bluuebunny/crossref_metadata_2025_split huggingface dataset:
Über den thermischen Zerfall von ClONO2 in Gegenwart von NO, ClNO und N2
Authors: Knauth H.‐D. 
Published: March 2014

AbstractUm zu einer Aussage über die Kinetik des Schrittes

zu gelangen, wurde der thermische Zerfall von ClONO2 in Gegenwart von NO und ClNO mit N2 als Fremdgaszusatz bei Drücken zwischen 20 und 375 Torr und Temperaturen zwischen 333 K und 363 K IR‐photometrisch untersucht. NO wandelt die OCl‐Radikale schnell in Cl‐Atome um, welche ihrerseits von ClNO unter Rückbildung von NO abgefangen werden. Ein Vergleich von gemessenen mit über Modellrechnungen gewonnenen Konzentrations‐Zeit‐Kurven, für die aus Messungen an den Systemen NO/ClONO2 und ClNO/ClONO2 erhaltene k‐Werte verwendet wurden, zeigen, daß k erst bei p/Torr = 375 signifikant (ca. 20%) vom Niederdruckbereich abweicht. Für den Niederdruckbereich des Schrittes (1) mit N2 als Stoßpartner wurden die Arrheniusparameter lg(A10/cm3 mol−1 s−1) = 18,9 ± 0,1 und E10/kJ mol−1 = 99,6 ± 0,8 ermittelt.
Phase Boundary Processes in the System (Cd, Pb) (S, Se)
Authors: Leute Volkmar , Böttner Harald 
Published: March 2014

AbstractThe topochemical behaviour of the solid state reaction between PbS and CdSe shows a remarkable dependence of the reaction temperature: at low temperatures closed product layers are formed, at high temperatures a topotactical growth of needles is observed. The measurement of the free standard enthalpy of the chalcogen exchange process at the interface in the reaction between PbSe and CdS shows that local equilibrium is established. The reaction paths, used for the interpretation of the reaction, were calculated from microprobe measurements.
Anomalous Properties of Composite Materials with Fibre and Layer Structures Caused by Internal Phase Boundaries
Authors: Frommeyer G. 
Published: March 2014

AbstractPhase boundaries and size effect contributions on mechanical and physical properties of composite systems such as Ag – Cu, Ag – Ni, Cu – Fe. and FeNi30 – Cu with discontinuous fibre and layer microstructures (layer‐ or fibre thickness < 1000 Å) are studied. The special defect structure of these heterogeneous composites caused an anomalous high tensile strength, an extraordinary change in electrical conductivity and also in the behaviour of the magnetic hardening. As principal mechanism is the intensive interactions of the physical parameters, such as dislocation density, mean free path of the conduction electrons, magnetism vector and Bloch walls, with the internal phase boundaries discussed.
On the Martensitic Transformation in the Intermetallic System β′‐(Au, Pd)∼0.5Zn∼0.5
Authors: Krompholz Klaus , Weiss Alarich 
Published: March 2014

AbstractThe martensitic phase transformation of alloys Au100−xZnx, 47 ⩽ x ⩽ 52, was studied in the temperature range 15 K ⩽ T ⩽ 100 K by measurements of the Hall coefficient RH, the specific electrical resistivity ρ, and by X‐ray powder diffraction. The influence of a third component on the martensitic transformation was investigated by replacing gold partially with palladium. A martensitic phase transformation was thereby found for the quasibinary section Au50−xZn50Pdx in the range 0 ⩽ x < 2.03. The Hall coefficient RH is very sensitive to the martensitic phase transformation in the systems Au100−xZnx and Au50−xZn50Pdx. – From X‐ray powder investigations on Au49.03Zn50.97 at T = 20 K, a hexagonal unit cell with a = (7.658 ± 0.003) Å, c = (5.476 ± 0.003) Å, c/a = 0.715 ± 0.006 was found and the atomic arrangement for this structure is proposed. Very small deformations are experienced by the cubic high temperature phase during transformation. The Bain distortion is discussed and compared with the distortion in the system Au100−xCdx. – The very similar mechanism of the martensitic phase transformation in Au100−xZnx and Au100−xCdx is discussed and a common dependence of the transformation temperatures for alloys Me1Me11 on the radii quotient r(Me1)/r(Me11) is proposed.
Über die Reaktionen von NO und von ClNO mit ClONO2 in der Gasphase (Teil 2)
Authors: Knauth H.‐D. 
Published: March 2014

AbstractDie Reaktion von NO mit ClONO2 wurde in der Gasphase im Temperaturbereich von 303 bis 343 K bei Drücken zwischen 3 und 50 Torr IR‐photometrisch untersucht. Hauptprodukte der Reaktion sind NO2 und Cl2, als Nebenprodukt entsteht ClNO. Drei Schritte bestimmen die Geschwindigkeit der Reaktion:magnified imageDem unter den angegebenen Bedingungen im Niederdruckbereich ablaufenden Schritt (1) folgt die schnelle Reaktion NO + OCl r̊ NO2 + Cl, an die sich Cl‐Atome verbrauchende Reaktionen anschließen. Für die Hauptmeßtemperatur 343 K wurden folgende Parameter gefunden: k · 10−3/cm3 mol−1 s−1 = 17; 71; 9,7; 8,6; 5,4; 5,2 für Mi = ClONO2; ClNO; NO; NO2; Cl2; N2. Schritt (2)gefolgt von NO + Zwischenprodukte führt zu dem Nebenprodukt ClNO. Aus der Temperaturabhängigkeit resultieren die Parameter der einfachen Arrheniusgleichung: lg(A2/cm3 mol−1 s−1) = 12,1 ± 0,1 und E2/kJ mol−1 = 49,6 ± 1. – Messungen an dem zur Wandkatalyse neigenden System ClNO/ClONO2(/N2) ergaben für 343 K den Wert k3/cm3 mol−1 s−1 = 1,18 · 104, der als oberer Grenzwert für die Konstante der homogenen Reaktion (3) angesehen werden muß. Aus der Bildungsgeschwindigkeit des Nebenprodukts ClNO2 gemäß der Bruttogleichung ClNO + ClONO2 = 2ClNO2 läßt sich ein oberer Wert für die Geschwindigkeitskonstante der Reaktionmagnified imagezu k343k17/cm3 mol−1 s−1 ⩽ 2 · 107 abschätzen. – Reaktionsmechanismen werden diskutiert und nach einem Modell berechnete Konzentrations‐Zeit‐Profile mit gemessenen verglichen.
Depolarized Rayleigh Scattering: Reorientational Motion and Orientational Correlations in Acetonitrile and Carbon Disulfide
Authors: Versmold H. 
Published: March 2014

AbstractDepolarized Rayleigh scattering experiments on neat acetonitrile and carbon disulfide as well as on mixtures of these liquids with carbon tetrachloride are reported. The collective reorientational correlation time τLShas been determined which is then compared with the single particle correlation time τS. From the comparison information on an orientational structure factorg(2), which is closely related to the Kirkwoodg‐factor of polar fluids, can be obtained. Combination ofg(2)and Kirkwoodg‐factor results shows that a preferred antiparallel alignment is the most probable orientational structure in acetonitrile. For CS2a Kirkwoodg‐factor cannot be defined due to symmetry. Here the experiments indicate a preferred parallel arrangement of neighbouring molecules.
Nahordnung in Flüssigkeiten, VII. Additivitätseffekte in mehrfach chlorsubstituierten Benzolen
Authors: Domke Wolf‐Dieter , Lippert Ernst 
Published: March 2014

AbstractMit Hilfe der 1H‐Kernresonanzspektroskopie wird das Mischassoziationsverhalten schwacher Lewissäuren (mehrfach‐chlorsubstituierte Benzole) mit organischen Basen (HMPT) untersucht. Die im Frequenzsweep‐Verfahren gemessene Abhängigkeit der Lösungsmittelverschiebung von der Basenkonzentration wird nach dem Kontaktmodell [18] ausgewertet. Die einer schwachen H‐Brücke entsprechenden Wechselwirkungsenergien (‐9,6 bis −16,8 kJ/mol) zwischen den Aromatenprotonen und der Base zeigen Additivität in Beiträgen von 0‐, m‐ und p‐Chloratomen. Das additive Verhalten substituentenstellungsspezifischer Wechselwirkungsinkremente wird durch thermodynamische Messungen bei den Dichlorbenzolen bestätigt.
The Electrooxidation of Ethyleneglycol at Gold in Potassium Hydroxide
Authors: Hauffe W. , Heitbaum J. 
Published: March 2014

AbstractInvestigations of the anodic oxidation of ethylene glycol at gold in alkaline solutions by cyclic voltammetry at stationary as well as rotating ring‐disc electrodes and by controlled potential electrolysis combined with chemical and mass spectroscopic analysis yield the following results:1) Within the overall reaction 8 electrons per EG‐molecule are transferred the final product beeing oxalate. Glycol‐aldehyde, glycolate, glyoxal, and glyoxalate have been identified as intermediates or by products.2) The kinetics of the process is determined by a 1‐electron step, the transfer coefficient amounts α = 0.34. The anodic reaction orders are ZEG = 1 and ZOH‐ = 0, rsp.These results are interpreted by means of a reaction mechanism. The process is assumed to be catalyzed by a gold oxide surface species.
Photoelectrochemical Reactivity of Oxacarbocyanine and Rhodamine B Dimers at the Surface of Anthracene and p‐Chloranil Single Crystals
Authors: Killesreiter Hermann 
Published: March 2014

AbstractAt the surface of anthracene and p‐chloranil single crystals the sensitizing efficiency of dimers has been compared to that of monomers for the dyes 3,3′‐diethyl‐2,2′‐oxacarbocyanine chlorate and rhodamine B. Both molecules aggregate by hydrophobic interaction and their energetic levels are quite comparable. But steric hindrance is possible because of the carboxylic group of rhodamine B. – Using well‐defined ratios of monomers/dimers by means of the rigid structure of monolayers in sandwich cells it turned out with stearyl‐substituted cyanine dyes and with rhodamine B molecules embedded in arachidic acid layers, that the smaller sensitizing efficiency of dimers can be discussed in terms of energy relations and steric factors of the dimer molecule. – By comparison of these experiments with sensitization by the same dyes in solution it can be proved a previous suggestion that adsorption phenomena favour the adsorption of monomers in case of the rhodamines. Therefore it can be explained, why their aqueous solutions show no dimer band in the action spectra of the photocurrent, whereas the cyanines do. Thus, the combination of investigations with rigid structures of monolayers and with dye solutions makes sensitized photocurrents to a useful tool for the spectroscopy of adsorbed molecules.
Kinetics of Metal Ion Adsorption and the Influence of Surface Structure
Authors: Schultze J. W. , Dickertmann D. 
Published: March 2014

AbstractFor various metallic adsorption systems on single crystal planes of gold and silver electrodes, the existence of two or more types of adsorption layers can be proved. Models of close packed monolayers (A), ordered structures (B) and random layers (C) are discussed with reference to possible desorption mechanisms and processes such as surface diffusion and charge transfer. In analogy to electrocrystallization theory, direct and indirect desorption processes are distinguished. – Potentiodynamic and galvanostatic measurements in various systems show different layer transformations and desorption processes. In case of strong lateral attraction, the desorption takes place by an island mechanism. The exchange current densities are often smaller than those of the corresponding metal electrode. In the system Au(111)/Bi3+(B), galvanostatic transients can be explained by a rapid surface diffusion B r̊ C from the edge of the island to the free surface with a following rate determining charge transfer process C r̊ S to the solution. In systems with lateral repulsion, e.g. Pt(poly)/Cu2+, on the other hand, only the charge transfer process can be seen.
Vapour Pressures of Molten Alkali Chloride–Aluminium Chloride Mixtures
Authors: Linga Hogne , Motzfeldt Ketil , Øye Harald A. 
Published: March 2014

AbstractVapour pressures have been measured for molten mixtures in the systems MCl–AlCl3 where M = Li, Na, or K, in the composition range 0 to 50 mol.‐% AlCl3. Based on earlier work it is assumed that the main species in the vapour are MAlCl4(g) and AlCl3(g), with minor contributions from Al2Cl6(g) and MCl(g). The liquids are considered as binary mixtures MCl–MAlCl4 with unsymmetrical positive deviations from ideality. By means of this model, the measured vapour pressures are interpreted in terms of partial pressures of each of the vapour species; thermodynamic data are derived for the molten mixtures, and calculated phase diagrams on the MCl side are presented for the three systems.
Fluid Mixtures at High Pressures Fluid Phase Equilibria in the Systems Fluorobenzene + Water, 1,4‐Difluorobenzene + Water, and 1,2,3,4‐Tetrahydronaphthalene + Decahydronaphthalene(trans) + Water up to 360 MPa
Authors: Jockers R. , Schneider G. M. 
Published: March 2014

AbstractAs part of an extended research program concerning the phase behaviour and thermodynamics of fluid mixtures at high pressures the gas‐gas equilibria of the binary systems fluorobenzene + water and 1,4‐difluorobenzene + water as well as the liquid‐liquid equilibria in the ternary system 1,2,3,4‐tetrahydronaphthalene + decahydronaphthalene(trans) + water were measured in an optical high temperature high pressure cell in the temperature range from 280 to 420°C and at pressures up to 360 MPa. At high pressures all these systems show upper solution temperatures that rise with increasing pressure. – Additionally the critical phase behaviour of nearly all binary water systems investigated up to now is reviewed. The parameters that influence the phase separation in these systems are shortly discussed, and it is shown that the shapes and the relative positions of the steeply ascending branches of the criticalp(T) curves mainly depend on the size as well as on the π‐electrons of the molecules of the non‐aqueous component.
Electrochromic Changes of Light Absorption by the Electric Field of the Electrolytic Double Layer
Authors: Plieth W. J. , Gruschinske P. , Hensel H.‐J. 
Published: March 2014

AbstractThe optical properties of molecules adsorbed on a metal/electrolyte interface depend on the electric field across the double layer. The changes with the electrode potential can be measured by modulation reflection spectroscopy. This provides a method for measuring specifically optical properties of the adsorption layer.
Basicity of Diaza‐Aromatic Compounds, II
Authors: Bluhm Th. , Bluhm A. , Behjati B. , Knop J. V. 
Published: March 2014

AbstractThe pK values and the thermodynamic data for diazaphenanthrenes with both nitrogen atoms in one benzene ring were determined from the pH‐ and temperature‐dependence of the electron excitation spectra. – The basicity gradations of diazaphenanthrenes are discussed in connection with the known pK values of other diazaaromatic and monoaza‐aromatic compounds. It is found that the effect of a second nitrogen atom in lowering the basicity appears to be due not to an inductive but to an electrostatic field effect. – The theoretically expected linear relationship exists between the calculated total energy differences of the di‐ and the mono‐protonated diazaphenanthrenes on the one hand and the corresponding pK values on the other.
Bestimmung der Dissoziationsenergien des Iminoradikals aus Daten der Prädissoziation seines (c1 Π)‐Zustandes
Authors: Zetzsch C. 
Published: March 2014

AbstractDie Kombination von spektroskopischen Beobachtungen des (c1 Π)‐Zustandes von NH und ND ermöglicht die Konstruktion einer Grenzkurve für die Prädissoziation dieses Zustandes. Bei Interpretation der Beobachtungen als Prädissoziation durch Rotation ergibt sich für den Grundzustand (X3Σ−) von NH die untere Grenze der Dissoziationsenergie D0 > 3,45 eV.
Spectroscopic Study of Electronic Energy Transfer from N2(A) and CO(a) to NO in a Beam Experiment
Authors: Ottinger Ch. , Simonis J. , Setser D. W. 
Published: March 2014

AbstractNitric oxide molecules were excited into the A 2Σ+ state by near‐resonant excitation‐transfer collisions with metastable N2(A3Eu+) and CO(a3 Π) molecules in a beam‐gas experiment. The latter species were produced by near‐resonant charge transfer of N+2 and CO+ with NO. The rotational and vibrational excitation of NO(A), as deduced from the NO(A → X) emission spectra, are discussed. The cross sections for excitation of NO(A) by N2(A) and CO(a) drop by about two orders of magnitude between 1 and 200 eVLab. The excitation transfer reactions between N2(A) or CO(a) with NO to give NO(B2 Π), although also near‐resonant, do not occur appreciably in this energy range.
Grundlagen der Kinetik mineralbildender Prozesse
Authors: Schmalzried H. 
Published: March 2014

AbstractThe most complex physico‐chemical process “mineral formation in multicomponent system” is discussed in the sense of limiting cases. The following elementary processes are briefly treated: nucleation and formation of new phases, matter transport in one phase multicomponent system, heterogeneous reaction in multicomponent system. In many cases zero, one and two dimensional crystalline defects play an important role for the morphological and kinetical development of minerals. The role of point defect thermodynamics for the transport coefficient and transport theory of crystalline multicomponent systems is pointed out in some detail.
Mineral Reactions as Indicator of Non‐Ideal Mixing Properties of Supercritical Gas Mixtures
Authors: Ziegenbein Dieter 
Published: March 2014

AbstractThe investigation of suitable mineral equilibria (e.g. decarbonation reactions) allows to deduce the mixing properties of supercritical gas mixtures. The data obtained are best ascertained in an intermediate range of fluid composition and where ideal mixing occurs. The mixing properties of CO2 in CO2 – H2O mixtures are deduced from the equilibrium conditions of the reaction CaCO3 + SiO2 = CaSiO3 + CO2 at 4 kbar and 870 – 1070 K. The “close‐to‐Nature” high pressure experiments yield considerable larger positive deviation from ideal mixing than results deduced from P‐V‐T measurements or thermodynamic calculations.
Die Bedeutung des intermediär oxidierten Schwefels für die Genese hydrothermaler Sulfat‐Sulfid‐Lagerstätten
Authors: Oberste‐Padtberg Rüdiger 
Published: March 2014

AbstractWhat one observes in hydrothermal ore deposits and their wall rock are sulfates (baryte, anhydrite, alunite) and sulfides (pyrite, galena etc.). The nature of the ore forming solution has to be extrapolated. Many authors maintain that sulfur occurs in solution in the extreme oxidation states S6+ and S2− only. However, theoretical considerations and experiments show that intermediate oxidized sulfur species (IOSS) are more frequent than generally assumed. Under hydrothermal conditions (p, T, po2) sulfate will be reduced stepwise; IOSS are dominant. Oxidation, reduction and disproportionation lead to the formation of sulfides and/or sulfates. Sulfate‐acceptors resp. sulfide‐acceptors keep the disproportionation going. IOSS provide a new model to explain the transport of metals and sulfur in the same hydothermal solution and the simultaneous crystallization of sulfates and sulfides. A further advantage of this model is the fact that heavy metals and earth alkali metals are more soluble by orders of magnitude as IOSS than as sulfate and sulfide.
Kinetische Kohlenstoff‐Isotopenfraktionierung im CO2 – H2O‐System des Laacher Sees
Authors: Puchelt Harald 
Published: March 2014

AbstractUnexpected shifts of 13C concentrations observed with carbondioxide emerging from the water close to the eastern shore of Lake Laach could be explained by kinetic C isotopefractionation. This was caused by preferential 12C incorporation into HCO3‐ions as long as no saturation of CO2 was reached and time was not sufficient for establishing isotopic equilibrium. – Laboratory experiments with tank carbon‐dioxide bubbling through triple distilled water in columns up to 4 m high provided fractionations as large as 7.2‰. 13Carbon was found to be enriched in the passing carbondioxide. The effect decreased with time (i.e. with increasing saturation). – The fractionation becomes larger the higher the water column is. It depends also on the size of the carbondioxide bubbles and the water temperature. – These shifts of isotope ratios which occur frequently in nature invalidate fast conclusions regarding the origin of carbondioxide. Careful investigations of the degree of saturation and time available for equilibration are required before genetic conclusions from C isotope ratios are allowed.
Die Fraktionierung der stabilen Isotope des Kohlenstoffs und des Sauerstoffs bei der Bildung von Calcit an der Erdoberfläche
Authors: Usdowski E. , Hoefs J. , Menschel G. 
Published: March 2014

AbstractCalcite is not precipitated immediately from a supersaturated calcium bicarbonate solution because the initial activity of CO32− is small. Therefore, the solution degasses at first CO2 until at a critical value of ΔG of about – 1 kcal/mol calcite begins to nucleate. The fractionation of carbon isotopes between the dissolved carbonate and the atmosphere occurs under isotopic equilibrium. The precipitating calcite, however, exhibits substantial isotopic disequilibrium. The composition of the precipitated and the dissolved carbonate are virtually identical though they should differ by a Δ13C‐value of about 2‰. Isotopic disequilibrium is also indicated by the oxygen isotopes: 18O‐temperatures do not agree with the observed temperatures of calcite formation.
Quasi‐One‐Dimensional Behaviour of Hydrogen in H0.35MoO3 and H0.33WO3 as Revealed by Proton NMR
Authors: Ritter Cl. , Müller‐Warmuth W. , Spiess H. W. , Schöllhorn R. 
Published: March 2014

AbstractThe 1H NMR has been studied in the hydrogen bronzes H0.35MoO3 and H0.33WO3 prepared by galvanostatic cathodic reduction. Both systems reveal an extreme anisotropy of the hydrogen mobility due to quasi‐one‐dimensional behaviour. – In H0.35MoO3 the temperature dependent 1H wideline data give strong evidence that hydrogen is clustered in quasi‐one‐dimensional channels. Analysis of the temperature dependence of the second moment M2, the transverse relaxation time T2, and the spin‐lattice relaxation time T1 yields essentially the same valueEA = 30 kJ/mol for the activation energy of the translational motion of hydrogen within the channels. In H0.33WO3 evidence for the quasi‐one‐dimensional behaviour is provided by the frequency dependence of T1 and the marked non‐exponential recovery of the nuclear magnetization in the vicinity of the T1 minimum. The activation energy for the translational motion is EA = 3.6 kJ/mol only, indicating high mobility of hydrogen in this bronze.
Luminescence and Optical Absorption of Pure and Transition‐Metal‐Doped Al2TiO5 with a View to Solar Energy Applications
Authors: Lam R. U. E.'T. , Blasse G. 
Published: March 2014

AbstractThe luminescence properties and the diffuse reflection spectra of pure Al2TiO5, and Al2TiO5 – Me (Me = V, Cr, Mn, Fe, Co, Ni, Rh) are reported. Our measurements indicate that Al2TiO5 shows an optical absorption edge at 4.1 eV. This large bandgap makes the material unsuitable for solar energy applications. Al2TiO5 can be coloured by transition‐metal ions due to the occurrence of Men+ → Ti4+ charge‐transfer transitions.
The Influence of Illumination on the Flat Band Potential of the Contact TiO2/CH3CN(+ H2O)
Authors: Schumacher R. , Teschner D. M. , Heinzel A. B. 
Published: March 2014

AbstractResults are reported on the flat band potential Vfb of the contact TiO2/CH3CN. The informations were taken from capacitance/voltage and photocurrent/voltage measurements. As electrolyte either pre‐dried CH3CN or various mixtures of dried CH3CN with H2O were used. It was found that both the addition of H2O and illumination with band gap light affect Vfb considerably. – It could be shown that Vfb‐values determined from photocurrent/potential measurements differ up to 2 V from values evaluated from capacitance/potential measurements taken on unilluminated electrodes. However, Vfb‐values obtained from capacitance measurements on pre‐illuminated electrodes agree well with data from photocurrent measurements. The results are discussed in terms of alterations of the inner Helmholtz plane. Finally, consequences of the observed Vfb shifts on the charge transfer process are outlined.