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1.
Investigation of the state of the electrochemically generated adsorbed O species on Au films interfaced with Y2O3-doped-ZrO2 总被引:1,自引:0,他引:1
Adsorbed O species on Au interfaced with Y2O3-doped-ZrO2 are generated by electrochemical O2− supply. It was found that two oxygen chemisorbed states are formed, which desorb at 420 °C (state α) and 550 °C (state β)
with activation energies of desorption ranging between 115–145 kJ/mol and 235–270 kJ/mol, respectively. The strong interaction
of the β-state O species with the Au surface causes an over 600 mV increase in Au surface potential and work function while
the α-state O species is formed at even more positive catalyst-electrode potential. State α is attributed to normally adsorbed
atomic O while the more ionic state β is only created electro-chemically and is mainly responsible for the work function increase
of the Au catalyst-electrode surface. Their desorption activation energies of both states decrease linearly with increasing
catalyst-electrode potential with slopes of the order of four.
Paper presented at the 7th Euroconference on Ionics, Calcatoggio, Corsica, France, Oct. 1–7, 2000. 相似文献
2.
N. D. Strekal’ I. G. Motevich J. W. Nowicky S. A. Maskevich 《Journal of Applied Spectroscopy》2007,74(1):31-37
We present the IR absorption and surface-enhanced Raman scattering (SERS) spectra of the isoquinoline alkaloid berberine adsorbed
on a silver hydrosol and on the surface of a silver electrode for different potentials. Based on quantum chemical calculations,
for the first time we have assigned the vibrations in the berberine molecule according to vibrational mode. The effect of
the potential of the silver electrode on the geometry of sorption of the molecule on the surface is considered, assuming a
short-range mechanism for enhancement of Raman scattering.
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Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 1, pp. 31–36, January–February, 2007. 相似文献
3.
LiCoO2 particles were synthesized by a sol-gel process. X-ray diffraction analysis reveals that the prepared sample is a single
phase with layered structure. A hybrid electrochemical capacitor was fabricated with LiCoO2 as a positive electrode and activated carbon (AC) as a negative electrode in various aqueous electrolytes. Pseudo-capacitive
properties of the LiCoO2/AC electrochemical capacitor were determined by cyclic voltammetry, charge–discharge test, and electrochemical impedance
measurement. The charge storage mechanism of the LiCoO2-positive electrode in aqueous electrolyte was discussed, too. The results showed that the potential range, scan rate, species
of aqueous electrolyte, and current density had great effect on capacitive properties of the hybrid capacitor. In the potential
range of 0–1.4 V, it delivered a discharge specific capacitance of 45.9 Fg–1 (based on the active mass of the two electrodes) at a current density of 100 mAg–1 in 1 molL–1 Li2SO4 aqueous electrolyte. The specific capacitance remained 41.7 Fg–1 after 600 cycles. 相似文献
4.
A quantum-chemical calculation of the prodan molecule and its complexes in water for the geometry of the ground and fluorescent
states is carried out. To describe the fluorescent state, changes in the electronic state (population) on bonds and atoms
during transition of the molecule into an excited state are taken into account. A model of interaction of the prodan molecule
with a polar proton-donor solvent (water) is suggested. It is shown that interaction with the ionic forms (H3O+ provides an explanation for the sensitivity of prodan to the solvent (displacement of the fluorescence bands). The nature
of the electronic excited states of the prodan molecule and its complexes has been investigated. The constants of the rates
of radiative and nonradiative processes and the fluorescence quantum yields have been calculated.
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Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 3, pp. 330–334, May–June, 2005. 相似文献
5.
The electrochemical reduction of nitric oxide in the presence of the excess oxygen was reviewed. It was shown that the selectivity
and activity of the cathodes is strongly dependent on the composition and on the microstructure of the cathode material. A
concept of electrochemical reactor with multilayer electro-catalytic electrode was proposed and successfully designed in Advanced
Manufacturing Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Nagoya, Japan.
The typical values of current efficiency in such electrochemical reactors are of the order of 10–20% at gas composition: 1,000 ppm
NO and 2% O2 balanced in He and at gas flow rate 50 ml/min. The value of current efficiency depends on the functional multi-layer electrode
composition, structure, and operating temperature. Such electrochemical reactors show the value of NO/O2 selectivity (ν
sel) higher than 5 (ν
sel > 5) at intermediate temperature and up to ν
sel = 25 at low temperature operation. It was shown that multilayer electro-catalytic electrode should consist at list from three
main functional layers: cathode, electro-catalytic electrode, covering layer, in order to operate as an electrode with high
selectivity. 相似文献
6.
The Thermal Desorption or Temperature Programmed Desorption (TPD) technique has been used for the study of oxygen adsorption
on Pt, Ag and Au catalyst films deposited on YSZ. The catalyst film was deposited on the one side of the YSZ specimen while
on the other side gold counter and reference electrodes were deposited, constructing a three-electrode electrochemical cell
similar to those used in Electrochemical Promotion studies. Oxygen adsorption has been carried out either by exposing the
samples to gaseous oxygen (gas phase adsorption) or by the application of a constant current between the catalyst/working
electrode and the counter electrode (electrochemical adsorption) or by mixed gas phase and electrochemical adsorption. Oxygen
adsorption was carried out at temperatures between 200 and 480 °C. After exposure to gaseous oxygen, normal adsorbed atomic
oxygen species have been observed on Pt and Ag surfaces while there was no detectable amount of adsorbed oxygen on Au. Electrochemical
O2− pumping to Pt, Ag and Au catalyst films creates strongly bonded “backspillover” anionic oxygen, along with the more weakly
bonded atomic oxygen. Electrochemical O2− pumping to Pt, Ag and Au catalyst films in presence of preadsorbed oxygen creates strongly bonded “backspillover” anionic
oxygen, with a concomitant pronounced lowering of the Tp of the more weakly bound preadsorbed atomic oxygen. The two oxygen species co-exist on the surface. The activation energy
for oxygen desorption or, equivalently, the binding strength of adsorbed oxygen was found to decrease linearly with increasing
catalyst potential, for all three metal electrodes.
Paper presented at the 4th Euroconference on Solid State Ionics, Renvyle, Galway, Ireland Sept. 13–19, 1997 相似文献
7.
I. G. Motevich N. D. Strekal’ J. W. Nowicky S. A. Maskevich 《Journal of Applied Spectroscopy》2007,74(5):666-672
We have studied the absorption, fluorescence, and surface-enhanced Raman scattering (SERS) spectra of sanguinarine using a
silver hydrosol and an electrochemical cell with a silver working electrode for different pH values in the medium. We carried
out quantum chemical calculations in order to interpret the electronic and vibrational spectra and to establish their correlations
with the structure of the molecules. We optimized the structure and determined the spectral characteristics of the cationic
and neutral forms of the sanguinarine molecules in solution and adsorbed on the surface of an anodized Ag electrode for different
potentials.
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Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 5, pp. 604–609, September–October, 2007. 相似文献
8.
T. I. Kovalevskaya 《Journal of Applied Spectroscopy》1998,65(3):459-462
The IR absorption spectra of thin nitrobenzene, ethylene glycol, and glycerin layers in an electric field are investigated.
It was established that the spectrum change and electro-optical effects depend on the molecular structure of these liquids.
Grodno State University, 22, Ozheshko St., Grodno, 230023, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol.
65, No. 3, pp. 441–444, May–June, 1998. 相似文献
9.
We present results of research on the effect of the parameters of an XeCl-laser excitation system patterned after an LC-inverter
on the energy characteristics of the laser. The effect of each of the parameters and their collection is established. We obtained
conditions for matching the parameters of the excitation circuit of an XeCl-laser on satisfaction of which the lasing energy
acquires a maximum value. It is shown that the energy characteristics of the laser are determined by the processes occurring
in the inversion circuit and by the dynamics of the voltage across the interelectrode spacing.
To whom correspondence should be addressed.
Reported at the Second International Scientific and Technical Conference on Quantum Electronics, Minsk, November 23–25, 1998.
Ya. Kupala Grodno State University, 22, Ozheshko Str., Grodno, 230023, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii,
Vol. 66, No. 5, pp. 702–707, September–October, 1999. 相似文献
10.
S as additive in Mg–Cu<Subscript>2</Subscript>O seawater batteries using Ni foam-supported electrode
Cu2O with S as additive electrode using Ni foam as the substrate is prepared in Mg–Cu2O seawater battery. The morphology and electrochemistry performance of electrode are investigated. The excellent electrochemical
properties of Ni foam-supported electrode indicate that it is suitable for seawater devices. The cell voltage of Mg–Cu2O seawater batteries is elevated by sulphur addition. Sulphur participates in the electrochemical reactions; the elevation
in cell voltage is 200–350 mV according to the ratio of Cu2O to S. 相似文献
11.
For a model with the SU(2)L×SU(2)R×U(1){B−L} gauge group, the passage of neutrino flux through a substance is studied. It is shown that Higgs charged physical bosons
can considerably change the potential of neutrino interaction with the solar substance. An analytical expression for the survival
probability of left-handed electron neutrinos is derived in the two-flavor approximation.
Yanka Kupala Grodno State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 32–37, January,
2000. 相似文献
12.
LiMn2O4 spinel cathode was synthesized by the sol–gel method by using glycolic acid as a chelating agent. The sample exhibited a
pure cubic spinel structure without any impurities in the X-ray diffraction (XRD) patterns. The result of the electrochemical
performances on the sample compared to those of electrodes based on LiMn2O4 spinel synthesized by solid state. LiMn2O4 synthesized by glycolic acid-assisted sol–gel method improves the cycling stability of electrode. The capacity retention
of sol–gel-synthesized LiMn2O4 was about 90• after 100 cycles between 3.0 and 4.4 V at room temperature. The electrochemical performance of the LiMn2O4 (sol–gel) and LiMn2O4 (solid state) were investigated under 40• between 3.0 and 4.4 V. XRD results of the cathode material after 50 cycles at 40•
revealed that LiMn2O4 (sol–gel) could effectively suppress the LiMn2O4 dissolving of into electrolyte and resulted in a better stability. 相似文献
13.
O. V. Ovchinnikov E. A. Kosyakova M. S. Smirnov A. B. Evlev V. G. Klyuev A. N. Latyshev A. N. Utekhin 《Journal of Applied Spectroscopy》2007,74(5):681-686
For microcrystals of Zn0.6Cd0.4S with adsorbed molecules of a number of organic dyes, we have observed sensitized anti-Stokes luminescence excited by radiation
with wavelengths in the range 610–750 nm and flux density 1014–1015 photons/cm2·sec. The positions of the bands in the excitation spectra for such luminescence match those of the absorption spectra for
the adsorbed dye molecules, which is evidence in favor of a cooperative mechanism for its appearance. We have shown that enhancement
of the anti-Stokes luminescence is possible when silver atoms and few-atom clusters appear on the Zn0.6Cd0.4S surface in addition to the dye molecules. We hypothesize that its excitation in the latter case occurs as a result of two-photon
optical transitions. These transitions occur sequentially, with transfer of an electron or the electronic excitation energy
from the dye molecules to silver atoms and few-atom clusters adsorbed on the surface of Zn0.6Cd0.4S, creating deep localized states in the bandgap with photoionization energies 1.80–2.00 eV.
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Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 5, pp. 617–621, September–October, 2007. 相似文献
14.
V. A. Svetlichnyi M. P. Samtsov O. K. Bazyl’ O. V. Smirnov D. G. Mel’nikov A. P. Lugovskii 《Journal of Applied Spectroscopy》2007,74(4):524-532
We present results of experimental and theoretical studies of the optical characteristics of a new indotricarbocyanine dye
that is capable of effectively limiting the power of laser radiation in the visible spectral range. The spectral-luminescent
and energy characteristics of the dye molecules and their absorption spectra from the excited state with nanosecond resolution
are investigated experimentally. Quantum-chemical methods are used to calculate electronic absorption spectra from the ground
(S0 → Sn) and excited (S1 → Sn) states and to determine the nature of electronic states of the molecule and the rate constants of intramolecular photophysical
processes. The results of the theoretical research agree with experimental data. It is shown that the investigated dye has
singlet-singlet absorption at 400–600 nm. Nonlinear absorption of the dye upon excitation by radiation of the second harmonic
of a Nd:YAG laser is studied by z-scanning with an open diaphragm. The ratio of dye absorption cross sections from the excited
and ground states at 532 nm is determined in the framework of a three-level model. The results are compared with those for
previously studied compounds.
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Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 4, pp. 473–480, July–August, 2007. 相似文献
15.
N. I. Selivanov L. G. Samsonova V. Ya. Artyukhov T. N. Kopylova 《Russian Physics Journal》2011,54(5):601-606
Results of quantum-chemical studies of the nile red (NR) molecule and its protonated structures by the INDO/S method are presented.
It is demonstrated that the best agreement between the calculated and experimental data is obtained for the flat molecule
in the ground electron state. Energies of the strongest singlet and triplet electronic states, molecular nature of these states,
transition oscillator force, dipole moments in the ground and excited states, electron density distribution around atoms and
molecular fragments in the S0 and S1 states, and rate constants of radiative, internal, and intercombination conversion are presented for the NR molecule and
its protonated structures. The most probable NR protonation centers are analyzed using the molecular electrostatic potential
(MESP) method. It is established that the reaction of proton addition to the NR molecule proceeds at the cyclic nitrogen atom.
As demonstrated the results of quantum-chemical calculations, low fluorescent properties of the protonated NR structures (with
a quantum yield of 4%) are due to a high rate of the S1 – T4 intercombination conversion. 相似文献
16.
《Surface science》1996,364(1):L530-L539
In situ electrochemical scanning tunneling microscopy (ECSTM) has been employed to follow the renewal process of a graphite electrode accompanied by flavin adenine dinucleotide (FAD) electrochemical reaction which involves adsorption of the reduced form (FADH2) and desorption of the oxidized form (FAD). The renewal process initiates from steps or kinks on the electrode surface, which provide high active sites for adsorption. This renewal depends on the working electrode potential, especially in the range near the FAD redox potential. Our experiment suggests that delamination of the graphite surface is caused by interaction between the substrate and adsorbed molecules. A simple model is proposed to explain this phenomenon. 相似文献
17.
Abstract SERS has been used as a state-resolving probe to study the adsorption states. in the case of pyridine (Py) adsorbed on the Ag electrode surface, the equilibrium and transition between two adsorbed states, i.e., the perpendicular mode adsorbed through the nitrogen lone-pair electrons and the flat mode through the π electrons of the aromatic ring, were studied. It was found that in the low pyridine concentration or the initial stage of adsorption, the flat mode was favored. While the concentration became higher and the adsorption tended to equilibrium, the adsorbed molecules would transit to the perpendicular mode. The similar phenomenon was also observed when changing the applied electric potential and the pH value of the solution. In the case of the adsorption of Methylene Blue (MB) on the HNO3-etched silver surface, the influence of Cl? ions on the adsorption states of MB was investigated. It showed that MB molecules adsorbed on the silver surface tended to transform from the “lying-down” state to the “end-on” state while adding Cl? ions. 相似文献
18.
W.L. Winterbottom 《Surface science》1973,36(1):205-224
One of the major difficulties encountered in catalytic research has been the experimental characterization of the catalyst surface in its working state. Using thermal desorption techniques, we have developed a method capable of providing a quantitative measure of the concentrations of certain adsorbed reactants during catalysis. In a study of the oxidation of CO on polycrystalline platinum, three distinct reaction mechanisms have been distinguished: (1) the interaction of an oxygen molecule with a vacant Pt surface site and an adjacent adsorbed CO molecule forming a complex which dissociates to form a CO2 molecule and an adsorbed oxygen atom; (2) the reaction between adsorbed CO and an adsorbed oxygen atom, a process in which surface transport is required to bring the reactants together; and (3) the reaction between a colliding CO molecule and an adsorbed oxygen atom. Rate constants for the reaction steps have been measured, and the active surface sites and reactive surface states on the Pt catalyst have been characterized in terms of the adsorption properties of CO. 相似文献
19.
用CVD法在不同表面处理后的n-Si片上生长n-Fe2O3,薄膜,构成双层结构半导体光电极,研究界面态对电极性能的影响。由光萤光谱判断在距Fe2O3价带顶1.6eV处存在高态密度的界面态,对费密能级起钉扎作用,按这种能带图所作的理论计算与分析,给出光萤光谱的合理解释,并为电容-电压曲线及光电流-电压曲线的实验结果所证实。这种具有高态密度界面态的双层半导体结构,为稳定性良好、光电转换效率高的太阳能光电极提供了有希望的途径。
关键词: 相似文献
20.
Subthreshold photoemission from copper nanoclusters formed on the SiO2 surface has been observed under irradiation of the surface by photons in the 3.1–6.5-eV energy range. The average size of
copper nanoclusters on the silicon oxide surface is 250–500 nm. Besides the conventional photoemission from the filled Shockley
surface state (SS), strong photoemission has been recorded at incident photon energies of 0.5 eV below the work function of
the copper surface. This emission is assumed to be generated in direct electron transitions from the SS state to the unfilled
electron surface states formed by the Coulomb image potential, followed by escape from these states into vacuum. 相似文献