Anomalies in the structure and properties of titanium diselenide intercalated by iron

The transition between the heavy and localized polaron modes in the Fe _x TiSe₂ compounds used as an example is studied by methods of thermal analysis, neutron diffraction, and dc conductivity. It is found that the transition under investigation is accompanied by an anomaly in the behavior of the crystallographic parameters. The changes observed in the character and magnitude of the electrical conductivity at a higher temperature, as well as the thermal effect, are attributed to thermal broadening of the polaron band. The difference between the data for Fe _x TiSe₂ and the previously obtained results for Ag _x TiTe₂ correlates with the difference in the binding energies of the polaron bands in these materials.     

On distance subgraphs of graphs in spaces of lower dimensions

This paper studies the problem on the frequency of the event where a graph with a fixed number of vertices contains induced subgraphs that are isomorphic to distance graphs in spaces of definite dimensions. In particular, the case of plane and three-dimensional spaces is considered.     

Intensification of shock-induced combustion by electric-discharge-excited oxygen molecules: numerical study

Mechanisms of combustion enhancement in a supersonic H₂–O₂ reactive flow behind an oblique shock wave front are investigated when vibrational and electronic states of O₂ molecule are excited by an electric discharge. The analysis is carried out on the base of updated thermally nonequilibrium kinetic model for the H₂–O₂ mixture combustion. The presence of vibrationally and electronically excited O₂ molecules in the discharge-activated oxygen flow allows to intensify the chain mechanism and to shorten significantly the induction zone length at shock-induced combustion. It makes possible, for example, to ignite the atmospheric pressure H₂–O₂ mixture at the distance shorter than 1 m behind the weak oblique shock wave at a small energy E_s = 1.2 × 10^–2 J · cm^–3 input to O₂ molecules. At higher pressure it is needed to put greater specific energy into the gas in order to ignite the mixture at appropriate distances. It is shown that excitation of O₂ molecules by electric discharge is much more effective for accelerating the hydrogen–oxygen mixture combustion than mere heating the gas.     

Photoelectron spectra and steric structure of sulfenamides

According to the data from photoelectron and UV spectroscopy, the molecules of N,N-dimethylmethane sulfenamide and N,N-diethylpropane-2-sulfenamide have a conformation with orthogonal orientation of n_N and n_S orbitals, while N,N-dimethylbenzene sulfenamide in the gas phase exists in conformational equilibrium of the planar and skewed conformers.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 77–80, January, 1990.We would like to thank F. G. Nasybullina for conducting the GLC analysis.     

Synthesis of γ- dihydropyrones and β- dihydrofuranones on the basis of acetylenic γ- and δ-keto alcohols and acetals of γ- and δ-formyl alcohols

Acetylenic - and -keto alcohols and acetals of acetylenic - and -keto alcohols and acetals of acetylenic - and -formyl alcohols undergo cyclization to -dihydropyrones and -dihydrofuranones under the influence of acids.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1471–1473, November, 1976.     

Kinetics of Detonation Initiation in the Supersonic Flow of the H2 + O2 (Air) Mixture in O2 Molecule Excitation by Resonance Laser Radiation

The possibility of initiating detonation in the supersonic flow of the H₂ + O₂ (air) mixture behind the front of the inclined shock wave by O₂ molecule excitation to the O₂(a ¹_g) and O₂(b ¹·⁺ _g) states by laser radiation with a wavelength _I = 1.268 m and 762 nm is considered. Resonance laser radiation intensifies chain combustion due to the formation of new pathways for generating active atoms O^· and H^· and radicals OH and has a substantially nonthermal character. Even at low (3 kJ/cm²) energies of radiation with _I = 762 nm applied to the gas, detonation combustion can occur even at a distance of 1 m from the front at the gas temperature as high as 600 K.     

Tetrazoles. 21. Reaction of benzonitrile with salts of hydrazoic acid

The reaction of benzonitrile with the ammonium, alkyl-, dialkyl-, and trialkylammonium salts of hydrazoic acid in DMF at 100C produces 5-phenyltetrazole. The yield of 5-phenyltetrazole is practically independent of the structure of the ammonium cation. Under the same conditions, the tetraalkylammonium salts of hydrazoic acid do not react with benzonitrile. It was proposed that the formation of 5-substituted tetrazoles from nitriles and the salts of hydrazoic acid proceeds by the mechanism of 1,3-dipolar cycloaddition.For Communication 20, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1086–1089, August, 1986.     

IR study of the peculiarities of the stabilization of the NH4Na-Y zeolite structure during its hydrothermal dealumination

The variations in the structure of deep-level calcinated NH₄Na-Y zeolite (68 % NH₄ ⁺, Si/Al = 2.56) at 873 K (stage I of the hydrothermal dealumination) as a result of ammonation and subsequent calcination in water vapor at 973 and 1023 K (stageII) were studied using the IR spectra of zeolite framework vibrations. It was shown that ammonation of the product of stageI promotes the formation of linear disiloxane bonds and extra-framework =Al^VI-OH species identified by absorption at 482, 1196 cm^–1, and 524, 612, 829 cm^–1. The ammonation is also accompanied by an increase in the excessive negative framework charge (ENFC), which is manifested in the high-frequency (HF) shift of the bands that have maxima in thev _as (TO₄) region and equals 10 cm^–1, and also by a decrease in the unit cell parameter (a ₀) by 0.14 Å. The decrease in both the ENFC anda ₀ for the products of stageII, v _as (TO₄) = 10–20 cm^–1 and a ₀ = 0.07–0.14 Å, is due to the formation of nonlinear disiloxane bonds and non-framework aluminum hydroxide species identified by the absorption bands at 478, 1173 cm^–1 and 530, 615, 835 cm^–1.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 660–664, April, 1993.     

On the possibility of plasma chemical conversion of hydrogen chloride

The possibility of plasma chemical conversion of hydrogen chloride was explored. It was shown that, for the typical conditions of atmospheric pressure discharges, the use of pure HCl as the plasma-forming gas does not provide the conversion degrees higher than 4%. It was found that high (>95%) HCl conversion degrees, as well as maximum yields of Cl₂ may be obtained in HCl-O₂ mixtures due to the plasma-assisted oxidative decomposition of the reactant. The optimal process conditions in terms of the electron density and feed gas composition were determined.