Electronic absorption spectra of merocyanine forms of spiropyrans

A simple method is proposed for the measurement of the absorption spectra in the visible and UV regions of photocolored solutions of spiropyrans, formed by the action of constant lowintensity UV irradiation, and for the construction, on the basis of these data, of the absorption spectra of the merocyanine forms of spiropyrans. The absorption spectra of the merocyanine forms of two spiropyrans in various solvents are examined.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1534–1538, November, 1972.     

Theoretical and Experimental Studies of the Nature of the Catalytic Activity of VO x /TiO2 Systems

The states of supported vanadium and the nature of activation of ammonia adsorbed on vanadium sites of V _x /Ti₂ catalysts are studied by ⁵¹V NMR spectroscopy and diffuse-reflectance IR Fourier-transform (DRIFT) spectroscopy using cluster quantum chemical calculations of N₃ adsorption. We employ the V _x /Ti₂ catalyst of two types: the monolayer catalyst in which vanadium is located on the surface of well-crystallized anatase and the catalyst in which vanadium embedded in the anatase lattice at a rather great depth. It is shown that ammonia is predominantly adsorbed on Lewis acid sites of the monolayer catalyst, whereas most of N₃ adsorbed on the catalyst containing bulk vanadium is in the form of ammonium ions. Analysis of experimental and calculated data suggests that, in the monolayer catalyst, N₃ molecules in the selective reduction of nitrogen oxides are activated on Lewis acid sites. Ammonia activation involves the dissociation of the N–H bond in a coordinated molecule, which results in the formation of the amide V–N₂ group and a water molecule coordinated by a V⁵⁺ ion. It is likely that, in the case of the catalyst containing bulk vanadium, this reaction occurs with the predominant participation of ammonium ions.     

Electroconductivity changes of Na-modified TiO2 and Pt/TiO2 films

Electrolytic supporting of metallic sodium on the surface of TiO₂ and Pt/TiO₂ films is shown to change significantly the Fermi level of the semiconductor substrate already at small concentrations of sodium. The steady-state catalytic activity changes only at high concentrations of supported sodium, varying the chemical composition of the active phase. The contact process does not play any significant role in the catalytic process.

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, TiO₂ Pt/TiO₂ . , . .

     

Modeling the photoelectron spectra of the valence O2p-band of zinc oxide by the Xα-scattered wave method

The photoelectron spectra (PES) of the valence O2p-band of zinc oxide are modeled by Xα-scattered wave cluster calculations in a wide range of incident quantum energies hv (from 30 to 150 eV and 1253.6 eV). For the Zn₁₀O₁₀ cluster, the calculated intensities of PES reproduce well the specific features of the experimental spectra. It is shown that Zn3d-electrons participate in covalent binding of zinc and oxygen. The admixture of the Zn3d-states in the hybrid orbitals of the valence band is ≈7%. Deceased. Translated fromZhurnal Struktumoi Khimii, Vol. 38, No. 5, pp. 877–886, September-October, 1997.     

The early universe and cosmogenesis

We extrapolate the Cosmological Standard Model to the past, determine initial geometrical conditions in the early universe, and consider a new cosmogenesis paradigm based on the concept of black-and-white holes with integrable singularities.     

Electrochemical Characterization and Voltammetric Determination of Benzoyl Derivatives of Phenobarbital Using Glassy Carbon Electrode

The electrochemical behavior of a number of benzoyl barbiturates was studied using a glassy carbon electrode (GCE). The kinetics of the electrode process is determined, the contribution of physical adsorption to the electrochemical process is estimated, and the mechanism of the possible electrochemical reaction is proposed. It is shown that the electrochemical reduction potentials of benzoyl phenobarbital derivatives are determined by the LUMO energies, calculated by the B3LYP 6‐311+G method. It is established that the process is quasi‐reversible, complicated by adverse reactions. The influence of halogen type and its position in the benzoyl residue of the studied substances on the analytical signal is established. The effective values of the dissociation constants of various forms of benzoyl derivatives were calculated using the example of halonal, for which the values 3.16 ? 10^?8 and 6.31 ? 10^?12, respectively, were found.     

Acyl and aroyl derivatives of 4-amino-1,2,5-trimethylpiperidine

N-Substituted amides of some aliphatic and aromatic acids, respectively, have been obtained by the acylation and aroylation of 4-amino-1,2,5-trimethylpiperidine.     

Radial oscillations of vapor bubbles in solutions

The dynamics and heat and mass transfer of vapor bubbles in binary systems are investigated. An anomalous effect of the component composition on the bubble dynamics in boiling nonideal solutions is established. It is shown that in some binary systems the value of the logarithmic decay rate for small free radial oscillations does not lie within the limiting values calculated for the pure components, which is associated with the cardinal importance of the effect of diffusion in the liquid phase on the intensity of the phase transitions.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 3, pp. 108–113, May–June, 1989.