The Optimal Axis-Symmetrical Plasma Potential Distribution for Plasma Mass Separation

The mass separation of chemical element mixtures is a relevant task for numerous applications in the nuclear power industry. One of the promising approaches to solve this problem is plasma mass separation. In a recent study, the efficiency of plasma mass separation in a configuration with a potential well and a homogeneous magnetic field was experimentally demonstrated. This article examines the possibility of increasing the distance between the deposition regions of charged particles with different masses by varying the profile of the electric field potential. Such correlation can be considered as the control in a system of active particles. A cylindrical coordinate system is used. The electric field is axially symmetrical, and the magnetic field is directed along the axis of the symmetry. The corresponding mathematical problem was solved in a general way. The criteria for increasing the distance between the deposition areas of the “light” and “heavy” components of the mixture have been formulated. A high sensitivity of particle trajectories to the electric field potential in the region of the pericentres of the trajectories of charged particles was detected. Recommendations for the practical implementation of the optimal spatial separation of ion fluxes are proposed.     

Band structure of electronic levels and the formation of the fluorescence spectra of polar compounds in polar media

The paper sets out a statistical theory of the effect exerted by interactions of constant dipoles in solutions on the fluorescence spectra of polar compounds. The theory is based on the concept of band structure of the electronic levels of a polar impurity (dissolved) molecule in polar media. Institute of Molecular and Atomic Physics, Academy of Sciences of Belarus, 70, F. Skorina Ave., Minsk, 220072, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 2, pp. 209–216, March–April, 1997.     

Magnetic nanocomposites based on cyclodextrin-containing molecular tubes and iron nanoparticles

Stabilization of metallic nanoparticles may be achieved by the formation of their adducts with polymers and/or nanotubes of various chemical composition. Here, water-soluble nanotubes based on β-cyclodextrin (β-tubes) were used for entrapping of Fe nanoparticles obtained by the reduction of iron-containing precursors ([Fe₃(CO)₁₁H][Et₄N] cluster and FeSO₄). Using methods of light-scattering, viscometry, and isothermal diffusion measurements, it was shown that the adducts are associated in aqueous solutions. The presence of iron nanoparticles and the shape and size of adducts were verified by transmission electron microscopy. The adducts are long (up to 600 nm and longer), translucent associates consisting of denser walls and transparent cores. The width of nanotubes is ∼150 nm and the thickness of the wall 3–25 nm. Their magnetic properties were demonstrated by electron paramagnetic resonance method. The mechanism of self-assembly of the adducts is discussed.     

Unified Synthetic Approach to 2-Substituted 6-Methylisocytosines and Their 5-Bromo Derivatives

6-Methyl-4(3H)-pyrimidinones containing 2-alkyl-, 2-cycloalkyl-, and 2-arylalkylamino groups were synthesized and brominated to obtain 5-bromo derivatives.     

New quasiparticles hystons and coherent photoinduced dynamics of molecules in polar disordered media

Using methods of statistical thermodynamics, it is shown that after pulse excitation the evolution of a “polar luminescent probe—polar disordered medium” system is described by an equation of damping vibrations. This allows the conclusion that in the solvate shell of the probe molecule synchronous rotational vibrations (librations) of the molecules of the medium occur, whose damping is caused by dielectric friction. Such a collective synchronous motion is considered as a motion of a quasiparticle called a hyston. The moment of inertia J_n and mass M_h of a hyston are defined as J_h=2m² ₁a^-3Ω₀ ^-2(ε-1)/(2ε+1), M_h=J_hM_s/J_s, where m₁ is the dipole moment of the probe molecule in the excited S₁-stute; a is the Onsager radius; Ω₀ is the cyclic frequency of harmonic vibrations of the hyston; ε is the dielectric constant; M_s and J_s are the mass and moment of inertia of a molecule of the medium, respectively. The correlation function of the motion of the molecules c(t) is a solution of the equation of hyston motion. The fluorescence response s(t) in measurements with time resolution coincides with the correlation function: s(t)=c(t). The concepts concerning hystons make it possible to describe macroscopic photoinduced coherent motion that is manifested against a background of thermal motion of the medium molecules. Institute of Molecular and Atomic Physics, National Academy of Sciences of Belarus, 70, F. Skorina Ave., Minsk, 220072, Belarus. Translated from Zhurnal Prikladnei Spektroskopii, Vol 65, No. 2, pp. 176–183, March–April, 1998.     

Orientational resolvation of S1-excited 4,4'-dinitrophenyl-1,3,5-hexatriene molecules in alcohols

Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 53, No. 6, pp. 961–967, December, 1990.     

Solvatochromic shift of the 0-0 phosphorescence band and change of polarizability in the a 1δg → X 3Σ g? -transition in the oxygen molecule

We used known experimental data to analyze the influence of intermolecular interactions on the position of the 0-0-band a¹Δ_g → X³Σ _g ⁻ phosphorescence of molecular oxygen in solutions. A bathochromic (red) shift caused by dispersion interactions and fluctuations of the internal electric field (induction effect) is analyzed employing new formulas obtained by us in the framework of the Onsager model. The contributions from intermolecular repulsion and higher multipole interactions to the shift of the spectrum are also discussed. It is found that the polarizability in the a¹Δ_g state is higher than in the X³Σ _g ^t- state by 0.19 ± 0.03 ų. Taking into account the induced nature of O₂ phosphorescence in solutions, it is noted that the change of polarizability Δα_eg = 0.19 ų should differ from the change of Δα_eg inherent in free molecular oxygen. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 4, pp. 453–459, July–August, 2007.