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Stepanov, S. V.; Byakov, V. M.
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1 Citations
A mathematical model for the formation of main transient and final radiolysis products generated in tracks of fast electrons and positrons in water and aqueous solutions was constructed and described in terms of equations of inhomogeneous chemical kinetics in part 1 of this study. The model takes into account the reactions of a solute with epithermal electrons, thermal, and hydrated electrons; the ambipolar character of diffusion of charged intratrack particles; and new pathways of the formation of hydrogen and positronium due to the appearance of weakly bound states of electrons. In the present paper, the model was quantitatively fitted to experimental data on both time variation in the yields of radiolytic products (H3O+, e
aq−
, H, OH, OH−, H2O2) in pure water and the yields of hydrogen (H2, H), hydrated electron (e
aq−
) and positronium (Ps) in various dilute and concentrated aqueous solutions.
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By
Brichkin, S. B.; Spirin, M. G.; Tovstun, S. A.; Gak, V. Yu.; Mart’yanova, E. G.; Razumov, V. F.
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7 Citations
Indium phosphide colloidal quantum dots with a zinc sulfide shell, an average core diameter of 3 nm, a luminescence peak position of 600 nm, and a luminescence quantum yield up to 50% have been synthesized. By analyzing the stationary absorption and luminescence spectra in terms of the Kennard—Stepanov relationship, the values of homogeneous width and inhomogeneous broadening have been obtained, which determine the resulting width of the spectra: the corresponding full widths at half maximum (FWHM) were 31, 63, and 70 nm. From the value of inhomogeneous broadening and the sizing curve of indium phosphide, polydispersity of the synthesized particles has been estimated as 11%. Analysis of the luminescence decay kinetics has revealed three reproducible peaks with maxima near 4.35, 35 (main) and 200 ns in the lifetime distribution. It has been found that although repeated washing of the synthesized particles with methanol can decrease the quantum yield, the lifetime distribution observed remains constant, which in the context of the “blinking” effect indicates a very short luminescence decay time of the particles in the OFF-state.
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Davidenko, N. A.; Davidenko, I. I.; Savchenko, I. A.; Popenaka, A. N.; Derevyanko, N. A.; Ishchenko, A. A.; Kulinich, A. V.
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Absorption spectra of poly[4-metacryloyloxy-(4′-carboxy-3′-oxy)azobenzene] films and their complexes with cobalt, without additives or doped with a merocyanine dye whose absorption spectrum lay in the near IR region, were studied before and after switching on an external electric field. An external electric field effect was found on the light transmittance of films within the dye absorption region, which indicated sensitization of the electrooptical effect. The electrooptical properties of the films resulted from spatial reorientation of dipole moments of azobenzene groups in an external electric field, which initiated turning of dye molecules. A phenomenological model was proposed to explain the sensitization of the electrooptical effect.
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By
Piskarev, M. S.; Gilman, A. B.; Shchegolikhin, A. N.; Shmakova, N. A.; Yablokov, M. Yu.; Kuznetsov, A. A.
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2 Citations
A change in the contact properties of the surface of tetrafluoroethylene-vinylidene fluoride copolymer films by a dc discharge treatment has been studied, depending on the treatment time and the discharge current. It has been shown that the treatment of the films at the anode and cathode leads to a significant decrease in the contact angle and an increase in the total surface energy and its polar term. The change in the contact properties of the plasma-modified films during storage and heating has been studied as well. The experiments have shown that the formation of polyconjugated structures and crosslinking of macromolecules take place in the film surface layer during long-term treatment at the anode (>60 s, 50 mA), processes that result in an acetone-insoluble layer. The composition and surface structure of the films have been examined by Fourier-transform IR spectroscopy and X-ray photoelectron spectroscopy. The formation of new oxygen-containing groups and double bonds on the polymer surface and crosslinking of macromolecules in the case of anode treatment have been revealed. It has been found experimentally that the discharge treatment increases the peel strength in the Scotch® 810/copolymer film system.
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Plotnikov, V. G.; Smirnov, V. A.; Alfimov, M. V.
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8 Citations
The main concepts of the nature of electronically excited states in polyatomic molecules and the intramolecular and intermolecular processes of their evolution are reported. The dependence of the probabilities of these processes on the electronic structure of the molecule is considered. Possible mechanisms of the dissociation of electronically excited molecules with bond cleavage are discussed, and the theoretical results of this consideration are given. The experimental data obtained by the authors are interpreted. In this case, attention is focused on C-H-bond photodissociation processes in a condensed phase, which are the best studied processes. The dissociation of other bonds is briefly discussed.
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By
Yakushin, R. V.; Kolesnikov, V. A.; Brodskiy, V. A.; Ofitserov, E. N.; Chistolinov, A. V.; Perfil’eva, A. V.; Solov’eva, I. N.; Kandelaki, G. I.
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The effect of dielectric-barrier discharge plasma treatment on the valence state of metal ions in aqueous solutions of manganese, iron, cobalt, and nickel (Mn, Fe, Co, Ni) salts has been studied. The efficiency of recovery of sparingly soluble compounds of transition metals during the treatment of model solutions in a plasma reactor designed by the authors has been evaluated. The possibility of hydrogen peroxide formation in water by barrier discharge treatment has been shown, and the change in the redox potential of the system has been analyzed.
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By
Ol’khov, Yu. A.; Allayarov, S. R.; Dixon, D. A.
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3 Citations
Six topological structures (an amorphous and five crystalline blocks) have been detected in a polytetrafluoroethylene film with a pseudo-network structure. During the Γ-irradiation of the polymer in air, the crystalline fractions degrade and gradually convert into amorphous and cluster states with the increasing radiation dose. After irradiation at a dose of 90 kGy, the polymer loses its capability for crystallization and forms a completely amorphous topological structure. However, regardless of dose in the range of 3–90 kGy, the topological structure of the polymer irradiated in a vacuum remains unchanged and consists of amorphous, cluster, and crystalline blocks.
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By
Grishina, A. D.; Tedoradze, M. G.; Kolesnikov, V. A.; Mal’tsev, E. I.; Brusentseva, M. A.; Kostenko, A. I.; Popov, A. F.; Vannikov, A. V.
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1 Citations
A polymer containing donorN-epoxypropylcarbazolyl groups and the acceptor tris(8-quinolinolato) aluminum (Alq3) was shown to form a light-sensitive, acid-producing polymeric composition. The acid in the presence of 8-quinolinol (8-hydroxyquinoline) ensured photochemical dissolution of aluminum in the polyeric layer, yielding additionally organic aluminum complexes, such as Alq3, Alq2+, and Alq
2+
, and Alq3-con-taining polymers. This led to a emergence of electroluminescence (EL) upon application of a potential difference to a sandwich diode representing transparent anode/exposed polymer layer/aluminum cathode. Electroluminescence did not appear at an Alq3 concentration of 6 wt % and less in the composition, and only partial dissolution of the aluminum film after its deposition on the exposed polymeric layer provided the emergence of EL whose intensity increased with increasing the dose absorbed by the polymer. The addition of the chemical sensitizer dimethylaminobenzaldehyde to the composition triggered the conventional process of chemical amplification which consists in thermal buildup of the acid in exposed area. This provided a significant increase in concentration of organoaluminum complexes and enhancement of EL intensity.
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By
Vreshch, O. V.; Davidenko, N. A.; Dekhtyarenko, S. V.; Ishchenko, A. A.; Kokozay, V. N.; Kozinetz, A. V.; Skryshevsky, V. A.; Tretyak, O. V.
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2 Citations
The electric and photoconductive properties of films of polymer composites containing heterometallic complexes [Cu(phen)2Fe(CN)5NO]· 2H2O or [Cu(phen)2Br]2[Fe(CN) 5NO]DMF (where phen is 1,10-phenanthroline and DMF is dimethylformamide) and a merocyanine dye were studied. The photocurrent is greater for the bromide complex and increases upon introduction of a merocyanine dye into the composites. The photocurrent also increases upon the application of an external magnetic field and saturates in fields of <1 kOe. It is assumed that the sensitization of photoconductivity by the merocyanine dye is due to photogeneration of triplet charge pairs from dye molecules and transport of nonequilibrium charge carriers in and between the particles of the complexes, rather than to an increase in the absorbance.
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