Synthesis and luminescence properties of neutral Tm(III), Dy(III), and Gd(III) complexes with 1,3-bis(1,3-dimethyl-1H-pyrazol-4-yl)-1,3-propanedione and 1,10-phenanthroline

Neutral complexes of composition [LnL₃Phen], where Ln = Tm, Dy, and Gd, were synthesized by the reaction of LnCl₃ with heterocyclic diketone 1,3-bis(1,3-dimethyl-1H-pyrazol-4-yl)-1,3-propanedione (HL, 1) and 1,10-phenanthroline in an aqueous alcohol solution in the presence of NaOH. The composition of the complexes was proved by elemental analysis. Their optical and luminescence properties were studied.     

Nonlinear diffraction and total internal reflection in optical-beam interaction in defocusing media

We elaborate the theory of reflection of an optical signal beam from an inhomogeneous channel created by a high-power laser beam of different frequency in a nonlinear defocusing medium. We study the effects of total internal reflection and nonlinear diffraction in the interaction of these beams. We derive and analyze the equation for the trajectory of the reflected signal beam and obtain the expression for the critical value of beam-intersection angle below which the total internal reflection occurs. We discuss the results of numerical modeling of nonlinear Schr¨odinger equations for envelopes of the beams in media with quadratic, photorefractive, and thermal nonlinearities. We present experimental data on the interaction of beams of argon and helium–neon lasers in a cuvette with tinted alcohol.     

Thermodecomposition ofo-benzoquinone complexes of transition metals

Thermodecomposition of 3,5- and 3,6-di-tert-butyl-o-benzoquinone complexes of Cu, Fe, Co, Cr, Mo, and W has been investigated in the solid phase by the thermogravimetric method. The relative stability of a series of complexes has been determined from the temperatures at which their decomposition begins. Detachment of a neutral electron-donor ligand takes place in the first stage. Detachment of ano-quinone ligand and decomposition of theo-benzoquinone formed occur in the next stage. Thermodecomposition of Fe, Co, Cr, Mo, and W complexes gives oxides or carbides, while copper complexes decompose to pure metal.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 327–329, February, 1994.     

Stereochemical and electronic structure of the free base,cation, and dication of porphin

The equilibrium stereochemical and electronic structure of the free base and the mono- and dications of porphin was calculated by the MO-LCAO SCF method in the CNDO/2 approximation. Successive protonation of the porphin molecule leads to an increase in the dimensions of the conjugation contour and to stage-by-stage exclusion of the nitrogen atoms. It was also established that single and double protonation of the free base does not lead to destruction of the coplanarity of the porphyrin macrocycle.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 24, No. 3, pp. 339–343, May–June, 1988.     

Discrete diffraction and waveguiding of optical beams in a cascade-induced lattice

Regularities of anisotropic discrete diffraction in a cascade-induced lattice formed by two crossed pump waves in a quadratically nonlinear medium have been studied. The transition from diffraction of a signal beam in free space to discrete diffraction with further capture into a waveguide in a defocusing lattice with an increase in the pump wave intensity has been traced. Diffraction-free propagation of a tilted beam is described.     

Preparation of Silicon Thin Films of Different Phase Composition from Monochlorosilane as a Precursor by RF Capacitive Plasma Discharge

Monochlorosilane/argon/hydrogen (SiH₃Cl-Ar-H₂) mixture of different ratios was investigated from the point of PECVD application. RF capacitive plasma discharge of 40.68 MHz frequency was used. The process of deposition was studied by optical emission spectroscopy. The silicon thin films of different phase composition were obtained. The thin films were characterized by Raman-spectroscopy, atomic force microscopy, and secondary ion mass spectrometry. The exhaust gas mixture was analyzed by IR-spectroscopy in outlet of the reactor during PECVD process. The chemical mechanism for the deposition process was also proposed.     

Investigation on possibility of rearrangement of pyrimidine-5-carboxylic acids esters

A previously reported rearrangement of pyrimidine-5-carboxylic acids esters to 5-acylpyrimidones does not, in fact, occur in any of the examples studied by us.     

Features of the Adsorption of Molecular Oxygen at the Anionic Vacancies on the (110) Face of the Surface of Rutile

The electronic structure of clusters modelling the adsorption complexes of the oxygen molecule on single isolated and adjacent anionic vacancies of the (110) face on the surface of rutile was studied. It was concluded that two types of such adsorption complexes exist on the defective surface of rutile.     

Clarification of a dilute suspension of calcium carbonate in the presence of Praestol flocculants and aluminum sulfate coagulant

Russian Journal of Applied Chemistry - Kinetic features of clarification of 1% suspension of calcium carbonate under the action of coagulants (aluminum sulfate, hydroxoaluminum chloride) and...     

Sedimentation of kaolin suspension with copolymers of sodium 2-acrylamido-2-methylpropanesulfonate with sodium acrylate

The sedimentation kinetics of kaolin suspension under the action of copolymers of sodium 2-acrylamido-2-methylpropanesulfonate with sodium acrylate was studied. The infl uence exerted on the process by the concentration, molecular weight, chemical composition, and conformational state of copolymer macromolecules in solution, and also by the concentration and particle size of the dispersed phase and by salt additives (NaCl, CaCl₂) was examined.