Inhibiting Effect of Fullerene C60 and Other Antioxidants on Thermal Oxidative Degradation of Copolymers of Methyl Methacrylate with Methacrylamides

Copolymers of methyl methacrylate with methacrylamides undergo thermal oxidative degradation less actively than polymethyl methacrylate. Additions of fullerene C60 inhibit degradation.     

Nonradiative deactivation of the electronic excitation energy in cyanine dyes: influence of binding to DNA

The processes of nonradiative deactivation of electronic excitation energy in cyanine dyes determine their quantum yield. Because of that, the study of the influence of cyanines binding to DNA on these processes can provide information on the causes leading to the cyanines fluorescence intensity enhancement in the presence of DNA. In the presented paper, the activation energies of nonradiative degradation of electronic excitation, quantum yields and rate constants of nonradiative transitions of several cyanines in free state and in the presence of DNA were established and compared. The mechanisms of nonradiative deactivation of dye excitation energy were discussed.     

Calculation of the fine structure of the triplet state $$\tilde a^3 A_2 $$ of the ozone molecule by the method of multiconfiguration self-consistent field

The zero-field splitting of the \(\tilde a^3 A_2 \) state of the O₃ molecule is interpreted on the basis of ab initio quantum-chemical calculations. The spin—orbit coupling with the ground X¹A₁ state is shown to make the main contribution to the zero-field splitting of the \(\tilde a^3 A_2 \) term (the state of the ³σπ type). The calculated parameters D and E agree well with experiment.     

Spin-orbit coupling in oxygen near the dissociation limit

By using the method of configuration interactions in the valence basis with triple exponentials, the spectrum of the oxygen molecule is calculated in a range of internuclear distances from 1.2 to 2.45 Å, with the matrix of configuration interactions being diagonalized with regard to the spin-orbit coupling. The matrix elements of the spin-orbit coupling are presented, along with the spin splittings of triplet and quintet states. Particular attention is given to the intermediate range for the breaking of the O=O bond (1.8–2.45 Å), where the strong mixing of multiplets and rearrangement of the valence bonding to the atomic limit O(³ P)+O(³ P) occur. Other dissociation limits up to O(¹ D)+O(¹ D) are also taken into account. The results obtained are discussed in the context of the theory of the chemical bond, catalysis, radiation collisions, and the theory of spectral bands for high vibrational quantum numbers.     

Effect of absorption of low-molecular-weight compounds by some polymer flocculants

The sorption properties of the intramolecular complex - poly(acrylamide) to poly(vinyl alcohol) grafted copolymer (PVA-PAA_N) in block state were investigated with respect to a number of compounds. The relatively small molecules of phenol, phenylalanine in water solution as well as nitrobenzene in hexane are strongly absorbed by PVA-PAA_N films. The large humine acid molecules (sizes are larger by more than ≈ 10 times) are absorbed by PVA-PAA_N very weakly. It was determined the absorption influence on the character of polymer film solution. In a number of cases the oscillation of the dilution and sorption were observed when determining the critical concentrations of guest molecules in the upper layer of polymer films were achieved. The possible mechanisms of absorption were discussed.     

The peculiarities of sorbtion mechanism of phenole molecules by films of PVA‐PAAN interpolymer complex

The peculiarities of sorbtion mechanism of phenole molecules by poly(vinylalcohol) and poly(acrylamide) (PVA‐PAA_N) films are examined. An analytical model of absorbtion process based on diffusive character of penetration of phenole molecules in polymer film with the following spontaneous capturing by selftuning traps is proposed. The analytical results can be easy compared with experimental data obtained by spectrophotometry method. The comparison of theory and experiment gives the average value of resulting diffusion lenght of phenole molecule during «free» life‐time <l>∼10⁻⁶ cm.     

Analysis of the latent structure of luminescence and absorption spectra of thallium complexes

Comprehensive investigations of luminescence, excitation, and absorption spectra as well as of the luminescence kinetics of a frozen LiCl-Tl⁺ solution are carried out. It is established that the luminescence spectrum consists of four components. One component is caused by luminescence of the matrix and the remainder by luminescence of one luminescence center, namely, by the saturated complex of thallium TlCl₂(H₂O)Cl₄. The absorption spectrum consists of three components. Their parameters have been evaluated. Each component of the luminescence spectrum is excited in several components of the absorption spectrum. It is found that the luminescence spectrum components and their intrinsic absorption bands are located differently on the frequency axis. These data are similar to those obtained for other activated solutions of electrolytes. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 67, No. 1, pp. 75–78, January–February, 2000.