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Chaikovskaya O. N. Levin P. P. Sul"timova N. B. Sokolova I. V. Kuz"min A. V. 《Russian Chemical Bulletin》2004,53(2):313-317
The spectra and kinetics of short-lived intermediates formed from aqueous (0.1 N NaOH) solutions of the natural mixture of humic and fulvic acids (HFA) were studied by laser flash photolysis using excitation wavelengths of 337, 390, 470, and 520 nm. Laser photolysis of HFA with light of 520 and 470 nm results in the formation of triplet excited states (THFA) characterized by the broad absorption spectrum with a maximum near 630 nm and lifetimes of 0.15 ms in deoxygenated solutions. The formation of two types of THFA with lifetimes of 0.1 and 2 ms and absorption spectra with maxima at 570 nm is observed under photolysis with light of 337 and 390 nm. The estimation of quantum yields of THFA gives 1 and 0.3% under photolysis with excitation wavelengths of 337 and 520 nm, respectively. The rate constants of THFA quenching by molecular oxygen are equal to (7—8)·108 L mol–1 s–1. 相似文献
46.
V. K. Gryaznov A. N. Ivanova G. L. Gutsev A. A. Levin A. V. Krestinin 《Journal of Structural Chemistry》1989,30(3):469-472
Branch of the Institute of Chemical Physics, Academy of Sciences of the USSR. Translated from Zhurnal Strukturnoi Khimii, Vol. 30, No. 3, pp. 132–134, May–June, 1989. 相似文献
47.
The problem of obtaining the matrix elements of Hartree-Fock Hamiltonians for alkanes using the EO method is considered. It has been shown that the data on the electronic structure of diamond together witht 1/e splitting in the neopentane photoelectron spectrum are helpful to produce such EO method parameter scale which involves even “through space” interactions. In terms of the EO method the photoelectron spectra of propane, butane, isobutane, and neopentane are interpreted. The valence band structure of polyethylene in analytical form is obtained. 相似文献
48.
A method has been developed for the one-stage conversion of aromatic carboxylic acids into symmetrical 2, 5-diaryl-1, 3, 4-oxadiazoles by heating them with hydrazine hydrochloride in polyphosphoric acid. 相似文献
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Lamberov A. A. Levin O. V. Egorova S. R. Evstyagin D. A. Aptikasheva A. G. 《Russian Journal of Applied Chemistry》2003,76(3):351-357
The method of low-temperature adsorption of nitrogen was applied to study structural characteristics of commercial peptized aluminum hydroxides. An increase or decrease in the porometric volume, depending on the nature and concentration of the peptizing agent, was analyzed. The phenomena observed are explained in terms of the mechanism suggested for formation of the pore system in commercial aluminum hydroxides. The dependence of the physicomechanical properties of active aluminum oxide on synthesis conditions and texture characteristics of commercial aluminum hydroxides was studied. 相似文献
50.
A. P. Klyagina I. F. Golovaneva G. G. Sadikov A. A. Levin 《Russian Chemical Bulletin》1990,39(8):1615-1617
A correlation between the stereochemistry and sign of the Cotton effect for * transition in the spectra of dimolybdenum tetracarboxylates and related compounds has been accomplished by constructing, within the framework of a one-electron model of optical activity, a 32-sector rule based on data from x-ray structure analysis and circular dichroism for dimolybdenum tetra-(R)-mandelate. It has been shown that a positive value of the pseudoscalar function xyz(x2–y2)(a2-z2) corresponds to a negative Cotton effect for the * transition in the case in which the dominant contribution to this effect comes from Rx components of the rotator strength of the transition.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1783–1785, August, 1990. 相似文献