Raman Scattering Study of Natural and Synthetic Compounds Containing Polyene Chains

Doklady Physics - The dependence of Raman spectra of the molecules containing polyene chains on the conjugation length, structure of side and end groups, and isomer type is analyzed theoretically.     

Specific Features of Distribution and Relaxation of Elastic Stresses in Homoepitaxial CVD Films of Germanium and Diamond

Crystallography Reports - The real structures of epitaxial CVD films of germanium and diamond have been comparatively analyzed. The influence of the specific features of elastic-stress distribution...     

An integrodifferential indicator for the problem of single beam tomography

This article continues the authors’ study of the problem of X-ray tomography with few directions of the probing radiation. In the previous articles some special integrodifferential operators were used to process the available information. We propose a new formula for this operator, give theoretical justification of our algorithm, and include the results of appropriate simulations.     

Synchronization in ensembles of delay-coupled nonidentical neuronlike oscillators

Nonlinear Dynamics - We study both numerically and experimentally the synchronization in an ensemble of nonidentical neuronlike oscillators described by the FitzHugh–Nagumo equations. The...     

The sum of coefficients of bounded univalent functions

We solve the maximal value problem for the functional in the class of functionsf(z)=z+a ₂z²+… that are holomorphic and univalent in the unit disk and satisfy the inequality |f(z)|<M. We prove that the Pick functions are extremal for this problem for sufficiently largeM whenever the set of indicesk ₁,…,k_m contains an even number. Translated fromMatematicheskie Zametki, Vol. 61, No. 5, pp. 728–733, May, 1997. Translated by S. S. Anisov     

Microphotoluminescence of C<Subscript>60</Subscript> Fullerites Synthesized under a Pressure of 13 GPa and Temperatures of 770–2100 K

C₆₀ fullerite samples synthesized under a pressure of P = 13 GPa and temperatures of T_s = 770 ? 2100 K were studied by scanning microphotoluminescence (MPL) at room temperature. The MPL of cleaved chip surfaces indicates the presence of emitting areas with linear dimensions from 35 to 350 μ. A band at 700 nm, which is characteristic for linear and planar C₆₀ polymers, was revealed in all 3D-polymerized fullerites too. New bands at 1100?2300 nm are observed in PL spectra of substances synthesized at 870 ≤ T_s ≤ 1270 K. Separated areas of several optically active moieties responsible for luminescence in the range 1100?2300 nm were detected by MPL cartography. The origin of this band is tentatively attributed to traps located on C₆₀-oxygen and nitrogen inclusions associated with defects of the crystal lattice.     

Structural characterization of interfaces in the AlxGa1?xAs/GaAs/AlxGa1?xAs heterostructures by high-resolution X-ray reflectometry and diffractometry

The structural properties of multiplayer Al_xGa_1−x As/GaAs/Al_xGa_1−x As systems (x ≈ 0.2) grown on GaAs(001) substrates are studied by the methods of double-crystal X-ray diffractometry and reflectometry. The depth profiles of deformation, amorphization, and density of the layers are obtained. It is shown that despite small differences (5–7%) in the densities of the Al_xGa_1−x As layers and the substrate and the small thickness of the AlAs layer (1–2 nm) separating the GaAs quantum well, it is possible to reconstruct the heterostructure model by the method of X-ray reflectometry and to determine the thickness of the transitional layers at a resolution of 0.1–0.2 nm. It is also established that the reflectometry data obtained complement the X-ray diffraction data considerably and allow one to estimate the roughness and the character of the aluminum distribution at the interfaces. __________ Translated from Kristallografiya, Vol. 50, No. 5, 2005, pp. 801–812. Original Russian Text Copyright ? 2005 by Lomov, Sutyrin, Prokhorov, Galiev, Khabarov, Chuev, Imamov.     

Influence of π stacking on the magnetic properties of the copper(II) complex with 6-phenyl-3-(2-pyridyl)-5-trifluoroacetylmethylidene-4,5-dihydro-1,2,4-triazine

The new N,N,O-ligand 6-phenyl-3-(2-pyridyl)-5-(trifluoroacetylmethylidene)-4,5-dihydro-1,2,4-triazine (L) was synthesized, and its complex with Cu^II was prepared. The structure of the complex was established by X-ray diffraction. Magnetic measurements and ESR studies were carried out. Ab initio calculations of the electronic structure, exchange interactions, and the effective magnetic moment were performed. The intrastack polarization effect between the π states of 1,2,4-triazine and the d states of copper was revealed and numerically validated. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 549–554, March, 2008.