Luminescent properties of AIIB2IIIC4VI compounds

Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 62, No. 3, pp. 145–151, May–June, 1995.     

Nonstandard formulation of perturbation theory for Green's function

Perturbation theory is developed for two-variable Green's functions (GF) when the initial GF is linked simultaneously to several higher-order GF. The total mass operator of the initial GF is obtained mathematically correctly in a form convenient for use. As an example of the application of this method, the mass operator of a nuclear spin anticommutator GF is calculated.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, pp. 43–49, July, 1988.     

Exciton and impurity electroabsorption in GaSexTe1-x〈Sn〉 single crystals

The exciton and impurity electroabsorption has been studied in GaSe_xTe_1-x〈Sn〉 (0.7 ?χ?1) exhibiting the properties of residual conductivity (RC). It has been shown that the broadening of the negative exciton peak, the nature of the field dependence of the electroabsorption signal, and its anisotropy in the exciton and impurity region are associated with the presence of internal chaotic fields E_int ≈ 10³ ? 10⁴ V cm^?1 coming into play because of the fluctuating distribution of the tin impurity and the defects inherent in layer crystals. Based on investigations of the impurity electroabsorption (IEA), the depth of occurence (hv = 1.18 eV) and the concentration (N = 10¹⁶cm³) of impurity centres have been determined.     

Increase in Selectivity of Toluene Disproportionation and in <Emphasis Type="Italic">p</Emphasis>-Xylene Yield by Optimization of Zeolite Microporous Structure

The possibility of increasing the yield of target products and para-selectivity of toluene disproportionation on modified zeolites by optimization of their microporous structure was studied.     

Isotopic exchange between molecular oxygen and MO·SiO2

Russian Chemical Bulletin -     

Cascade parametric light amplification with low-frequency pumping

Cascade parametric amplification in a regular domain structure is examined theoretically taking the variations in phase of all the interacting waves in a dissipative medium into account. Analytic expressions are obtained for the conversion efficiency of the laser energy with low-frequency pumping. The dependence of the parametric amplification efficiency on the number of layers is given. Ways of increasing the frequency conversion efficiency are discussed. The presence of a nonzero input intensity at the sum frequency is found to cause a nonlinear increase in the high-frequency signal at the output of the structure. As the losses of the interacting waves increase, both the frequency conversion efficiency and the optimum domain length decrease.     

Optimal control problem for a quasilinear parabolic equation with controls in the coefficients and with state constraints

We consider an optimal coefficient control problem for a quasilinear parabolic equation. We study the well-posedness of the problem and obtain a necessary condition for optimality.     

Six-Nuclear Complexes of Platinum(II) and Palladium(II) with Mercamine and β-Mercaptoethanol

The platinum(II) and palladium(II) complexes [Pt₆(SCH₂CH₂NH₂)₈]Cl₄ and [Pd₆(SCH₂CH₂OH)₈ Cl₄· 5H₂O with mercamine and β-mercaptoethanol, respectively, were synthesized. It was found on the basis of the comparison of IR and X-ray electron spectra of the ligands and complexes, and also of the data of X-ray diffraction analysis that the bidentate coordination of ligands through sulfur and nitrogen atoms is realized in the platinum(II) complex. In the palladium(II) complex β-mercaptoethanol is coordinated in a mixed-mode type. In both complexes sulfur atoms of the ligands occupy a bridging position.