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1.
The (CO2)i(H2O)10 clusters with the kinetic energy corresponding to a temperature of 233 K is simulated by the molecular dynamics method. The stability of these clusters with respect to thermal, mechanical, and dielectric perturbations, as well as to the absorption of CO2 molecules, is studied. It is shown that the cluster composed of 10 water molecules remains thermodynamically stable if it captures one or two CO2 molecules. Clusters are absolutely unstable when 3 ≤ i ≤ 9. A metastable state of clusters is achieved at i > 9.__________Translated from Kolloidnyi Zhurnal, Vol. 67, No. 3, 2005, pp. 308–314.Original Russian Text Copyright © 2005 by Galashev, Rakhmanova, Chukanov. 相似文献
2.
The simulation of the absorption of CO2 molecules by the (H2O)10 cluster is performed by the molecular dynamics method using the modified TIP4P model of water. The detailed structure of (CO2)i(H2O)10 clusters (0≤i≤11) is analyzed by the statistic geometry method based on the construction of the Voronoi polyhedra. The obtained distributions of the geometric elements of polyhedra indicate the significant changes in the structure of a cluster after the absorption of one CO2 molecule. Only polyhedra characterizing the structure of unstable water clusters that absorbed six or seven CO2 molecules demonstrate a nonsphericity close to the ideal tetrahedron. Linear CO2 molecule tends to be oriented in a cluster so that the average angle formed by this molecule and permanent dipole moments of water molecules would be equal to about 30°.__________Translated from Kolloidnyi Zhurnal, Vol. 67, No. 3, 2005, pp. 315–321.Original Russian Text Copyright © 2005 by Galashev, Rakhmanova, Chukanov. 相似文献
3.
A. E. Galashev V. N. Chukanov A. N. Novruzov O. A. Novruzova 《Russian Journal of Electrochemistry》2007,43(2):136-145
Molecular dynamics method is used for studying complex permittivity ɛ and the stability of individual water clusters as a
function of the number of involved molecules (7 ≤ i ≤ 20) and also the corresponding characteristics of water aggregates with a captured CO2 or CH4 molecule. Absorption of the latter molecules leads to considerable changes in dielectric properties and stability of clusters.
In particular, upon the addition of a CO2 molecule to a water cluster, the oscillation parameters of the real and imaginary parts of the permittivity change. Capture
of a CH4 molecule by a water aggregate changes the ɛ(ω) dependence from the relaxation to resonance type. For i ≥ 15, the thermal stability of individual water clusters can be lower than that of aggregates CO2(H2O)
i
and CH4(H2O)
i
. The mechanical stability of (H2O)
i ≥ 13 clusters can exceed that of heteroclusters under consideration. Clusters (H2O)
i
and CO2(H2O)
i
have approximately the same dielectric stability, whereas aggregates CH4(H2O)
i
exhibit lower stability with respect to electric perturbations.
Original Russian Text ? A.E. Galashev, V.N. Chukanov, A.N. Novruzov, O.A. Novruzova, 2007, published in Elektrokhimiya, 2007,
Vol. 43, No. 2, pp. 143–153. 相似文献
4.
Anodic oxidation of highly oriented pyrolytic graphite in an electrolyte containing concentrated sulfuric and anhydrous phosphoric acids is studied for the first time. The synthesis was carried out under galvanostatic conditions at a current I = 0.5 mA and an elevated temperature (t = 80°C). Intercalation compounds of graphite (ICG) are shown to form at all concentration ratios of H2SO4 and H3PO4 acids. The intercalation compound of step I forms in solutions containing more than 80 wt % H2SO4, a mixture of compounds of intercalation steps I and II forms in 60% H2SO4, intercalation step II is realized in the sulfuric acid concentration range from 10 to 40%, and a mixture of compounds of intercalation steps III and II is formed in 5% H2SO4 solutions. The threshold concentration of H2SO4 intercalation is ∼2%. With the decrease in active intercalate (H2SO4) concentration, the charging curves are gradually smoothed, the intercalation step number increases, and the potentials of ICG formation also increase. As the sulfuric acid concentration in the electrolyte changes from 96 to 40 wt %, the filled-layer thickness d
i in ICG monotonously increases from 0.803 to 0.820 nm, which apparently is associated with the greater size of phosphoric acid molecules. With further increase in H3PO4 concentration in solution, d
i remains unchanged. According to the results of chemical analysis, both acids are simultaneously incorporated into the graphite interplanar spacing and their ratio in ICG is determined by the electrolyte composition.__________Translated from Elektrokhimiya, Vol. 41, No. 5, 2005, pp. 651–655.Original Russian Text Copyright © 2005 by Leshin, Sorokina, Avdeev. 相似文献
5.
Autocorrelation functions of the total dipole moment of clusters composed of H2O and N2O molecules are calculated in terms of the molecular dynamics method. The IR absorption and reflection spectra of systems composed of (H2O)i, N2O(H2O)i, and (N2O)2(H2O)i clusters (2 ≤ i ≤ 20) are obtained on the basis of these functions. Frequency-dependent dielectric permittivity of clusters increases after the absorption of N2O molecules. The absorption coefficient of cluster systems with trapped N2O molecules increases at low frequencies and decays at frequencies ω > 500 cm?1. The inclusion of N2O molecules increases also reflection coefficient R and changes the pattern of R(ω) spectra. The absorption of IR radiation increases with the number of H2O molecules in clusters. Dielectric losses also increase with an increase in i number upon the absorption of N2O molecules. The number of electrons interacting with an incident electromagnetic wave increases upon the capture of N2O molecules. 相似文献
6.
V. M. Bzhezovskii N. N. Il’chenko M. B. Chura L. G. Gorb L. M. Yagupol’skii 《Russian Journal of General Chemistry》2005,75(1):86-93
The potential functions of internal rotation around the C
-S bond in the C6H5S(O)CH3 and C6H5S(O)CF3 molecules were obtained by ab initio MP2(full)/6-31+G* calculations. The stationary points were identified by solving the vibrational problems. The structures in which the plane of the C
-S-C
bonds is approximately perpendicular to the benzene ring plane correspond to the energy minimum. The barriers to rotation around the C
-S bond, corrected for the zero-point vibration energy, are 21.29 [C6H5S(O)CH3] and 28.98 [C6H5S(O)CF3] kJ mol−1. The bond angles (deg) are as follows: 95.7 (CSC), 107.1 (C
SO), 106.3 (C
SO) in C6H5S(O)CH3; 93.5 (CSC), 108.2 (C
SO), 105.2 (C
SO) in C6H5S(O)CF3. The bond lengths are as follows (Å): 1.520 (S=O), 1.804 (C
-S), 1.810 (C
-S) in C6H5S(O)CH3; 1.507 (S=O), 1.799 (C
-S), 1.870 (C
-S) in C6H5S(O)CF3. According to the results of NBO calculations, the formally double S=O bond consists of a strongly polarized covalent σ bond (S→O) and an almost ionic bond. An increase in the S=O bond multiplicity relative to a single bond is mainly due to hyperconjugation by the mechanism n(O)→σ*(C
-S) and n(O)→σ*(C
-S) and, to a lesser extent, by interaction of the oxygen lone electron pairs with the Rydberg orbitals of the S atoms, characterized by a large contribution of the d component.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 1, 2005, pp. 96–104.Original Russian Text Copyright © 2005 by Bzhezovskii, Il’chenko, Chura, Gorb, Yagupol’skii. 相似文献
7.
Investigations of phase transitions in barium cerate are carried out by methods of dilatometry and differential scanning calorimetry. Thermal desorption of gases and temperature dependences of electroconduction in dry and humid air are studied. Barium cerate exhibits complex polymorphism, undergoing a number of structural conversions at 300– 1300 K. The peaks in the spectra of thermal desorption of CO2 and H2O correlate with variations in the crystal lattice. Structural changes in BaCeO3 affect activation energies for the carrier transport and the shares of partial conductivities.__________Translated from Elektrokhimiya, Vol. 41, No. 5, 2005, pp. 620–626.Original Russian Text Copyright © 2005 by Kuz’min, Gorelov, Vaganov, Korzun, Kazantsev, Aksenova, Khromushin. 相似文献
8.
An extended hydrogen-bonded two-dimensional fumarato-bridged complex [Co(μ-fumarato)(γ-methylpyridine)2(H2O)2]∞ has been synthesized and its crystal structure determined by single crystal X-ray analysis. The X-ray analysis reveals that the cobalt atom is positioned in distorted octahedral surroundings. An extended twodimensional structure was formed through interchain hydrogen bonding. Magnetic measurements showed the presence of weak antiferromagnetic exchange interactions between the cobalt(II) ions within the chain, based on the
spin Hamilitonian H = −2J ∑ Si Si+ 1 (J = − 0.22 cm−1). 相似文献
9.
Z. Z. Baroš B. K. Adnađević 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2011,85(13):2295-2298
The influence of the molar ratio h = [H2O]/[Ti(OR)4] (R = Pr
i
) on the kinetics of the titanium-oxo-alkoxy clusters (TOAC) nucleation was studied. Clusters were formed by the titanium
tetraisopropoxide Ti(OPr
i
)4 chemical reaction with H2O in n-propanol solution, with the fixed concentration of Ti(OPr
i
)4 (c = 0.04 M), molar ratio h ∈ {11, 14, 17, 20} and temperature T ∈ {298, 308, 318} K. It was determined that the isothermal rate of clusters nucleation is a power law function of the molar
ratio h. The kinetic parameter β value changes complexly as h and T change. The value of apparent activation energy of the nucleation process (E
a) decreases with the increase of value h. It was found that nucleation is a reaction with complex kinetics whose elementary stages are hydrolysis Ti(OR)4 to Ti(OR)3OH and formation of titanium-oxo-alkoxy clusters [Ti
n + βOβ](OR)4n + 2β through the alcoxolation reaction. 相似文献
10.
The time curves of full polarization resistance of Ni cermet electrode modified with CeO2 − δ additive were studied by means of impedance spectroscopy in binary gas mixtures x% H2 + (100 − x)% H2O, 10% CO + 90% CO2 and multicomponent gas mixtures H2 + CO2 + H2O + CO + Ar of various composition at the temperature of 900°C. The Ni cermet electrode degradation rate in binary gas mixtures
H2 + H2O was shown to increase sharply at the partial water pressure over 45%. The Ni cermet electrode degradation rate in the mixture
of 10% CO + 90% CO2 was significantly lower than that in 10% H2 + 90% H2O. The major changes in the electrode characteristics upon long exposure in working conditions were accounted for by changes
in the high-frequency partial polarization resistance. In the course of long testing, the electrode microstructure was not
significantly changed. In the presence of hydrogen-containing components (H2 and H2O), the carbon-containing components (CO and CO2) were shown to make an insignificant contribution to the current generation processes in Ni cermet electrode. It was suggested
that strong degradation of Ni cermet electrode was caused by poisoning its reaction sites with strongly linked adsorption
forms of water (hydroxyls) at the positive charge of electrode. 相似文献
11.
The interaction of IR radiation with water clusters that have absorbed NO2 molecules is studied by the molecular dynamics method in terms of the polarizable model. Induced dipole moments of H2O and NO2 molecules diminish during the addition of one to six NO2 molecules to (H2O)50 cluster. The integral intensity of IR absorption by a system consisting of (NO2)
i
(H2O)50 heteroclusters with 1 ≤ i ≤ 6 decreases, whereas the power of heat emission rises as compared with an (H2O)
n
system. The decrease in the IR absorption and the increase in the IR emission by water clusters with the capture of NO2 molecules are nonmonotonic. The absorption of NO2 molecules by water clusters causes a noticeable reduction in the intensity of the first peak and the confluence of the fourth
and fifth peaks in the Raman spectrum. 相似文献
12.
Vibrational spectra of finely divided amorphous CsHSO4,Cs5H3(SO4)4 · H2O, and composites based on these are measured and analyzed. An analysis of the spectra indicates the occurrence of substantial changes in the system of hydrogen bonds and in the spectral range of the sulfate group of acid sulfates in the composites. Structural dynamics of the SO4 tetrahedrons is in full conformance with protonic conduction and the data of x-ray diffraction analyses accompanied by differential scanning calorimetry. It is shown that mobility of protons in the composites increases. A mechanism of the formation of the composites and their conduction is proposed.__________Translated from Elektrokhimiya, Vol. 41, No. 5, 2005, pp. 640–645.Original Russian Text Copyright © 2005 by Ponomareva, Lavrova, Burgina. 相似文献
13.
The absorption of CO and NO molecules by (H2O)20 clusters was studied by the method of molecular dynamics. In general, the clusters containing CO molecules are more stable mechanically, while the clusters with NO molecules are more stable against heating. The mobility of NO molecules in such clusters is higher than that of CO molecules. The total dipole moment, the static dielectric permeability, the number of active electrons in the clusters, and the specific number of hydrogen bonds between water molecules possess peak values when the number of doping molecules i = 6. IR absorption spectra mostly acquire a smooth shape at i > 6. Capture of CO and NO molecules by water cluster operates as anti-greenhouse effect. 相似文献
14.
Rajeev K. Sinha Edith Nicol Vincent Steinmetz Philippe Maître 《Journal of the American Society for Mass Spectrometry》2010,21(5):758-772
Gas-phase infrared photodissociation spectroscopy is reported for the microsolvated [Mn(ClO4)(H2O)
n
]+ and [Mn2(ClO4)3(H2O)
n
]+ complexes from n = 2 to 5. Electrosprayed ions are isolated in an ion-trap where they are photodissociated. The 2600–3800 cm−1 spectral region associated with the OH stretching mode is scanned with a relatively low-power infrared table-top laser, which
is used in combination with a CO2 laser to enhance the photofragmentation yield of these strongly bound ions. Hydrogen bonding is evidenced by a relatively
broad band red-shifted from the free OH region. Band assignment based on quantum chemical calculations suggest that there
is formation of water—perchlorate hydrogen bond within the first coordination shell of high-spin Mn(II). Although the observed
spectral features are also compatible with the formation of structures with double-acceptor water in the second shell, these
structures are found relatively high in energy compared with structures with all water directly bound to manganese. Using
the highly intense IR beam of the free electron laser CLIO in the 800–1700 cm−1, we were also able to characterize the coordination mode (η2) of perchlorate for two clusters. The comparison of experimental and calculated spectra suggests that the perchlorate Cl—O
stretches are unexpectedly underestimated at the B3LYP level, while they are correctly described at the MP2 level allowing
for spectral assignment. 相似文献
15.
G. B. Andreev M. Yu. Antipin N. A. Budantseva E. V. Tuchina L. B. Serezhkina A. M. Fedoseev A. B. Yusov 《Russian Journal of Coordination Chemistry》2004,30(12):868-873
A complex of uranyl perchlorate with imidazolidine-2-one as the molecular ligand, [UO2(Imon)4(H2O)](ClO4)2 (I), was synthesized and structurally characterized by X-ray diffraction analysis. The coordination number of the uranium atom is 7. The nearest environment of the uranyl ion includes four O atoms of the imidazolidine-2-one molecules and one O atom of the water molecule. The perchlorate anions are outer-sphere ligands. The crystals are monoclinic: space group P21/c; a = 16.294(3) Å, b = 16.135(3) Å, c = 9.987(2) Å, = 97.69 (3)°, V = 2603.0 (9) Å3, (calcd) = 2.117 g/cm3, Z = 4. The IR and luminescence spectra of the complex were recorded.Translated from Koordinatsionnaya Khimiya, Vol. 30, No. 12, 2004, pp. 919–924.Original Russian Text Copyright © 2004 by Andreev, Antipin, Budantseva, Tuchina, Serezhkina, Fedoseev, Yusov. 相似文献
16.
R. L. Frost W. Martens M. O. Adebajo 《Journal of Thermal Analysis and Calorimetry》2005,81(2):351-355
Summary High resolution TG coupled to a gas evolution mass spectrometer has been used to study the thermal properties of a chromium based series of Ni/Cu hydrotalcites of formulae NixCu6-xCr2(OH)16(CO3)×4H2O where x varied from 6 to 0. The effect of increased Cu composition results in the increase of the endotherms and mass loss steps to higher temperatures. Evolved gas mass spectrometry shows that water is lost in a number of steps and that the interlayer carbonate anion is lost simultaneously with hydroxyl units. Differential scanning calorimetry was used to determine the heat flow steps for the thermal decomposition of the synthetic hydrotalcites. Hydrotalcites in which M2+ consist of Cu, Ni or Co form important precursors for mixed metal-oxide catalysts. The application of these mixed metal oxides is in the wet catalytic oxidation of low concentrations of retractable organics in water. Therefore, the thermal behaviour of synthetic hydrotalcites, NixCu6-xCr2(OH)16CO3×nH2O was studied by thermal analysis techniques in order to determine the correct temperatures for the synthesis of the mixed metal oxides. 相似文献
17.
N-Sulfinyltrifluoromethanesulfonamide CF3SO2N=S=O reacts with salicylaldehyde, 2-furaldehyde, 2-thiophenecarbaldehyde, 3-methyl-1-phenyl-1H-pyrazole-4-carbaldehyde, and 2-phenyl-2H-1,2,3-triazole-4-carbaldehyde to afford the corresponding N-aryl(hetaryl)methylidenetrifluoromethanesulfonamides in high yields. Reactions of the latter with aniline give no adducts at the C=N bond but transamination products. The reaction of trifluoromethanesulfonamide with phenyl isocyanate led to formation of N,N′-diphenylurea instead of expected N-phenyl-N′-(trifluoromethylsulfonyl)urea.__________Translated from Zhurnal Organicheskoi Khimii, Vol. 41, No. 7, 2005, pp. 1006–1010.Original Russian Text Copyright © 2005 by Shainyan, Tolstikova. 相似文献
18.
O. A. Novruzova O. P. Rakhmanova A. E. Galashev 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2007,81(11):1825-1828
The stability and structure of water clusters absorbing nitrogen molecules or argon atoms was analyzed by molecular dynamics simulation at 233 K. The (?μ/?i)V, T derivative of the chemical potential, a value characterizing the stability of a cluster with respect to its size, depends linearly on the number of molecules i. According to this criterion, the clusters under study become stable near i = 40. The average length of H-bonds increases monotonically in the growing cluster of pure water and exhibits oscillatory behavior if the growing cluster contains N2 molecules or Ar atoms. The number of H-bonds per molecule oscillates between one and six as the cluster size changes. These oscillations are damped in pure water and sustained for clusters containing impurities, especially argon. 相似文献
19.
I. A. Charushnikova A. M. Fedoseev Z. A. Starikova 《Russian Journal of Coordination Chemistry》2005,31(8):603-607
The crystal structure of Na3NpO2(OOCCH3)3ClO4 · H2O was studied by single-crystal X-ray diffraction method. The structure is composed of the complex anions NpO2(OOCCH3)3]2−, perchlorate anions, Na cations, and water molecules. The oxygen environment of Np(V) is a hexagonal bipyramid whose equatorial plane is formed by the oxygen atoms of three acetate ions. In addition to the acetate anions, the structure contains the perchlorate ion whose oxygen atoms, except for one, are included in the coordination environment of Na+ cations.__________Translated from Koordinatsionnaya Khimiya, Vol. 31, No. 8, 2005, pp. 636–640.Original Russian Text Copyright © 2005 by Charushnikova, Fedoseev, Starikova. 相似文献
20.
L. V. Parfenova S. V. Pechatkina L. M. Khalilov U. M. Dzhemilev 《Russian Chemical Bulletin》2005,54(2):316-327
The composition of intermediates of the Cp2ZrCl2-catalyzed hydroalumination of α-olefins by isobutylalanes (HAlBui
2, AlBui
3, ClAlBui
2) was studied by dynamic 1H and 13C NMR pectroscopy. The reaction of Cp2ZrCl2 with isobutylalanes affords the complex (Cp2ZrHCl·HAlBui
2)2 responsible for α-olefin hydroalumination.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 311–322, February, 2005. 相似文献