bluuebunny/crossref_metadata_2025_split huggingface dataset:
Infrared spectroscopy of the electrochemical double layer via electrode emersion
Authors: Hansen Galen J. , Hansen Wilford N. 
Published: March 2014

AbstractInfrared reflection Spectroscopy was used via electrode emersion to study both adsorbed and non‐specifically adsorbing species within the electrochemical interphase on gold, ex situ. A cell was designed which allowed the electrode to rotate and continuously emerse from solution. The parallel‐polarized IR beam was reflected from the rotating surface above the solution at approximately 80°. FTIR spectra were taken of gold electrodes emersing from aqueous solutions of crystal violet, HCIO4, and D2SO4 at various electrode potentials, and ratioed as a function of potential. Active vibrational bands of crystal violet which strongly adsorbs to the gold, and of ClO4− and SO42− ions within the more ideally‐polarizable double layer, are easily seen. Changes in band intensities as a function of potential are, to first order, as expected.
Electroreflectance at the semiconductor/electrolyte interface. A comparison of theory and experiment for n‐GaAs
Authors: Abrantes L. M. , Peat R. , Peter L. M. , Hamnett A. 
Published: March 2014

AbstractThe electroreflectance spectra of GaAs in a number of different electrolytes have been measured in the neighbourhood of the E0 transition. The spectra have been found to exhibit appreciable differences suggestive of changes in the potential distribution in the depletion layer. In one case, that of n‐GaAs in 0.1 M KOH, a detailed analysis has been carried out of lie electroreflectance spectrum using an intermediate field model and incorporating a linear field distribution within the depletion layer. A good fit to the experimental data is obtained from this model and it is found that about 70% of the potential change at the interface is accomodated across the depletion layer.
Electrochemical photooxidation of carboxylates on CdS electrodes
Authors: Feiner A. S. , McEvoy A. J. , Vlachopoulos N. , Grätzel M. 
Published: March 2014

AbstractPhotoelectrochemical oxidation of formate and of some α hydroxycarboxylate species took place at CdS semiconductor photoanodes. The mechanism of the formate dissociation, yielding carbon dioxide and hydrogen, was investigated. The hydroxy groups of the hydroxycarboxylate ions were oxidised to the corresponding ketones. Current enhancement (“current doubling”) effects were noted. The photooxidative reactions competed effectively with CdS photocorrosion.
Stabilization of CdS and CdSe photoelectrodes modified by a catalyst‐containing polythiophene coating
Authors: Gningue Diariatou , Horowitz Gilles , Gamier Francis 
Published: March 2014

AbstractThe protection of CdS and CdSe by a conductive polymer is studied in aqueous solutions of ferrous/ferric redox couple and lithium perchlorate indifferent electrolyte. The polymer is poly(bithiophene) which is grown photoelectrochemically in an acetonitrile solution containing the dimer 2,2′‐bithiophene and lithium perchlorate as the supporting salt. The dimer was chosen as the starting material because photocorrosion of the semiconducting substrate competes with electropolymerization when using a solution of the monomer, leading to very unhomogeneous and poorly adhesive polymers. The protection by the as grown polymer against photodegradation of the semiconductor in an aqueous solution is rather poor, due to a spontaneous reduction of the polymer to its neutral form where its conductivity is lowered by several orders of magnitude. A significant improvement of the protection is obtained by including noble metal clusters on the polymer overlayer. The inclusion is realized by electrochemical reduction of a salt of the metal.
Migration of high energy defects after Pd‐implantation in oxide films on titanium
Authors: Elfenthal L. , Leitner K. , Schnltze J. W. , Meyer O. 
Published: March 2014

AbstractIon implantation in oxide films causes a structural amorphization and high energy lattice defects which influence the electrode capacity, electron transfer reactions and photo processes. Repassivation taking place continuously with increasing potentials yields a migration and annihilation of defects which can be followed by the same measurements, each of them reflecting different aspects. The repassivation charge refers to the defect migration and new oxide formation. The capacity shows the decrease of the dielectric constant D and the donor concentration N. Electron transfer measurements prove the migration of ions with electronic states near the Fermi level EF and the growth of insulating layers. The photocurrent demonstrates the decrease of amorphicity with repassivation.
High Temperature Reactions of CH3 2. H‐Abstraction from Alkanes
Authors: Möller W. , Mozzhukhin E. , Gg. Wagner H. 
Published: March 2014

AbstractThe rate coefficients of the reactions CH3 + C2H6 → CH4 + C2H5 (1) and CH3 + CD4 → CD4 → CH3D + CD3 (2) were determined at high temperatures behind incident shock waves by time‐resolved measurements of the absorption of the methyl radical at 216.5 nm. The resulting Arrhenius expressionsk1 = 1013.3±04 exp (−(6800 ± 1000) K/T) cm3 mol−1 s−1 1100 < T/K < 1400k2 = 1013.8+06 exp (−(8800 ± 1600) K/K) cm3 mol−1 s−1 1100 < T/K < 1500are in good agreement with earlier indirect measurements at high temperatures. Comparison with data at lower temperatures leads to strongly curved Arrhenius plots.
Molecular Orientation and Photoelectric Properties of Alloxazine Monolayer Assemblies
Authors: Nagamura Toshihiko , Matano Koichi , Ogawa Teiichiro 
Published: March 2014

AbstractLangmuir‐Blodgett (LB) films of an alloxazine derivative with two dodecyl chains at 1,3‐positions showed UV/vis dichroism at normal incidence. Spectral shifts indicating aggregation of chromophores were also observed. Angular dependences of polarized absorption spectra indicated that alloxazine rings were biaxially oriented with respect to the film plane and to the dipping direction. The molecular orientation of alloxazine rings in the film plane was suggested to be induced during the transferring process of monolayers. Alloxazine LB films showed photoelectric responses corresponding to the absorption spectra. The in‐plane photoconductivity was almost isotropic and was greater than that of the through‐plane one by about five orders of magnitude.
Homogeneous Optical Linewidth of Impurities in Organic Glasses in the Low Temperature Regime
Authors: Reineker P. , Kassner K. 
Published: March 2014

AbstractWe present a microscopic model for the dephasing of optical impurities in amorphous hosts. To describe the dynamics of the glass an ensemble of two‐level systems (TLSs) is introduced, a well‐known procedure. The TLSs are coupled to an impurity as well as to the matrix vibrations, which we consider a heat bath. A lineshape expression from linear response theory is evaluated for the cases of both a single TLS and many TLSs interacting with the impurity. We find that the magnitude of experimental linewidths can be explained only, if the latter situation is realized. We offer several explanations of the temperature dependence of experimentally observed dephasing rates which are all compatible with the mathematical structure of the theory.
Microwave Conductivity in the Pure and Iodine‐Doped Organic Conductor α‐(BEDT‐TTF)2I3
Authors: Kremer W. , Helberg H. W. , Gogu E. , Schweitzer D. , Keller H. J. 
Published: March 2014

AbstractThe microwave conductivity in dependence of temperature was measured on pure and iodine doped crystals of α‐(BEDT‐TTF)2I3 along the stack direction [100] and perpendicular to it [010]. The exposure times to iodine were varied in many steps between 2 min and 360 min. The contactless microwave technique enables to keep the same crystal in each case throughout all measurements. — The results show that the microwave conductivity vs. temperature is not influenced distinctly by iodine doping. Only at the onset of the plateau range immediately below the metal‐insolator transition at 135 K a small enhancement of the conductivity is found for exposure times larger than 60 min. — In no case a transition to a superconducting state is observed. Therefore recently reported superconductivity may be due to surface effects.
Polymeric Phthalocyanines and their Precursors, 13 Synthesis, Structure and Electrochemical Properties of Thin Films of Polymeric Phthalocyanines from Tetracarbonitriles
Authors: Wöhrle Dieter , Schmidt Volker , Schumann Bernd , Yamada Akira , Shigehara Kiyotaka 
Published: March 2014

AbstractThin films (45 – 1200 nm thickness) of polymeric phthalocyanines were prepared by the reaction of copper films on various carriers with gaseous aromatic tetracarbonitriles. The films were characterized by IR, UV/VIS, and ESCA spectra. The electrical conductivity is in the order of 10−2‐10−5 S cm−1. The electrochemical activity of the films on graphite was studied in acid and alkaline electrolyte. The films exhibit rapid reduction and reoxidation. The pH dependence corresponds to that of the hydrogen electrode approximately.
Bidirectional Coupled Diffusion of Glycine Driven by pH Gradients
Authors: Leaist Derek G. 
Published: March 2014

AbstractStokes magnetically‐stirred diaphragm cells have been used to determine multicomponent diffusion coefficients for aqueous glycine + hydrochloric acid + sodium hydroxide solutions at 25°C. In acidic solutions, pH gradients drive coupled flows of glycine toward the low‐pH region of the solution, countercurrent to the flow of H+ ions. In alkaline solutions, the coupled flow of glycine travels in the opposite direction, “up” the pH gradient. The diffusion measurements also show that gradients in concentration of glycine can produce large coupled flows of H+ and OH− ions. Equations are developed to predict multicomponent transport coefficients for glycine and related ampholytes in acid‐base solutions.
Determination of the Effective Charge Numbers of Colloidal Spheres by Electrophoretic Mobility Measurements
Authors: Okubo T. 
Published: March 2014

AbstractThe effective charge number of colloidal spheres was determined for monodisperse polystyrene latices (91∼2950 nm in diameter and 1.0 ∼ 3010°C/cm2 in charge density) by electrophoretic mobility measurements. The fraction of free macroions and/or gegenions (β) in deionized suspension is smaller than unity and decreases rapidly with increasing sphere analytical valency (Z). The relation, logβ = 2.61‐0.87 log Z is obtained for the deionized suspension. The β‐value decreases on the addition of sodium chloride. β for the organic solvent‐water mixtures (organic solvents: methanol, ethanol, propanol, 1,4‐dioxane, ethylene glycol, propylene glycol, N‐methylformamide. and N‐methylacetamide) is determined as a function of volume fraction of the organic solvent.
Electronic Spectra and Structures of Cation Radicals Produced from p‐Phenylenediamine and 2, 7‐Diaminonaphthalene
Authors: Hoshi Toshihiko , Okubo Jun , Yananoto Masanori , Tanabe Seiichi 
Published: March 2014

AbstractPolarized absorption spectra of cation radicals produced from p‐phenylenediamine and 2,7‐diaminonaphthalene have been determined in poly(vinyl alcohol) matrices (PVA film) at 97 K. Partially oriented free radicals in the PVA films to measure the polarized absorption spectra were prepared by two methods: (1) irradiation of p‐phenylenediamine with a polarized UV light in the unstretched (isotropic) PVA film at 97 K, and (2) irradiation of 2,7‐diaminonaphthalene with an unpolarized light in the stretched (anisotropic) PVA film at 97 K. – The 498 nm and ∼330 nm bands of the cation radical of p‐phenylenediamine are polarized along the longer molecular axis (Z), and these bands correspond to the calculated transitions (2B3u→2B2g), D1 → Do and D3 → D0, respectively. The 375 nm band is polarized along the shorter molecular axis, and assigned to D2 → D0 (2Au → 2B2g). The odd electron of this radical is almost localized on the two nitrogen atoms. – The 580 nm band of the cation radical of 2,7‐diaminonaphthalene is polarized along the shorter molecular axis (Z, C2 axis), and assigned to the calculated transition D1 → Do (2A2 → 2A2). The 477 nm and ∼400 nm bands correspond to the calculated transitions (2B → 2A2) D2 → Do and D3 → Do, respectively, and these transitions are polarized along the longer molecular axis. In this case, the odd electron is localized on the two nitrogen atoms by 84% and on the two carbon atoms at 1 and 8 positions by 15%.
Molecular motions from two‐dimensional NMR of powders: Comparison of rotational jumps and diffusive reorientations
Authors: Schmidt C. , Blümich B. , Wefing S. , Kaufmann S. , Spiess H. W. 
Published: March 2014

AbstractWith the two‐dimensional (2D) exchange NMR experiment on polycrystalline or amorphous solids it is possible to study reorientations in the slow motion limit. Anisotropic interactions lead to 2D powder spectra exhibiting characteristic singularities (“ridges”). From such a powder spectrum the relative orientations of a coupling tensor at the beginning and at the end of the mixing time can be measured without reference to any model of reorientation. The method is demonstrated for hexamethylbenzene and linear polystyrene.
Schwingungsenergieumverteilung in Lösung
Authors: Kaiser W. , Seilmeier A. 
Published: March 2014

AbstractLarge molecules are vibrationally excited via resonant absorption of infrared picosecond pulses or via electronic absorption and subsequent rapid internal conversion. The relaxation of vibrational energy is monitored by a second light pulse which measures changes in the long‐wavelength tail of the electronic absorption. Very rapid intramolecular energy redistribution (τinter < 2 ps) is observed, followed by intermolecular energy transfer to the surrounding (tinter ∼ 10 ps).
The orientation axis comparison of order parameters of anthraquinone dyes in a liquid crystal phase
Authors: Kuball H.‐G. , Strauss A. , Kappus M. , Fechter‐Rink E. , Schönhofer A. , Scherowsky G. 
Published: March 2014

AbstractThree different molecule‐fixed coordinate systems have a distinct significance for the calculation of order parameters. Only one of them is suitable to define an orientation axis (x*3) in order to obtain order parameters which can be used for a comparison between systems of different molecules. For the majority of point symmetry groups, these axes x* are fixed by symmetry. The selection of the orientation axis x*3 from the x3 depends on a special quantitative condition. By means of 15 aminoanthraquinones dissolved in the compensated nematic phase of cholesteryl chloride/cholesteryl laurate and in addition some of them in ZLI 1695 (Merck), the consequences of the choice of the reference axis x3 for determining order parameters have been analyzed. By this it has been shown experimentally that order parameters ‐ measured by different methods IR, UV, e. g. ‐ are only comparable if they refer to x*3. For two dyes (4,12) the orientation axis x*3 switches about π/2 depending on the special type of substituents. For the structure ‐ order parameter relation it has been shown that the 15 dyes can be arranged in two series. One series obeys the usual rule of increasing S* with increasing length to width ratio. The second series does not fit in this dependence.
X‐ray absorption spectroscopy of amorphous rare‐earth transition‐metal oxides
Authors: Torkler A. , Beuthien H. , Gunßer W. , Niemann W. 
Published: March 2014

AbstractAmorphous rare‐earth transition‐metal oxides (a‐YFeO3, a‐GdCrO3) were prepared by annealing the co‐precipitated hydroxides. The short‐range order shows a strong dependence on the annealing process. Structural parameters were determined by EXAFS investigations at the K edges of the transition metals. In a‐YFeO3 the iron oxygen distances and the coordination numbers are both considerably lower than in the crystalline structure. Cr K‐EXAFS and XANES measurements on a‐GdCrO3 indicate the existence of a mixture of octahedrally and tetrahedrally coordinated chromium. Furthermore, a shift of the Cr‐K‐absorption edge during the annealing process is evidence of a changing chromium valence.
The static structure factor of cesium over the whole liquid range up to the critical point
Authors: Winter R. , Hensel F. , Bodensteiner T. , Gläser W. 
Published: March 2014

AbstractThe paper presents the first neutron scattering investigation of the static structure factor S(Q) of expanded liquid cesium from the melting point up to its critical point at conditions near the liquid‐vapour coexistence curve (critical data of cesium: Tc = 1924 K, pc = 92.5 bar, dc = 0. 379 g/cm3). The characteristic changes of the microscopic structure — such as the distance and number of nearest neighbours — are derived as a function of density. The reported results give useful information about the density dependent changes in the electronic structure in course of the transition from a metallic to a nonmetallic state which occurs in the expanded metal. In particular, the results provide direct experimental evidence for the limitation of the nearly‐free‐electron (NFE) model in describing the electrical transport properties of low density fluid cesium.
Generation and deactivation of 1O2 (1Δ) by helianthrene and helianthrene‐derivatives
Authors: Acs A. , Schmidt R. , Brauer H.‐D. 
Published: March 2014

AbstractThe photooxygenation of helianthrene (H), mesodiphenylhelianthrene (MDH) and mcsodiphenylbenzhelianthrene (MDBH) has been studied kinetically by several independent methods in different solvents. The results indicate that singlet oxygen (1Δ) is generated only by oxygen quenching of the lowest triplet states via the process: T1 + 3Σ ↔ So + 1Δ, which occurs with unit efficiency for all three hydrocarbons. H is the most reactive 1Δ‐acceptor hitherto known. In solvents of low viscosity like acetone the rate constant of reaction is kτ = 4.6 · 109 M−1 s−1. MDH and MDBH are not only very reactive 1Δ‐acceptors but also efficient 1Δ‐quenchers. In a mixture of toluene and methanol (1 Vol.%) for MDBH the rate constants of physical quenching and photooxygenation amount to k11n = 6.3 · 109 M−1 s−1 and k7 = 0.2·109 M−1 s−1.
Acid‐Base‐Equilibria at Semipermeable Membranes, their Influence on pH‐Triggered Permeabilities
Authors: Schlögl Reinhard W. , Hirsch‐Ayalon Paul 
Published: March 2014

AbstractThe theory of Donnan‐equilibria is extended to systems in which chemical equilibria are involved. Equal temperatures of the outer phases, as well as ideal solutions are assumed. The membranes shall be impermeable for at least one ionic species. Comparison of the theory with experimental data at precipitation membranes shows a conspicuous dependence of the permeabilities on the pH‐values of the fluid phases. A hypothetical model to explain this effect is discussed.
E.M.F. and Calorimetric Investigations of Antimony Oxides
Authors: Knauth P. , Schwitzgebel G. 
Published: March 2014

AbstractThermodynamic data of the antimony oxides were determined by solution calorimetry in molten NaOH/KOH (483 K), drop and differential scanning calorimetry and solid state electrochemistry. The formation of Sb2O4 from Sb2O3 and Sb2O5 is an exothermic process (ΔR H (483 K.) = — 25 ± 4 kJ/mol). The molar heat capacity data of the antimony oxides are discussed in comparison with the different CP functions of the literature. The Gibbs free energies of formation at 873 K of Sb2O3 (—472 ± 5 kJ/mol) and Sb2O4 ( — 570 ± 10 kJ/mol) are consistent with calculated values from data compilations.
Structure Determining Interaction in Liquids — An Investigation of Bromobenzene by X‐Ray and Neutron Diffraction Experiments
Authors: Bertagnolli H. , Engelhardt T. , Chieux P. 
Published: March 2014

AbstractX‐ray and neutron diffraction experiments on liquid bromobenzene are reported. After usually applied data reduction and evaluation the intramolecular contribution was separeted from the total intensity and the intramolecular structure in the liquid phase was determined. The combination of X‐ray and neutron differential cross sections permits an assignment of intermolecular distances to specific atom pairs. With this identification a two‐dimensional model is deduced. A quantitative calculation gives a refined model, reproducing both X‐ray and neutron data. The structure of the first coordination sphere is determined by strongly attractive forces between the bromine atom and the phenyl ring as well as a specific attraction of bromine atoms themselves leading to a characteristic distribution of distances.
Correlation Properties of Vibrational Energy Levels of CO2
Authors: Jost Rémy , Delon Antoine , Pebay‐Peyroula Eve 
Published: March 2014

AbstractWe calculate the statistical correlation properties and the eigenvalues of the potential energy surface of CO2 and observe a smooth change of the NND from Poisson to Wigner distribution between 20000 and 30000 cm−1.
Molecular Beam Study of Ethyl Nitrite Photodissociation and Unimolecular Decay of Ethoxy Fragments
Authors: Felder Peter , Keller Beat A. , Effenhauser Carlo S. 
Published: March 2014

AbstractThe UV photodissociation of ethyl nitrite at excitation wavelenghts of 350, 248 and 193 nm was studied by photofragment translational spectroscopy in a pulsed molecular beam. At all three wavelengths the first dissociation step yields nitric oxide and ethoxy radicals, accompanied by a considerable release of translational energy. At 350 nm the ethoxy radicals are formed with internal energy low enough to be stable under collisionless conditions. At 248 and 193 nm significant fractions of the ethoxy radicals emerge with sufficient internal energy to decay spontaneously into formaldehyde and methyl radicals. At 248 nm a kinematic analysis of the photofragment arrival time distributions is consistent with a sequential dissociation mechanism.
Photodissociation of H2O2/D2O2 from the Lowest Excited State: The Origin of Fragment Rotation
Authors: Klee S. , Gericke K.‐H. , Comes F. J. 
Published: March 2014

AbstractIn order to elucidate the photofragmentation dynamics of small non‐planar molecules, hydrogen peroxide was prepared in its first excited electronic state, Ã1A. The variety of scalar (internal state distribution, translational energy) and vectorial (angular distribution, rotational alignment, correlations between rotational and translational motion) properties of the resulting hydroxyl radicals was analysed by LIF‐Doppler and ‐polarisation spectroscopy. The influence of the upper state repulsive potential and of initial parent vibrational excitation on final product rotation was determined by using deuterium peroxide and internally cold parent molecules.
Dissociation Kinetics of Benzene Van‐der‐Waals Cluster Ions
Authors: Kiermeier A. , Ernstberger B. , Neusser H. J. , Schlag E. W. 
Published: March 2014

AbstractBenzene clusters (C6H6)n are produced in a supersonic jet expansion and ionized by two‐photon absorption in a reflectron time‐of‐flight mass spectrometer. Cluster ions are produced with a small amount of energy (several hundred meV) and a slow decay on the us time scale is observed. The reflectron mass spectrometer serves as an instrument for the direct observation of all major dissociation paths of clusters near threshold. The precursor ion mass and the daughter ion mass can be assigned unambiguously by the analysis of kinetic energy. In particular the unimolecular fragmentation pathways of benzene cluster ions up to n = 7 are displayed. It was found that close to the dissociation threshold, the elimination of one neutral benzene monomer is the favoured process.