Chemistry Commons^™

Electroreduction Of Holmium Ion On Iron Electrde In Molten Cholorides, Qiqin Yang, Guankun Liu, Yuzhi Su

Journal of Electrochemistry

The cyclic voltammetry, open circuit potential-time curve after poteritiostatic electrolysis, current-time curve at potential step, X-ray diffraction and electron probe microanalysiswere used to investigate the electrode process of Ho(Ⅲ) reduced on iron electrode in molten chloridesand the phases of surface alloy layer. The Ho-Fe alloys are formed at first, and then the metallic holmium is deposited when Ho(Ⅲ) is reduced on iron electrode. The charge transfer is reversible. The free energies of formation for the four inter metallic compounds of Ho-Fe system, the diffusion coefficients and diffusion activation energy of Ho in alloyed cathode are determined.

Study Of Electrochemical Properties Of Ni(Oh)2/Niooh With Spectroscopic Ellipsometry, Shengtao Zhang, Zongqing Huang

Journal of Electrochemistry

Electrochemical reactions of Ni(OH)₂ /NiOOH system were studied by using in-situ spectroscopic ellipsometry and the conventional electrochemical metheds. By fitting data from ellipsometric measurements, a transformation medel of the surface film was obtained for cathedic and anodic processes. The results indicated that the transformation medel after cobalt implantation almost remained the same as that before cobalt implantation, but the electrochemical properties were affected obviously by implantation of cobalt.

The Study Of The Growth Processes Of The Oxides On Lead Electrodes In Sulfuric Acid Solution, Hesheng Zhai, Xuguang Chen, Jinkua You, Yong Yang, Zugeng Lin

Journal of Electrochemistry

The growth processes of PbO and PbO₂ on lead electrodes have been investigatedby using in-situ methods that are combined with temporary AC resistance measurment technique and in-situ laser scanning photoelectrochemical microscopy. It is found that a linear relationship existsbetween the electrode resistance(R) and^1/2 after the electrode is oxidized at +0.6 V(vs.Hg/H₂SO₄/35% H₂SO₄) for more than 5 min. This result suggests that the growth of PbO is well distributed during the early stage of oxidation. The study by using laser scanning photoelectrochemical microscopy has further proved this point. The results also …

Application Of Inhibitor To Improve The Anticorrosion Performance Of Electrophoretic Coating, Changshou Cai, Fangteng Su, Bihuan Liu, Guomou Wen, Jingdong Guo, Renxin Liu, Weidong Tian

Journal of Electrochemistry

To improve the anti-corrosion performance of electrocoating, organic andinorganic inhibitors are applied in an anodic electrophoretic-coating. The results show that the deposition of polymer with zinc phospate exhibits a high inbihition efficiency. The inhibition mechanism of the inhibitor in electrocoating has been studied.

Application Of Voltammetry In Analysis Of Electroplating Baths, Jiayuan Xu, Shaomin Zhou

Journal of Electrochemistry

Based upon the electrochemical characteristics of the components or impurities tobe determined in the electroplating baths, and the inhibition or activation effect of the additives used on the electrodepcosition processes of metals and alloys, direct voltammetry, indirect voltammetry andvoltammetry with anodic stripping of metallic deposits, were suggested to determine the concentrationof some components, several impurities and the additives usually used in the electroplating baths. The procedure of those methtods are simple and rapid ,and are suitable to be used for in-situ control in electroplating workshops.

The Device Of Wy-Ⅱ Type Cyanide Monitor And Its Applications, Xianmin Wang

Journal of Electrochemistry

A device of WY-Ⅱtype micro-computerized cyanide monitor is presented, in which the cyanide analvsis is carried out by means of microcoulomb-iodimetric with automatic following system. This instrument can be successifully employed to analyze the cyanides in industrial waste-waterfor vavious departments of chemical industry. A serious of experimental tests showed that the analytical sensitivity went up to 0.01 mg/L and the accuracy of determination was excellently coincided with that of national standard method and other methods.

The Catalytic Behavior For Ni-W Electrode Modified By Carbon Ion Beam Implantion, Jishuang Zhang, Yaojiao Lv, Qinglian Li, Baoen Shen

Journal of Electrochemistry

The hydrogen evolution activity in acidic and basic mediums for Ni-W electrodemodified by carbon ion bean implantation was investigated. The experimental results show thiselectrode has superior catalytic activity for the hydrogen evolution reaction than that of the unmodified Ni-electrode. Long period testing of electrolysis under high current density show that this electrode hasalonger useful life hence it is a practical electrode material. The temperature effect of electrocatalytic property was also inverstigated. The experimental regularities are explained on the basis of the formation of surface multialloys of Ni-W-WC.

The Effect Of Some Ions On Cr2O72- Anodic Formation Process At Pt And Pbo2 Electrodes, Shixiong Jin, Zhigang Zhou, Lan Wang

Journal of Electrochemistry

The influence of Ag₂SO₄, Li₂SO₄, Na₂SO₄, K₂SO₄, (NH₄)₂SO₄,MgSO₄ and KF on the evolution of O₂ and the formation of Cr₂O at Pt and PbO₂ anodes was investigated in mixed H₂SO₄-Cr₂(SO₂)₃ solutions. The kinetic data related respectively to Cr₂O formation and O₂ evolution at Pt and PbO₂ anodes were measured by method of resolving the steady-state polarization curve. The Tafel slope …

A Investigation Of Hydrogen-Storage Alloy As Catalytic Electrode For Hydrogenation Of Nitrobenzene, Shigang Lu, Hanxi Yang, Changfa Wan

Journal of Electrochemistry

Since hydrogen-storage alloy ean not only absorb hydrogen atoms to form highlyreactive metal hydride as hydrogen source by electrolysis but also possesses a certain catalytic activityfor hydrogenation,it is thus feasible to utilize the allov as a novel electrode for electrolvtichydrogenation in organic electroreduction. This work employed misch metal AB₅ type alloy as acatalytic electrode and studied the electrochemical hydrogenation of nitrobenzene.

The hydrogen-storage electrode (MH) was a plastic bonded electrode sheet made from a paste of Mm(NiCoMnAl)₅ alloy powder and teflon emulsion. The electrolysis was performed at constantcurrent and controlled potential in a three electrode cell of H-type …

Electrocatalytic Oxidation Of Formaidehyde And Formic Acid On A Pt/SbAd Electrode, Hong Li, Lincai Jiang, Xiong Jiang

Journal of Electrochemistry

The electrocatalytic activity for the oxidation of formaldehyde and formic acid ona Sb-modified platinum (Pt/Sb_ad) was investigated. Results showed that the Pt/Sb_ad electrode was electrocatalytically more active than a Pt electrode in the anodic oxidation of formaldehyde and formicacid. In the case of formaldehyde, an oxidation peak appeared at a potential of ca. 0.7V. During the oxidation of formic acid, a 4-fold increase in the 1st peak current was observed. The Sb-modified platinum electrode was found to be most electrocatalytically active at a coverage of 0.75±0.05. The electrocatalytic activity of the Pt/Sb_ad electrode can be best …

Synthesis Of LiXCoo2 And Its Behaviour In Rechargeable Lithium Battery, Mingfeng Guo, Ruimin Yang, Zebo Zhang, Jincao Ye

Journal of Electrochemistry

The Variations of crystal lattice parameters of Li_xCoO₂ during charge anddischarge have been st ud ied by XRD and AAR spectroscopy. It was found that the Li_xCoO₂ crystalvolume expanded during charge and contracted during discharge. The crystal lattice structure was broken because of the formation of Co₃O₄ when deeply charge.The variation of lattice parameter C₀ value in cycling process was similar to that in charge process.The variation of 006 peak was the mostsensitive in every case. In case of preheating for 20 hours at 700℃ before operating high temperature, the …

The Electrode Process Of Y(Ⅲ) On Copper Electrode And Its Surface Metallizing, Chungen Zhou, Shuzhen Duan

Journal of Electrochemistry

The reduction of yttrium ion on copper electrode in NaCl-KCl-YCl₃ molten saltshas been investigated. The results indicate that the formation of intermetallic compounds is occuredbefore the metallic yttrium to be formed. The formation of intermetallic compounds is controlled bythe process of which yttrium atoms are diffusing into copper electrode. The kinetic characters todiffusion of yttrium atoms were also discussed.

Design And Performance Of The Advanced-Light-Source Double-Crystal Monochromator, G. Jones, S. Ryce, Dennis W. Lindle, B. A. Karlin, J. C. Woicik, Rupert C. Perera

Chemistry and Biochemistry Faculty Research

A new “Cowan type” double-crystal monochromator, based on the boomerang design used at National Synchrotron Light Source (NSLS) beamline X-24A, has been developed for beamline 9.3.1 at the Advanced Light Source (ALS), a windowless ultrahigh vacuum beamline covering the 1-6 keV photon-energy range. Beamline 9.3.1 is designed to simultaneously achieve the goals of high energy resolution, high flux, and high brightness at the sample. The mechanical design of the monochromator has been simplified, and recent developments in technology have been included. Measured mechanical precision of the monochromator shows significant improvement over existing designs. In tests with x-rays at NSLS beamline …

Observation Of Parity-Unfavored Transitions In The Nonresonant Photoionization Of Argon, B. Langer, J. Viefhaus, Oliver Hemmers, A. Menzel, R. Wehlitz, U. Becker

Environmental Studies Faculty Publications

Single-photon ionization of an atom or molecule can be subdivided into parity-favored and -unfavored transitions, the latter characterized by electron emission, preferentially perpendicular to the electric vector. The nonresonant existence of these transitions is shown experimentally and studied over an extended energy range for a variety of satellite transitions in atomic argon. The spectra exhibit several clearly resolved satellite lines with strongly negative β values close to -1, independent of the photon energy. The results confirm the corresponding predictions of angular-momentum transfer theory.

Dynamic Phenomena In Layer Superconducting Cuprate And Organic Metals, Juana Acrivos, Lei Chen, C. Burch

Faculty Publications, Chemistry

Dynamic electron spin resonance (ESR) and extended x-ray absorption edge fine structure (XAFS) measurements suggest that layered organic metals and cuprate superconductors behave similarly. The response to microwave radiation in a modulated external magnetic field indicates that: (i) triplet state, T * ESR is observed below Tc for both; (ii) the condensation of free spin doublet D to T* occurs above the transition temperature to superconductivity Tc (10 ± 1 K for the organic metal (BEDT-TTF)3Ta2F11 and 92 to 12 K for YBa2Cu3O7-δ and its rare earth derivatives); (iii) antiferomagnetic (AF) resonance is detected above Tc for the organic metal. …

Three-Body Analytical Potential For Interacting Helium Atoms, Carol A. Parish, Clifford E. Dykstra

Chemistry Faculty Publications

Large basis set ab initio calculations have been carried out for a dense grid of points on the He, potential energy surface. Three-body contributions were extracted at every point, and a number of concise functional representations for the three-body potential surface were then examined. Three-body multipolar dispersion terms and other radial and angular terms were used in the representations, and an assessment of relative importance of the different terms is presented. Combined with a two-body He-He potential, the results of this work should offer a high quality interaction potential for simulations of aggregated helium.

Dynamic Phenomena In Superconducting Oxides By Esr, Juana Vivó Acrivos, Lei Chen, C. M. Burch, P. Metcalf, J. M. Honig, R. S. Liu, K. K. Singh

Faculty Publications, Chemistry

Dynamic electron spin resonance (ESR) measurements compare the paramagnetic and antiferromagnetic (AF) properties of superconducting oxides in the range 4 K to room temperature, at 8 MHz and 9.36 GHz. Two are derivatives of YBa2Cu30 7: 1: Nd(Nd0.05Ba0.95 )2Cu30 7, Te0 =72 K and II: Y0.2Cao.8Sr2[Cu2(Tlo.5Pb0.5 )]07, Te0 =108 K and two are cases where AF ordering dominates the weak superconductivity: III: Nb01.1> 1. 25 ~Teo~ 10 K and IV: La2Ni04.00, 70 K :::: Teo:::: 40 K. At temperatures 298:::: T:::: 64 K, the ESR absorption by I indicates orthorhombic symmetry. The peaks at Ke =2.06, gb =2.13, and Ka …

Effective, Reliable, Inexpensive Cryofixation Device, Lawrence A. Mink, Roger A. Buchanan

Journal of the Arkansas Academy of Science

No abstract provided.

Observation Of Non-Isotropic Auger Angular Distribution In The C(1s) Shape Resonance Of Co, Oliver Hemmers, Franz Heiser, J. Eiben, R. Wehlitz, U. Becker

Environmental Studies Faculty Publications

Angle-resolved high-resolution C(KVV) Auger spectra of CO were taken in the vicinity of the C(1s) σ^* shape resonance. These spectra show clear evidence for the theoretically predicted anisotropic K-shell Auger emission in molecules. Complementary results from angle-resolved photoion spectroscopy show that the small size of the observed effect is, besides the varying intrinsic anisotropy of the Auger decay, also due to a smaller anisotropy in the primary absorption process than originally predicted but in good agreement with more recent calculations. Contrary to this, satellite Auger transitions show unexpectedly large anisotropies.

Electronegativity And Bond Type 2. Evaluation Of Electronegativity Scales, Gordon Sproul

Natural Sciences Faculty Publications

No abstract provided.

Multiplet-Changing Auger Transitions In Valence Double Photoionization, U. Becker, Oliver Hemmers, B. Langer, I. Lee, A. Menzel, R. Wehlitz, M. Ya Amusia

Environmental Studies Faculty Publications

The decay of valence satellite states in neon above the first double-ionization threshold has been studied experimentally and theoretically. Special emphasis was given to differentiate between two decay modes: valence Auger and valence-multiplet Auger decay. It is shown that the latter process is predominant in the low kinetic energy part of the spectrum. The main structures of this low-energy Auger spectrum could be designated by help of calculated transition energies and decay rates.

Pairwise And Many-Body Contributions To Interaction Potentials In He(N) Clusters, Carol A. Parish, Clifford E. Dykstra

Chemistry Faculty Publications

High level ab initio calculations have been carried out to assess the pairwise additivity of potentials in the attractive or well regions of the potential surfaces of clusters of helium atoms. A large basis set was employed and calculations were done at the Brueckner orbital coupled cluster level. Differences between calculated potentials for several interacting atoms and the corresponding summed pair potentials reveal the three‐body and certain higher order contributions to the interaction strengths. Attraction between rare gas atoms develops from dispersion, and so helium clusters provide the most workable systems for analyzing nonadditivity of dispersion. The results indicate that …

High-Energy Behavior Of The Double Photoionization Of Helium From 2 To 12 Kev, Jon C. Levin, Ivan A. Sellin, B. M. Johnson, Dennis W. Lindle, R. D. Miller, Y. Azuma, H. G. Berry, D.-H. Lee, N. Berrah

Chemistry and Biochemistry Faculty Research

We report the ratio of double-to-single photoionization of He at several photon energies from 2 to 12 keV. By time-of-Aight methods, we find a ratio consistent with an asymptote at 1.5%±0.2%, essentially reached by h v≈4 keV. Fair agreement is obtained with older shake calculations of Byron and Joachain [Phys. Rev. 164, 1 (1967)], of Aberg [Phys. Rev. A 2, 1726 (1970)], and with recent many-body perturbation theory (MBPT) of Ishihara, Hino, and McGuire [Phys. Rev. A 44, 6980 (1991)]. The result lies below earlier MPBT calculations by Amusia et al. [J. Phys. B 8 …

Absolute-Convective Instabilities And Their Associated Wave Packets In A Compressible Reacting Mixing Layer, F. Q. Hu, T. L. Jackson, D. G. Lasseigne, C. E. Grosch

Mathematics & Statistics Faculty Publications

In this paper the transition from convective to absolute instability in a reacting compressible mixing layer with finite rate chemistry is examined. The reaction is assumed to be one step, irreversible, and of Arrhenius type. It is shown that absolute instability can exist for moderate heat release without backflow. The effects of the temperature ratio, heat release parameter, Zeldovich number, equivalence ratio, direction of propagation of the disturbances, and the Mach number on the transition value of the velocity ratio are given. The present results are compared to those obtained from the flame sheet model for the temperature using the …

Viscosities Of Vegetable Oils And Fatty Acids, Hossein Noureddini, B. C. Teoh, L. Davis Clements

Papers in Biomaterials

Data for viscosity as a function of temperature from 24 to 110°C (75 to 230°F) have been measured for a number of vegetable oils (crambe, rapeseed, corn, soybean, milk- coconut, lesquerella) and eight fatty acids in the from Cg to CZZ The viscosity measurements were performed according to ASTM test methods D 445 and D 446. Several correlations were fitted to the experimental data. Correlation constants for the best fit are presented. The range of temperature in which the correlations are valid is from 24°C (75°F), or the melting point of the substance, to 110°C (230°F). The correlation constants are …

Fragment Rotational State Distributions From The Dissociation Of Neibr: Experimental And Theoretical Results, Thomas Alex Stephenson

Chemistry & Biochemistry Faculty Works

The IBr fragment rotational state distributions that result when the NeIBr van der Waals molecule undergoes vibrational predissociation have been measured in a pump-probe laser-induced fluorescence experiment. Independent of initial vibrational state and the number of quanta of vibrational energy lost from the I-Br coordinate, the rotational distributions extend over the full range of energetically accessible states. From the observation of energetic constraints on the rotational distribution, the dissociation energy (D0) is calculated to be 65.5 +/- 1.2 cm-1 for the A electronic state, v=16. For the X electronic state, v=0, D0=71.8 +/- 1.2 cm-1. Quantum mechanical bound state calculations …

Vibrational Branching Ratios From The Dissociation Of The Neibr Van Der Waals Molecule, Sarah Anne Walter , '91, Thomas Alex Stephenson

Chemistry & Biochemistry Faculty Works

The degree of vibrational excitation in the IBr fragment from the vibrational predissociation of NeIBr (A (3)PI(1)) has been measured using two-color pump-probe laser-induced fluorescence spectroscopy. We find that for the lowest initial vibrational states examined, DELTA-upsilon = -1 dissociation pathways dominate the dynamics, while this channel is closed for upsilon greater-than-or-equal-to 17. From this result, the A state binding energy (D0) of the complex is determined to be 67 +/- 4 cm-1, while that in the X electronic state is found to be 73 +/- 4 cm-1. The X state binding energy is identical to that for NeI2 and …

Evidence For Atomic Processes In Molecular Valence Double Ionization, U. Becker, Oliver Hemmers, B. Langer, A. Menzel, R. Wehlitz, W. B. Peatman

Environmental Studies Faculty Publications

Complete molecular valence-electron spectra were measured for CO. Unexpectedly, discrete lines at low kinetic energies were found, superimposed on a continuous energy spectrum representing direct double-ionization processes. The appearance of these lines is discussed in the context of the formation of the C⁺+O⁺ ion pair near its associated threshold at 38.4 eV. It is ascribed to valence-excited repulsive (CO⁺)^* states, which dissociate to a large part rapidly into atomic fragments before electronic relaxation takes place. From our spectra, partial cross sections for the different processes leading to dissociative valence double ionization are derived.

Surface Structure Of √3x√3r 30 Cl/Ni(111) Determined Using Low-Temperature Angle-Resolved-Photoemission Extended Fine Structure, Li-Qiong Wang, Z. Hussain, Z. Q. Huang, A. E. Schach Von Wittenau, Dennis W. Lindle, D. A. Shirley

Chemistry and Biochemistry Faculty Research

A surface structural study of the √3 × √3 R30° Cl/Ni(111) adsorbate system was made using low-temperature angle-resolved photoemission extended fine structure. The experiments were performed along two emission directions, [111] and [110], and at two temperatures, 120 and 300 K. The multiple-scattering spherical-wave analysis determined that the Cl atom adsorbs in the fcc threefold hollow site, 1.837(8) Å above the first nickel layer, with a Cl-Ni bond length of 2.332(6) Å, and an approximate 5% contraction between the first and the second nickel layers (the errors in parentheses are statistical standard deviations only).

Electron-Energy And –Angular Distributions In The Double Photoionization Of Helium, R. Wehlitz, Franz Heiser, Oliver Hemmers, B. Langer, A. Menzel, U. Becker

Environmental Studies Faculty Publications

Photoelectron spectra of helium have been measured at different angles and at various energies above the double-ionization threshold up to 120 eV to investigate the behavior of the energy and angular distributions, of shake-off electrons. Both energy and angular distributions clearly show a U-shaped profile which turns to a flat curve near threshold pointing to a uniform intensity distribution over the kinetic energy for all angles in this excitation energy regime. Our results for the angular-distribution asymmetry parameter indicate qualitative agreement with theoretical predictions but fail to provide them quantitatively.