The Photophysical Properties Investigation of Hybrid Associates of Methylene Blue Molecules with Colloidal CdS Quantum Dots and CdS / Cd(OH)2 "Core-Shell" Systems

The spectral properties of associates of methylene blue molecules with colloidal CdS quantum dots and CdS / Cd(OH)2 «core-shell» systems were investigated. It is shown that according to env ironment methylene blue changes its photophysical properties during association. These properties are due to changes of MB structure as a result of oxidation-reduction reactions. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3527

Spectral Manifestation of Hybrid Association of Zn0.7Sd0.3S Colloidal Quantum Dots with J-Aggregates of Thiacarbocyanine Dye

Spectral properties of mixtures of Zn0.7Sd0.3S colloidal quantum dots with mean diameter value of 3.5 nm with the molecules of 3,3'-di(γ-sulfopropil)-9-ethyl-4,5,4',5'-dibenzo-thiacarbocyanine betaine pyridine salt (DEC), prepared in gelatin were investigated. The obtained data indicated that the formation of well-luminescent trans-J-aggregates and spectral tuning in the position of the absorption band of DEC and the luminescence band of quantum dots, providing requirements for resonant energy transfer in the hybrid associate are the determinant factors in the increase of the luminescent emission of DEC molecules, interacting with Zn0.7Cd0.3S colloidal quantum dots. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3532

Comparison of superconductivity in Sr_2RuO_4 and copper oxides

To compare the superconductivity in strongly correlated electron systems with the antiferromagnetic fluctuations in the copper oxides and with the ferromagnetic fluctuations in Sr_2RuO_4 a t-J-I model is proposed. The antiferromagnetic coupling J results in the superconducting state of d_{x^2-y^2} symmetry and the ferromagnetic coupling constant I results in the spin-triplet p-type state. The difference in the gap anisotropies provides the large difference in T_c values, for the typical values of the coupling constants: T_c of order of 1K for the ruthenate and T_c of order of 100K for the cuprates.Comment: 4 pages, RevTEX, 3 figs. Submitted to Phys. Rev. Let

Dynamical Scaling: the Two-Dimensional XY Model Following a Quench

To sensitively test scaling in the 2D XY model quenched from high-temperatures into the ordered phase, we study the difference between measured correlations and the (scaling) results of a Gaussian-closure approximation. We also directly compare various length-scales. All of our results are consistent with dynamical scaling and an asymptotic growth law $L \sim (t/\ln[t/t_0])^{1/2}$, though with a time-scale $t_0$ that depends on the length-scale in question. We then reconstruct correlations from the minimal-energy configuration consistent with the vortex positions, and find them significantly different from the ``natural'' correlations --- though both scale with $L$. This indicates that both topological (vortex) and non-topological (``spin-wave'') contributions to correlations are relevant arbitrarily late after the quench. We also present a consistent definition of dynamical scaling applicable more generally, and emphasize how to generalize our approach to other quenched systems where dynamical scaling is in question. Our approach directly applies to planar liquid-crystal systems.Comment: 10 pages, 10 figure

Luminescence spectra and kinetics of disordered solid solutions

We have studied both theoretically and experimentally the luminescence spectra and kinetics of crystalline, disordered solid solutions after pulsed excitation. First, we present the model calculations of the steady-state luminescence band shape caused by recombination of excitons localized in the wells of random potential induced by disorder. Classification of optically active tail states of the main exciton band into two groups is proposed. The majority of the states responsible for the optical absorption corresponds to the group of extended states belonging to the percolation cluster, whereas only a relatively small group of “radiative” states forms the steady-state luminescence band. The continuum percolation theory is applied to distinguish the “radiative” localized states, which are isolated in space and have no ways for nonradiative transitions along the tail states. It is found that the analysis of the exciton-phonon interaction gives the information about the character of the localization of excitons. We have shown that the model used describes quite well the experimental cw spectra of CdS(1−c)Sec and ZnSe(1−c)Tec solid solutions. Further, the experimental results are presented for the temporal evolution of the luminescence band. It is shown that the changes of band shape with time come from the interplay of population dynamics of extended states and spatially isolated “radiative” states. Finally, the measurements of the decay of the spectrally integrated luminescence intensity at long delay times are presented. It is shown that the observed temporal behavior can be described in terms of relaxation of separated pairs followed by subsequent exciton formation and radiative recombination. Electron tunneling processes are supposed to be responsible for the luminescence in the long-time limit at excitation below the exciton mobility edge. At excitation by photons with higher energies the diffusion of electrons can account for the observed behavior of the luminescence

Musculature of the ovipositor of Scathophagidae (Diptera) with reference to the larval habits

Structure of the ovipositor sclerites and musculature was investigated in 4 species of Scathophagidae: Cordilura ciliata (Meigen, 1826), Scathophaga suilla (Fabricius, 1794), S. litorea (Fallén, 1819) and Pogonota barbata (Zetterstedt, 1860). Adaptations of the ovipositor structure and muscles associated with changes of the oviposition substrate due to new larval habits (plants and semi-liquid material) are analyzed. Changes of the ovipositor structure of scathophagids with phytophagous larvae to ovipositor structure in scathophagids with other types of the larval feeding habits are based more on the ovipositor skeleton than on its muscle

The stability analysis of single motion mode of a three-axes rotating body in the atmosphere

Abstract: The boundary of the asymptotic stability region of a three- axes body motion is analytically created in parameter space. The body that is provided by a rotatable parachute spins about the principal axis of inertia with constant angular velocity. Parachute gives body rotation via special suspender. The constant velocity vector of mass center of the body coincides with the spinning body axis and is pointed downward along the vertical.Note: Research direction:Theoretical and applied problems of mechanic