factor S(q) and changes of molecular weights of scattering aggregates.
The Mercury‐Photosensitized Decomposition of Hexamethyldisilane
Authors: Davidson I. M. T. , Potzinger P. , Reimann B. 
Published: July 2012

AbstractThe kinetics and mechanism of the mercury‐photosensitized decomposition of hexamethyldisilane have been studied. It has been confirmed that the initially‐formed radical, Me3SiSi(Me2)CH2, undergoes a unimolecular rearrangement; Arrhenius parameters have been measured for this rearrangement and for subsequent reactions of the rearranged radical:magnified imageThe significance of these Arrhenius parameters in silicon chemistry is discussed by means of thermochemical calculations.
Solvation of Beryllium Ions in Water‐Hexamethylphosphoric Triamide Mixtures
Authors: Füldner H.‐H. , Strehlow H. 
Published: July 2012

AbstractThe relative amounts of the differently solvated species Be(HMPT)i(H2O)2+4‐i have been determined as a function of solvent composition using 31P‐NMR measurements. The formation of a Bc(NO3)+ inner‐sphere complex was established at higher mole fractions of HMPT. The consecutive stability constants of the Be‐HMPT complexes were obtained and compared with those calculated more indirectly using Bjerrum's method [1].
Ionic Dissociation of Aqueous Hydrobromic Acid. Part 4. Estimate from 81Br and High Temperature 1H Nuclear Magnetic Resonance Data
Authors: Soffer N. , Marcus Y. 
Published: July 2012

AbstractNuclear quadrupole relaxation and chemical shift data for 81Br in aqueous 10 to 20 m hydrobromic acid and viscosity data were obtained at 27 °C. They are consistent with previously obtained 1H NMR data. New 1H chemical shifts obtained at 90 and 120 °C lead to degrees of dissociation that do not differ significantly from the values obtained at 6 to 60 °C.
The Formation of Carbonaceous Species from Carbonmonoxide and from Carbonmonoxide/Hydrogen on Cobalt Catalysts. Indications of Metal‐Support Interaction
Authors: Outi A. , Rautavuoma I. , Van Baan Hessel S. Der 
Published: July 2012

AbstractThe reaction of carbon monoxide and carbon monoxide/hydrogen mixtures with two catalysts, a pure cobalt catalyst and a cobalt on alumina catalyst has been studied, mainly in the thermobalance. It appears that the support prevents carbon diffusion into the cobalt crystallites, whereas on the pure cobalt catalysts the carbide Co3C is formed as the first product. Hydrogen efficiently prevents the formation of carbides in the pure cobalt catalysts; on the supported catalysts relatively large quantities of intermediates are deposited from carbon monoxide/hydrogen mixtures. The observed effects are explained by an interaction between alumina and cobalt that reduces the cobalt‐carbon bond strength and the hydrogen activity on the supported catalyst.