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21.
The adsorption of I− ions on the Cd(0001) single crystal plane from solutions in methanol has been investigated by impedance measurement method.
The ionic charge due to the specific adsorption has been obtained using the mixed-electrolyte method for both electrode charge
and electrode potential as the independent electrical variables. The Gibbs energy of adsorption of ions has been calculated
using the different modifications of the virial adsorption isotherm. It was found that under comparable conditions, the results
obtained at constant electrode potential and at constant electrode charge are coincident and the adsorption of I− anion increases in the sequence of solvents: water < methanol, ethanol, and metals: Cd < Bi. The electrosorption valency
has been calculated. It was found that on the Cd(0001) plane the electrosorption valency of I− anions has a constant value that is similar for methanol and ethanol and also for these solvents on Bi single crystal planes. 相似文献
22.
Meeri Lembinen Ergo Nõmmiste Heigo Ers Borja Docampo-Álvarez Jaanus Kruusma Enn Lust Vladislav B. Ivaništšev 《International journal of quantum chemistry》2020,120(14):e26247
On the example of 40 ion pairs (5 cations times 8 anions), this study demonstrates how the core-level binding energy values can be calculated and used to plot theoretical spectra at low computational cost using density functional theory methods. Three approaches for obtaining the binding energy values are based on delta Kohn–Sham (ΔKS) calculations, 1s KS orbital energies, and atomic charges. The ΔKS results show reasonable agreement with the available experimental X-ray photoelectron data. The 1s KS orbital energies correlate well with the ΔKS results. Atomic charge correlation with ΔKS is improved by accounting for the charges of neighboring atoms. Assignment of binding energies to atoms and the applicability of the mentioned methods to model systems of ionic liquids are discussed. 相似文献
23.
24.
Enn Lust Gunnar Nurk Alar Jänes Mati Arulepp Priit Nigu Priit Möller Silvar Kallip Väino Sammelselg 《Journal of Solid State Electrochemistry》2003,7(2):91-105
Electrical double layer and electrochemical characteristics at the nanoporous carbon|acetonitrile interface with additions
of Et4NBF4, Et3MeNBF4, EtMe3NBF4, LiClO4, and LiBF4 have been studied by cyclic voltammetry and impedance spectroscopy methods. A value of zero charge potential, dependent on
the structure of the cations as well as on the composition of the anions, the region of ideal polarizability, and other characteristics
has been established. Analysis of the complex plane plots shows that the nanoporous carbon|acetonitrile+0.1 M electrolyte
(Et4NBF4, Et3MeNBF4, or EtMe3NBF4) interface can be simulated by the equivalent circuit, in which the two parallel conduction parts in the solid and liquid
phases are interconnected by the double layer capacitance in parallel with the complex admittance of the hindered reaction
of the charge transfer process or of the partial charge transfer (i.e. adsorption stage limited) process. The values of the
characteristic frequency depend on the electrolyte composition and on the electrode potential, i.e. on the nature of the ions
adsorbed at the surface of the nanoporous carbon electrode. In the region of moderate a.c. frequencies, the modified Randles-like
equivalent circuit has been used for simulation of the complex plane plots. In the region of negative surface charge densities,
the intercalation process of Li+ ions from LiClO4 and LiBF4 solutions into the surface film is possible and these data can be simulated using the modified Ho et al. model or Meyer et
al. model.
Electronic Publication 相似文献
25.
Kinetics of the reaction between acetylene and phenylmagnesium bromide were investigated in diethyl ether in the presence of small additions of triethylamine and without a catalyst. The mechanistic scheme suggested by Grignard et al. was supplemented with the reaction of bromomagnesiumacetylene with the Grignard reagent. The rate constants for individual reactions were determined. Triethylamine catalyzes the reactions to different extents, the conversions of bromomagnesiumacetylene being the most susceptible to the catalysis. The possible ways of the action of the catalyst were discussed and the importance of nucleophilic assistance was stressed. 相似文献
26.
Arvet Pedas Enn Tamme 《Applied Numerical Mathematics》2011,61(6):738-751
A fully discrete version of a piecewise polynomial collocation method is constructed to solve initial or boundary value problems of linear Fredholm integro-differential equations with weakly singular kernels. Using an integral equation reformulation and special graded grids, optimal global convergence estimates are derived. For special values of parameters an improvement of the convergence rate of elaborated numerical schemes is established. Some of our theoretical results are illustrated by numerical experiments. 相似文献
27.
Arvet Pedas Enn Tamme 《Journal of Computational and Applied Mathematics》2011,235(12):3502-3514
In the first part of this paper we study the regularity properties of solutions of initial value problems of linear multi-term fractional differential equations. We then use these results in the convergence analysis of a polynomial spline collocation method for solving such problems numerically. Using an integral equation reformulation and special non-uniform grids, global convergence estimates are derived. From these estimates it follows that the method has a rapid convergence if we use suitable nonuniform grids and the nodes of the composite Gaussian quadrature formulas as collocation points. Theoretical results are verified by some numerical examples. 相似文献
28.
Eneli Härk Karmen Lust Alar Jänes Enn Lust 《Journal of Solid State Electrochemistry》2009,13(5):745-754
Electrochemical impedance spectroscopy has been applied for investigation of the hydrogen evolution kinetics at the electrochemically
polished Bi(001) plane, and the complicated reaction mechanism (slow adsorption and charge-transfer steps) has been established.
The charge-transfer resistance and adsorption capacitance values depend noticeably on the electrode potential applied. The
adsorption resistance is maximal in the region of electrode potential E
min = −0.65 V vs. (Hg|Hg2Cl2|4 M KCl), where the minimal values of constant phase element (CPE) coefficient Q have been calculated. The fractional exponent α
CPE values of the CPE close to unity (α
CPE ≥ 0.94 and weakly dependent on the electrode potential and pH of solution () have been obtained, indicating the weak deviation of Bi(001)|HClO4 + H2O interface from the ideally flat capacitive electrode. Q differs only very slightly from double-layer capacitance C
dl values in the whole region of potentials and , investigated. 相似文献
29.
Enn Lust Priit Möller Indrek Kivi Gunnar Nurk Silvar Kallip 《Journal of Solid State Electrochemistry》2005,9(12):882-889
Cyclic voltammetry, chronoamperometry and electro-chemical impedance have been used for the analysis of the following medium
temperature half-cells: Ce0.85Sm0.15O1.925| La0.6Sr0.4CoO3-δ, Ce0.85Sm0.15O1.925| Pr0.6Sr0.4CoO3-δ and Ce0.85Sm0.15O1.925| Gd0.6Sr0.4CoO3-δ. The influence of the atomic mass of the A–site cation in the perovskite cathode on the oxygen reduction kinetics has been
discussed. The total polarisation resistance, obtained from the Z′′, Z′-plots, increases with the rise of atomic mass of the cation in the A-site position. Two different time constants have been
obtained for the oxygen electroreduction process, and the replacement of La3+ by Gd3+ in the cathode material decreases somewhat the surface catalytic activity, but the noticeably higher low-frequency series
resistance, i.e. mainly diffusion-like mass transfer resistance, values have been obtained. However, the mainly diffusion-limited
process at T≤773 K for Gd0.6Sr0.4CoO3-δ and the kinetically mixed process (diffusion + charge transfer) for Pr0.6Sr0.4CoO3-δ and La0.6Sr0.4CoO3-δ have been established. At higher temperature (T≥993 K) and more negative potentials, the O2 reduction process is limited mainly by the heterogeneous charge transfer step.
Presented at the fourth Baltic Conference on Electrochemistry, Greifswald, March 13–16, 2005. 相似文献
30.
Enn Otsa L. S. Kudrjawzewa O. G. Eisen E. M. Piotrowskaja 《Monatshefte für Chemie / Chemical Monthly》1980,111(3):607-617
The vapour-liquid equilibrium data obtained from isobarict-x-measurements have been used for calculation of the group UNIFAC parameters and excess free enthalpyG
E
of binary mixturesn-alkanes with isomericn-alkynes. The UNIFAC model gives satisfactory predictions for the systems studied. The temperature dependence ofG
E
was estimated on the basis of the heats of mixing measured earlier. The influence of the position of triple bond in the molecules ofn-alkynes on the excess thermodynamic functions is considered. 相似文献