Chemical Composition of Shale Kerogen (Kerogen-70) from Leningrad Oblast

The chemical composition of various extracts from oil shale (kerogen-70) was studied in detail.     

Adducts of Diethyldithiocarbamate Complexes of Zinc(II) and Copper(II) with Piperidine [M(Pip)(Edtc)2] and Their Solvated Forms [M(Pip)(Edtc)2] · L (L = C6H6, C5H5N,C4H9NO): Synthesis,EPR and Solid-State (13C, 15N) CP/MAS NMR Studies

Crystal adducts of diethyldithiocarbamate complexes of zinc(II) and copper(II) with piperidine (Pip) were synthesized, and their solvated forms with the outer-sphere molecules of benzene, pyridine (Py), and morpholine (Mf) were obtained. Adducts with composition [M(Pip)(Edtc)₂] · L (L = Py, Mf) were shown to be able, in principle, to give solvated isomers [M(L)(Edtc)₂] · Pip with the Pip molecule arranged in the outer sphere. The composition, structure, and properties of the obtained adducts were studied by EPR, high-resolution solid-state ¹³C, ¹⁵N NMR spectroscopy. Solvation of all three adducts with Pip, Mf, and Py was found to result in a substantial increase in the contribution of the trigonal–bipyramidal component to the geometry of a copper coordination pentahedron. In addition, for adducts with Mf and Py, a structural unification of two isomeric forms was observed at the molecular level to yield a qualitatively new (rather than intermediate) state. It was shown that in all solvated forms of the copper(II) adducts, the metal polyhedron is mainly a trigonal bipyramid, while the square–pyramidal contribution is insignificant. Results of (¹³C, ¹⁵N) NMR studies revealed a structural inequivalence of the Edtc^–ligands in the zinc adducts under investigation.     

Surface Polaritons in Silicon-Doped Aluminum and Gallium Nitride Films

Optics and Spectroscopy - The reflection and attenuated total reflection spectra of aluminum and gallium nitride films doped with silicon on sapphire substrates with a buffer layer of aluminum...     

Accurate X-ray diffraction studies of KTiOPO<Subscript>4</Subscript> single crystals doped with niobium

Single crystals of potassium titanyl phosphate doped with 4% of niobium (КТР:4%Nb) and 6% of niobium (KTP:6%Nb) are studied by accurate X-ray diffraction at room temperature. The niobium atoms are localized near the Ti1 and Ti2 atomic positions, and their positions are for the first time refined independent of the titanium atomic positions. Maps of difference electron density in the vicinity of K1 and K2 atomic positions are analyzed. It is found that in the structure of crystal КТР:4%Nb, additional positions of K atoms are located farther from the main positions and from each other than in КТР and KTP:6%Nb crystals. The nonuniform distribution of electron density found in the channels of the КТР:4%Nb structure is responsible for ~20% increase in the signal of second harmonic generation.     

Slow light with integrated gain and large pulse delay

We demonstrate slow and stored light in Rb vapor with a combination of desirable features: minimal loss and distortion of the pulse shape, and large fractional delay (>10). This behavior is enabled by (i) a group index that can be controllably varied during light pulse propagation, and (ii) controllable gain integrated into the medium to compensate for pulse loss. Any medium with the above two characteristics should be able to realize similarly high-performance slow light.     

Representation of exact and semiclassical eigenfunctions via coherent states. Hydrogen atom in a magnetic field

Global formulas for eigenfunctions and solutions to the Cauchy problem, including the path integral representation, are obtained using the coherent states technique. The reduction of coherent states via symmetry groups is studied for a transformation from Bessel to hypergeometric states. The eigenfunctions of the Hamiltonian for the hydrogen atom in a homogeneous magnetic field are expressed in terms of Bessel coherent states. For a small field, after quantum averaging, the Hamiltonian is represented in terms of generators with quadratic commutation relations. The irreducible representations of this quadratic algebra are realized on hypergeometric states. The notion of deformed hypergeometric states is also introduced for this quadratic algebra as an analog of squeezed Gaussian packets of the Heisenberg algebra. The asymptotic equations of eigenfunctions with respect to a small field and a large leading quantum number are derived using these states and their deaveraging. Some explicit formulas for the Zeeman splitting of the spectrum are obtained up to the fourth order with respect to the field, as well as for lower and upper levels in the cluster, including the case of incidence on the center.Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 108, No. 3, pp. 339–387, September, 1996.     

Instantons via breaking geometric symmetry in hyperbolic traps

Using geometrical and algebraic ideas, we study tunnel eigenvalue asymptotics and tunnel bilocalization of eigenstates for certain class of operators (quantum Hamiltonians) including the case of Penning traps, well known in physical literature. For general hyperbolic traps with geometric asymmetry, we study resonance regimes which produce hyperbolic type algebras of integrals of motion. Such algebras have polynomial (non-Lie) commutation relations with creation-annihilation structure. Over this algebra, the trap asymmetry (higher-order anharmonic terms near the equilibrium) determines a pendulum-like Hamiltonian in action-angle coordinates. The symmetry breaking term generates a tunneling pseudoparticle (closed instanton). We study the instanton action and the corresponding spectral splitting.     

Synthesis and study of some imidazole derivatives

The preparation of esters of 4(5)-hydioxymethylimidazole with mono-, di-, and trichloroacetic acids is described. It has been established that in the reaction of imidazolylmethyl chloroacetate with diethanolamine, the latter is alkylated with the imidagolylmethyl part of the ester, giving rise to bis(2-hydroxyethyl)aminomethylimidazole.For communication II, see [1].