Modification of GaAs by medium-energy N<Stack><Subscript>2</Subscript><Superscript>+</Superscript></Stack> ions

The modification of GaAs with a 2500-eV beam containing N ₂ ⁺ and Ar⁺ ions is examined with Auger electron spectroscopy. Most implanted nitrogen atoms are found to react with the matrix, substituting arsenic atoms to produce a several-nanometer-thick layer of the single-phase GaAs_1−x N_x (x=6%) solid solution. The GaN phase is absent. Displaced arsenic atoms and nitrogen atoms unreacted with the matrix are present in the layer and on its surface. The former segregate, whereas the latter form molecules.     

Synthesis and thermal decomposition of cobalt-containing oligosilanes

Oligo(phenylcobaltcarbonylsilane) was prepared from oligo(phenylsilane) and dicobalt octacarbonyl. The reaction proceeds with elimination of H₂ and CO and insertion of cobalt carbonyl fragments into the silicone backbone of oligosilane. Oligosilane containing cobalt carbonyl groups in side organic substituents was obtained from oligolmethyl(phenylethynyl)Isilane and CO₂(CO)₈. The reaction of 1,2-bis(phenylethyny1)tetramethyldisilane with Co₂(CO)₈ proceeds with the sequential attachment of cobalt carbonyl fragments to ethynyl groups to form disilane derivatives [²-CCPhCo₂(CO)₆] Thermal decomposition of cobalt-containing oligosilanes affords a mixture of paramagnets and ferromagnets.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya. No. 10, pp. 2561–2567, October, 1996.     

Alkyl 3-Nitroacrylates in Reactions with Substituted Hydrazines

Russian Journal of General Chemistry - The reactions of alkyl 3-nitroacrylates with representatives of aryl(hetaryl) carboxylic acid hydrazides and substituted phenylhydrazines were studied. It was...     

Alkyl-2,3-dibromo-3-nitroacrylates in the reactions with substituted hydrazines

The interaction of alkyl 2,3-dibromo-3-nitroacrylates with aroylhydrazines at room temperature or with 2,4-dinitrophenylhydrazine under reflux gives the corresponding 2-aroyl(aryl)hydrazono-3-bromo-3-nitropropanoates. Refluxing of ethyl 2,3-dibromo-3-nitroacrylate with a fourfold excess of benzoylhydrazine results in ethyl-2,3-bis(benzoylhydrazono)propanoate. The structure of compounds obtained has been proved by IR, ¹H NMR, ¹³C-{¹H} NMR, and electron spectroscopy methods.     

Reaction of alkyl 3-bromo-3-nitroacrylates with substituted hydrazines. Synthesis of N′-substituted alkyl 3-nitropyruvate hydrazones

Russian Chemical Bulletin - The reaction of alkyl 3-bromo-3-nitroacrylates with substituted phenylhydrazines and hydrazides of aromatic acids proceeds through the formation of aza-Michael adducts....     

Isospin symmetry and giant resonance in nuclei of mass number <Emphasis Type="Italic">A</Emphasis> = 14

An analysis of the cross sections for photon absorption by isobar nuclei ¹⁴C and ¹⁴N in the giant-dipole-resonance region demonstrates a high degree of isospin symmetry for this type of collective excitations in the above nuclei. Giant resonances in A = 14 isobar nuclei are related by a simple rescaling procedure that is based on the fact that, for these nuclei, the isospin remains a good quantum number in the process of dipole excitations of energy up to about 40 MeV. The features of the isospin splitting of the giant resonance in the ¹⁴C nucleus are refined. The shape of the cross section for photoabsorption in the ¹⁴C nucleus—in particular, a large width of the giant resonance in this nucleus—is exhaustively explained.     

Some Features of the Reactions of 3-Nitro-6-phenylhexa-3,5-dien-2-one with Thiophenols

The reaction of 3-nitro-6-phenylhexa-3,5-diene-2-one with 4-methyl- and 4-chlorothiophenols yields 1,4- and 1,6-addition products at conjugated dienone system. By the example of the 1,4-addition adduct of 4-methylthiophenol, its conversion in solution to the 1,6-addition product was shown. 4-Methyl-3-nitro-2-styryl-2,3-dihydrobenzo[b][1,4]thiazepine was synthesized by reacting 3-nitro-6-phenylhexa-3,5-dien-2-one with o-aminothiophenol.     

Size effects on polaritons in thin crystals with perfect interference spectra

Size effects on polaritons in thin plane parallel CdS and CdSe crystals are discussed. For samples not thinner than 0.1 μm the measurements of transmittance and reflectance show the size quantization of the mechanical exciton dispersion and a shift of the resonance frequency of the exciton to the high-energy side with decreasing thickness. However no evidence for the alteration of the oscillator strength or other parameters has been obtained. This conclusion is in conflict with the recently published data taken on CdS samples. The stability of the polariton dispersion in our case is supported by the theoretical study of reflectance ignoring the effects of the finiteness of the exciton radius.     

Rank Analogs of Hall's and Baer's Theorems

Siberian Mathematical Journal -