bluuebunny/crossref_metadata_2025_split huggingface dataset:
Predicting the Gas‐Liquid Critical Properties of Binary Mixtures: An Alternative to Conventional Mixing Rules
Authors: Sadus Richard J. 
Published: July 2012

AbstractThe critical properties of binary mixtures are predicted using a theoretical alternative to the conventional mixing rules for the contribution of the attractive equation of state parameter for the mixture. The method does not require adjustable combining rule parameters and the only experimental input data are the critical properties of the component pure substances. The comparison of calculated critical properties with experimental data yields very good agreement. The discrepancy between theory and experiment is often similar to that obtained by using optimized adjustable combining rule parameters. Consequently, genuinely accurate a priori predictions of critical equilibria are possible for many binary mixtures containing either non‐polar or weakly polar components.
Spectroscopy and Thermodynamics of Electrons in Yttria‐Stabilized Zirconia
Authors: Wiemhöfer H.‐D. , Vohrer U. 
Published: July 2012

AbstractElectronic energy gap, position of Fermi level in the gap and the density of states in the valence band range have been measured for Y2O3‐stabilized cubic ZrO2 as function of oxygen partial pressure and temperature using UV‐Photoelectron‐Spectroscopy (UPS) and Electron‐Energy‐Loss‐Spectroscopy (EELS). A thermodynamic evaluation for the position of the Fermi energy gives the scale of electrode potentials for oxygen electrodes on stabilized zirconia with regard to the band scheme. The data are compared with further literature results from electrochemical and spectroscopic techniques and a model for the electronic band scheme of yttria‐stabilized cubic zirconia is proposed. The differences of thermal and optical values for the band gap are discussed as well as the comparability of thermal and spectroscopic values for electronic energies.
On the Persistence of Molecular Symmetry in the Solid State and the Role of Molecular Group Dipole Moments. Centrosymmetry in Bis‐(Chloromethyl)benzenes
Authors: Basaran Rcha , Dou Sli‐Qi , Weiss Alarich 
Published: July 2012

AbstractThe crystal structures and the 35Cl NQR spectra of 1,4‐bis(chloromethyl)‐2,3,5,6‐tetrachlorobenzene, 1,4‐(CH2Cl)2C6Cl4; 1,4‐bis(chloromethyl)‐2,3,5,6‐tetramethyl‐benzene, 1,4‐(CH2Cl)2C6(CH3)4; 1,4‐bis(chloromethyl)benzene, 1,4‐(CH2Cl)2C6H4; 1,2‐bis(chloromethyl)benzene, 1,2‐(CH2Cl)2C6H4 are reported. – The compounds 1,4‐(CH2Cl)2C6Cl4 and 1,4‐(CH2Cl)2(CH3)4 are isostructural, space group C–P1, Z = 1. 1,4‐(CH2Cl)2C6Cl4: a = 893.1(4) pm, b = 655.1(3) pm, c = 494.5(2) pm, α = 98.32(2)°, β = 96.87(2)°, γ = 103.60(2) 92°; 1,4‐(CH2Cl)2C6(CH3)4: α = 902.3(4) pm, b = 809.4(4) pm, c = 442.5(2) pm, α = 87.38(2)°, β = 83.02(2)°, γ = 65.00(2)°. 1,4‐(CH2)2C6H4 crystallizes monoclinic, C–P21/c, Z = 2, a = 848.8(4) pm, b = 465.0(2) pm, c = 1042.2(5) pm, β = 99.21(2)°. 1,2‐(CH2Cl)2C6H4 is noncentrosymmetric, orthorhombic, C–Fdd2, Z = 8, a = 1562.0(4) pm, b = 1358.0(3) pm, c = 790.4(2) pm. – The 35Cl NQR spectra of 1,4‐(CH2Cl)2C6(CH3)4, 1,4‐(CH2Cl)2C6H4, and 1,2‐(CH2Cl)2C6H4 are singlets, with negative temperature coefficients dν(35Cl)/dT over the temperature range 77 K–Tmelt and the frequencies are in the range 34.4 ≥ ν(35Cl)/MHz ≥ 31.8. 1,4‐(CH2Cl)2C6Cl4 shows a 35Cl NQR triplet, with negative temperature coefficients for 77 ≤ T/K ≤ 420, 37.5 ≥ ν(35Cl)/MHz ≥ 33.8, too. In this compound a phase transition occurs, with a wide hysteresis, Tc, up = 366 K, Tc, down = 328 K. The inductive effect on the 35Cl NQR in the CH2Cl group is strong. – In molecular crystals the complete symmetry of the free molecule seldom persists in the solid state. The molecular symmetry in the condensation process is fully or partially lost due to the van der Waals interaction of neighboring molecules. The compensation of the partial dipole moments of the two chloromethyl group in para position retains the molecular symmetry Ī in the solid phases. It will be discussed that in benzene derivatives either Ī, m or 2 are the “hard” symmetry elements, preserved in the solid state.
Aggregation of Silver Particles in Silver Alginate Films
Authors: Yonezawa Y. , Kijima M. , Sato T. 
Published: July 2012

AbstractThe variation of the absorption spectra of silver alginate (SA) films upon irradiation with 253.7 nm light has been studied. When the SA film was photolyzed at room temperature (T = 300 K) in vacuum, the intense colloidal absorption band around λ = 407 nm due to large silver particles (metallic silver particles) appeared. Irradiation at liquid nitrogen temperature (T = 77 K) caused the growth of a small peak around 337 nm, together with a broad background absorption extending from 600 nm to less than 200 nm. Major products at low temperature seem to be small silver particles (relatively large silver clusters and quasi‐metallic silver particles). After photolysis at 77 K and heating until 300 K was achieved, the variation of the absorption spectrum of the SA film during dark storage in vacuum was monitored. The 337 nm peak was slightly decreased in the initial stage and then, the colloidal absorption band (415 nm) increased monotonously for 20 h. Rapid diffusion of silver atoms and clusters under irradiation in air at room temperature has been suggested.
Optically Detected Small‐Polaron Hopping in Manganosite, Mn1‐δO
Authors: Becker K. D. , He T. 
Published: July 2012

AbstractThe absorption spectrum of single crystalline MnO has been measured at 1000°C as a function of oxygen partial pressure, p. The observed p‐dependence of the spectra is discussed in the framework of the point defect structure of the compound. From the line‐shape of the defect‐induced contribution to the absorbance and from its p‐dependence it is concluded that this contribution is due to small‐polaron hopping of electron holes.
Dynamic Light Scattering Experiments with Aqueous Solutions of a Cascade Molecule: Benzene[9]3‐arborol
Authors: Engelhardt Th.‐P. , Belkoura L. , Woermann D. , Grimme W. 
Published: July 2012

AbstractResults of dynamic light scattering experiments with aqueous solutions of benzene[9]3‐arborol (molar mass, M = 1.486 · 103 g mol−1; spherical dimension (radius) estimated on the basis of molecular models, a ≈︁ 1 nm) at 25° are reported. They indicate that benzene[9]3‐arborol molecules in aqueous solution form aggregates which have dynamic properties similar to that of single polymer chains in good solvents in the cross over region (q rh) ≈︁ 1 (q, absolute value of the scattering vector, (rh, hydrodynamic radius of the scattering particles). A double logarithmic plot of maximum value of the distribution of relaxation rates of the autocorrelation function of the scattered light intensity Γmax versus the q (0.68 ≤ (q/q+) ≤ 2.40; q+ = 105 cm−1) gives a straight line with a slope D* = (2.46 ± 0.05) independent of concentration (Γmax ∼ (q/q+)D*). The size of the scattering particles appear not to change with concentration in the concentration range studied (3.5 · 10−3c+ ≤ c ≤ 13.37 · 10−3c+; c+ = 1 mol dm−3). Values of D* (2 ≤ D* ≤ 3) indicate that the experiments are carried out in the non‐universal crossover regime (q rh) ≈︁ 1. From the ratio (Γmax/q2) refering to the limit q 0 a hydrodynamic radius of rh of the order rh = O(100 nm) is calculated. This is in agreement with the conclusion drawn from the q‐dependence of Γmax (i.e. (q rh) ≈︁ 1). – The partial molar volume of benzene[9]3‐arborol in aqueous solution increases with concentration only in very dilute solutions. It is practically constant in the concentration range in which the dynamic light scattering experiments are carried out. The surface tension of these solutions at the air/solution interface decreases only slightly with concentration reflecting the hydrophilic character of the surface of the aggregates.
Microscopic Origins of Photorheological Effects Induced by the Photoisomerization of Stilbene Carboxylic Acids in Aqueous Cetyltrimethylammonium Bromide Solutions
Authors: Kerperin Karl Josef , Wolff Thomas 
Published: July 2012

AbstractAqueous micellar solutions containing cetyltrimethylammonium bromide (CTAB) and solubilized 3‐stilbene carboxylic acid (3‐SC) or 4‐stilbene carboxylic acid (4‐SC) known to exhibit photorheological effects were investigated via (i) oscillatory shear viscometry, (ii) static and dynamic light scattering and (iii) electrically induced birefringence. The presence of 3‐SC and 4‐SC induces the formation of swollen micelles as revealed from light scattering data. The viscosity increase observed upon in situ photoisomerization of 3‐SC and 4‐SC is accompanied by a further increase in micelle size as shown by light scattering data. Only solutions containing 3‐SC at concentration ratios cCTAB/c3‐sc ≤ 6.5 show non‐Newtonian flow such as shear thinning, thixotropy and viscoelasticity, which are indicative of the presence of anisometric micelles. Photoisomerization induces non‐Newtonian features in systems containing 4‐SC and increases these features in 3‐SC solutions. Two shear stress relaxation mechanisms are resolved from relaxation spectra.
Estimation of Nitta‐Chao Interaction Parameters for Low Molecular Mass Analogues of Polymers. 1‐Chloroalkane + n‐alkane mixtures
Authors: Fernández J. , Pías L. , Paz Andrade M. I. , Legido J. L. , Lorenzana T. , Diez J. 
Published: July 2012

AbstractExcess molar volumes at 298.15 K, vE, were measured for binary mixtures of a 1‐chloroalkane (from 1‐chloropentane to 1‐chloroheptane) with a n‐alkane (from n‐heptane to n‐decane). These vE values together with literature data on vapor‐liquid equilibria, activity coefficients at infinite dilution, enthalpies of mixing, excess capacities and excess volumes of 1‐chloroalkane + n‐alkane were examined on the basis of the Nitta‐Chao group‐contribution model. The properties of many other systems can be predicted using the CH2/Cl parameters determined in this paper. A comparison with the predictions of DISQUAC and UNIFAC (version of Larsen et al.) models is presented. The new data and the calculated parameters could be used for the predictions of thermodynamical properties of mixtures involving polymers.
On the Influence of Steps on the Rotational Anisotropy of the Second Harmonic Generation from Ag Electrodes
Authors: Friedrich K. A. , Richmond G. L. 
Published: July 2012

AbstractThe second harmonic generation (SHG) from stepped Ag(111) based surfaces in an electrolyte solution have been measured and analyzed. The rotational anisotropies from these surfaces show a pronounced effect due to the lowering of the surface symmetry relative to a (111) surface. The results from the stepped surfaces are interpreted in terms of a pseudo mirror plane. The SH response has also been measured during the underpotential deposition (UPD) of lead onto the stepped crystals and the results are compared to the well known Ag(111)/Pb2+ system. The SH response during adsorption on defect and terrace sites on Ag(111) are monitored separately and the contribution from the steps to the SH anisotropy is discussed.
Wavelength Dependent Second Harmonic Generation: A New Spectroscopic Tool for the Study of Interfaces
Authors: Buck M. , Eisert F. , Grunze M. , Träger F. 
Published: July 2012

AbstractThe adsorption of n‐hexadecane thiol on gold in ethanol has been examined by wavelength dependent second harmonic generation (SHG). In addition to the amplitude, the phase of the second harmonic signal has been measured. At fundamental wavelengths of 1064 nm and 532 nm the temporal dependence of the SH signal reveals that the second order susceptibility is linearly related to the thiol coverage. Between 610 nm and 660 nm a dramatic variation of the time dependent second harmonic signal both in magnitude and in phase is observed due to a coverage dependent resonance. The results demonstrate the potential of second harmonic generation as a spectroscopy for monitoring the effect of adsorbates on the electronic properties of surfaces.
In situ UV‐VIS‐Spektroelektrochemie an LIGA‐Strukturen
Authors: Neudeck A. , Dunsch L. 
Published: July 2012

AbstractA new electrochemical cell for in situ UV/VIS‐spectroscopy using micro‐structurised metal foils (LIGA‐structures) as working electrodes is presented. With this new type of a spectroelectrochemical cell high‐sensitive spectroscopic studies of redox components can be carried out in the transmission procedure during dynamic electrochemical experiments. The capability of this new cell is shown for the electron‐transfer reaction of methylviologen and Wursters blue. The thin layer behavior of this cell is demonstrated.
Evaluation of the IR Attenuated‐Total‐Reflection (IR‐ATR) Technique for Detecting Adsorbates on Electrodes
Authors: Johnson Brian W. , Pettinger Bruno , Doblhofer K. 
Published: July 2012

AbstractTheoretical spectroscopic responses of various different IR‐ATR crystal/metal combinations (Ge, BaF2/Pt, Au) in contact with a third medium consisting of an adsorbate and/or water have been calculated via the well known Fresnel formulae. The theoretical results are compared to experimental IR spectra. — The sensitivity for detecting the third phase in the IR‐ATR spectrum varies widely for the different systems. However, with all systems the highest sensitivity was found at an angle of incidence of the IR radiation close to the critical angle (defined by the crystal/solution combination). Adsorbates on the metal films were found to yield remarkably high IR‐ATR signals which should allow their convenient experimental detection.
Transient Spectroscopy of Donor‐Acceptor Complexes
Authors: Anders J. , Byrne H. J. , Reichenbach J. , Kaiser M. , Schmelzer M. , Wagner Th. , Roth S. 
Published: July 2012

AbstractThis paper gives an introductory review into molecular electronics, discussing shift registers and cellular automata as examples of long‐term goals. Langmuir‐Blodgett films of functionalised polyenes are presented as steps towards such final goals. The switching behaviour of some prototype molecules (in particular of substituted bianthrone) is investigated by transient spectroscopy in the picosecond regime.
An EXAFS Study of Binuclear Group VIA Complexes in Solution: Distinction Between Metal‐Phosphorous Single and Double Bonds
Authors: Ertel Teja , Hückmann Sabine , Bertagnolli Helmut 
Published: July 2012

AbstractAn EXAFS spectroscopical distinction between tungsten‐phosphorous single and double bonds in three binuclear group VIA complexes of the type R1R2P = MLn with R1=Mes, R2 = CpW(CO)2PH2Mes and MLn = CpW(CO)2 (compound 1) or R1 = Mes, R2 = CpW(CO)3 and MLn = CpW(CO)2 (compound 2) or R1 = Mes, R2 = CpW(CO)3 and MLn = CpMo(CO)2 (compound 3) in benzene solution is presented. The obtained distances are compared with results of X‐ray diffraction and 31P‐NMR studies.
Preparation of Thin Cation‐Exchanger Films from Benzenesulfonyl Fluoride by Glow Discharge Plasma Processes
Authors: Uchimoto Yoshiharu , Yasuda Kazuaki , Ogumi Zempachi , Takehara Zen‐Ichiro , Tasaka Akimasa , Imahigashi Takashi 
Published: July 2012

AbstractNovel ultra‐thin films of a sulfonate cation exchanger were prepared by plasma polymerization followed by hydrolysis. The use of gas mixtures of 1,3‐butadiene and benzenesulfonyl fluoride or benzenesulfonyl chloride as starting monomers was investigated. Benzenesulfonyl fluoride was found to be adequate to introduce sulfonyl halide into plasma polymers, whereas benzenesulfonyl chloride tended to be decomposed during exposure to glow discharge plasma. The influence of the level of input RF power on the properties of the resulting cation‐exchange films was also investigated. The films produced using benzenesulfonyl fluoride has a cation‐exchange capacity of 1.45 meq g−1, which is comparable to those of commercially available cation exchange membranes.
On Mesoscopic water droplets dispersed in butyl rubber
Authors: Pelster R. , Kops A. , Nimtz G. , Enders A. , Kietzmann H. , Pissis P. , Kyritsis A. , Woermann D. 
Published: July 2012

AbstractWater dispersed in butyl rubber containing hydrophilic components has been studied with differential scanning calorimetry, dielectric spectroscopy in the frequency range from 5 Hz to 10 GHz, thermally stimulated depolarisation currents, and small angle X‐ray measurements. Hydrophilic components in the rubber matrix act as adsorption sites for water molecules. Two populations of water droplets with radii of the order of magnitude of 2 nm are formed. In the mesoscopic hydrophobic confinement the dielectric relaxation of the liquid water droplets is shifted to higher frequencies compared with bulk water. The relaxation of water in the frozen droplets is slower compared to that of bulk ice. Neither molecular water nor clusters of bulk water are found in the rubber.
Tortuosity Factor in Non‐Homogeneous Membranes
Authors: Maskell W. C. 
Published: July 2012

AbstractThe tortuosity factor, Θ, in an homogeneous gel is substantially greater than that in a matrix composed of nonconducting particles for a given volume fraction of the solid. It is proposed that a non‐homogeneous membrane has a tortuosity which lies between these two extremes and a theoretical framework has been developed to describe such a system. The theory is applied to regenerated cellulose which is a well‐characterised heterogeneous membrane. The assumption made is that the real anionic mobility within the membrane is equal to the anionic mobility in the external solution when a small correction is made for electroconvection. Application of the theory indicates that for regenerated cellulose equilibrated in solutions in the range 0–2 M KOH the fraction of cellulose comprising non‐conducting regions is 32%. This is in good agreement with the value of 36% derived from ion‐exchange measurements.
The WSe2/Tungsten‐Oxide Interface: Structure and Photoluminescence
Authors: Tenne R. , Eherman K. , Mahalu D. , Peisach M. , Kautek W. , Wold A. , Matson R. , Waldeck D. H. 
Published: July 2012

AbstractA “mixed” surface of WSe2, which contains both the |c and τc facets was produced by mechanical indentation, followed by photoelectrochemical etching, and chemical cleaning. This surface was shown to exhibit low surface recombination velocity, and consequently high solar to electrical conversion efficiency, in the past. Using O18 as a tracer for nuclear activation analysis it is shown that, after the above surface treatment, the surface of the ||c facet is covered with a thin (3–5 monolayers) film of tungsten oxide. The structure of the crystalline oxide phases that comprise the tungsten‐oxide/WSe2 interface are investigated with powder X‐ray diffraction. X‐ray photoelectron spectroscopy is used to study the chemical bonding at the interface. A model is proposed to explain the absence of surface recombination at this interface.A strong above the bandgap luminescence is observed from ||c facets of “mixed” surfaces, and from crystal edges (||c) which were allowed to “age” fcr a few weeks in the air. The origin of this luminescence was investigated in some detail, and a mechanism, involving partially oxidized ||c surface which possibly leads to quantum confinement of excitons in ||c edges of WSe2, is proposed.
Conductance of Sodium and Tetraethylammonium Iodides in Mixtures of Water with 1‐Propanol and with 2‐Propanol
Authors: Hawlicka Ewa , Grabowski Roman 
Published: July 2012

AbstractThe conductivities of NaI and Et4NI in mixtures of water with 1‐propanol and 2‐propanol at 25°C are reported. The conductivity data were analyzed via the Fuoss‐Hsia equation to find both the equivalent conductance λ0 as well as the association constant KA, simultaneously/Basing on variations of the Walden products the effect of the solvent composition on the ionic solvation has been discussed. In alcohol deficit mixtures, wherein hydrophobic interactions play an important role, the dehydration of Na+ and of Et4N+ ions has been found. For the same compositions the distances between ions forming the ionic pairs also diminish. Et4N+ and I− forming pairs shared one water molecule, whereas Na+ and I− are able to form even contact ionic pairs.
Eine gaskinetische Studie zur Reaktion von HOCl mit F‐, Cl‐ und H‐Atomen bei Raumtemperatur
Authors: Vogt R. , Schindler R. N. 
Published: July 2012

AbstractThe reactions of HOCl with F‐, Cl‐ and H‐atoms were investigated at room temperature in a discharge flow system equipped with an OH‐resonance fluorescence cell and a mass spectrometric detector. All kinetic studies were carried out under pseudo first order conditions with HOCl being the minority component. Branching ratios for individual processes were obtained by following simultaneously the rates of HOCl consumption and product formation. The following rate constants (in units cm3 molecule−1 s−1) were determinedF + HOCl → Products	k(1) = (4.9±0.6)·10−11	(1)	→ ClF + OH k(1a) = (1.2±0.4)·10−11	(1a)CL + HOCl → Products	k(2) = (1.4±0.37)·10−12	(2)	→ Cl2 + OH k(2a) = (3.4±1.4)·10−13	(2a)H + HOCl → Products	k(3) = (3.5±0.7)·10−12	(3)	→ HCl + OH k(3a) ≤ (6.7±2.1)·10−13	(3a)Calibration for [HOCl] using reaction (1) for gas titration is discussed. The data are evaluated to yield ΔHf (298) = ‐79.7 kJ mol−1 for the heat of HOCl formation.
About the Rate of the Reaction of NH(X3Σ−) with O2 over a Large Temperature Range
Authors: Hennig G. , Röhrig M. , Gg. Wagner H. 
Published: July 2012

AbstractMeasurements of the rate of the reaction NH(X3Σ−) + O2 at low and high temperatures show strongly different apparent energies of activation. In order to check the consistency of both sets of measurements the reaction was investigated in the intermediate temperature range. These experiments confirm a strongly curved Arrhenius plot for the rate of this reaction.
On the Stability and on the Formation of Two‐dimensional Condensed Equilibrium Films in an Aprotic and in Aqueous Solution — Part I: The Thermodynamics of Condensed 2‐Thiohydantoin at the Mercury Interface in Nonaqueous Acetonitrile, Tetraethylammoniumperchlorate
Authors: Schrettenbrunner M. , Chaiyasith P. , Baumgärtel H. , Retter U. 
Published: July 2012

AbstractThe behaviour of 2‐thiohydantoin at the interface mercury/nonaqueous acetonitrile, tetraethylammoniumperchlorate has been investigated by measuring the double layer capacitance in the potential range between 1.1 V≤‐E≤0.5 V. It is shown that a condensed adsorbate is established in a specific interval of potential, temperature and concentration of 2‐thiohydantoin. From the experimental data the molecular surface area in the condensed state and the sum of adsorption and intermolecular interaction energy of condensed molecules has been evaluated. The values are comparable to those of aqueous systems.
In‐Situ Electrochemical Actinometry Using An Azo Monolayer Film
Authors: Morigaki K. , Liu Z. F. , Hashimoto K. , Fujishima A. 
Published: July 2012

AbstractWe previously proposed an in‐situ electrochemical actinometric technique. It was established on the photoelectrochemical properties of azobenzene derivatives in the assembled monolayer film where incident photon number can be calculated from the faradaic charge quantity which flows during the light irradiation. Here, we show that the light intensity can be estimated more directly from the saturation current of cathodic reaction in the above azobenzene monolayer system. When the actinometric light is irradiated at a cathodic potential, azo molecules undergo trans to cis isomerization and selective reduction of cis isomer occurs simultaneously. The linearity between light intensity and cathodic current was derived theoretically and examined experimentally. This allows simpler in‐situ measurements of light intensity in photochemical and photoelectrochemical experiments.