Simulation of exposure of light-sensitive layers: Processes involving reversible reactions

Analytic expressions relating the concentration of a light-sensitive component and the intensity of exposure UV light to the sample thickness and exposure time of light-sensitive materials with the restricted mobility of reactants were found. The processes of image formation were considered, which involve the following reversible photochemical reactions: (1) both steps are photochemical, ; (2) a thermal reaction acts as a reversible step, ; and (3) both thermal and photochemical reactions are reversible steps, .__________Translated from Khimiya Vysokikh Energii, Vol. 39, No. 3, 2005, pp. 218–222.Original Russian Text Copyright © 2005 by Zelentsov, Simdyanov.     

interaction of nitro compounds with radicals: a quantum chemical study

Photoreduction of nitro compounds is accompanied by formation of various radical products that can react with the starting nitro compound, thus causing deviation of the decomposition kinetics from the first-order kinetics with respect to the nitro compound. The results of quantum chemical modeling of the reactions of nitro compounds with radicals and the pathways of further transformations of radical adducts formed in the reactions are presented. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 202–206, February, 2006.     

Optimization of reliability and longevity of cylindrical shells subject to corrosive wear

The problem of the optimal (with respect to the minimum average rate of weight loss in a structure) design of a smooth cylindrical shell loaded by an axial compressive force and under corrosive wear, the rate of which depends exponentially on the stresses, is solved. The problem is solved analytically using apparatus of the method of Lagrange multipliers.Translated from Matematicheskie Metody i Fiziko-mekhanicheskie Polya, No. 26, pp. 59–63, 1987.     

Novel methods for calculating the fine vibronic spectra of polyatomic molecules

Novel approximate methods for calculating the vibrational structure of the electronic spectra of polyatomic molecules—a method for the direct calculation of the overlap integrals of vibrational wave functions for the electronic states involved in a transition and a variational method for the solution of the vibrational problem for the excited states—are discussed. The methods are based on the consideration of the displacement and entanglement of normal coordinates, the quasiorthogonality of the Dushinsky transformation, and the classification of the states by total vibrational quantum numbers. Matrix perturbation theory is employed. It is shown that the accuracy of these methods compares well with the accuracy of the available “exact” techniques (the errors are ∼1 cm⁻¹ for frequency and 10% for relative intensity). At the same time, calculations by the new methods are performed more than two orders of magnitude faster than by the previously known methods. K. A. Timiryazev Agricultural Academy, Moscow. Translated fromZhurnal Strukturnoi Khimii, Vol. 36, No. 2, pp. 217–230, March–April, 1995. Translated by I. Izvekova     

Effect of the polyoxoanion of phosphotungstic acid on the photoconversion efficiency of dye-sensitized solar cells based on titanium dioxide

A method for fabricating form composite photoanodes based on titanium dioxide and phosphotungstic acid has been developed. The introduction of the polyoxometalate into a porous titanium dioxide layer increases the photoconversion efficiency of dye-sensitized solar cells and affects characteristics such as open-circuit voltage and short-circuit current.     

Quantum chemical simulation of silicon tetrachloride hydrogenation

The quantum chemical calculation of the activation parameters of the reduction of a SiCl₄ molecule with molecular hydrogen, atomic hydrogen, and atomic chlorine was performed. The energy parameters were determined within the scope of the density functional theory (DFT) with the complete geometry optimization by the unrestricted UB3LYP/6-311+G(d) method. The calculated activation energies allow one to exclude the participation of molecular hydrogen in processes of dehalogenation of chlorosilanes.     

Variational method for the calculation of the vibrational structure of the electronic spectra of polyatomic molecules. I

A method is proposed to calculate the vibrational structures of the electronic spectra of polyatomic molecules based on the variational solution of the vibrational problem in the excited state with the vibrational wave functions of the ground state as basis set. The electrono-vibrational problem leads to an evaluated and diagonalized variational matrix. The elements of the variational matrix have a simple form which is easily evaluated, has a clear physical meaning and is directly interconnected with observed spectral effects. This allows preliminary estimation of spectral phenomena and correction of the molecular model to take account of experimental results. The use of contemporary methods of diagonalization of the variational matrix, which possesses a characteristic structure, facilitates a tenfold increase in the speed of the method in comparison with traditional methods.K. A. Timiryazev Agricultural Academy. Translated from Zhurnal Strukturnoi Khimii, Vol. 34, No. 1, pp. 141–148, January–February, 1993.     

Effect of Nitrene Multiplicity on Product Yields upon Photooxidation of Organic Azides

The effect of the spin state of intermediate species on the product yields upon photooxidation of 4,4"-diazidodiphenyl was studied. It was found that addition of triplet photosensitizers to the reaction mixture resulted in a substantial increase in the yield of nitroso compounds. Maximum sensitizing effect is observed for the photosensitizers with a triplet level energy of 250 kJ/mol or higher. Using the solvents stabilizing the nitrene adduct with oxygen RNOO^Sbrings about an increase in the yields of both nitro and nitroso compounds. This result indicates that the nitrene adduct is the precursor of the above-mentioned compounds.