Reaction of 3,3,3-trifluoropropene-1 with bromoform and methylene bromide

The radical telomerization of 3,3,3-trifluoropropene with bromoform and methylens bromide has been studied. The nature of the products with bromoform depends substantially on the method of initiation. In the presence of Fe(CO)₅ + DMF, telomers of CHBr₂(CH₅₂CHCF₃)_nBr are formed, while with initiation with benzoyl peroxide other compounds are also formed that contain two, three, or four bromine atoms per molecule. To elucidate the formation of these products a reaction scheme is proposed that involves rearrangement of CHBr₂CH₂CH(CF₃)CH₃CHCF₃ radicals to CBr₂CH₂CH(CF₃)CH₂CH₂CF₃ radicals.Deceased.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2558–2562, November, 1989.     

GaAs traveling-wave optical modulator using a modulated coplanar strip electrode with periodic cross-tie overlay

This paper proposes and analyzes a GaAs traveling-wave optical modulator which uses a modulated coplanar strip electrode with periodic cross-tie overlay. This slow-wave structure can be designed to satisfy phase velocity and impedance matching conditions simultaneously. The dominant conductor loss in the slow-wave structure is reduced using the modulated coplanar strip electrode. The calculated 3-dB modulation bandwidth (100 GHz) is much wider than the bandwidth limit (30 GHz) of conventional electrode structures that are limited by phase velocity mismatch.This work was supported by the U.S. Army Research Office under contract DAAL-03-88-K-0005 and the Texas Advanced Technology Program.     

Vibrations of a magnet levitated over a flat superconductor

Based on a dipole-dipole interaction model, we discuss the levitation force and related vibration problems to understand the effects of flux pinning in type-II superconductors, and the applications of levitation in superconducting systems.     

Atom-atomic potentials and the correlation distribution functions for modeling liquid benzene by the molecular dynamics methods

A brief review of the potential functions used in the molecular dynamics modeling of liquid benzene is presented. The structural characteristics of liquid benzene obtained from the correlation distribution functions are discussed. It is demonstrated that, within the framework of this approach, the predicted structure of liquid benzene is virtually independent of the form of the potential used.     

The structure of CeAlO3 by Rietveld refinement of X-ray powder diffraction data

The room temperature structure of perovskite CeAlO₃ has been reinvestigated by X-ray powder diffraction. The Rietveld refinement has confirmed the tetragonal symmetry; but revealed a super cell, a=5.32489(6) Å and c=7.58976(10) Å, with the space group I4/mcm. In CeAlO₃, the distortion from the ideal cubic perovskite is caused by the cooperative tilting of the AlO₆ octahedra around the primitive cubic [001]_p-axis.     

Chemisorption at interfaces between organic semiconductors and metals: role of the electron affinity

Chemisorption is a well-known phenomenon for many interfaces between organic semiconductors and metals. It is shown that many published data indicate that the occurrence of chemisorption can be rationalized upon the consideration of the metal work function versus the electron affinity of the organic semiconductor.     

Pattern formation on a nonlinear periodic electrical network

It is observed experimentally that a periodic array of resistively coupled LC-oscillators with ans-shaped nonlinearity exhibits stable non-uniform voltage and current distributions. The dependence of the resulting structure on the coupling resistance and the boundary conditions is investigated. The structure is rather insensitive to variations of the boundary values. The experiments are well described by a two-variable reaction-diffusion equation.     

Radial and angular correlation in heliumlike ions

In the framework of nonrelativistic variational formalism a new type of basis set is proposed, to estimate separately the effect of radial and angular correlations on the ground‐state energy for helium isoelectronic sequence H^? to Ar¹⁶⁺. Effect of radial correlation is incorporated by using multiexponential functions arising from product basis sets suitably formed out of Slater‐type one‐particle orbitals. The angular correlation can be switched on by incorporating an expansion in terms of basis involving interparticle coordinates. With a set of six‐term Slater‐type one‐particle basis and five‐term interparticle expansion, the ground‐state energy of helium is estimated as ?2.9037236 (a.u.) compared with the multiterm variational estimates ?2.9037244 (a.u.) due to Pekeris and Thakkar and Smith and Drake. Matrix elements of different operators in the ground state have been calculated and found to be in good agreement with available accurate results. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003