Structure of copper halide nanocrystals in photochromic glasses

The crystal structure of CuCl nanocrystals with effective radii ranging from 2.4 to 18.5 nm in photochromic glasses heat treated under different conditions is investigated using exciton spectroscopy, x-ray powder diffraction, and small-angle x-ray scattering. It is revealed that the size dependence of the energy of the Z ₃ exciton exhibits an anomalous behavior. The results obtained suggest that small-sized CuCl nanocrystals can crystallize in a modification different from the stable cubic modification.     

Resonance Radiative Collision of Charged Particles in an External Magnetic Field

We analyze bremsstrahlung due to collision of a relativistic electron with an ion in an external longitudinal magnetic field. Within the framework of the perturbation method, a general expression for the electric field of radiation is derived. It is shown that the magnitude of the resonance peak of the spectral line is determined by the small dissipative force of radiation reaction. The influence of the external field on the specific intensity and polarization of the wave is analyzed in detail.     

Non-adiabatic transitions from I2(E0g+ and D0u+) states induced by collisions with M = I2(X0g+) and H2O

The stepwise two-step two-color and three-step three-color laser excitation schemes are used for selective population of rovibronic levels of the first-tier ion-pair E0(g)(+) and D0(u)(+) states of molecular iodine and studies of non-adiabatic transitions to the D and E states induced by collisions with M = I(2)(X) and H(2)O. Collection and analysis of the luminescence after excitation of the v(E) = 8, 13 and v(D) = 13, 18 vibronic levels of the E and D states in the pure iodine vapor and the gas-phase mixtures with H(2)O provide rate constants for the non-adiabatic transitions to the D and E state induced by collisions with these molecules. Vibrational distributions for the [formula: see text] collision-induced non-adiabatic transitions (CINATs) are obtained. Rather strong λ(lum)(max) ≈ 3400 ? luminescence band is observed in the I(2) + H(2)O mixtures, whereas its intensity is ~100 times less in pure iodine vapor. Radiative lifetimes and quenching rate constants of the I(2)(E,v(E) = 8, 13 and D,v(D) = 13, 18) vibronic state are also determined. Rate constants of the [formula: see text], v(E) = 8-54, CINATs are measured again and compared with those obtained earlier. New data confirm resonance characters of the CINATs found in our laboratory about 10 years ago. Possible reasons of differences between rate constant values obtained in this and earlier works are discussed. It is shown, in particular, that differences in rate constants of non-resonant CINATs are due to admixture of water vapor in iodine.     

Theoretical simulation of the dead zone in hologram recording on photopolymerizable materials

Recording of a diffraction grating in a photopolymerizable material in the presence of a liquid crystal is studied theoretically in terms of the polymerization equation with allowance for diffusion. A model explaining the occurrence of recording delay time (dead zone) by the presence of oxygen or other impurities that prevent the formation of free radicals is put forward. The dead zone duration versus the writing radiation intensity is derived.     

A system of differential equations connected with a polynomial class of shifts of a box spline

Translated from Matematicheskie Zametki, Vol. 44, No. 6, pp. 705–724, December, 1988.     

Synthesis and thermal decomposition of halogenoalkoxy-, halogenoalkylthio-, and halogenoalkoxyamino-sym-triazines 13. Synthesis and thermolysis of 4,6-disubstituted 2-(2-chloroethoxy)- and 2-(2-chloroethylamino)-sym-triazines

4-Amino-, 4-methoxy-, 4-methylthio-, 4-alkylamina-, and 4-dialkylamino-6-alkyl(dialkyl)amino-2-(2-chloro-ethoxy)-sym-triazines and the corresponding 2-(2-chloroethylamino)-sym-triazines were obtained. Their cyclization led to the sym-triazinium chlorides or imidazo-sym-triazines.For Communication 12, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 228–230, February, 1992.     

Hydroconversion of Oxidation Products of Sulfur-Containing Aromatic Compounds

Hydroconversion of benzo- and dibenzothiophene sulfone on a Ni–Mo sulfide catalyst based on mesoporous aluminosilicate Al-HMS and on unsupported catalysts prepared in situ in the course of decomposition of poorly soluble precursors (molybdenum hexacarbonyl, nickel naphthenate) was studied. Hydrogenation of sulfones was perfpormed at 250, 340, and 380°С and elevated СО pressure in the presence of water ensuring in situ generation of hydrogen via water-gas shift reaction.     

Synthesis of New Substituted 2,3-Dihydro-1,4-dioxin-2-ones and 1,4-Dioxan-2-ones

3-Alkyl-6-methyl-2,3-dihydro-1,4-dioxin-2-ones reacted with acetyl chloride in the presence of zinc(II) chloride to give the corresponding 3-alkyl-5-acetyl-6-methyl-2,3-dihydro-1,4-dioxin-2-ones. Oxidation of the latter with hydrogen peroxide in formic acid, followed by treatment with magnesium bromide, afforded 3-alkyl-6-methyl-1,4-dioxane-2,5-diones. Successive chlorination and dechlorination of 6-hydroxymethyl-1,4-dioxan-2-ones yielded 6-methylene-1,4-dioxan-2-ones.