bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electrochemical Studies of Magnetron Sputtered ZnO Film Electrodes
Authors: Yonezawa Y. , Inaba H. , Hada H. 
Published: July 2012

AbstractThe electrochemical behavior of magnetron sputtered ZnO film electrode was studied. The photocurrent‐potential characteristics under irradiation of UV‐light were interpreted by the Gärtner‐Butler model. As ZnO films show a good transparency in the visible region of the spectrum and respond only to the shorter‐wavelength light less than ca. 500 nm, they offer excellent electrodes for the study of spectral sensitization of ZnO. The action spectra of the sensitized photocurrent by rhodamine B and sodium fluorescein reflect the absorption spectra of adsorbed dye layer at the ZnO film, respectively. The quantum efficiency of the photocurrent was determined and compared with that obtained for the ZnO single crystal electrode.
A Proton NMR Study of the Dynamics of Ligand Exchange on Tetrakis(1,1,3,3‐Tetramethylurea)Beryllium(II) and its Dimethyl Sulphoxide Analogue
Authors: Lincoln Stephen F. , Tkaczuk Michael N. 
Published: July 2012

AbstractA1H (90 MHz) NMR study of 1,1,3,3‐tetramethylurea exchange on [Be(O=C(NMe2)2)4]2+in the non‐co‐ordinating diluents CD3NO2and CD3CN shows that the exchange rate is independent of the free 1,1,3,3‐tetramethylurea concentration. Typicallyk1(298.2 K) = 1.39 ± 0.09 s−1, ΔH#= 77.1 ± 1.5 kJ mol−1, and ΔS#= 16.4 ± 4.3 JK−1mol−1for a solution in which [Be(O=C(NMe2)2)42+], [O=C(NMe2)2]free, and [CD3NO2] = 0.00743, 0.0334, and 18.3 mol dm−3respectively. The exchange parameters determined in CD3CN differ slightly from those determined in CD3NO2but in both cases the data are considered to typify a dissociative (D) solvent exchange mechanism. Dimethyl sulphoxide exchange on [Be(O=SMe2)4]2+in CD3NO2diluent is characterised by an exchange rate =k2[Be(O=SMe2)42+][O=SMe2]freefor whichk2(298.2 K) = 143 ± 10 dm3mol−1s−1, ΔH#= 51.1 ± 0.6 kJ mol−1, and ΔS#= −32.3 ± 2.2 JK−1mol−1, and which is considered to typify an associative (A) solvent exchange mechanism. Mechanistic comparisons are made with the data from other studies of solvent exchange on beryllium(II).
Surface Enhanced Raman Scattering of Cyanide Chemisorption Layers on Silver/Electrolyte Interfaces; Potential‐ and Time Dependence
Authors: Plieth W. , Roy B. , Bruckner H. 
Published: July 2012

AbstractThe dependence of the surface enhanced Raman signal of CN− ions on silver/electrolyte interfaces at 2114 cm−1 on the electrode potential was investigated by a periodic pulse program allowing the registration of the time dependence. The results can be interpreted by concentration changes in the diffusion region in front of the electrode as well as by reorganization processes of silver deposits on the electrode surface.
A Comparative Study of the Viscosity Coefficients of Some Nematic Liquid Crystalss
Authors: Kneppe H. , Schneider F. , Sharma N. K. 
Published: July 2012

AbstractThe viscosity coefficients η1, η2, η3 and η12 of 4‐n‐pentyl‐4'‐cyanobiphenyl, 4‐n‐octyl‐4'‐cyanobiphenyl, 4‐methoxy‐4'‐n‐butylazoxybenzene and an aromatic ester mixture were determined in the nematic phase region. Except for 4‐n‐octyl‐4'‐cyanobiphenyl, the viscosity coefficients of the liquid crystals show the following properties: 1) Three of the viscosity coefficients are related by an equation of the form Σ Aiηi = 0, in which the corresponding constants Ai are very similar for the different liquid crystals. 2) The equation ηi =aijηj + bij is valid with the exception of the neighbourhood of the clearing point. 3) The reduced viscosity coefficients 3ηi/(η1 + η2 + η3) of the different liquid crystals exhibit a very similar dependence on the reduced temperature and a nearly linear dependence on the degree of order. The viscosity coefficients η2 and η12 of 4‐n‐octyl‐4' ‐cyanobiphenyl show a divergence at the transition to the smectic phase, whereas η1 and η3 show the normal temperature dependence.
Molecular Aggregation of Sodium Deoxycholate in Water and Water‐Urea Mixtures; a Multistep Process
Authors: Sesta B. , La Mesa C. , Bonincontro A. , Cametti C. , Di Biasio A. 
Published: July 2012

AbstractDensimetric, viscometric, conductometric, and microwave dielectric measurements have been performed on sodium deoxycholate in water and water‐urea solutions, at several temperatures, in order to obtain further informations on the first critical micellar concentration and on super‐aggregation phenomena. – Some interesting results are obtained, especially those casting light on the interactions occurring at the interface between water molecules and micelles. These aggregation processes may be of interest in biological fluids, for example in the solubilization of cholesterol and several other lipids.
Hydrodynaimcal Properties of Nucleosomes
Authors: Bernengo J. C. , Bezot P. , Roux B. , Marion C. 
Published: July 2012

AbstractDynamic light scattering and electric birefringence have been used together to measure both translational and rotational diffusion constants of nucleosomes oligomers. Assuming an ellipsoïdic model, the overall size and shape of these oligomers have been calculated; incertitude determinations, carefully carried out, give an idea of the actual validity of this type of results. Monomer and dimer can be considered as weakly elongated ellipsoïds, while trimer to hexamer are better represented by spheres. De la Torre and Bloomfield modelisation has also been applied to interpret our experimental results, leading for the monomer and dimer to dimensions which are reasonnably well in accordance with electron microscopic determinations.
On the Mechanism of Water Cluster‐Ion Formation in Carbon Dioxide
Authors: Warneck Peter , Rakshit Asit B. 
Published: July 2012

AbstractA drift chamber mass spectrometer has been used to study the formation of water cluster‐ions in carbon dioxide containing traces of water vapour. The dominant reaction sequences were identified up to the fourth generation of daughter ions starting with CO+2. The subsequent reaction mechanism remains uncertain and several possibilities are discussed. The final ions are H3O+ H2O and H3O+ (H2O)2. The significance of the reaction schemes to the radiation chemistry of carbon dioxide is pointed out.
The Influence of Counter‐Ion Concentration on the Aggregation Behaviour of Viscoelastic Detergents
Authors: Hoffmann H. , Platz G. , Rehage H. , Schorr W. 
Published: July 2012

AbstractThe influence of excess Sodiumsalicylate (NaSal) on the properties of viscoelastic detergent solutions of Cetylpyridiniumsalicylate (CPySal) has been studied by static and dynamic light scattering, electric birefringence and rheological measurements. It is observed that the rodlike micelles which are present in these solutions and which are responsible for the elastic behavior grow rapidly in length with the increase of the NaSal concentration until the NaSal reaches 5 · 10−4 M. At this excess NaSal a 1 · 10−3 M CPySal solution contains rods which are at least 2000 Å long. To higher concentrations of NaSal the lengh L and the molecular weight Mw of the micelles is independent on the NaSal concentration. The elasticity and the electric birefringence disappear for NaSal concentration above 5 · 10−3 M. The loss of these properties is believed to be due to the coiling of the long rods. In the viscoelastic region the viscosity of the solutions is shear rate dependent. It decreases with increasing shear rate.
The Surfactant‐Block Structure of Micelles, Synthesis of the Droplet and of the Bilayer Concept
Authors: Fromherz Peter 
Published: July 2012

AbstractThe experimental data concerned with the molecular structure of surfactant micelles are considered. A consistent rationalization of the observations is not attained by the conventional ideas of packing: The droplet‐model describes the thermodynamical data, the bilayer‐fragment model the structural data. A new packing mode is suggested which combines the features of those two models: The parallel correlation of the molecules is limited to a range corresponding to the length of the molecules. An isometric compact assembly is attained which provides a consistent description of the pertinent experimental data. The principle of block‐assembly is applied to the construction of narrow curvatures made from amphiphilic molecules as in liquid crystals, microemulsions and lipidmembranes.
Conductive and Convective Heat Transfer below Evaporating Liquid Surfaces
Authors: Schreiber D. , Cammenga H. K. 
Published: July 2012

AbstractAn apparatus for the measurement of the total heat flux and the subsurface temperature distribution and oscillation in evaporating liquids is described and measurements on water are reported. It is shown that the critical Rayleigh number for the transition from laminar to turbulent flow and the coefficient in the equation for laminar heat flow increase considerably with increasing aspect ratio. A stagnant conductive subsurface layer does not exist, but the amplitude of convective motions is damped in approaching the surface whereas their frequency remains unaltered.
Neue experimentelle Möglichkeiten für das Studium der molekularen Struktur und Dynamik von Flüssigkeiten
Authors: Versmold H. 
Published: July 2012

AbstractThe general space‐time‐pair distribution function G (RA (0), ΩA (0), RB (t), ΩB(t) plays an important role for the theoretical description of liquids. In this report first the relationship between the space‐time‐pair distribution function and static pair distribution functions, which characterize the liquid structure, and time correlation functions, which can be used to comprehend the dynamics of liquids, will be introduced. As an experimental method, which is particularly suited to determine the static pair distribution function, coherent neutron scattering is discussed. The power of this method for the determination of the liquid structure is demonstrated by considering the examples of a fused salt and a molecular liquid. For investigations of the dynamics of liquids incoherent neutron scattering and several spectroscopic experiments have been in use during the last few years. The relationship between these experiments and time correlation functions is presented. A discussion concerning the possibility to study translational and rotational dynamics by incoherent neutron scattering follows. Finally, by referring to a depolarized Rayleigh experiment, the relationship between spectroscopic experiments and orientational correlation functions, which describe the reorientational dynamics in liquids, is illustrated.
The Thermal Conductivity of Water to 250°C and 350 MPa
Authors: Dietz F. J. , De Groot J. J. , Franck E. U. 
Published: July 2012

AbstractAn apparatus is described to measure the thermal conductivity of aqueous and polar fluids at high pressures. The pulse heated wire method is used with a modification to permit AC heating and measurement. Experiments were performed with water from 30°C to 250°C and from 0.1 MPa to 350 MPa. With a pressure increase from saturation pressure to 350 MPa, the thermal conductivity increases at 30°C from 0.610 to 0.757 and at 250°C from 0.617 to 0.849 Wm−1 K−1. Isobars have maxima at 130°C for saturation pressure and at 200°C for 350 MPa. The accuracy of the present results is estimated to be ±0.8%. Isochors have no maxima. The thermal conductivity increases with temperature and density. A comparison with all previous high pressure data for water and with high pressure data for methanol, toluene and n‐heptane is made. The thermal conductivity of supercooled water at high pressures is discussed.
Bestimmung der partiellen Strukturfaktoren aus der Röntgenstrahlenbeugung an flüssigem Silicium‐ und Germaniumtetrachlorid und ihren Mischungen
Authors: Baier Hans‐Rudolf , Weidner Jörg‐Ulrich 
Published: July 2012

AbstractLiquid SiCl4, liquid GeCl4 and mixtures SiCl4/GeCl4 are investigated to yield partial structure factors and pair correlation functions for a liquid tetrachloride system, applying the method of chemical substitution to obtain independent x‐ray diffraction experiments. The properties of the liquid system and the experimental results correspond to the criteria of applicability of the method.—X‐ray diffraction investigations were performed with the pure components and three differently concentrated mixtures at 20 °C. The molecular structure was determined by best fit procedures. The model parameters compare quite favourably with those of the literature. The three partial structure factors of pairs ZZ, ZL, LL were calculated from the five linear equations after separating the intramolecular contributions. Z refers to the molecular centre, L to the chloride atom. From the structure factors the partial pair correlation functions are accessible. The range of orientational correlation was estimated making use of the experimental results.
Depolarisierte Rayleighstreuung an flüssigen binären Mischungen
Authors: Vilhjalmsson R. 
Published: July 2012

AbstractThe molecular reorientation in mixtures of benzene with triethylamine and nitrobenzene with chloroform has been studied at several temperatures and solution concentration. The correlation time τLS for benzene in triethylamine is a linear function of η/T for every concentration but the slope depends on concentration indicating a slight change from “slip” towards “stick” boundary conditions with increasing triethylamine concentration. The extrapolated value for η/T is 0.7 ps for all concentrations. In the nitrobenzene‐chloroform system only the correlation times of nitrobenzene are linear dependent of η/T. The correlation times of chloroform are shorter and have also a smaller activation energy. A comparison with NMR‐data is discussed.
Messungen des zweiten Virialkoeffizienten von Gasen und Gasmischungen bei Zimmertemperatur mit einer Expansionsapparatur
Authors: Schramm B. , Müller W. 
Published: July 2012

AbstractWe describe an expansion apparatus for measurements of second virial coefficients of pure gases and mixtures at room temperature. We present experimental data of CO, CO2, Xe, CH4, CF4and of the binary mixtures Ne/Xe, Ar/N2, Ar/CO, Ar/CO2, and CH4/CF4.
Untersuchung der micellaren Eigenschaften von Tensidlösungen mit Hilfe eines solvatochromen Pyridinium‐N‐phenoxids
Authors: Plieninger P. , Baumgärtel H. 
Published: July 2012

Abstract4‐(2,4,6‐Triphenylpyridinium)‐phenoxide exhibits a strong bathochromic shift of the lowest absorption band in aqueous micellar solutions. The spectroscopic behaviour reveals that the adsorption equilibrium of the dye depends on the concentration and chain length of the surfactant and on the ion strength of the solution. From our results we conclude that the betain is bound in the interface micelle/solution; it may be used as an indicator of polarity of the interface.
A Method to Determine Excess Energies in Dissociative Electron Attachment Processes
Authors: Illenberger E. 
Published: July 2012

AbstractThe initial translational energies of negative ion fragments arising from dissociative electron attachment have been measured over the resonance curve using a time‐of‐flight technique in combination with mass analysis in a quadrupole mass filter. This yields information on the distribution of the excess energy when the negative molecular ion formed on electron attachment decomposes. Experimental results are presented showing that this technique is a useful method to determine more accurately thermochemical parameters of the decomposition products involved in dissociative electron attachment processes.
The Continuum Analogue of Multipolar Lattice Sums
Authors: Steinhauser O. 
Published: July 2012

AbstractAfter a short review on multipolar lattice sums their continuum analogue is derived extensively using the method of multipole expansion. Decomposing the total continuum energy into pair contributions the influence of long‐range interactions on the structure of polar liquids is discussed. The numerical efforts to compute the continuum energy are drastically reduced as compared to the lattice sum. Apart from this a close correspondence between the lattice sums and their continuum analogue can be established.
My Fifty Years of Theoretical Chemistry, I: Chemical Kinetics
Authors: Hirschfelder Joseph O. 
Published: July 2012

AbstractThe 1930's were the Golden Age of discovery; the 1980's are the Laser Age. Theoreticians used to solve practical problems; once again they are turning in that direction. Theoretical research led the way in the Golden Age. Although there has been great progress in the theory, we still have many of the same problems which were troublesome 50 years ago: We dont understand the semi‐empirical schemes (INDO, CNDO, MINDO, ) which are used to calculate the energy of organic molecules; and, the apriori calculation of reaction rates is still difficult. Many new theoretical techniques are being devised to respond to the fantastic precision of present experimental state‐to‐state chemistry!
Chemical Dynamics in Surface Reactions
Authors: Ertl G. 
Published: July 2012

AbstractChemical interactions of gaseous molecules with solid surfaces may proceed with or without bond‐breaking (dissociative and non‐dissociative chemisorption, respectively). The formation of new molecules via surface reactions of these species forms the basis of heterogeneous catalysis. Experimentally accessible information on the processes involved will be briefly outlined by means of a few selected examples.
Liquid Mixtures of Sodium and Sodium Hydride at High Pressures and Temperatures
Authors: Klostermeier W. , Franck E. U. 
Published: July 2012

AbstractThe hydrogen pressure in equilibrium with liquid phases of the system sodium‐sodium hydride has been measured from 650 to 900 °C and up to 900 bar. A detailed description of the apparatus is given. The autoclave was of a nickel base superalloy and contained an outer and an inner compartment with equilibrated hydrogen pressures. At 900°C and 650 bar the maximum solubility of NaH in liquid Na is 19 mole percent. Sieverts' law is closely obeyed to 5% NaH. Sodium solubility in the liquid NaH is below 2%. The melting point of NaH was found at 632 °C and 106 bar, the enthalpy and entropy of fusion as 26.2 ± 0.7 kJ mol−1 and 29.0 ± 0.8 JK−1 mol−1. The enthalpy of solution of liquid NaH in liquid Na is 27.4 kJ mol−1. Equations and data for solubility, activity coefficients etc. of NaH are given. The critical solution point for Na and NaH is estimated to be at 1500 ± 70 K, 2500 ± 600 bar and x(NaH) = 0.65 ± 0.05.
Diffusion and Thermal Diffusion in Binary Mixtures of Deuterium with Neon, Argon, Krypton and Xenon at 300 K
Authors: Trengove R. D. , Dunlop Peter J. 
Published: July 2012

AbstractDiffusion coefficients and thermal diffusion factors are reported for binary mixtures of deuterium with neon, argon, krypton and xenon at 300 K. The data are used to test the Chapman‐Enskog theory and some of the potential functions which have been reported for these systems.
The Luminescence Properties of Some Ruthenium(II) Complexes and Solid Dye Films in Relation to Their Application in Photoelectrochemical Cells
Authors: Breddels P. A. , Blasse G. 
Published: July 2012

AbstractEnergy transfer phenomena in Ru(bpy)3(ClO4)2 are investigated in order to estimate the optimum layer thickness when this complex is used as a sensitizer on a semiconductor electrode in a photoelectrochemical cell. The optimum thickness appeared to be about five molecular layers. We also examined the luminescence properties of solid dye films of some Ru(bpy)2+3 complexes. It is shown that the luminescence intensity can be used as a probe for studying the behaviour of the light‐sensitive electrode in a photoelectrochemical cell.
Molecular Motion of [(CH3)3NH]⊕ Ions in Solid Trimethylammonium Hexahalometallates(IV) as Studied by 1H NMR and 35Cl NQR
Authors: Ikeda Ryuichi , Kadel Rainer , Weiss Alarich , Ishida Nobuko , Nakamura Daiyu 
Published: July 2012

AbstractThe temperature dependence of the 1H spin‐lattice relaxation time, T1, and of the second moment of 1H NMR spectra were studied in a series of trimethylammonium hexahalometallates(IV), (triMA)2MX6, (M = Pt, Sn, Te; X = Cl, Br, I). From X‐ray powder diagrams taken at room temperature, it was found that these complexes are isomorphous throughout the series. The unit cell dimensions were determined. A single 35Cl NQR line was observed for (triMA)2SnCl6 and for (triMA)2TeCl6 in agreement with the crystal symmetry of these complexes. By 1H NMR, two kinds of motions of the ion (triMA), a) the intraionic reorientations of the CH3 groups and b) the reorientation of the whole cation about its C3 axis, have been observed separately in most of the complexes studied. The activation energies of these motions imply that the ions (triMA) are more freely rotating in the hexahalometallate(IV) complexes as compared to the (triMA) halides.
Sustained Oscillations of an Autocatalytic Reaction in a Stirred Flow Reactor
Authors: Geiseler W. 
Published: July 2012

AbstractIn the present paper we report on the discovery and some initial investigations of sustained limit cycle oscillations in the stirred flow oxidation of cerous ions by acidic bromate. In order to find and measure the region of oscillations in the parametric plane of the inflow concentrations of bromate and bromide, a linear concentration gradient method was applied. At present the described flow oxidation is the simplest chemical oscillator fully understood in terms of elementary reaction steps.
Cotton‐Mouton Effect and Rotational Zeeman Effect in Dilute Gases — Two Complementary Methods for the Determination of Molecular Magnetic Properties
Authors: Geschka H. , Pferrer S. , Häußler H. , Hüttner W. 
Published: July 2012

AbstractThe first‐ and second‐order rotational Zeeman effect was investigated in isobutane. The magnetic‐field induced birefringence was measured at room temperature in several gases formed by axially symmetric molecules using pressures up to 1 bar. For benzene vapour these measurements were extended to higher temperatures. The susceptibility anisotropies obtained from the Cotton‐Mouton constants of the gases agree well with those measured directly by the rotational Zeeman effect which indicates that hyperpolarizabilities are negligible. The corresponding temperature independent contribution to the Cotton‐Mouton effect of benzene vapour proves to be less than 3% of the Cotton‐Mouton constant at room temperature.
Diode Laser Spectrum of the Fundamental v2 Band of HNCO
Authors: Lemoine B. , Yamada Koichi , Winnewisser G. 
Published: July 2012

AbstractInfrared spectrum of HNCO near 5 μm was measured by a diode laser spectrometer with source frequency modulation and Stark modulation methods. The subbands of the v2 fundamental band were identified for Ka = 0 to 4. The subband origins and the effective rotational constants for these subbands were determined. The rotational fine structure of the v2 band suggests that the levels are perturbed by accidental resonances.
Charged Thermodynamically Stable Heterophase Fluctuations in Compressed Mercury Vapour
Authors: Hefner W. , Sonneborn‐Schmick B. , Hensel F. 
Published: July 2012

AbstractMeasurements of the real part of the infrared dielectric constant of sub‐ and supercritical mercury vapour indicate that the interaction of the thermally generated charged particles with neutral atoms stabilize regions of higher than average density in the compressed high temperature vapour. A model calculation supports the hypothesis that under certain conditions of the vapour charges tend to stabilize dense liquid droplets which approach metallic conditions while the macroscopic system is still in the nonmetallic region.