Chemistry Commons^™

Inhibition Of N,N'-O-Phenylen-Bis(3-Methoxysalicylidenimine) On Copper In Halide Solutions, Hou-Yi Ma, Shen-Hao Chen, Zhen-Lan Quan, Lin Niu, Shu-Lan Li

Journal of Electrochemistry

Inhibition of N,N'-o-phenylen-bis(3-methoxysalicylidenimine) (V-o-Ph-V) on corrosion and anodic disslution of copper in neutral NaCl and NaBr solutions was investigated in terms of potentiostatic steady-state polarization and A.C. impedance techniques. The inhibition mechanism of V-o-Ph-V to copper corrosion was interpreted in detail by comparing the electrochemical behaviors of copper in halide solutions with or without V-o-Ph-V. Besides, the inhibition effect of self-assembled V-o-Ph-V film on copper corrosion in NaCl was also studied.

Study On Preparation Of Coarse And Fine γ-Lialo2 Mixed Powder Used For Mcfc Matrix, Hua-Xin Lin, Bao-Lian Yi, Lian-Ying Kong, En-Jun Zhang, Li Zhou, Feng-Xia Wang

Journal of Electrochemistry

Coarse α-LiALO₂ powder was transferred completely to γ-LiAlO₂ at 900 ℃ for ten hours. Fine γ-LiALO₂ powder was prepared by “chloride” synthesis. MCFC matrix was fabricated by mixing the coarse and fine γ-LiALO₂ powder and by tape cast. The out'put voltage of the cell assembled with the matrix was 0.85 and 0.75 V respectively at 200 and 300 mA/cm ², and power density was about 250 mW/cm². The performance of the matrix fabricated with the mixed powder was obviously more advanced than that of the matrix fabricated with only coarse γ-LiALO₂ powder.

Fabrication And Examination Of Reduced Temperatrue Solid Oxide Fuel Cell Using A Supported Thin Ysz Electrolyte Substrate, Yi-Huang Zhang, Yong-Lei Dong, Yi Jiang, Zhi-Gui Lu, Jing-Wang Yan

Journal of Electrochemistry

By using a cost-effective wet process,dense yttria stabilized zirconia (YSZ) films on Ni-YSZ anode substrates have been prepared successfully. The YSZ film was characterized to be around 10 μm in thickness, sufficiently dense, uniform and crack free. A single solid oxide fuel cell fabricated from the supported YSZ film electrolyte on the anode substrate and a LSM cathode prepared on the YSZ film was tested. The power density reached to 0.1 W/cm² at 800 ℃, showing a reasonable performance. Further analysis on both electrodes shows that the anodic overpotential was much larger than IR drop (including YSZ resistance and …

Quantum Calculations On The Vibrational Predissociation Of Nebr2: Evidence For Continuum Resonances, Thomas Alex Stephenson, N. Halberstadt

Chemistry & Biochemistry Faculty Works

Quantum mechanical calculations on the vibrational predissociation dynamics of NeBr2 in the B electronic state have been performed and the results compared with both experimental data and other computational studies. For vibrational levels with v less than or equal to 20 we find that the vibrational state dependence of the predissociation lifetimes is in qualitative agreement with experimental measurements, as are the calculated Br-2 fragment rotational distributions. For higher vibrational levels, the B <-- X excitation profiles are well represented by a sum of two Lorentzian line shapes. We attribute this result to the presence of long-lived resonances in the dissociative continuum that are reminiscent of long-lived dissociative trajectories in previous classical studies of NeBr2. (C) 2000 American Institute of Physics. [S0021-9606(00)00205-1].

Lifetime Effects On The Dissociation Of Core-Excited N2 And Co Molecules, N. Saito, A. Hempelmann, F. Heiserq, Oliver Hemmers, K. Wieliczek, J. Viefhaus, U. Becker

Environmental Studies Faculty Publications

Vibrational-resolved ion and ion-pair yield spectra of N₂ and CO taken at their 1s⃗π^* resonance excitations reveal decay-channel-dependent core hole lifetimes. The linewidths of the yield spectra tend to be shortened when the number of electrons ejected in the deexcitation process increases, finally becoming narrower than the total ion yield or absorption natural lifetime width of the core-excited states of N₂ and CO, respectively. In contrast to this, the linewidths of the yield spectra for the singly charged molecular ions, N₂⁺ and CO⁺, are shown to be broader than their corresponding natural linewidths. …

Solid State Phase Transitions Characterized By Esr And Xas, Juana Vivó Acrivos

Faculty Publications, Chemistry

Measurements of the relaxation time,  of electron systems to a disturbance, by two different spectroscopic methods are examined in detail, with the purpose to establish how the presence of fluctuations near a solid state phase transition are made evident in insulators, conductors and superconductors. The absolute temperature and the relaxation time determine the thermodynamic stability of the electronic system near a phase transition by the Uncertainty Principle. At a given temperature T, Landau and Lifshitz obtain the stability from the lower limit of the uncertainty in entropy in units of the Boltzmann constant, S/kB << 1 when T  >> 3.82 K ps. Magnetic resonance …

Photoabsorption Spectra Of Argon Cation Clusters: Monte Carlo Simulations Using Many-Body Polarization, Jose A. Gascon, Randall W. Hall

Collected Faculty Scholarship

A simple, semiempirical model that includes many-body polarization is used to study the ground and excited stateproperties of Ar+N clusters (N=3–23) at 80 K. For purposes of comparison, a model that does not include many-body polarization is used to study clusters with N=3–27.Monte Carlo simulations are used to calculate the average properties of these clusters. The model is similar to one previously used to study argon cation clusters without many-body polarization. The photoabsorptionspectrum is in good agreement with experiment; in particular, the photoabsorptionspectra for cluster sizes 4–10 do not show the blueshift that is seen with models that do not …

Spin-Exchange Term In The Solvent Equation Of State Near The Critical Point For Electron Transfer Reactions, Juana Vivó Acrivos

Faculty Publications, Chemistry

Phenomenological Equations of State (EOS) for fluids near their critical point have been obtained using literature compression factor data, Zc = Pc Vc/(n R Tc) = 0.40 to 0.10 in Table I (Pc, Vc/n, Tc are the pressure, volume per n mole, and the absolute temperature of the fluid at the critical point). The objective is to explain the deviations from the van der Waals value, Zc(vdW) = 3/8 (-70 % for molten Se and alkali metals up to 6 % for molten Pb, Hg, and In) by including in the commonly used phenomenological thermodynamic relations a term which explicitly …

Electronic Properties Of Small Neutral And Charged Beryllium Clusters, Andrew M. Kolchin, Randall W. Hall

Collected Faculty Scholarship

We determine the atomic and electronic structures for neutral and singly positively chargedberyllium clusters containing from two to six atoms using density functional theory in the local spin density approximation. Ions are moved with a steepest descent method and the electronic wave functions optimized using a fictitious dynamics with simulated annealing, as conceived by Car and Parrinello [Phys. Rev. Lett. 55, 2471 (1985)]. Shell-like orbitals, filling angular momentum states in the order: 1s 1p 2s 1d are obtained. We employ a Mulliken population analysis using an atomic basis to examine how the shell orbitals arise from atomic orbitals. This analysis …

Versatile Apparatus For Measuring Kinetics Of Gaseous Reactions By A Relative Method, Edmond W. Wilson Jr., Holly A. Sawyer, Amber A. Sawyer

Journal of the Arkansas Academy of Science

It is important that accurate, reproducible values for the rates of chemical reactions occurring in the atmosphere be obtained. The value of accurate kinetics measurements is to improve the accuracy of mathematical models used to forecast the state of the atmosphere. We describe a versatile, robust apparatus for obtaining atmospheric reaction rate values and their temperature dependencies by a relative method. This relative method has the advantage over absolute methods in that errors due to impurities and adsorption on walls of the reaction apparatus are minimized. In addition, relative values serve as an important verification for absolute values. The apparatus …

Microhollow Cathode Discharge Excimer Lamps, Karl H. Schoenbach, Ahmed El-Habachi, Mohamed M. Moselhy, Wenhui Shi, Robert H. Stark

Bioelectrics Publications

Microhollow cathode discharges are high-pressure, nonequilibrium gas discharges between a hollow cathode and a planar or hollow anode with electrode dimensions in the 100 μm range. The large concentration of high-energy electrons, in combination with the high-gas density favors excimer formation. Excimer emission was observed in xenon and argon, at wavelengths of 128 and 172 nm, respectively, and in argon fluoride and xenon chloride, at 193 and 308 nm. The radiant emittance of the excimer radiation was found to increase monotonically with pressure. However, due to the decrease in source size with pressure, the efficiency (ratio of excimer radiant power …

Study Of The Amplitude Of Pressure And Thrust Oscillations In A Lab-Scale Hybrid Rocket, Ann Wright, Lawrence Dunn, Brian Alford, Justin Patton, M. Keith Hudson

Journal of the Arkansas Academy of Science

Hybrid rockets are being studied as a potential replacement for the solid rocket boosters on the NASA space shuttle. One physical characteristic of hybrid rockets that must be understood and overcome is potentially severe pressure oscillations during combustion. Pressure oscillations inside the rocket combustion chamber lead to oscillations in the thrust of the rocket. These oscillations are damaging to potential human passengers and cargo and must be minimized. Current theories surmise that the oscillations are caused by combustion chamber geometry, oxygen feed line parameters, and/or fuel combustion characteristics. This study focuses on the role of the fuel characteristics in pressure …

Method Development By Hplc For Separation Of Various Hydrocarbon Groups In Coal Samples From Batu Arang, Selangor, Yong Chee Hui Audrey

Student Works (2000-2009)

A preliminary work involving method development for normal stationary phase (silica) pennits the high-performance liquid chromatographic separation or aliphatic and polyaromatic hydrocarbon (PAHs) classes. The Soxhlet extraction method was applied on the coal rock samples and normal phase (silica) short column clean-up separation from highly polymeric material in the coal extract. Method developed on analytical and preparative normal phase silica HPLC columns were to fractionate coal rock extracts, isocratic elution of hexane: ethyl acetate (95 :5, V:V) was found to be quite a good mobile phase. An alternative fractionation method, preparative thin layer chromatography (TLC), was also investigated to separate …

Beyond The Dipole Approximation: Angular-Distribution Effects In The 1s Photoemission From Small Molecules, Dennis W. Lindle, Oliver Hemmers, H. Wang, P. Focke, I. A. Sellin, J. D. Mills, J. A. Sheehy, P. W. Langhoff

Environmental Studies Faculty Publications

Over the past two decades, the dipole approximation has facilitated a basic understanding of the photoionization process in atoms and molecules. Recent experiments on the 1s inner shells of small molecules at relatively low photon energies (⩽ 1000 eV) show strong nondipole effects. They are significant and measurable at energies close to threshold, in conflict with a common assumption that the dipole approximation is valid for photon energies below 1 keV.

A Time Resolved Laser Spectroscopy Study Of Resonance Energy Transfer Between Tb(Iii) And An Organic Dye: 6-Hydroxy-5-[(2-Methoxy-5-Methyl-4-Sulfophenyl)Azo]-2-Naphthalenesulfonic Acid Disodium Salt, Ronald Wesley Tennis

Masters Theses

Intermolecular energy transfer is a process of crucial importance to photochemistry and photophysics. Complexed lanthanide ions are well suited as energy transfer donors because they display dependable absorption and luminescence qualities with narrow rare-earthion emission in addition to relatively long excited-state lifetimes.

This project used a pulsed nitrogen laser and high speed digital techniques to study energy transfer dynamics between excited state Tb(acac)₃ and an ionic organic dye called Red 40. Luminescence decay profiles of excited terbium atoms in the presence of the quencher were measured in both high and low viscosity solvents. The effects of solvent viscosity and …

Electrodeposition Of Copper On Polished Copper Electrode, Jia Tsung Ling

Student Works (2000-2009)

This project studies the surface morphology of the copper deposit from three different bath solutions on polished copper (3.1 mm in diameter) electrode by using Scanning Electron Microscopy. The behaviour of glycine as an additive in a bath solution containing 0.3 M of copper (II) sulphate and 2.2 M of sulphuric acid was studied by using cyclic voltammetry. In this project, glycine did not involved directly in the reaction of CU²⁺/CU couple but increased the potential and current density of the plating process. However, glycine has the properties for inhibiting the deposition of copper onto the copper disc. Moreover, block …

Study On Electrochemical Reduction Properties Of Nitrobenzene, Chu-Na Ma, Wen-Kui Zhang, Hui Huang, Yong-Ping Gan

Journal of Electrochemistry

The electrochemical reduction characteristics of nitrobenzene was extensively investigated by using the techniques such as quasi-steady-state polarization, cyclic voltammetry, fast linear potential sweep method and chronoamperometry in this paper. The electroanalytic properties of Cu, Cu-Hg and Cu-Ni electrodes were evaluated. Based on the study of the transient steping behaviour of nitrobenzene to PAP, the reduction mechanism was discussed. The results showed that the transition steps existed on the electrochemical reduction of nitrobenzene in acidic solution, the reactant is also absorbed on electrodes surface. The control step in the reduction of nitrobenzene was ascribed to the diffusion of nitrobenzene and its …

A Novel Reaction Region Moving Electrode System For Electrochemical Power Sources, Jin-Kua You, Que Tu, Zheng-Jian Wang, Jie Sun, Zu-Geng Lin

Journal of Electrochemistry

In most of practical rechargeable batteries, charging/discharging process is always concerned with phase-transformation in the solid state. Due to the irreversibility of the phase-transformation, the cyclic performance of the rechargeable batteries are limited. In this paper, a novel reaction-region moving counter electrode system is constructed in our laboratory. The electrode system is operated at room temperature and cycled in solid-liquid phase during charging/discharging processes. With this electrode, the metal-complexes are firstly deposited (i.e. charging process) on the nearest working electrode and gradually extended to those another working electrodes several centimeters away from the counter electrode. The deposite is dissolved again …

High Performance Proton Exchange Membrane Fuel Cells, Jing-Rong Yu, Bao-Lian Yi, Ming Han, Xiao-Liang Cheng, Zhi-Gang Shao, Jing-Xin Zhang

Journal of Electrochemistry

Proton-exchange membrane fuel cells(PEMFC) using a perfluorosulfonic acid proton exchange membrane as an electrolyte can simplify water and electrolyte management. In this paper, the effects of thickness of PEM on the performance of PEMFC were studied. The Nafion-112 PEM and low platinum loading E-TEK electrode yielded very high power density, of the order of 0.95 W/cm². The energy-conversion efficiency, the degree of platinum utilization and stability for PEMFC using Nafion 112 and E-TEK electrode were also investigated.

Electro-Oxidation Of Phenol On Sno2/Ti Electrodes Prepared By Thermal Oxidation, Qing-Song Zhang, Hui-Huang Wu

Journal of Electrochemistry

A SnO₂/Ti electrode prepared by thermal oxidation was used as the anode for galvanostatic electrolysis in acidic solution containing phenol, the time-dependances of phenol concentration, chemical oxygen demand in solution(COD) and instantaneous current efficiency were determined during electrolysis. The results show that with the SnO₂/Ti anode instead of Pt, the COD significantly decreases at the same charge passage, and average current efficiency of oxidation increases by three times. The mechanism for phenol oxidation at two electrodes was discussed.

Characterization And Electrochemical Behaviour Of Ce(Ⅲ) Amino Acid Imidazole Ternary Complexes, Hui-Xia Wu, Ze-Min Wang, Hai-Feng Yang, Zong-Rang Zhang

Journal of Electrochemistry

Two Ce(Ⅲ)-amino acid-imidazole teranry complexe were synthesized,These complexes have the composition of Ce(Trp)₃IM(NO₃)₃·3H₂O and Ce(Phe)₃IM(NO₃)₃ respectively. The IR spectra indicate that the carboxy group of amino-acid and the N atoms of imidazole are coordinated with Ce(Ⅲ) ion. Cyclic voltammetry was used to study the electrochemical behaviour of Ce(Ⅲ) ion, the mixture of Ce(Ⅲ) with ligands, and Ce(Ⅲ) binary or ternary complexes. Within the scan range of -0.1 to 1.10 V (vs.SCE), both of ternary complexes depicted completely irreversible electron transfer process.

Investigation Of Sodium Hypophosphite Anodic Oxidizing Behavior In The Process Of Acid Electroless Nickel Deposition, Mei-Yuan Wang, Ya-Fei Kuang, Yan Xu

Journal of Electrochemistry

The anodic oxidizing behavior of sodium hypophosphite in the process of electroless nickle deposition (pH=5.5) was investigated with the linear potential sweep method and alternating current impedance. The results indicated that, the oxidation of NaH₂PO₂ was a complicated electrochemical process and affected by the concentration of NaH₂PO₂, the temperature of the bath, the sweep rate and the existence of nickel ion. The NaH₂PO₂ electrooxidation reaction was very likely preceded by heterogeneous interface transformation process, which might be the control step of the whole anodic process.

Studies Of The Electrode Preparation Of Electrode From Lead Carbonate For Lead Acid Batteryⅰ. The Activation Of The Pme, Zhong-Xu Dai, Di-Hua Wang, Jun-Wei Jiang, Yun-Hong Zhou, Jin-Yun Zou

Journal of Electrochemistry

Lead carbonate which was an intermediate product in lead hydrometallurgy without pollution of lead vapor and sulfur dioxide was selected as electrode material of lead-acid batteries. In the present work, the performances of PbO₂/PbSO₄ or PbSO₄/Pb electrode transformed from PbCO₃ have been investigated by powder microelectrode technique combined with cyclic voltammetry. The results show that the CV characteristics of either negative or positive electrode prepared from PbCO₃ is as good as that of both electrodes made from lead oxide produced by mill machine,when a powder microelectrode with PbCO₃ transformed into PbSO 4 …

The Studies Of The (Photo) Electrochemical Character On The Electrodeposited Silver Indium Selenium Thin Films, Shao-Ai Xie, Xun-Nan Deng, You-Jin Kua

Journal of Electrochemistry

A photoelectrochemical cell (PEC) is constructed, using an AgInSe₂ film photoanode made from electrodeposition and a platinium electrode in aqueous polyiodide or polysufide electrolyte. The V_oc and I_sc of PEC have been tested and measured, and the effect of chemical decoration on the photoanodes also studied.

Studies On Methods Of Fuel Cells Electrodes Preparation, Jun Gu, Sheng Sui, Guang-Qiang Li, Zhitong Sui

Journal of Electrochemistry

In fuel cells, the structure of electrodes is an important factor which effect the cell performance. To improve the structure and the performance of electrodes, a new method of providing fuel cell electrodes is proposed in this paper. PTFE (polytetrafluoroethylene) and ethyne black was ground for about half an hour in a high-speed grinder, then the catalyst was added into the grinder and milled for an hour. This milled catalyst was transferred into a mixer followed by the addition of surface-active agent. After a suspension was formed, it was filtered under vacuum condition.Then a thin uniform filter-cake of the catalyst …

Prparation Of Nanocrystaline Tio2(Anatase) With High Thermal And Textural Sability By Electrochemical Method, Dao-Bao Chu, Xing-Fu Zhou, Chang-Jian Lin, Jian-Guang Tang

Journal of Electrochemistry

Titanium alkoxides were prepared by anodic dissolution of metallic titanium in absolute ethanol in the presence of HN(C₂H₅)₂·HCl (electro-conductive additives). The solution was directly hydrolyzed to prepare nanocrystalline of TiO₂ (about 10nm)by a sol-gel process. The precursor gels was calcined at T =450 ℃ and 720 ℃ for 30 min, and nanocrystalline of TiO₂ (anatase) with high textural and thermal stability was obtained. FTIR, XRD, TEM were used to characterize the structure of titanium alkoxides and nanocrystalline of TiO₂. The characteristics of nanocrystalline of TiO₂ was depended on the …

Surface Enhanced Raman Spectroscopic Study Of Scn- Adsorbed At The Copper And Gold Nanowire Arrays, Jian-Lin Yao, Guo-Ping Pan, Kuan-Hong Xue, Yong Xie, Jing Tang, Bin Ren, Dong-Mei Sun, Bing-Wei Mao, Zhong-Qun Tian

Journal of Electrochemistry

Two-dimensional arrays of Cu and Au nanowires have been fabricated by template synthesis method, using the anodic aluminum oxidation films as the template. The morphology of the nanowire array was monitored by atomic force microscope (AFM) in the dissolution processes of the alumina film. Based on the probe molecule strategy, the spectral feature of SCN^- adsorbed at the Cu and Au nanowires with different diameters has been investigated by surface enhanced Raman spectroscopy (SERS). The results reveal that the intensity of the SERS bands depends on the length of the exposed nanowires. The C≡N stretching vibration frequency (ν_{CN …}

Aes Multi-Layer Structural Analysis Of Si Based Anodic Porous Alumina Films And Studies On Its Formation Mechanism, Jun-Hui Wu, Jian-Ping Zou, Qing Zhu, Xi-Mao Bao

Journal of Electrochemistry

400 nm aluminum films were deposited onto a p-type, 0.5 Ω·cm,〈100〉oriented silicon wafers using electron beam evaporation technique. Then, the wafers was immersed in 15 wt% H₂SO₄ for porous-type over-anodization under a constant voltage of DC 60V. During the anodization,the temperature of the electrolyte was maintained at 0 ℃. The obtained samples were investigated by means of transmission electron microscopy, scanning electron microscopy, and AES depth profile for multi-layer structural information. In addition, the basic anodic formation mechanism of the Si-based aluminum films was brielfly discussed.

Photoelectrochemical Studies On The Tio2 Nanostructured Porous Film Sensitized By Cyanine Dye, Li Zhang, Mai-Zhi Yang, Xue-Bin Qiao, Yan-Zhong Hao, En-Qing Gao, Sheng-Min Cai

Journal of Electrochemistry

The photoelectrochemical behaviors of the TiO₂ nanostructured porous film sensitized by cyanine dye were investigated in this paper. The results showed that the excitaed state level matched the conduction band edge of TiO₂ nanoparticle. Therefore the sensitization of the dye can increase the photocurrent intensity of the TiO₂ nanostructured electrode obviously and results in a red-shift of optical absorption from the ultra-violet region to the visible. As a result, the light-to-electricity conversion efficiency was improved evidently, the maximum value of IPCE has reached 12.1%.

The Preparation Of Flexible Polymeric Anode And The Measurement Of Its Protective Ability For Cathodic Protection, Ai-Ling Du, He-Ming Zhang, Ming-Zong Zhang, Shi-De Ma

Journal of Electrochemistry

The flexible electrode, whose shape can be changed freely, was made of ethenyl copolymer and conductive component and proper amount of additive for cathodic protection. The resistance of electrode was measured.In low concentration of H₂SO₄, the flexible electrode can be used as auxiliary anode to protect the carbon steel. The protection ability of the flexible auxiliary anode was measured too.