Physical Chemistry Commons^™

Studies Of Abnormal Infrared Effects Of Nanometer Thin Films Of Transition Metals And Alloys In Acid Solutions, Shi-Gang Sun, Ming-Sen Zheng, Guo-Qiang Lu, Li-Rong Cai, Sheng-Pei Cehn, Xiao-Yin Xiao

Journal of Electrochemistry

The adsorption of CO on electrodes of nanometer thin films of transition metals (Pt, Pd, Rh, Ru) and alloys (PtPd, PtRu) prepared under cyclic voltammetric conditions has been studied by in situ FTIR spectroscopy. The abnormal infrared effects (AIREs) have been explored as a novel and general phenomenon. The AIREs consist mainly in the inversion of the direction of IR band and the significant enhancement of IR absorption by adsorbed CO species. It was revealed that the enhanced IR absoroption of adsorbed species in AIREs depends strongly on the nature of metal or alloy, and on the structure and the …

Investigations Of Lithium Ion Battery Electrolyte Solution, Jing-Li Han, Qing-Guo Liu

Journal of Electrochemistry

Synthesis and electrochemical investigations of {LiB[(SO₃)C₆H₃(O)(COO)]OC₆H₅} in EC/DMC or DMSO/PC mixtures are presented.

Studies Of The Preparation Of Electrodes From Lead Carbonate For Lead-Acid Battery Ⅱ. The Preparation Of Paste Electrodes, Zhong-Xu Dai, Di-Hua Wang, Hao-Hao Ke, Jin-Yun Zou, Yun-Hong Zhou

Journal of Electrochemistry

The positive and negative pastes were prepared by mixing PbCO₃ and H₂SO₄ solution as well as relative additives, respectively. The effects of the various formation methods and the charge/discharge conditions on discharge capacity and active material utilization of both electrodes were examined. The results indicate that the performance of the positive electrode formed at 2.0 mA/cm² is better than that formed at higher current density under the same charge/discharge condition, the PAM utilization reaches 74.4 % under discharging at 2.0 mA/cm²; and the property of the negative electrode formed by unsymmetrical square wave …

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.

Deposition And Characterization Of Electroless Nickel-Phosphorus-Boron Coatings From Acidic Bath, Tai-Xiang Jiang, Hui-Huang Wu

Journal of Electrochemistry

Acknowledgments The authors gratefully acknowledge Professor B.W.Mao for use of AFM facilities at her laboratory. We would also like to thank J.Tang for assistance with AFM measurements.

Sprayed And Thermally Evaporated Carbon Films As Anodes For Lithium Ion Batteries, Shu-Gao Zhang, M.Schleich Donald

Journal of Electrochemistry

Carbon films were made using spray-thermal evaporation from a kind of pyrolytic carbon powder. The films obtained with graphite structure were both potentio-statically and galvanostaically tested. Cycling patterns indicated a reduction peak on the first cycle corresponding to the formation of solid electrolyte interface, and the capacity values and x values were quite acceptable compared to theoretical ones when charging-discharging current density was suitable. Based on the experimental results, the obtained carbon films could be used as anode materials for relatively determining the electrochemical performances of cathode materials.

Study On Oxygenation Of Histidion-Cobalt And Monoiodohistidine-Cobalt Complexes By Cyclic Voltammtry, Yi Zhang, Ji-De Wang, Fan Yue, Xiao-Gang Zhang, Qi-Jun Song

Journal of Electrochemistry

The oxygenation of Histidine-Co and Monoiodohistidine-Co complexes were studied by cyclic valtammtry under certain conditions. The possibility of studing the oxygenation processes by cyclic voltammetry method was proposed and discussed in comparison with the results of potentiometry and spectrophotometry.

Studies On Electrochemical Synthesis Of 4,5-Disubstituted-1,2- Benzoquinones And The Reaction Mechanism, Xian-Zhang Bu, Gui-Wu Xiao, Lin Ma, Xing-Chum He, Ling-Quan Gu

Journal of Electrochemistry

The oxidation peak potentials (E_p) of alinine derivates and catechol in 0.1 mol/L KCl+15% alcohol solution were measured by cyclic voltammograms technique. The electrochemical oxidation condition was set according to the E_p. Three derivates of 4,5-disubstituted -1,2-benzoquinones were prepared via electrochemical oxidation-Michael addition reaction. The possible mechanism of electrochemical oxidation-Michael addition reaction is presented.

The Study On Fabricating Thin Electrodes For Polymer Electrolyte Membrane Fuel Cells (Pemfc), Yong-Sheng Yang, Jing-Hua Liu, Chang-Peng Liu, Gong-Quan Sun, Chang-Zhi Li, Tian-Hong Lu

Journal of Electrochemistry

To lower platinum loading in electrodes for polymer electrolyte membrane fuel cell, a new thin electrode fabrication technique (TEFT) was developed in this work. A series of low Pt loading electrodes with smooth and uniformed surface were fabricated by the TEFT. As a result, the maximum power density of the cell with platinum loading of 1 mg/cm² and Nafion 117 membrane as electrolyte was up to 0.3 W.cm^-2. Moreover, the effects of PTFE and Nafion content in cathodes on the performance of PEMFC with low Pt loading electrodes (1 mg Pt/cm²) were examined systematically.

Microsystem And Electrochemistry, Zhong-Qun Tian, Jian-Jun Sun

Journal of Electrochemistry

Microsystem or micro electromechanical system (MEMS) is briefly introduced. The electrochemical applications in microsystem are reviewed and prospective applications of microsystem in electrochemistry are discussed. Along with the rapid development of micro_ analytical chemical systems or lab-on-chips in 21st century, electrochemistry may play an increasingly important role in microsystem technology.

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.

Electrochemical Characterization Of Ir-Ta-Ti Metal Oxide Coated Titanium Anodes, Ting-Yong Wang, Li-Kun Xu, Guang-Zhang Chen

Journal of Electrochemistry

Ir-Ta-Ti metal oxide coated titanium anodes of variable composition were prepared by thermal decomposition. Their micro morphorogies and electrochemical properties were characterized by scanning electron microscope, open circuit potential, cyclic voltammetry, consumption rate measurements and accelerated life test. The SEM results indicated that all coatings were of a porous and cracked-mud microstructure influenced greatly by the composition of coatings. The electrochemical measurements showed that the Ir-Ta-Ti ternary oxide-coated anodes exhibited excellent electrochemical activity and electrochemical stability in both acidic media and seawater which were affected by the composition and microstructure of the coatings. Owing to good corrosion resistance and low …

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 …

An Eis Study On The Synergetic Filming Between Cathodic Protection And The Corrosion Inhibitor, Yong-Tao Zhao, Jian-Hua Wu, Jian-Hua Qian, Hui Yu

Journal of Electrochemistry

The electrochemical impedance spectroscope (EIS) of 907A steel in seawater was investigated to study the film formation and destruction. The corrosion protection mechanism of the synergy interaction between cathodic protection and YKI-5 corrosion inhibitor (a mixture of polyhydric alcohol phosphate ester, phosphate and polyphosphate) is discused. Typical EIS spectral changes were clearly observed during the film formation and destruction processes. EIS results indicated that the film seemed to formed a multi-layered structure which consist of an inner layer (this may be an inhibitor-metal complex layer) and many outer layers of calcareous deposits. The film possesses of good persistency under the …

Electro-Oxidation Of Glyoxal To Glyoxalic Acid, Yin-Sheng Chen, Xin-Sheng Zhang, Jun Hu, Ying-Chun Dai

Journal of Electrochemistry

An investigation has been made to obtain the glyoxalic acid by the electrochemical oxidation of glyoxal solution with hydrochloric acid under various experimental conditions.The cell used consists of a lead cathode, a DSA anode and a cation-exchange membrane of model CM001. The current efficiency and yield for glyoxalic acid generation were 80.0% and 91.1% respectively, under optimal operating conditions: velocity of electrolyte flow 1.4 m·s^-1 ,current density 450 A·m^-2, temperature 30～40 ℃, initial concentration of glyoxal and hydrochloric acid 9.1%～16.0%, 4%～6%, respectively.

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 …