bluuebunny/crossref_metadata_2025_split huggingface dataset:
Untersuchungen von Ionenreaktionen mittels Photoionisations‐Massenspektrometrie V. Reaktionen von N+2 und CO+
Authors: Warneck Peter 
Published: March 2014

AbstractDie Reaktionen der Ionen von molekularem Stickstoff und Kohlenmonoxyd mit neun neutralen Reaktionspartnern (H2, CO2. CH4, N2O. SO2. O2, C2H2, COS und NO) wurden hinsichtlich ihrer Geschwindigkeitskonstanten und der Produktverteilungen untersucht und mit‐einander verglichen. Zum Vergleich wurden außerdem nach der Theorie von Gioumousis und Stevenson berechnete Geschwindigkeitskonstanten herangezogen; die Theorie sagt für beide Ionen mit demselben Neutralreaktanten gleiche Geschwindigkeitskonstanten voraus. sofern die Reaktionswahrscheinlichkeit eins ist. In der Tat ergaben die Experimente (mit wenigen Ausnahmen) gleiche Werte, selbst wenn die Reaktionswahrscheinlichkeit kleiner war als eins. Der vorherrschende Mechanismus ist Ladungsaustausch, aber bei den Reaktionen von CO+ werden vergleichsweise häufig auch Umlagerungen beobachtet. Die Ergebnisse legen nahe, daβ der Reaktionsmechanismus durch die Stärke der chemischen Wechselwirkung beim Nahkontakt der Reaktionspartner bedingt ist. Dieser Gesichtspunkt wird anhand eines Potentialmodells diskutiert, wobei die Reaktion von N2+ mit Sauerstoff zur Veranschaulichung herangezogen wird.
Eine Untersuchung der Elektroneneinfangreaktion durch einfache Cyanide im thermischen Energiebereich
Authors: Mothes K. G. , Schultes E. , Schindler R. N. 
Published: March 2014

AbstractDie folgenden absoluten Geschwindigkeitskonstanten k[cm3 ‐ Molekül‐1 sec‐1] für den Einfang thermischer Elektronen in der Gasphase wurden mit Hilfe der ECR‐Technik erhalten:magnified imageAus der Änderung der relativen Signalgröße bei Erhöhung der Elektronenenergie im Resonator werden neue Informationen über den Verlauf des Wirkungsquerschnittes im Energiebereich 0,03 eV bis ca. 0,3 eV erhalten.
Kristallisationsvorgänge bei der elektrolytischen Kupferabscheidung auf polykristalline Kupferunterlagen. II. Einfluß eines primären Grenzflächeninhibitors auf die Kristallisation, Keimbildungsprozesse
Authors: Eichkorn G. , Fischer H. , Mache H.‐R. 
Published: March 2014

AbstractDas in Teil I dieser Arbeit abgeleitete Verfahren zum Abtrennen der Kristallisations‐ von der Gesamtüberspannung wird auf die Kupferabscheidung mit primärem Grenzflächeninhibitor (β‐Naphthochinolin) angewendet. Für den untersuchten Gefügeübergang: feinkristalline, hochaktive Kupferunterlage/relativ gröber kristalliner Kupferniederschlag wurde eine Zunahme der Kristallisationsüberspannungsänderung mit der Stromdichte und der Inhibitorkonzentration gefunden.Durch röntgenographische Linienbreitenmessung wurde die Teilchengröße der Niederschläge bestimmt. Durch Kombination der Teilchengrößemessungen mit den elektrochemischen Messungen konnte mit Hilfe einer modifizierten Volmer‐Gleichung nachgewiesen werden, daβ bei der Abscheidung des arteigenen, den Elektrolysebedingungen angepaßten Niederschlags die Bildung zweidimensionaler Keime die wesentliche Kristallisationshemmung darstellt. Außerdem wurden Werte für die kritische Bildungsenthalpie von (220)‐Netzebenenkeimen ermittelt.
Die Pt‐Netzelektrode als Bezugselektrode bei polarographischen Untersuchungen an Merocyaninen in aprotonischen Lösungsmitteln
Authors: Jacobs Erwin P. , Dörr Friedrich 
Published: March 2014

AbstractBei polarographischen Untersuchungen an Polymethinfarbstoffen wurde eine Pt‐Netzelektrode als Bezugselektrode erprobt. Die Messungen wurden in Propylencarbonat und Hexamethylphosphorsäuretriamid durchgeführt; als Vergleichselektrode diente eine gesättigte Kalomel‐elektrode. Unter Verwendung der Leitsalze Tetraäthylammoniumjodid und Tetrabutylammoniumjodid wurden die Halbstufenpotentiale der Merocyanine vom Typ (CH3)2N‐(CH = CH‐)nCHC(CN)2, n = 0,1,2,3,4 bestimmt.Es zeigte sich, daβ die Pt‐Netzelektrode unter den angegebenen Bedingungen sehr gut reproduzierbare Ergebnisse liefert und somit als Bezugselektrode verwendet werden kann.
Feldionenmikroskopische Untersuchungen an Gold. Beobachtung und Deutung von Spotstrukturen
Authors: Schmidt W. , Krautz E. 
Published: March 2014

AbstractStrukturierte Bildpunkte, die auch als direkte Molekülabbildungen gedeutet wurden, sind bereits 1950 mit dem Feldelektronenmikroskop (FEM) beobachtet worden. Ähnliche Spotstrukturen konnten auch bei Abbildungen im Feldionenmikroskop (FIM), u. a. bei Wolfram mit Methan als Abbildungsgas, nachgewiesen werden. Mit Argon als Abbildungsgas konnten nun höher symmetrische Spotkonfigurationen auf Goldspitzen gefunden werden, die ihre Form nur bei Veränderung der Spitzenspannung verschiedentlich ändern.Die Elektronen‐Hohlrohrwellen‐Theorie, die von A. P. Komar und A. A. Komar zur Erklärung der „Molekülabbildungen”︁ im FEM verwendet wurde, kann auch zur Deutung der im FIM gefundenen Spots herangezogen werden. Damit werden die verschiedenen Spotstrukturen bestimmten Schwingungsmoden der Elektronen in whiskerartigen Erhöhungen auf der FIM bzw. FEM‐Spitze zugeordnet. Die berechneten Moden für elliptische Querschnitte stimmen mit den beobachteten Formen gut überein.
Analysis of the Thermodynamic Behavior of Hydrogen in Body‐Centered‐Cubic Metals with Application to Niobium‐Hydrogen
Authors: O'keeffe M. , Steward S. A. 
Published: March 2014

AbstractA critical analysis of experimental data for the Nb‐H system shows that the partial molar entropy data are best interpreted by assuming a random solution of hydrogen in the metal on one site per metal atom even in concentrated solutions. A possible geometrical interpretation of this result is suggested.
A Mass‐Spectrometric Study of the Thermal Dissociation of Thorium Iodides
Authors: Knacke O. , Münstermann E. , Probst H. 
Published: March 2014

AbstractSolid ThJ4 dissociates thermally below 500°C to form ThJ4‐gas, molecular iodine vapour and, successively, the solid sub‐iodides ThJ3, ThJ2, ThJ and, eventually, the metal. By sublimating and dissociating solid ThJ4 from a Knudsen cell, the partial pressures of ThJ4 and J2 are both determined simultaneously by means of a mass‐spectrometer and calibrated partly gravimetrically. The measurements reported here and complementary earlier DTA measurements allow to calculate the heats of formation and standard entropies of the various iodides as well as the phase diagrams of the system Th — J. The main results of the mass‐spectrometric effusion experiments are the stepwise dissociation of ThJ4, its unexpected high dissociation pressure as compared with published estimates and the probable existence of a stable lower iodide with composition near ThJ.
Polarized Emission Studies and Crystal Data of KLi[Pt(CN)4] · 2H2O
Authors: Holzapfel W. , Yersin H. , Gliemann G. , Otto H. H. 
Published: March 2014

AbstractPolarized emission of KLi[Pt(CN)4] · 2H2O (KLiCP) single crystals was monitored in the temperature range from 295 to 5 K and compared with the polarized emission of several other tetracyanoplatinates(II) with columnar structures of in‐chain Pt‐Pt‐distances between R = 3.15 and R = 3.67 Å. A correlation between the energetic position of the emission maxima and the Pt‐Pt‐distance of adjacent molecules in the column is used to predict R for KLiCP by use of spectroscopic data. The in‐chain Pt‐Pt‐distance found by this method is (3.20 ± 0.01) Å. — X‐ray diffraction measurements yield, that KLi[Pt(CN)4] · 2H2O crystals are orthorhombic with lattice constants a = 10.296(2) Å, b = 14.390(3) Å, c = 6.399(2) Å. The probable space group is C92v — P21 cn. The observed density is D0 = 2.64(3) g/cm3 and the calculated one Dx = 2.671(2) g/cm3 for 4 formula units per unit cell. X‐ray powder data are given. The [Pt(CN)4]2−‐complexes lie in columns along [001]. The groups are separated by c/2 ≡ R = (3.200 ± 0.002) Å, which agrees with the spectroscopic prediction and confirms the former correlation.
The Role of Phase Boundaries in Phase Transformations in Metals
Authors: Hillert Mats 
Published: March 2014

AbstractThe diffusion of solute atoms inside and in front of migrating phase boundaries is considered for various types of phase transformations in alloys. A model is developed which evaluates the Gibbs energy loss due to this diffusion. This model can be used to describe cases where there is a deviation from local equilibrium at the migrating phase boundary. In particular, massive transformation, diffusionless solidification and discontinuous precipitation are considered.
The Influence of Grain Boundaries on the Thermal Stability of Lamellar Microstructures
Authors: Frebel Manfred , Duddek Gerd , Graf Wolfram , Faridani Mohammed Nuhi , Otte Bernhard 
Published: March 2014

AbstractLamellar alloys consist of lamellar grains which are separated from one another by grain boundaries. The normal components of the forces exerted on the grain boundaries by the lamellar interfaces depend on the angle between the lamellae and the grain boundaries. Generally the net force resulting from the forces of the lamellae of two neighbouring grains is different from zero thus giving rise to migration of the grain boundary. As the lamellae of the growing grain tend to grow normal to the moving boundary an enlargement of the interlamellar spacing is observed which leads to a discontinuous coarsening reaction. The morphology and the kinetics of this reaction are presented in three examples: a lamellar microstructure created by a discontinuous precipitation reaction (α‐Ni ‐ In solid solutions), a unidirectionally transformed eutectoid (β‐Cu‐In) and a unidirectionally solidified eutectic (Pb ‐ Sn).
The Role of Phase Boundaries in Heterogeneous Solid State Reactions (I) Classification and the Dynamic Equilibrium at Interfaces
Authors: Schmalzried Hermann 
Published: March 2014

AbstractFor a discussion of mobile phase boundaries between two phases a classification is given into coherent, semicoherent and incoherent boundaries. In case of coherent and semicoherent boundaries the interface mobility is defined and discussed for the example α/β‐Ag2S and NiO/NiAl2O4/Al2O3.
On the Kinetics of the Formation of Micelles in Aqueous Solutions III
Authors: Chan S.‐K. , Herrmann U. , Ostner W. , Kahlweit M. 
Published: March 2014

AbstractAs a supplement to our previously published analyses of the amplitudes and the time constants of the relaxation processes in aqueous solutions of ionic surfactants, this paper presents the results of experiments with some cationic and anionic surfactants together with a more detailed discussion of the concentration dependence of the time constant of the slow relaxation process.
Influence of Excess Energy on the Low Temperature Fluorescence from Inhomogenously Broadened Lines in Anthracene
Authors: Friedrich J. , Flatscher G. , Dörr F. 
Published: March 2014

AbstractThe shape of the low temperature fluorescence of anthracene dissolved in a 2 methyl‐tetrahydrofuran glass is investigated as a function of increasing excess energy. The excitation energy was scanned up to 2000 cm−1 above the origin. The change in the bandshape is attributed to three different mechanisms: an increasing coupling between the impurity molecules and the lattice with increasing site energy, a population of a few discrete sites via vibrational transitions, the inhomogenous widths of which are strongly overlapping, and a phonon assisted population of lower sites which is very efficient at certain positions of excitation.
A Combined Flash Photolysis/Shock‐Tube Study of the Absolute Rate Constants for Reactions of the Hydroxyl Radical with CH4 and CF3H around 1300 K
Authors: Ernst J. , Wagner H. Gg. , Zellner R. 
Published: March 2014

AbstractA combined flash photolysis/shock‐tube technique for the direct investigation of the rates of bimolecular reactions of the OH radical at temperatures between 1000‐1500 K is described. In this technique shock heated mixtures of approximately 0.5% of H2O in Ar and containing small amounts of a selected reactant, are subjected to flash photolysis as an instantaneous source of OH. The shock wave only serves to heat the gas mixture; thermal decomposition does not occur. Formation and subsequent decay of OH are monitored by time resolved UV resonance absorption. – First results with this technique have been obtained for the reactions (1) OH + CH4 r̊ CH3 + H2O and (2) OH + CF3H r̊ CF3 + H2O. Rate constants were found to be k1 (1300 K) = (2.5 ± 0.8) 1012 and k2 (1350 K) = (4.0 ± 1.0) 1011 cm3/mol · s. The result for reaction (1) is shown to confirm previously suggested non‐Arrhenius behaviour for this reaction, and in combination with low temperature data yields k1(T) = 106.19 (T/K)2.13 exp(‐1234 K/T) cm3/mol · s. The dependence of k1, on temperature is described in terms of transition state theory.
Instability of CdSe and CdS Photoanodes in Sulfide‐Polysulfide Electrolyte
Authors: Gerischer H. , Gobrecht J. 
Published: March 2014

AbstractA transformation of the surface of CdSe and CdS single crystal photoanodes under illumination in sulfide/polysulfide redox electrolytes to polycrystalline or amorphous CdS has been found. A reaction mechanism is proposed and its thermodynamics are discussed. The discovered transformation could cause problems for the application of these systems for electrochemical solar cells.
Zur Ion‐Lösungsmittel‐Wechselwirkung beim Transport in wäßrigen Elektrolytlösungen
Authors: Schönert H. 
Published: March 2014

AbstractDie Reibungskoeffizienten Rik, die in den phänomenologischen Gleichungen der irreversiblen Thermodynamik auftreten und die das isotherme Transportverhalten in Mischphasen beschreiben, können einerseits aus konventionellen Transportexperimenten (Äquivalentleitfähigkeit, Überführungszahlen, Diffusionskoeffizient) bestimmt und andererseits nach Debye‐Hückel‐Onsager berechnet werden. Zwischen den experimentellen und theoretischen Werten der Rii besteht eine in der Konzentration lineare Differenz, die ionenspezifisch ist und die sich mit dem ionenspezifischen B‐Term der Viskosität korrelieren läßt.
Equation of State for the Vapour of Concentrated and Diluted Hydrochloric Acid
Authors: Kindler Wolfgang , Wüster Günter , Ran Hans 
Published: March 2014

AbstractPressure‐volume‐temperature relations have been measured for hydrochloric acid with mole fractions of HCl up to 0.23 at temperatures up to 780 K and pressures up to 150 bar. A simplified Redlich‐Kwong equation was fitted to the results and is able to describe the behaviour in the single‐ (vapour‐) phase region fairly well (mostly ± 1%). The saturation line is also given as a function of temperature and mole fraction of HCl.
13C Relaxation Rates in the System Pyridine‐Methanol
Authors: Kratochwill A. 
Published: March 2014

AbstractThe13C‐relaxation rates and the NOE have been determined at 30°C for the o‐, m‐, and p‐carbons of pyridine in mixtures with methanol. The intramolecular dipolar part is analyzed with Woessner's symmetric rotator model. Pyridine reorients anisotropically with the fastest motion around the C4–N–OH axis,D∥/D⟂∼ 4.
On the Pressure Dependence of the Reaction of HO with CO
Authors: Biermann H. W. , Zetzsch C. , Stuhl F. 
Published: March 2014

AbstractThe reaction of HO with CO was studied at 300 K using pulsed vacuum uv photolysis of H2O to generate HO. Resonance absorption was used to monitor HO in the presence of large amounts of N2 or He. The rate constant of this reaction was found to be independent of pressure in the range from 25 to 750 Torr. However traces of impurities in the reaction system and also small amounts of added O2 cause the rate constant to increase at high pressures. A mechanism is proposed to explain this effect.
Calculation of the Structure of Laminar Flat Flames II: Flame Velocity and Structure of Freely Propagating Hydrogen‐Oxygen and Hydrogen‐Air‐Flames
Authors: Warnatz J. 
Published: March 2014

AbstractThe solution of the conservation equations governing a freely propagating laminar flat flame has been performed for the hydrogen‐oxygen‐nitrogen system. A reaction mechanism with rate constants from recent reviews is given which reproduces within the limits of experimental errors flame velocities in hydrogen‐oxygen and hydrogen‐oxygen‐nitrogen mixtures between 10 cm/s and 1000 cm/s.
Infrared Chemiluminescence Studies of the Reactions H + S2Cl2, H + SOCl2 and H + SCl2
Authors: Bardorff W. , Heydtmann H. 
Published: March 2014

AbstractInfrared chemiluminescence studies of the bimolecular reactions H + S2Cl2, H + SOCl2, and H + SCl2 were carried out in order to explore the primary vibrational‐rotational distributions of the excited product molecule HCl. Assuming no formation of HCl(v′ = 0) in the case of the reactions H + SOCl2 and S2Cl2 at least 38%, respectively 32% of the available energy enter vibration and rotation of the newly formed HCl molecule. In contrast for the reaction H + SCl2 more than 56% of the available energy are transferred to the internal degrees of freedom of HCl. The bimodal rotational distribution of the HCl formed by H + SCl2 reported previously [4] was confirmed.
Struktur und Eigenschaften silikatischer Schmelzen als Faktoren der magmatischen Gesteinsbildung
Authors: Seifert F. 
Published: March 2014

AbstractNatural silicate melts (magmas) are highly polymerized and their structure can essentially be described by the anionic species three‐dimensional network (3D), sheet‐ and chain‐like unit. The concentration of these species depends on the ratio of nonbridging oxygens to tetrahedrally coordinated cations (NBO/T), temperature and electronegativity of the network modifier. Their concentration controls e.g. viscosity, density, solubility of fluids and crystallization of the melts. Melts with a high proportion of 3D units with six‐membered rings (e.g. NaAlSi3O8) exhibit a decrease of viscosity with increasing pressure.
ApVT‐Apparatus for Measurements on Gas/Oil Solutions up to 2000 Bar and 440K
Authors: Killesreiter H. , Wiese P. , Kuss E. 
Published: March 2014

AbstractA high pressure piezometer is described with which pVT‐measurements on solutions of gases in liquids like oils can be performed at pressures and temperatures up to 2000 bar and 440 K, respectively. The present investigations deal mainly with the system squalane/CO2 at different mole fractions, but also with squalane/N2. – The high accuracy of the measurements reveals a pronounced structure of the pV‐curves in dependence on temperature and mole fraction. At larger mole fractions is the unequivocal assignment of the phases ambiguous, and the representation of the experimental data in terms of an equation of state not possible for the whole pressure and temperature range. However, for solutions with lower mole fractions could be determined the saturation pressures and the isothermal compressibility in the unsaturated region. Furthermore, the molar excess volumes of the mixtures have been calculated and the phase behaviour has been discussed briefly.
Solubility Constants and Free Enthalpies of Metal Sulphides and Carbonates
Authors: Gamsjäger H. , Reiterer F. , Heindl R. 
Published: March 2014

AbstractSolubility constants, *Kpso = [Fe2+]P [H+]−2, of iron(II) sulphide phases such as troilite, FeS, hexagonal pyrrhotite, FeS1,11, and natural monoclinic pyrrhotite, FeS1,14, have been determined at 323.15 K and total anionic molality, I = 1.0 mol kg−1 (Na)ClO4. At the same conditions the equilibrium constant for the reaction Fe2+ + 2Tl(s) ≈ Fe(s) + 2Tl+ was measured and used for the evaluation of the standard electrode potential of Fe2+/Fe. The respective solubility constants combined with the standard electrode potential of Fe2+/Fe and the well known thermodynamic data of hydrogen sulphide led to the free enthalpies of formation, ΔfG⊖ of the above mentioned iron(II) sulphide phases. Nickel(II) carbonate, NiCO3, was synthesized and its solubility constant determined at 348.15, 358.15 and 363.15 K and at I = 1.00 and 0.20 mol kg−1 (Na)ClO4. From the results obtained the ΔfG⊖ of NiCO3 was calculated and turned out to be considerably more negative (> 30 kJ mol−1) than the value previously accepted.
Partikelmeßtechnik
Authors: Leschonski K. 
Published: March 2014

AbstractParticle characterization comprises the measurement and the quantitative description of physical properties of dispersed particulate systems such as geometrical size, settling rate, optical properties but also of concentration, velocity, flowability. It deals on the one hand with single stationary or moving particles and on the other hand with the properties of a bulk material. — After describing the main areas of particle characterization this paper concentrates on optical methods such as image analysis, and light scattering techniques. A new instrument for diffraction pattern analysis and its theoretical background and an on‐line photometric surface area analyzer finally is described.
Electrical Double Layer and London — van der Waals Forces in Soap Films Studied by Laser Light Scattering
Authors: Joosten J. G. H. 
Published: March 2014

AbstractElectrical double layer and London — van der Waals forces in soap films are studied as a function of thickness by means of time‐averaged light scattering and Photon Correlation Spectroscopy. The free films are drawn from a solution containing 10−2 mol/dm3 of the cationic surfactant dodecyltrimethylammonium bromide. Thermally excited surface waves on the interfaces of a film give rise to a measurable diffuse reflection, being a combination of squeezing mode and bending mode scattering. Because of the large difference in the characteristic time scales the dynamics of the squeezing and bending modes can be studied separately. The relaxation of the bending mode was measured using Photon Correlation Spectroscopy yielding the surface tension of the soap film. Up to frequencies of about 4 MHz this tension appears to be equal to the bulk value of the surface tension. From thickness and angle dependent time‐averaged light scattering experiments we obtained V″, being the second derivative of the free energy of film formation with respect to film thickness. The experimental data are interpreted by the DLVO theory using the Lifshitz theory for the London — van der Waals part of V″. We found an exponential thickness dependence of the electrical double layer contribution to V″. The experimental decay length of the latter contribution agrees very good with the theoretical value of the Debye length. For the surface potential a value of 95 mV was found.
Rate Constants and Vinoxy Product Yield in the Reaction OH + Ethylene Oxide
Authors: Lorenz K. , Zellner R. 
Published: March 2014

AbstractAbsolute rate constants and the vinoxy (CH2CHO) product yield for the reaction of OH radicals with ethylene oxide (C2H4O) have been determined using a combined laser photolysis/resonance fluorescence (laser induced fluorescence) technique. The rate constant for OH decay is k1 = (1.1 ± 0.4)‐ 10−11 exp[‐(1460 ± 150) K/T] cm3/s over the temperature range T = 298–435 K. The branching ratio for vinoxy (VO) formation at 298 K is found to be ϕvo = 0.08 and 0.23 at 13 and 80 mbar, respectively. A potential energy scheme accounting for reagent ring opening and the formation of vinoxy is presented.
Diffusion and Thermal Diffusion in Some Binary Mixtures of the Major Components of Air
Authors: Robjohns H. L. , Dunlop Peter J. 
Published: March 2014

AbstractDiffusion coefficients are reported for the systems N2‐CO2, O2‐CO2, N2‐O2and Ar‐CO2. Thermal diffusion factors have also been measured for the first two systems and used, together with the above diffusion coefficients and second virial coefficients from the literature, to derive approximate spherical potentials to describe the unlike interactions in these two systems.