Combined MEIS/TEM study of structural defects in Si implanted with a high dose of 100 keV Si ions

Medium-energy ion scattering and transmission electron microscopy have been used to study the structural perfection of a Si single crystal implanted with 100 keV Si ions at a dose of 1×10¹⁷ cm^?2, which exceeds the amorphization threshold by two orders of magnitude. The implantation of Si ions was found to produce a high density of extended defects without amorphization of the Si layer. The increasing depth dependence of the full width at half-minimum of the dip in angular scans of backscattered protons, was observed in a Si layer containing a high density of extended defects, in contrast to the decreasing dependence in the perfect Si crystal.     

Algorithm for determining the aerodynamic characteristics of a freely flying object from discrete data of ballistic experiment. Part I

In part 1 of this paper, an algorithm for numerically solving the inverse problem of motion of a solid through the atmosphere is described that constitutes the basis for identifying the aerodynamic characteristics of an object from trajectory data and the respective identification procedure is presented. In part 2, methods evaluating the significance of desired parameters and adequacy of a mathematical model of motion, approaches to metrological certification of experimental equipment, and results of testing the algorithm are discussed.     

Synthesis and structure of mixed-metal thiolate complex Cp′Cr(CO)2(μ-SBu)Pt(PPh3)2: Side-on-coordination of Cr–S double bond with platinum

The reaction of [Cp′Cr(CO)₂(μ-SBu)]₂ (1) (Cp′ = MeC₅H₄) with (PPh₃)₂Pt(PhCCPh) gives Cp′Cr(CO)₂(μ-SBu)Pt(PPh₃)₂ (2) which could be regarded as a product of the substitution of acetylene ligand at platinum by a monomeric chromium–thiolate fragment. According to the X-ray diffraction analysis 2 contains single Cr–Pt (2.7538(15)) and Pt–S (2.294(2) Å) bonds while Cr–S bond (2.274(3) Å) is shortened in comparison with ordinary Cr–S bonds (2.4107(4)–2.4311(4) Å) in 1. The bonding between Cr–S fragment and platinum atom is similar to the olefine coordination in their platinum complexes.     

Electro- and Magnetotransport near a LaAlO3/SrTiO3 Interphase Boundary

Comparison of the channel spectra of medium energy ion scattering, visualized for LaAlO₃/(001)SrTiO₃ heterostructures with a thickness of the lanthanum aluminate layer of one to six unit cells, indicates that the lanthanum aluminate layer grows coherently on a TiO₂-terminated surface of a strontium titanate substrate. The resistance of the interphase boundary in the heterostructure with a thickness of the LaAlO₃ layer of six unit cells decreased with temperature. At T < 100 K, the positive magnetoresistance and Hall mobility of electrons increased sharply with decreasing temperature.

     

Similarity between the heat transfer to a model in an underexpanded dissociated-air jet of a high-frequency plasmatron and to a sphere in a high-velocity flow in the terrestrial atmosphere

On the basis of the local heat transfer modeling concept the parameters of supersonic flow past a cylindrical flat-faced model, 0.01m in radius, in an underexpanded dissociate-air jet of the VGU-4 high-frequency plasmatron are recalculated to the conditions of sphere entry in the terrestrial atmosphere. The heat transfer parameters, similar in the experiment and the atmospheric entry, are determined.     

Monolithic white LEDs: Approaches, technology, design

The results of investigations of monolithic white InGaAlN LEDs with an active region containing several thin InGaN layers, emitting in the range from blue to yellow-green, and separated by short-period InGaN/GaN superlattices, are presented. The influence of the growth conditions and layer sequence in the active region on the optical properties of monolithic white LEDs was studied with the aim of controlling their color parameters.     

Synthesis of fluorine-containing esters of 2,5-furandicarboxylic acid

Fluorinated esters of 2,5-furandicarboxylic acid have been synthesized starting from 2,5-furan dicarboxylic acid dichloride and fluorine-containing diols. The reaction control was performed by means of ¹H, ¹⁹F NMR, and IR-spectroscopy. Thermal stability, as well as glass transition temperature, and intrinsic viscosity parameters of the obtained oligomers have been determined.     

The use of temperature to simplify formose sugar composition

Form ose reaction, the Ca(OH)₂ catalyzed condensation of HCHO to a complex mixture of sugars, does not lose its autocatalytic nature at 98°C. The induction period is 15 sec, and then, at 18% total HCHO conversion, there was a period of approximately 3 sec duration in which the reaction had produced C₆ sugars at 84.3 wt.% selectivity. Glucose amounted to 90% of those sugars, and no branched sugars were detected. Conversion was complete within 3 min. The simple nature of the product was lost at lower temperatures or higher conversions.

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— HCHO, Ca(OH)₂, 98°C. 15 , 38%- HCHO 3 , C₆ 84,3 . %. 90%, . 3- . .

     

Multinuclear NMR Study of the Structure and Intramolecular Dynamics of (eta(2)-Acetone phenylhydrazonato)tetrafluorooxotungsten(VI)

Using one- and two-dimensional techniques of (1)H, (13)C, (15)N, and (19)F NMR spectroscopy, it was proved that acetone phenylhydrazone (H-aph) acts as a two-center N,N-donor ligand in the complex [WOF(4)(aph)](-). As a result of the coordination to tungsten, the ligand conformation changes from E to Z, and at the same time the phenyl ring is turned out of the >N-N=C< plane. At low temperatures (-30 degrees C), the equatorial plane of the pentagonal-bipyramidal tungsten polyhedron comprises two donor nitrogen atoms of hydrazone and three fluoro ligands. At elevated temperatures, stereoisomeric interconversion caused by hindered intramolecular rotation of the aph(-) ligand occurs. The mechanism of this process was elucidated on the basis of the dynamic effects in (19)F spectra and line-shape analysis of the trans-CH(3) resonance in (13)C spectra split due to direct "through-space" coupling with the proximate fluoro ligand.     

Nanoscale oxide surface modification of inorganic materials

A method of synthesis of metal oxide films by carboxylate pyrolysis on a substrate surface is developed. The optic physical properties of the obtained films are studied by spectrophotometry using specialdesign fiber-optic probes.