bluuebunny/crossref_metadata_2025_split huggingface dataset:
Photo‐Degradation and Fluorescence of Colloidal‐Cadmium Sulfide in Aqueous Solution
Authors: Henglein A. 
Published: July 2012

AbstractColloidal cadmium sulfide deposited on 13 nm silicon dioxide particles shows a weak fluorescence with a maximum at 620 – 660 nm (depending on the sample). Oxygen does not quench the fluorescence. All anions exert a quenching effect at concentrations below 10−3 M, S2‐, Br−, and I− being the most effective ones. Tl+, Ag+, Pb2+, and Cu2+ strongly quench the fluorescence at concentrations below 10−4 M. Nitrobenzene quenches at higher concentrations in the 10−3 M range. Quenching is attributed to adsorbed ions or molecules. In the case of the anions, a mechanism is proposed in which positive hole‐anion pairs are formed at the surface of the colloidal particles before neutralization by electrons takes place. In the case of the cations and of nitrobenzene, quenching is explained by electron capture. Colloidal CdS doped with less than 1% Cu2+ or Ag+ showed a much stronger fluorescence than undoped samples.—Colloidal cadmium sulfide is degraded by light only in the presence of oxygen the quantum yield in aerated solution being 0.04. The action of oxygen is mainly attributed to a reaction with intermediates of the sulfide oxidation by positive holes. In the presence of Tl+ or Pb2+ ions at some 10−5 M, the photo‐degradation is drastically promoted up to a quantum yield of 0.24. Cu2+ and Ag+, however, retard the degradation. Both effects are understood in terms of electron scavenging by the adsorbed metal ions and reoxidation of the reduced metal by oxygen or by positive holes. Sodium sulfide protects cadmium sulfide from degradation. In the absence of air, small amounts of hydrogen are formed in Na2S containing solution.
Dynamics of Simple Gas‐Surface Interaction. I. Rotationally Inelastic Collisions at Smooth Surfaces
Authors: Polanyi J. C. , Wolf R. J. 
Published: July 2012

AbstractWe report a trajectory study of the rotationally inelastic scattering of initially rotationless molecules BC at a smooth (uncorrugated) rigid surface. The potential energy function (p.e.fn.) was either purely repulsive (a “truncated Lennard‐Jones” potential) or embodied a 0.2 eV well. Mass combinations corresponded to N2, CO or HF. Examination of the final rotational state, jf, as a function of initial angle of BC to the surface, xi, showed how the outcome of a gas‐surface encounter altered with a systematic shift in location of the centre of mass of BC, for a given p.e.fn. The changing pattern of rotational rainbows was recorded, and differing types of gas‐surface encounter were analyzed and identified. Introduction of wells in the p.e.fn. gave rise to indirect trajectories, with a consequent reduction in average rotational energy of the BC (CO masses) scattered indirectly. This may have a bearing on the experimentally observed lag of rotational temperature for surface scattered molecules, as compared to surface temperature.
Progress and Prospect in Elementary Reaction Kinetics/Dynamics of Polyatomics
Authors: Kaufman Frederick 
Published: July 2012

AbstractThe present state of knowledge of two‐body elementary reaction rates of polyatomics is examined using five specific reactions as examples: OH + H2 → H2O + H, Cl + CH4 → HCl + CH3, OH + CH4 → H2O + CH3 and nine Cl, F‐substituted CH4 reactions, OH + HNO3 → H2O + NO3, and HO2 + O3 → OH + O2 + O2. For each reaction, experimental and theoretical results are given, and their accuracy is evaluated. Progress in experimental measurements seems to have outrun that in theoretical description. Ab initio quantum chemical calculations of potential energy surfaces, quantum tunneling corrections, and error and sensitivity analyses are greatly needed to improve our understanding of rate parameters.
Analysis of the Resonance in the Three Dimensional F + H2 Reaction
Authors: Wyatt Robert E. , McNutt Joe F. , Redmon Michael J. 
Published: July 2012

AbstractQuantum mechanical resonance structure in the three‐dimensional F + H2 reaction is analyzed in several ways: wavefunction density and flux maps in the transition state region, Argand diagrams which show the energy variation of S‐matrix elements, the time delay computed from the energy derivative of the phase of S‐matrix elements, and the energy variation of nodes in the product channel translational wavefunctions. In addition, differential cross sections for the v = 0 → v' = 2 reaction, computed from quantum reaction probabilities in an optical model, are compared with experimental data. These results are correlated with other recent theoretical results on this reaction, and some remaining theoretical problems are discussed.
Micellar Properties of 4‐Alkylamido‐2‐Hydroxybenzoic Acids
Authors: Pelizzetti Ezio , Pramauro Edmondo , Barni Ermanno , Savarino Piero , Corti Mario , Degiorgio Vittorio 
Published: July 2012

AbstractA series of 4‐alkylamido‐2‐hydroxybenzoic acids, containing 8–16 carbon atoms in the alkylamido group, has been synthetized and characterized. Surface tension measurements on aqueous solutions have been used to estimate the critical micellar concentrations and the area per molecule at the liquid‐air interface. Light scattering measurements allowed to calculate the aggregation number and the hydrodynamic radius of the micelles.
VUV Flash Photolysis Study of the Reaction of HO with HO2 at 1 atm and 298 K
Authors: Braun M. , Hofzumahaus A. , Stuhl F. 
Published: July 2012

AbstractEqual concentrations of HO and H were generated by flash photolysing small amounts of H2O diluted in N2 at a pressure of about one atmosphere. Using sensitive detection by resonance absorption, the HO radicals were monitored in the presence and in the absence of O2. In the presence of O2, the radicals were found to disappear significantly faster than in the absence of O2. This enhanced decay is attributed to the fast reaction of HO with HO2. Using simple kinetic arguments and computer modeling, the rate constant, k1, for the title reaction is estimated to be 1.1 · 10−10 cm3 s−1 (+25%; −35%).
Vibrational Energy Flow and Distribution in CF3J and CF3 after Infrared Multiphoton Excitation
Authors: Kauer Matthias , Kleinermanns Carlo 
Published: July 2012

AbstractTime and wavelength‐resolved infrared emission techniques are used to study the multiphoton excitation and dissociation of CF3J. Fluorescence is detected from the v1‐(sym. CF3‐stretch), v4‐(asym. CF3‐stretch), and v2‐(sym. CF3‐deform.)‐vibrational modes of CF3J and at laserenergies exceeding the dissociation threshold also from CF3 radicals and excited iodine atoms J*(2P1/2 → 2P3/2). – The pumped v1‐ladder of states (v1, v ≧ 1) is populated collision‐free as the fluorescence rise times show. Strikingly different, the v4(v = 1)‐mode is populated via collisions, while the higher v4‐states are populated collision‐free. The v4(v = 1)‐population rate is measured to be (7.1 ± 2). 1013 cm3 mol−1 s−1. – The v1‐ and v4‐emissions show a red‐shift of the band peak and band broadning with increasing laser energy according to higher quanta excitation. – To longer observation times the v1‐ and v4‐bands shift blue again and narrow somewhat according to vibrational relaxation. However at higher laser energies both band peaks do not shift back to their fundamental frequencies, but only decrease in intensity to longer times. This is interpreted as relaxation of these modes by coupling to low frequency modes like the C‐J‐vibrations, which can be easier V‐R, T deactivated. – At laser energies exceeding the dissociation threshold a new emission band is found at 1245 cm−1, due to the C‐F‐stretch of the vibrationally excited CF3‐radical. The rise of the fluorescence signal consists of two parts arising from initially vibrationally hot CF+3 and initially cold CF3, which is subsequently excited by collisions with a rate of (1.7 ± 0.5) · 1013 cm3 mol−1 s−1. – Activation‐ and deactivation rates for various spectral features of the vibrationally excited CF3J molecule and CF3 radical are presented.
Transport Properties of Liquids. IV. Self‐Diffusion, Viscosity, and Density of Irregular Liquid Mixtures: Crown Ether/Alcohol
Authors: Vogel Herbert , Weiss Alarich 
Published: July 2012

AbstractThe dynamic viscosities, the activation energies of the viscous flow Eηa, and the mass densities ϱ were measured for the binary systems 12‐crown‐4/D2O, 12‐crown‐4/ethylene glycol, 12‐crown‐4/methanol, 15‐crown‐5/D2O, 15‐crown‐5/ethylene glycol, and 15‐crown‐5/methanol as a function of temperature T and mole fraction x1 of the crown ether. – Mixtures with bifunctional “alcohols” (D2O, HOCH2CH2OH) showed “broad maxima” in their isotherms η(x1, T = const) and Eηa(x1, T = const), respectively. Correspondingly, the self‐diffusion coefficients D1 of the crown ethers in these mixtures pass a minimum. Quite different is the transport behaviour of the crown ether/methanol system; it behaves with respect to η and D1 almost as ideal system. – The results are discussed by assuming association in the systems, and such a model is also valid for dioxane/H2O and dioxane/ethylene glycol mixtures.
The Temperature Dependence of the Properties of Electrolyte Solutions. IV. Determination of Cationic Transference Numbers in Methanol, Ethanol, Propanol, and Acetonitrile at Various Temperatures
Authors: Barthel J. , Ströder U. , Iberl L. , Hammer H. 
Published: July 2012

AbstractCationic transference numbers and conductance data of KSCN and Me4NSCN in methanol (‐15°C to + 25°C), KSCN in ethanol (‐5°C to + 25°C) and propanol (+ 10°C and +25°C), Me4NClO4 and Et4NClO4 in acetonitrile (‐35°C to +25°C) were determined at electrolyte concentrations from 10−3 to 10−2 mol · kg−1. The transference numbers obtained by a moving boundary method were corrected for the changes of the calibration volume resulting from anodic reactions, conductance of the solvent and Joule heating. The data are discussed on the basis of transport equations which take into account short range interactions in the ion distribution functions.
Electrochemical Conversion and Storage of Solar Energy
Authors: Schoonman J. 
Published: July 2012

AbstractIn this study it is shown that the integration of a solid‐state electrode, comprising a proton conducting solid electrolyte and a hydride forming metal, into a photoelectrochemical cell makes solar energy conversion, and in situ storage of hydrogen feasible. The conversion and storage cell is built up of bulk‐, or surface‐doped n‐type SrTiO3 photoanodes, and Zr or Ti cathodes, which are separated from the aqueous electrolyte by the solid proton conductor hydrogen uranyl phosphate tetrahydrate (HUP). The analysis of photocurrent‐voltage characteristics along with the radiation intensity dependence, and of conductivity studies on HUP points to conditions for the improvement of the cell construction. The surface‐ and bulk‐doped SrTiO3 photoanodes employed here will not lead to efficient photoelectrolysis of water due to severe bulk recombination. The influence of electrolyte composition on the photoresponse is discussed. The conversion and storage concept introduced here allows the use of other types of stable photoanodes, and proton conducting solid electrolytes, provided that the solid electrolyte is stable against aqueous electrolytes and metallic hydrides.
Nature of the Electron‐Hole Pair in the System Anthracene Crystal/Rhodamine B Adsorbed from Aqueous Solution Part II: Dependence of Kinetics and Spin‐Dynamics on Shallow Surface Traps
Authors: Papier G. , Charl K.‐P. , Willig F. 
Published: July 2012

AbstractThe dependence of the rhodamine B sensitized hole current (SHC) and of its magnetic field modulation (ΔSHC) on the applied electric field has been measured in anthracene single crystals with different concentrations of shallow surface traps. Our theoretical model for the influence of the magnetic hyperfine effect (HF effect) on the charge carrier kinetics has been extended to account for the effect of shallow traps. The model predicts in agreement with the experimental finding as effect of shallow surface traps, firstly an increase in the magnitude and secondly an increase in the halfwidth of the magnetic field modulation of the SHC, and thirdly a weakened influence of the electric field on these two signals. The smallest concentration of shallow surface traps was found on naturally grown surfaces of sublimation crystals, whereas solution grown crystals showed in general a higher concentration of such traps. It was found that shallow hole traps can be induced with carbazol molecules.
Influence of Titanium Suboxides on the Photoelectrochemical Efficiency of Oxidized Titanium Electrodes
Authors: Antonucci V. , Miceli P. , Giordano N. , Bart J. C. J. 
Published: July 2012

AbstractPure titanium laminae were oxidized in CO2 atmosphere between 300°C and 700°C and used as electrodes in the photodecomposition of water. X‐ray diffraction and the method of interference indicators have been exploited to characterize the initial stages of the oxidation of titanium. Metallic interstitial suboxides TiO0+x are essentially photoinactive but promote the efficiency of an overlaying non‐stoichiometric rutile scale.
Ansätze zur Beurteilung des isothermen Umsatzverhaltens von “Supported Liquid‐Phase Catalysts”
Authors: Hesse D. 
Published: July 2012

AbstractThe investigation of isothermal conversion behavior of supported liquid‐phase catalysts has shown that the reaction rate as a function of liquid loading always reaches a maximum value, if the pore volume of the porous solid is filled between 40% and 60% with the catalyst solution. In order to interpret this particularity, a so‐called ideal SLP catalyst in which the pore space cannot be blocked by the impregnation process is discussed first. The results obtained lead to the conclusion that the conversion behavior of real SLP catalysts is mainly influenced by the blocking process. Its effect upon the reaction rate can be described by means of a parameter which values depend on the extent to which the permeability of the support changes with liquid loading. This function can be determined by measuring the overall effective gas diffusivity in the porous material loaded with the pure solvent.
Matrix Isolation Studies on Some Molecular Oxo‐anion Salt Vapours
Authors: Ogden J. S. 
Published: July 2012

AbstractIn this presentation examples are discussed to illustrate how matrix isolation may be used in the characterisation of high temperature molecules. It is evident that in addition to the stabilisation afforded by trapping in an inert environment at low temperatures, an important feature is the ability to obtain well‐resolved vibrational isotope data. For small, light molecules, this information can lead to estimates of bond angles, whilst for more complex species, the observation of characteristic isotope patterns produces a valuable indication of molecular shape.
Magic Numbers in Mass Spectra of Xe, C2F4Cl2 and SF6 Clusters
Authors: Echt O. , Reyes Flotte A. , Knapp M. , Sattler K. , Recknagel E. 
Published: July 2012

AbstractMass spectra of xenon clusters show pronounced intensity maxima for cluster sizes n* = 13, 19, 25, 55, 71, 87, and 147. The occurrence of these “magic numbers” is explained by shell closure of clusters growing in the icosahedral structure. Magic numbers in mass spectra of 1,2‐dichlorotetra‐fluoroethane are n* = 13 and 19. The only intensity maximum of sulfurhexafluoride clusters occurs at n* = 13, whereas a minimum is observed at n* = 18. In contrast, the size distributions of clusters of 17 other molecular gases decrease strictly monotonically with increasing size. The origin of these effects is discussed.
Thermodynamics and Electrochemistry of Simple Ions in Ammonia
Authors: Schindewolf U. 
Published: July 2012

AbstractA compilation of the thermodynamics of simple ions in ammonia is given, based on thermodynamic data of their salts, on some electrochemical data and on those of solvated electrons. The final data are expressed in terms of the solvation enthalpies, solvation entropies and electrode potentials of the ions. With the uncertainties of the work function of the metals and that of the surface potential of the solvent, the concept that solvated electrons are partner of any redox equilibria allows the calculation of the “absolute” electrode equilibrium potential of any electrode in contact with the solution of any redox pair. This is exemplified for a cesium and a silver electrode in ammonia. ‐ Finally the differences in the kinetics of solvated electrons in water and in ammonia with respect to the reaction with the solvent are expressed qualitatively by the transition state theory making use of the thermodynamic data of the solvated electrons. The high stability of electrons in ammonia is due to their very high positive partial molar entropy.
Energetics and Stabilities of the IIB/VIA‐Compounds at High‐Temperature Equilibrium Conditions
Authors: Grade M. , Hirschwald W. 
Published: July 2012

AbstractEquilibrium vaporization behaviour of twelve IIB/VIA‐compounds of the type MeX was studied by means of high‐temperature mass spectrometry. In all cases except HgTe the existence of stable MeX(g)‐molecules was established. Bond energies D0(MeXgas) were determined by the thermodynamic third‐law method and range as follows: ZnO(g) (280.1 kJ/mol)/ZnS(g) (224.8)/ZnSe(g) (170.8)/ZnTe(g) (117.7)/CdO(g) (230.3)/CdS(g) (208.5)/CdSe(g) (127.7)/CdTe(g) (100.1)/HgO(g) (221.1)/HgS(g) (217.3)/HgSe(g) (144.5). ‐ Comparison of the third‐law bond energies with existing experimental data, upper limits of D0 given by other authors, and semi‐empirical estimates shows basic agreement. Data for the heat of dissociative vaporization ΔH0R, the heat of atomization ΔH0at, the parameter magnified image, and the chemical stabilities of the IIB/VIA‐systems are also presented.
Photoelectrochemical Studies of Electrodes Coated with Merocyanine Dye
Authors: Mizutani Fumio , Iijima Sei‐Ichiro , Sasaki Kanji , Shimura Yukio 
Published: July 2012

AbstractDeposited films of merocyanine dye (3‐carboxymethyl‐5‐[2‐(3‐octadecyl‐2‐benzothiazolinylidene)ethylidene]‐2‐thioxo‐4‐thiazolidinone) show various kinds of intra‐ and intermolecular changes when they are heated and/or soaked in a neutral aqueous solution. The effect of such changes on photocurrent has been examined using electrodes coated with the dye film. A remarkable high quantum efficiency (above 10%) for cathodic photocurrent has been obtained when the dye film shows red‐shifted absorption bands owing to the dye aggregation. The high photoactivity is attributable to the high transfering ability of excitons in the aggregates.
Role of Solvation and Desolvation in Polymer “Catalysis” [1]. VI. Influence of Ionic Valencies of Reactants on the Desolvation Effects in the Spontaneous and Hg2+‐Induced Aquation of Co(NH3)5SO4+, Co(NH3)5Br2+ and Cr(NH3)5Br2+ [2]
Authors: Okubo Tsuneo , Yamamura Yoshio , Ise Norio 
Published: July 2012

AbstractSpontaneous and Hg2+‐induced aquation reactions of Co(NH3)5SO4+ are studied in the presence of sodium polyethylenesulfonate and sodium polystyrenesulfonate under high pressure. The spontaneous aquation rates are in the order of Co(NH3)5SO4+, Co(NH3)5Br2+ and Cr(NH3)5Br2+ and is accounted for in terms of the Brönsted‐Bjerrum theory. The volume of activation (ΔV#) of both spontaneous and Hg2+‐induced aquations of Co(NH3)5SO4+ greatly increased by addition of the macroions, which is attributed to stronger desolvation of the activated complex than the reactant in the strong electrostatic field of the macroions.
The Thermal Conductivity of Mixtures of Methane with Carbon Dioxide
Authors: Kestin J. , Ro S. T. , Nagasaka Y. 
Published: July 2012

AbstractThe paper is an addendum to two previous papers which contained data on the thermal conductivity of the systems H2‐ N2and N2‐ CH4. The present system is CH4‐ CO2, thus forming a natural progression in the complexity of the molecular structure of the set of binary systems under investigation. The system chosen for study is still characterized by nearly spherical intermolecular force potentials. — The results extrapolated to zero density show excellent agreement with the Monchick‐Pereira‐Mason theory and continue to demonstrate that the inelastic‐collision term is small (∼ 1%), thus asserting that the Hirschfelder‐Eucken approximation is acceptable. — At higher densities, the version of the Thorne‐Enskog theory due to Mason et al. gives a systematic deviation of only — 2% over the whole composition range.
Rapid, in situ detection of Agrobacterium tumefaciens attachment to leaf tissue
Authors: Simmons Christopher W. , Nitin N. , VanderGheynst Jean S. 
Published: July 2012

AbstractAttachment of the plant pathogen Agrobacterium tumefaciens to host plant cells is an early and necessary step in plant transformation and agroinfiltration processes. However, bacterial attachment behavior is not well understood in complex plant tissues. Here we developed an imaging‐based method to observe and quantify A. tumefaciens attached to leaf tissue in situ. Fluorescent labeling of bacteria with nucleic acid, protein, and vital dyes was investigated as a rapid alternative to generating recombinant strains expressing fluorescent proteins. Syto 16 green fluorescent nucleic acid stain was found to yield the greatest signal intensity in stained bacteria without affecting viability or infectivity. Stained bacteria retained the stain and were detectable over 72 h. To demonstrate in situ detection of attached bacteria, confocal fluorescent microscopy was used to image A. tumefaciens in sections of lettuce leaf tissue following vacuum‐infiltration with labeled bacteria. Bacterial signals were associated with plant cell surfaces, suggesting detection of bacteria attached to plant cells. Bacterial attachment to specific leaf tissues was in agreement with known leaf tissue competencies for transformation with Agrobacterium. Levels of bacteria attached to leaf cells were quantified over time post‐infiltration. Signals from stained bacteria were stable over the first 24 h following infiltration but decreased in intensity as bacteria multiplied in planta. Nucleic acid staining of A. tumefaciens followed by confocal microscopy of infected leaf tissue offers a rapid, in situ method for evaluating attachment of A. tumefaciens' to plant expression hosts and a tool to facilitate management of transient expression processes via agroinfiltration. © 2012 American Institute of Chemical Engineers Biotechnol. Prog., 2012