bluuebunny/crossref_metadata_2025_split huggingface dataset:
Experiments and Theoretical Considerations on the Solution of Oxygen in Binary Metal Alloys
Authors: Anik S. , Frohberg M. G. , Kapoor M. L. 
Published: July 2012

AbstractBy means of EMF measurements the activities of oxygen in the system copper‐oxygen‐bismuth were determined at 1473 K. From the results the unknown phase boundaries could be fixed. The miscibility gaps of the binary systems copper‐oxygen and bismuth‐oxygen extend far into the ternary system. The solubility of oxygen in homogeneous copper‐bismuth melts first shows an increasing tendency; later it decreases and arrives at a minimum at NCu/NBi = 4/6. In order to explain the solubility of oxygen in binary molten alloys a statistical model was derived. It was supposed that the oxygen atoms occupy a part of the interstitial lattice sites whereas the metal atoms occupy the substitutional sites. The model permits the determination of thermodynamic data of oxygen in the melt. Moreover it is possible to calculate the self‐interaction parameter of the interstitially solved component. The theoretical approach is checked by the own experimental results.
The Effect of Oxidation of Cu0.35V2O5 on its Activity in the Catalytic Oxidation of Carbon Monoxide
Authors: van den Berg J. , Brans‐Brabant J. H. L. M. , van Dillen A. J. , Geus J. W. , Lammers M. J. J. 
Published: July 2012

AbstractThe effect of oxidation of a copper‐vanadium bronze (β‐Cu0.35V2O5) catalyst was examined by studying the kinetics of the oxidation of CO between 200°C and 525°C in a continuous flow reactor. At 500°C the catalyst appeared to be slowly oxidised in an excess of oxygen to a mixture of CuV2O6 and highly disordered V2O5. – The solid‐state transformation could be inferred from the results concerning the catalytic activity, thermal analysis (TG, DTG, DTA), X‐ray powder diffraction, electron spin resonance, BET and scanning electron microscopy. – The kinetics can be described by an associative mechanism at temperatures up to about 400°C, whereas the reaction proceeds via the reduction‐oxidation mechanism at higher temperatures. This holds irrespective of the degree of oxidation of the catalyst. An anomalous order of the reaction‐rate with respect to oxygen was ascribed to a substantial amount of lattice defects present in the V2O5 matrix. These defects appear in a stabilising configuration.
Besteht ein Zusammenhang zwischen der Zahl primärer Rußpartikel und der Ionen‐dichte bei der Kohlenwasserstoffpyrolyse im thermischen Plasma?
Authors: Spangenberg H.‐J. , Börger I. , Lachmann J. 
Published: July 2012

AbstractDuring the pyrolysis of hydrocarbons in the plasma jet black carbon is formed, possessing special conditions. The primary particles of black carbon have diameters in the range of 3…7 nm. The measured ion density alongside the axis of the plasma jet increases in the region of the formation of the soot. Finally the problem is discussed whether a connection exists between the number of the formed primary particles of black carbon and the ion density in this region.
The Adsorption of CO on a Porous Pt‐Electrode in Sulfuric Acid Studied by DEMS
Authors: Wolter O. , Heitbaum J. 
Published: July 2012

AbstractThe adsorption and oxidation of CO on porous Pt‐electrodes was studied with Differential Electrochemical Mass Spectroscopy (DEMS). The following results were obtained:1. When CO is removed from the solution after adsorption has taken place, the adsorbed species mainly occupies two Pt‐sites. It is oxidized within two peaks at 0.52 and 0.73 V giving CO2 thereby consuming 2 electrons. No evidence of “reduced CO” was found independent of the adsorption potential.2. When CO is present in the solution, a physisorbed species reversibly bound to one Pt‐site covers about 60% of the electrode surface. It is oxidatively desorbed at 0.85 V.
Oxygen and Chlorine Evolution on Ruthenium‐Iron‐Disulphide Mediated by Low Energy Photons
Authors: Kühne H.‐M. , Tributsch H. 
Published: July 2012

AbstractIncorporation of iron (a few percent) into RuS2 (ΔEG = 1.85 eV) changes the energy gap to ΔEG = 1.1 eV. The resulting n‐type compound, which can approximately be described by “Ru1‐xFexS2”, is able to evolve oxygen and chlorine from aqueous electrolytes utilizing visible and near infrared light under energy gain with high quantum efficiency (23% to 60%). — Oxygen and chlorine evolution, mediated by infrared light, is found clearly below the respective redox potentials. Under such conditions of energy conversion the electrode does not indicate signs of photocorrosion. At more extreme electrode potentials traces of a ruthenium tetroxide species are observed — Attempts are made to correlate the (inhomogeneous) distribution of iron in Ru1‐xFexS2 electrodes with photocurrent spectra and scanning laser spot current patterns. — Experiments show that the electrode surface is subject to chemical changes during the photoreaction with water. They are investigated by means of capacity measurements, dynamic current voltage sweeps, and systematical variations of redox potentials in the electrolyte. — A model is presented which accounts for the role of iron in this compound and which explains its photoelectrochemical advantages compared to pure RuS2.
Untersuchung der Spektralsensibilisierung durch Verwendung einer chemischen Modifizierungstechnik
Authors: Nakao Masashi , Watanabe Tadashi , Itoh Kiminori , Fujishima Akira , Honda Kenichi 
Published: July 2012

AbstractSpectral sensitization process was examined by measuring the fluorescence intensities and the photocurrents caused by rhodamine B esterically bound with the surface species of SnO2. It was found that about 20% of its fluorescence intensity were reduced by the Sn02 substrate, and this value was well coincident with the maximum quantum efficiency of the sensitized photocurrent. From the results the charge transfer mechanism of supersensitization is discussed.
Study of the Vaporization of Amalgams with a New Knudsen Cell — Mass Spectrometer System. Part II: The Compounds Mg5Hg3, Mg2Hg, Mg5Hg2, and Mg3Hg and the Formation Enthalpies of All Compounds of the Mg — Hg System
Authors: Hilpert K. 
Published: July 2012

AbstractEvaporation of the compounds Mg5Hg3(s), Mg2Hg(s), Mg5Hg2(s), and Mg3Hg(s) was studied using a Knudsen cell‐mass spectrometer system. They evaporate according to the equations2 Mg5Hg3(s) ⇄ Hg(g) + 5 Mg2Hg(s),	(1)5 Mg5Hg(s) ⇄ Hg(g) + 2 Mg5Hg2(s),	(2)3 Mg5Hg2(s) ⇄ Hg(g) + 5 Mg3Hg(s), and	(3) Mg3Hg(s) ⇄ Hg(g) + 3 MgHg(s)	(4)The Hg partial pressures of Eqs. (1) to (4) arelog(pPa) = (4973.1 ± 60.3) K/T + (9.886 ± 0.12) (440 ‐ 540 K),log(pPa) = (6605.6 ± 69.1) K/T + (10.91 ± 0.11) (499 ‐ 7110 K),log(pPa) = (7118.3 ± 116.5) K/T + (10.91 ± 0.19) (548 ‐ 9890 K), andlog(pPa) = (7502.3 ± 58.8) K/T + (11.29 ± 0.10) (525 ‐ 695 K).The enthalpy changes of reactions Eqs. (1) to (4) were determined by the second and third law method. Formation enthalpies in kJ mol−1 at 298 K were obtained as –60.5 ± 4.3 (MgHg2), –56.4 ± 1.7 (MgHg), –217.1 ± 7.3 (Mg5Hg3), –79.8 ± 2.8 (Mg2Hg), –166.0 ± 6.8 (Mg5Hg2), and –84.2 ± 4.0 (Mg3Hg) for the compounds given in parentheses. Gibbs energies of formation of these compounds are also given. Formation entropies are discussed.
Diffusion in Liquid Mixtures of Light and Heavy Water
Authors: Weingärtner Hermann 
Published: July 2012

AbstractWith the aid of the diaphragm cell technique tracer diffusion of tritium‐labelled water in H2O—D2O mixtures has been measured at 8, 25 and 45°C. In addition, self‐diffusion coefficients in H2O—D2O mixtures have been determined by the proton n.m.r. spin‐echo technique. Paralleling the behaviour of the mutual diffusion coefficient, the tracer diffusion coefficients exhibit small negative departures from a linear concentration dependence which usually is predicted for diffusion in ideal systems.
Core and Valence Electron Binding Energies of FeI2 and Stabilities of Gas Phase Species
Authors: Grade M. , Rosinger W. , Dowben P. A. 
Published: July 2012

AbstractThe core and valence levels for FeI2 have been determined using XPS, UPS and electron impact techniques. The gaseous fragmentation products of FeI2 have also been studied. By combining the present data with available published data, thermodynamic cycles are constructed for gaseous neutral species, ionic gas‐phase species and molecular iodine adsorption on iron in an attempt to systematically characterize iodine interaction with iron. Comparisons with the other ferrous halides are also drawn.
Vaporization of Sodium Iodide and Thermochemistry of (NaI)2(g) and (NaI)3(g): An Experimental and Theoretical Study
Authors: Hilpert K. 
Published: July 2012

AbstractThe evaporation of NaI(s) has been investigated by high temperature mass spectrometry and mass‐loss Knudsen effusion experiments with a micro recording vacuum balance. The gaseous phase in equilibrium with NaI(s) consists of NaI(g), (NaI)2(g), and (NaI)3(g). Partial pressures given by the equationslog(pPa) = –(9.479±0.13) 103/T + 11.49±0.17 for (NaI)(g),log(pPa) = –(10.953±0.06) 103/T + 12.72±0.06 for (NaI)2(g), andlog(pPa) = –(13.543±0.11) 103/T + 13.58±0.15 for (NaI)3(g)were determined in the temperature range of the measurements 674 to 843 K. Sublimation enthalpies were obtained in kJ mol−1 for the reactionsi NaI(s) ⇄ (NaI)i(g) (i = 1,2,3)	(1)as ΔH00 = 196.3±4.4 (i = 1), ΔH00 = 226.8±1.3 (i = 2), and ΔH00 = 284.8±6.6 (i = 3). The enthalpy changes of the dimerization and trimerization reactionsi NaI(g) ⇄ (NaI)i(g) (i = 2,3)	(2)are ΔH00 = –165.8±8.9 (i = 2) and ΔH00 = –304.1±14.8 kJ mol−1 (i = 3). The given enthalpy values are averages of the values determined with the second and third law method for each of the reactions Eqs. (1) and (2). Molecular parameters were estimated for (NaI)3(g) and enthalpy increments as well as Gibbs energy functions computed with these data are given. The enthalpy change of the trimerization reaction, Eq. (2) (i = 3), was predicted with Pauling's model for alkali halides as ΔH00 = –293.4 kJ mol−1 which agrees well with our experimental value. Entropies of sublimation to monomer, dimer, and trimer as well as dimerization and trimerization entropies were obtained at 750 K as 130.1, 148.0, 173.9, –112.2, and –216.4 J mol−1 K−1, respectively. Appearance potentials of 8.7±0.1 (Na+), 14.4±0.2 (I+), 8.2±0.1 (NaI+), 8.6±0.1 (Na2I+), 7.5±0.1 (Na2I2+), 8.3±0.1 (Na3I2+), and 8.4±0.1 (Na3I3+) were determined in V for the ions given in parentheses. The data obtained are discussed in the context of literature data.
Titanium/Chromium Oxide Composite Electrodes – Basic Characteristics
Authors: Beck F. , Schulz H. 
Published: July 2012

AbstractTi sheet has been activated by the ceramic method, starting from solutions of Cr‐III‐chloride and Ti‐IV‐butanolate in isopropanole:A) via firing in air, TA = 350 – 750°C.B) As (A), but subsequent annealing in vacuum at TV = 450 – 850°C.Coulometric, chemical and X ray analysis led to the following results: Electrode A has a layer of α‐Cr2O3 at TA ≥ 450°C, which is anodically oxidized in 1 M H2SO4. With slow cyclic voltammetry, half peak potential is Up/2 (SHE) = 1.77 V. CrO3, which is formed, dissolves. The charge involved in this process is proportional to layer thickness. Electrodes fabricated by mode B carry predominantly a chromium layer at TV ≥ 700°C. These electrodes exhibited a dissolution peak at Up/2 (SHE) = 1.32 V (CrO3). It relates to the transpassive dissolution of chromium. – Steady state and nonsteady anodic and cathodic processes have been investigated with these new electrodes. Their application for electroorganic oxidations via redox catalysis is proposed.
Production and Properties of Atomic and Molecular Microclusters
Authors: Recknagel E. 
Published: July 2012

AbstractThis review reports on the microcluster research at Konstanz University. Metallic and ionic microclusters are produced by an inert gas condensation technique, while clusters from different gases are obtained by adiabatic expansion. An electronic time of flight‐mass‐spectrometer is used for cluster detection. Fragmentation processes, pronounced intensity distributions and the disintegration of multiple charged microclusters are discussed. An example of intramolecular reaction in organic clusters is given.
Comparison between Electron Diffraction Patterns of Ar, CH4 and N2 Clusters and Related Structures
Authors: Farges J. , De Feraudy M. F. , Raoult B. , Torchet G. 
Published: July 2012

AbstractClusters of Ar, CH4 and N2 are produced in a free jet expansion and studied by electron diffraction. Large clusters comprising several thousand molecules have a crystalline structure. Simple models have been constructed on the basis of the same fcc structure, with a particular attention paid to molecular motions in the case of N2. Small clusters with a few ten molecules have an amorphous structure, namely the polyicosahedral structure which has been established previously for small Ar clusters.
A Chemical Reaction and Charge Transfer in Heteroclusters of Fluorobenzene
Authors: Dimopoulou‐Rademann U. , Rademann K. , Bisling P. , Brutschy B. , Baumgärtel H. 
Published: July 2012

AbstractHeterodimers of fluorobenzene (FB) with 1,4‐dioxane and methanol were synthesized in a seeded supersonic beam and studied by resonant two‐photon ionization combined with TOF mass spectrometry. The electronic spectra near the origin of the S1(π π*)← S0 transition of FB revealed solvent induced shifts and spectral features due to the excitation of van der Waals modes. In addition, strong dynamic behaviour of the photo‐ionized dimers could be observed.
Metal‐Clusters: Preparation, Properties, Theory
Authors: Schumacher E. , Kappes M. , Marti K. , Radi P. , Schär M. , Schmidhalter B. 
Published: July 2012

AbstractMethods for the production of small molecules Mn with 2 < n < 100 are critically discussed and explained. The characterization must take into account the existence of a size‐distribution as a consequence of the generation process. Several new spectroscopic methods have been developed for the observation of single particle properties in these mixtures. They all make use of the mass spectrometer as detector. Discussed are the ionization‐potentials as function of size which do not reveal an abrupt change in electronic properties during the transition from a discrete molecular to a metallic behaviour. Certain aspects of the optical spectra of a few diatomic and triatomic clusters are then presented. Quantumchemical elucidations in the small cluster‐range are necessary and very helpful. However, more realistic computations are needed to understand spectra.
Theoretical Aspects of the Electronic Structure and the Stability of Small Clusters
Authors: Koutecký Jaroslav , Pacchioni Gianfranco 
Published: July 2012

AbstractThe investigation of the small clusters of metallic and nonmetallic elements shows that some clusters have some features common with the crystals (cluster bond lengths and cluster bond angles) and simultaneously other stable cluster forms exhibit very specific properties (for example, the planarity of Ia, IIIa, IVa‐tetramers, and Li6, Li7 clusters with pentagonal symmetries). The cluster stability and geometry can be generally well explained from the electronic properties of constituent atoms. Studies of the interactions of clusters with atoms and small molecules yield results which are interesting for the theory of chemisorption (for example, the donation, back‐donation picture of the CO‐metal interaction) and for the understanding of the electronic structure of organometallic compounds.
Calculation of Cluster Geometries with the Help of Hellmann‐Feynman Forces
Authors: Martins José Luís , Buttet Jean , Car Roberto 
Published: July 2012

AbstractThe equilibrium geometries of Nan clusters (n ⩽ 7) are calculated by letting randomly generated clusters relax under the action of the Hellmann‐Feynman forces. We find that clusters with five atoms or less have a planar structure whereas larger clusters have closely packed three‐dimensional geometries. The calculated adiabatic ionization potentials are in good agreement with the experimental appearance potentials.
Cluster Size Separation by Crossjet Deflection
Authors: Gspann J. 
Published: July 2012

AbstractIntersection of a beam of clusters with an uncondensed free jet leads to a size dependent cluster deflection. For large clusters the size distribution function may be obtained from the spatial distributions of mass flow and cluster sizes. Focusing of the average cluster trajectories results from the passage of regions of differing integral crossjet flow or of differing crossjet flow inclination. The limit of the resolution depends upon the prevailing type of collision, elastic reflection leading to a minimum beam spread proportional to the square root of the ratio of the beam and jet particle masses.
Optical Properties of Small Metallic Particles
Authors: Bennemann K. H. , Reindl S. 
Published: July 2012

AbstractA brief review of the electrodynamical properties of small metallic clusters is presented. Experimental results for absorption, photo‐yield and van der Waals interaction are given. Also, recent progress of the theory for the interaction between light and small metallic clusters is discussed. Comparison between experiment and theory shows that presently theory is not able to calculate correctly most of the electrodynamical properties of small clusters.
Gas Phase Chemical Reactions of Transition Metal Clusters
Authors: Riley S. J. , Parks E. K. , Pobo L. G. , Wexler S. 
Published: July 2012

AbstractTransition metal clusters are generated by pulsed laser vaporization and nucleation in a continuous gas‐flow reactor. Gaseous reactants are added downstream, and the resulting products expanded into vacuum, collimated into a molecular beam, and analyzed by pulsed laser nonresonant multiphoton ionization and time‐of‐flight mass spectrometry. Oxidation of iron clusters is found to yield iron‐deficient species with the approximate composition Fe0.9O. Nickel cluster oxidation gives oxygen‐deficient products having the formula NiO0.75. The relation of these results to bulk metal oxidation is discussed. Hydrogenation/deuteration of iron clusters is described, and evidence for H‐D exchange on iron clusters is presented. Reaction of iron clusters with CO is also reported.
Excitonic Clusters and the Phase Transitions in Fluid Mercury
Authors: Turkevich L. A. , Cohen M. H. 
Published: July 2012

AbstractWe review the metal‐nonmetal transition in expanded liquid mercury and the dielectric transition in dense mercury vapor. Previous explanations for these transitions are found to be deficient. We propose that the high‐temperature, high‐pressure fluid is an excitonic insulator phase. The condensation instability of the Frenkel excitons is shown to result from improved coordination within the fluid. The phase diagram for the excitonic insulator naturally explains both the metal‐nonmetal and the dielectric transitions.
Magnetic Measurements on Stable Fe(0) Microclusters. Part I
Authors: Schmidt F. , Stapel U. , Walther H. 
Published: July 2012

AbstractFe(0) microclusters have been isolated in a zeolite matrix. The magnetization isotherm at 4.2 K has been analyzed in terms of a sum of Brillouin functions corresponding to a distribution of cluster sizes. Each function represented a fraction of individual clusters with total cluster spin quantum number (N · S). The (N · S)‐value of clusters with an average of 7 atoms per cluster was found to be 4.
ESR‐Spectroscopic Investigation of the Homogeneous Electron Transfer Reactions between Substituted p‐Phenylenediamines and Quinonediimines, and the Validity of Marcus' Theory. I. Measurements at 293 K
Authors: Grampp Günter , Jaenicke Walther 
Published: July 2012

AbstractThe rate constants k1, and k2 of the self exchange reactions between the half oxidized and the totally oxidized or the reduced forms of some p‐phenylenediamine derivatives are investigated at 293 K by ESR line‐broadening in various aprotic solvents (dielectric constants ϵ between 4.7 and 49). The dimerization constants of the radicals at 183 K and the enthalpies of dimerization are measured, too. The results are discussed in terms of Marcus' theory. In k1, is found to depend linearly on γ = 1/n2 ‐ 1/ϵ (n = refractive index), the covered range being 0.27 < γ < 0.53. The distance parameter g is obtained from the slope and compared with values derived from different molecular models. The results are represented satisfactorily by ellipsoidal molecules with half axes obtained from crystallographic data, the distance in the activated complex being approximately the same as in the radical dimers. The inner reorganization energy is calculated by Hückel methods and compared with experimental values obtained from the intercept of the straight line ln k1 (γ). The deviations are considerable. The calculated Marcus activation free enthalpies are smaller then the measured ones. — The slow rate constant k2 of the second step can be computed, if the Coulomb forces between the radical cation and the dication of the quinone diimine are considered. The inner reorganization energy of the transformation between aromatic and quinoidic structures is negligible. The rate constants of different cross reactions with p‐phenylene diamines are calculated with Marcus' formula which, however, has to be extended by work terms. The symproportionation rate is nearly diffusion controlled. With some other reactions the conformity of measured and calculated rate constants is excellent.
The Redox‐Reaction [Fe(CN)6]3‐/4‐ on Electrodes Coated with Fixed Charge Polymer Films — Observation of Membrane Permeability Modulation by the Electrode Potential
Authors: Braun H. , Decker F. , Doblhofer K. , Sotobayashi H. 
Published: July 2012

AbstractThin films of anion exchangers were prepared from quaternized polyvinylpyridine on glassy carbon and Pt electrodes. To render the polymer insoluble in aqueous electrolytes it was cross‐linked chemically or by exposing the coated electrodes to synchrotron‐radiation. With these electrodes the redox system [Fe(CN)6]3‐/4‐ was investigated with electrochemical methods, including the rotated ring/disk technique. The high equilibrium concentration of [Fe(CN)6]3‐ in the polymer matrix leads to extensive cross‐linking and desolvation of the film rendering its permeability low. During cathodic reduction a large fraction of the produced [Fe(CN)6]4‐ leaves the polymer phase. Anions from the background electrolyte replace the redox‐system; the film swells. The electrochemical phenomena associated with this reversible film structure change are discussed, in particular, a remarkable electrochemical rectification effect.
Double Layer Simulation Studies in Ultrahigh Vacuum of Anion and Cation Hydration at Metal Surfaces
Authors: Sass J. K. , Bange K. , Döhl R. , Piltz E. , Unwin R. 
Published: July 2012

AbstractUsing low energy electron diffraction (LEED), thermal desorption spectroscopy (TDS) and measurements of work function changes (Δø), the coadsorption of water and ions on metal surfaces has been studied in ultrahigh vacuum. As an example of anion specific adsorption, the hydration of bromide on Cu(110) has been characterized with regards to inner layer composition, surface hydration number and the formation of long‐range order. Simulation of non‐specific adsorption of lithium ions has also been attempted. On Ag(110), a drastic reduction of the binding energy of lithium in the presence of water is attributed to this type of surface hydration. Such evidence is not observed on Cu(111), where substantial fragmentation of the water seems to occur. The electrochemical relevance of these results is discussed.