Photoluminescence Spectra of ZnS:Al Crystals Annealed in a Melt with Bismuth and Chlorine Ions

The results of the temperature investigations (77–520 K) of the photoluminescence (PhL) of lowohmage ZnS monocrystals annealed in bismuthbased melts are presented. It is shown that the ion composition of the annealing medium produces a determining effect on the formation of an impuritydefect composition of the radiative centers. The dominant contribution to the PhL radiation is attributed to the centers based on the vacancies of sulfur and zinc and aluminum and chlorine. In the nearsurface region and in the bulk of the crystal, the PhL spectra differ. The PhL spectra in the nearsurface region of the crystal are determined by the complex bismuth centers and correspond to the characteristic features of the intracenter transitions. We propose two possible models of radiative centers: (V_Zn ^/Bi_Zn )^times and DX centers. It has been found that the simultaneous action of the radiation from a pulsed nitrogen laser and the heating at a temperature from 410 to 518 K destroy the radiative bismuth centers and lead to the formation of precipitates Bi₂S₃ and BiS₂.     

An Elementary Method on a Minimization Problem

一、ＴｈｅＰｒｏｂｌｅｍ .Ｌｅｔｆ(ｘ) =ａｘ2 ｂｘ ｃ ａｘ2 ｐｘ ｑ,ｗｈｅｒｅａ >0 ,ｂ2 - 4ａｃ≤ 0ａｎｄｐ2 - 4ａｑ≤ 0 .ＯｕｒＰｒｏｂｌｅｍｉｓ“Ｗｈｅｔｈｅｒｄｏｅｓｍｉｎｘ∈Ｒｆ(ｘ)ｅｘｉｓ?Ｍｏｒｅｏｖｅｒ ,,ｉｆｍｉｎｘ∈Ｒｆ(ｘ)ｅｘｉｓｔｓ,ｔｈｅｎｍｉｎｘ∈Ｒｆ(ｘ)=?ａｎｄｉｎｔｈｉｓｃａｓｅｘ =?” .Ｎａｔｕｒａｌｌｙ ,ｗｅｋｎｏｗｔｈａｔｍｉｎｘ∈Ｒｆ(ｘ)ｅｘｉｓｔｓｆｒｏｍｔｈｅｋｎｏｗｌｅｄｇｅｏｆｍａｔｈｅｍａｔｉｃａｌａｎａｌｙｓｉｓ.Ａｌｓｏ,ｗｅｃａｎｇｉｖｅｔｈｅ…     

Comparison of the Activities of Pd(0) and Pd(I) in Low-Temperature Oxidation of Carbon Monoxide on the Pd/γ-Al2O3 Catalyst

Kinetics and Catalysis - Low-temperature oxidation of carbon monoxide on the Pd/γ-Al2O3 catalyst has been studied at room temperature and atmospheric pressure of air containing 100 mg/m3 CO....     

Invertible linear relations generated by an integral equation with Nevanlinna measure

We define families of maximal and minimal relations generated by integral equations with Nevanlinna operator measure and non-selfadjoint operator measure. We prove that if a restriction of a maximal relation is continuously invertible, then the inverse operator is integral. We study the case when the convergence of non-selfadjoint operator measures implies the convergence of the corresponding integral operators inverse to restrictions of maximal relations, and establish a sufficient condition for the validity of this implication. The obtained results are applicable to the study of differential equations with singular potentials.     

Linear relations generated by an integral equation with Nevanlinna operator measure

We define families of maximal and minimal linear relations generated by an integral equation with Nevanlinna operator measure and prove their holomorphic property. We also prove that if a restriction of a maximal relation is continuously invertible, then the operator inverse to this restriction is integral. We apply the obtained results for proving the constancy of deficiency indices of some integral and differential equations.     

Lithium insertion into silicon films produced by magnetron sputtering

Using the method of magnetron-plasma sputtering of polycrystalline silicon target, amorphous silicon films 32–214 nm thick were produced on various (copper and titanium, polished and rough) substrates. A study of their charge-discharge characteristics under the galvanostatic conditions showed that all thin-filmed electrodes are capable of reversible lithium insertion. The amount of lithium inserted in the first cycles is close to the theoretical one. An analysis of composition and morphology of surface layer and also the behavior of reversible and irreversible capacities during cycling showed that the degradation of capacity is caused by the exfoliation of films from the substrate (the effect is more pronounced for the specimens with polished substrates) and somewhat breaking (cracking) of films. The thicker are the films, the severer is the disruption of silicon films in the cycling. The adhesion of films to the substrate surface is favored by the film roughness. At sufficiently high adhesion of films, their electrochemical properties only slightly depend on the nature (copper or titanium) of substrate.     

On invertible contractions of quotients generated by a differential expression and by a nonnegative operator function

In the present paper, we describe invertible contractions of the maximal quotient generated by a differential expression with bounded operator coefficients and by a nonnegative operator function. We show that the operators inverse to such contractions are integral operators and prove a criterion for such operators to be holomorphic. Using the results obtained, we describe the generalized resolvents of symmetric quotients.     

The state of palladium and copper bromides in the PdBr2-CuBr2-THF-H2O system used in the conjugated process of cyclohexanecarboxylic acid production

The state of bromide complexes of palladium and copper in model solutions and under conditions of the conjugated catalytic synthesis of cyclohexanecarboxylic acid by the hydrocarboxylation of cyclohexene is studied by electron and infrared spectroscopy. It is found that during the conjugated process, copper exists in the form of copper(I) compounds, and palladium is present in the form of palladium(II) carbonyl complex.     

Radiation-Enhanced Thermal Depolymerization of Polytetrafluoroethylene

The initial stage of thermal and radiation-enhanced thermal depolymerization over the temperature range of 310–460°C in vacuum was studied for polytetrafluoroethylene specimens with different thicknesses. Conditions for the occurrence of depolymerization in the kinetic and diffusion regions were determined. The specific features of depolymerization kinetics for low-molecular-mass polytetrafluoroethylene specimens obtained by preliminary irradiation of virgin samples at room temperature were revealed. A possible role of depolymerization in radiation crosslinking of polytetrafluoroethylene irradiated above the crystallite melting point was considered.