Application of Racah algebra for point groups to the calculation of the energy spectra of complexes

Formulas are obtained for the matrix elements of the electrostatic interaction of the electrons of a complex; these are more convenient for calculations than the previously published formulas.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii Fizika, No. 7, pp. 91–93, July, 1971.We should like to thank V. I. Mitrofanov for a helpful discussion.     

Pade form of effective rotational molecular Hamiltonians

Effective rotational molecular Hamiltonians (ERH) are constructed which differ from the traditional representation of the ERH as a power series in the total angular momentum. A Padeform of the ERH is systematically obtained and the nonuniqueness of this form is emphasized.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii Fizika, No. 8, pp. 86–90, August, 1982.Finally, the authors thank A. V. Burenin for pointing out to us the advantages of the Pade representation of the ERH in the analysis of molecular spectra.     

A self-consistent method of constructing an effective rotational Hamiltonian

Methods have become widely used in molecular spectroscopy that involve the construction of effective rotational Hamiltonians [1, 2]. One of these methods has been developed by one of us over several years [3, 4]. A simple basis is provided for this method and it is shown that the scheme for constructing the effective operator for the rotational energy is substantially self-consistent.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 68–72, May, 1981.     

Phase equilibria and crystal structures of complex oxides in systems La-M-Fe-O (M = Ca or Sr)

Phase equilibria in systems La-M-Fe-O (M = Ca or Sr) at 1100° in air were studied. The homogeneity ranges and structures of solid solutions La_{1 ? x} M _x FeO_{3 ? δ} (0 ≤ x ≤ 0.3 for M = Ca and 0 ≤ x ≤ 0.8 for M = Sr), Sr_{2 ? y} La _y FeO_{4 ? δ} (0.8 ≤ y ≤ 1.0), and Sr_{3 ? z} La _z Fe₂O_{7 ? δ} (0 ≤ z ≤ 0.2) were determined using X-ray powder diffraction. The structural parameters of complex oxides were refined using the full-profile Rietveld technique. Correlations between the unit cell parameters and the compositions of solid solutions were derived. Isobaric/isothermal phase diagrams were constructed for systems La-M-Fe-O (M = Ca or Sr) at 1100°C in air.     

The oxygen nonstoichiometry,defect structure,and thermodynamic characteristics of disordering of nickel-and iron-substituted lanthanum cobaltites

The oxygen nonstoichiometry of nickel-and iron-substituted lanthanum cobaltites of the compositions LaCo_1?x Ni _x O_3?δ (x = 0.1, 0.3) and LaCo_0.9Fe_0.1O_3?δ was studied by high-temperature thermogravimetric analysis over the temperature and oxygen partial pressure ranges 1223–1473 K and 10^?3–0.21 atm. The partial replacement of cobalt with nickel (an acceptor impurity) in lanthanum cobaltite was found to increase the number of defects in the oxygen sublattice, whereas the replacement with iron (a donor impurity) decreased this number. Correlations between the experimental \(\log p_{O_2 } = f(\delta )\) dependences and the suggested models of formation of point defects were analyzed taking into account the formation of Schottky defects. Interrelation between the defect structure, partial molar thermodynamic characteristics of oxygen release from the crystal lattices of the oxides studied, and the nature of substituting impurities (Ni and Fe) in lanthanum cobaltite was demonstrated.     

Identification of Ge/Si intermixing processes at the Bi/Ge/Si(111) surface

The chemical contrast between Si and Ge obtained by scanning tunneling microscopy on Bi-covered Si(111) surfaces is used as a tool to identify two vertical Ge/Si intermixing processes. During annealing of an initially pure Ge monolayer on Si, the intermixing is confined to the first two layers approaching a 50% Ge concentration in each layer. During epitaxial growth, a growth front induced intermixing process acting at step edges is observed. Because of the open atomic structure at the step edges, relative to the terraces, a lower activation barrier for intermixing at the step edge, compared to the terrace, is observed.     

Symmetry breaking in the growth of two-dimensional islands on Si(111)

We find that the shape of two-dimensional (2D) Si or Ge islands has a lower symmetry than the threefold symmetry of the underlying Si(111) substrate if Bi is used as a surfactant during growth. Arrow-shaped or rhomb-shaped 2D islands are observed by scanning tunneling microscopy. This symmetry breaking is explained by a mutual shift between the surface reconstructions present on the substrate and on the islands. Using the kinematic Wulff construction the growth velocities of the steps could be determined from the island shape if the nucleation center has been located by a marker technique.     

Crystal structure and physicochemical properties of doped lanthanum manganites

Substituted lanthanum-strontium manganites La_0.7Sr_0.3Mn_0.9Me_0.1O_{3 ± ??} (Me = Ti, Cr, Fe, and Cu) are obtained by standard ceramic and glycerin-nitrate techniques. High-temperature powder X-ray diffraction is employed to study the crystal structure of La_0.7Sr_0.3Mn_0.9Me_0.1O_{3 ± ??} oxides. It is shown that in the range 298?C1023 K in air, La_0.7Sr_0.3Mn_0.9Me_0.103 ± ?? manganites crystallized in an orthorhombic cell (space group R-3c). The isobaric temperature dependences of unit cell parameters are determined. Thermal expansion coefficients are calculated for La_0.7Sr_0.3Mn_0.9Me_0.10_{3 ± ??} oxides. The conductivity of La_0.7Sr_0.3Mn_0.9Me_0.10_{3 ± ??} is studied as a function of temperature in the range 500 K ?? T ?? 1200 K in air. It is shown that substituting 3d metal for manganese considerably lowers the conductivity of basic La_0.7Sr_0.3Mn_0.9O_{3 ± ??}. The chemical stability of iron-substituted manganite La_0.7Sr_0.3Mn_0.9Fe_0.1O_{3 ± ??} is studied with respect to the electrolyte material.     

Exogenous iron redistribution between brain and liver after administering <Superscript>57</Superscript>Fe<Subscript>3</Subscript>O<Subscript>4</Subscript> ferrofluid to a rat brain ventricle

The natural excretion of ⁵⁷Fe enriched magnetic nanoparticles from a rat’s brain through its blood–brain barrier is studied. Dextran-coated iron oxide nanoparticles are transcranially injected into the rat’s brain ventricle. The injected nanoparticles undergo biotransformation into iron-containing proteins distributed over the brain tissues, while the exogenous iron transported from the brain to other organs is eliminated from the body over time.     

Separation of Contributions of the Magnetic Relaxation and Diffusion of Nanoparticles in Ferrofluids by Analyzing the Hyperfine Structure of Mössbauer Spectra

The theory and method for analysis of Mössbauer spectra of magnetic nanoparticles in a fluid have been developed by generalizing the model of the magnetic dynamics of a Néel ensemble of antiferromagnetic particles to the case of ferrimagnetic iron oxides. The resulting model describing the “superposition” of the magnetic dynamics and translational motion of nanoparticles in ferrofluids has been tested in application to the simultaneous analysis of Mössbauer spectra of “dry” magnetite nanoparticles and the same particles in glycerol.