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11.
Bodnarchuk M. I. Kovalenko M. V. Stroyuk A. L. Kuchmii S. Ya. 《Theoretical and Experimental Chemistry》2004,40(5):287-292
The photochemical behavior of solutions containing a mixture of CdS and CdTe nanoparticles under pulsed irradiation conditions was investigated. It was shown that electron transfer from the CdS particles to the CdTe nanoparticles occurs during the photoexcitation of such systems. The effectiveness of the process is increased with increase in the size of the CdTe nanoparticles. Such behavior is due to decrease in the potential of the CdTe conduction band with increase in the size of the nanoparticles as a result of the appearance of quantum-dimensional effects. 相似文献
12.
A. I. Kryukov S. Ya. Kuchmii A. V. Korzhak 《Theoretical and Experimental Chemistry》1996,32(5):258-261
A study was made of reactions forming chlorohydrins from cyclohexane and other olefins acted upon by H2O2 and HCl or H2O2 and TiCl4 in alcoholic solutions. The catalyzing action of titanium (1V) was established, and possible reaction mechanisms are discussed.L. V. Pisarzhevskii Institute of Physical Chemistry, National Academy of Sciences of Ukraine, 31 Prosp. Nauki, 252039, Kiev, Ukraine. Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 32, No. 5, pp. 295—299, September–October, 1996. Original article submitted February 9, 1996. 相似文献
13.
S. Ya. Kuchmii S. V. Kulik A. V. Korzhak A. I. Kryukov 《Theoretical and Experimental Chemistry》1985,21(5):536-542
In an investigation of electronic and ESR spectra, it has been established that titanium(III) with the thiocyanate ion (in ethanol) forms distorted tetrahedral and octahedral complexes. The tetrahedral compounds, which are hydroxo complexes of titanium(III) that contain one hydroxyl group and three thiocyanate ions in the coordination sphere, give signals in the ESR spectra with go=1.960, Ao=15.0·10–4 cm–1 g=1.958, A
Ti
=26.4·10–4cm–1, g= 1.691, ATi=9.0·10–4 cm–1. In the ESR spectra of liquid solutions, additional splitting on the nitrogen atoms is manifested(A
o
N
=2.2·10–4 cm–1), which indicates bonding of thiocyanate ions through the nitrogen atom. The pseudo-octahedral complexes of titanium(III), containing from two to six thiocyanate ions in the coordination sphere, are characterized by d-d absorption bands in the 520–590 nm region; and at 77°K, they give anisotropic ESR signals. On the basis of the temperature dependences of the equilibrium constants for the reaction of conversion of the tetrahedral complexes to the octahedral complexes, and also the lifetimes of the tetrahedral complexes, values have been estimated for the heat of reaction (H=26.8 kJ/mole) and the entropy change (S=–1.66 kJ/mole·°K) of the equilibrium process, and also the activation energy for the reaction of titanium(III) thiocyanate formation (E=37 kJ/mole).Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 21, No. 5, pp. 560–567, September–October, 1985. 相似文献
14.
A. I. Kryukov S. Ya. Kuchmii A. V. Korzhak A. N. Korol' 《Theoretical and Experimental Chemistry》1986,22(1):44-51
Electronic spectroscopy, ESR, and gas-liquid chromatography have been used in studying the action of light with =254 nm on ethanol-water solutions of titanium tetrachloride. It has been established that, in the course of irradiation, a photocatalytic process develops with the participation of coordination compounds of titanium(IV) and (III), resulting in oxidation and breakdown of the ethanol to form acetaldehyde, methane, ethane, ethyl chloride, and molecular hydrogen. In the presence of small amounts of added water (up to 0.5 M), the efficiency of CH4 and C2H7 formation is much lower but the yield of H2 is higher, in comparison with the yields of these products in absolute ethanol. With further increases in the water concentration, the rates of formation of methane, ethane, and acetaldehyde increase. The maximum quantum yields () are as follows: (CH4)=1.8 · 10–4 and (C2H6)=1 · 10–3 in absolute ethanol; (CH3CHO)= 1.6·10–2 in ethanol with the addition of 6.0 M H2O; (H2)=6.7·10–3 in solutions containing 0.5 M H2O. The observed differences in the product yields are explained by a change in the composition and structure of the titanium compounds that act as the photocatalyst, a change that takes place when the water concentration is varied. A mechanism is proposed for these reactions.Translated from Teoreticheskaya i Éksperimentai'naya Khimiya, Vol. 22, No. 1, pp. 51–58, January–February, 1986. 相似文献
15.
A. L. Stroyuk A. I. Kryukov S. Ya. Kuchmii V. D. Pokhodenko 《Theoretical and Experimental Chemistry》2005,41(2):67-91
The appearance of quantum size effects in ultradisperse semiconductors, their quantitative analysis, and their effect on the absorption of light and on the photophysical (vibrational relaxation of photogenerated “hot” charge carriers, band-band and “defect” luminescence) and certain primary photochemical processes (the accumulation of excess negative charge by the semiconductor nanoparticles, interphase electron transfer, etc.) are discussed.__________Translated from Teoreticheskaya i Eksperimental’naya Khimiya, Vol. 41, No. 2, pp. 67–87, March–April, 2005. 相似文献
16.
A. V. Korzhak S. Ya. Kuchmii A. I. Kryukov 《Theoretical and Experimental Chemistry》1987,23(2):172-177
It was established that in UV irradiation of solutions of TiCl4 in methanol, ethanol, isopropanol, and butanol, alcohol-chloride complexes of titanium(III) are formed. The quantum yields of the formation of coordination compounds of titanium(III) depend on the nature of the alcohol: 0.08 (methanol); 0.13 (ethanol); 0.20 (butanol); 0.22 (isopropanol). As complexes of titanium(III) accumulate in solution, there is a liberation of molecular hydrogen. The quantum yields of the formation of hydrogen, determined in a steady-state process, are correlated with the values of the C-H bond energy at the -carbon atom of the alcohol and are equal to 2·10–3, 3.4·10–3, 4.3·10–3 and 1·10–2 for solutions in methanol, butanol, ethanol, and isopropanol, respectively. A substantial increase in the quantum yield of the formation of molecular hydrogen was detected when a heterogeneous catalyst (palladium on silica gel) was used, and the possible mechanism of the process of photocatalytic liberation of hydrogen from alcohols with the participation of titanium complexes is discussed.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 3, No. 2, pp. 181–186, March–April, 1987.The authors would like to thank V. M. Granchak for his participation in the discussion of the results. 相似文献
17.
S. Ya. Kuchmii A. V. Korzhak A. I. Kryukov 《Theoretical and Experimental Chemistry》1999,35(3):153-157
The quantum yields of photocatalytic generation of hydrogen (
) from alcohol-water mixtures containing a suspension of Pd/CdS (or CdS and Pd/SiO2) increase in the presence of CCl4 or C6Cl6 additives, which undergo dehalogenation. The reasons for the increase in
are the increase in acidity during the process, and also suppression of electron-hole recombination as a result of acceptance
of electrons from the conduction band by the halogenated hydrocarbons, which leads to generation of additional amounts of
ethoxy radicals taking part in reduction of water.
L. V. Pisarzhevskii Institute of Physical Chemistry, National Academy of Sciences of Ukraine, 31 Prospekt Nauki, Kiev 252039,
Ukraine. Translated from Teoreticheskaya i éksperimental'naya Khimiya, Vol. 35, No. 3, pp. 162–166, May–June, 1999. 相似文献
18.
V. V. Shvalagin A. L. Stroyuk S. Ya. Kuchmii 《Theoretical and Experimental Chemistry》2004,40(6):378-382
Cathodic photocorrosion occurs upon stationary photoirradiation of ethanolic ZnO sols. The photocorrosion rate increases with decreasing particle size. This effect due to the appearance of quantum-sized effects in ZnO nanocrystals results from an increase in the reduction potential of the semiconductor upon irradiation, which may exceed the Fermi level for cathodic decomposition of zinc oxide nanoparticles.Translated from Teoreticheskaya i Éksperimentalnaya Khimiya, Vol.40, No.6, pp. 363–367, November–December, 2004. 相似文献
19.
Yats'kiv V. I. Korzhak A. V. Granchak V. M. Kovalenko A. S. Kuchmii S. Ya. 《Theoretical and Experimental Chemistry》2003,39(3):172-176
Peculiarities of the behavior of porous titanium dioxide in the photocatalytic evolution of molecular hydrogen from aqueous ethanolic solutions are shown to arise from the accumulation of long lived "free" electrons and titanium(III) ions in the irradiated samples, and the slow transport of electrons to the surface of the TiO2 particles. This explains the dependence of the effectiveness of the process on both the intensity of the irradiation and on the length of time the irradiated samples are kept in the dark. 相似文献
20.
N. F. Guba S. Ya. Kuchmii A. V. Korzhak A. I. Kryukov V. D. Pokhodenko 《Theoretical and Experimental Chemistry》1999,35(2):75-78
Nanostructural composites can be used as suspension electrodes; they are made by substitution cadmium(II) at the surfaces
of CdS microcrystals for Cu(I, II), Fe(III), Bi(III), and Sb(III). Features are considered in the photoelectrochemical action
mechanism of the various nanocomposites.
L. V. Pisarzhevskii Institute of Physical Chemistry, National Academy of Sciences of Ukraine, 31 Prospekt Nauki, Kiev 252039,
Ukraine. Translated from Teoreticheskaya i éksperimental'naya Khimiya, Vol. 35, No. 2, pp. 79–82, March–April, 1999. 相似文献