A three-dimensional lattice gas approximation for multilayer adsorption

A three-dimensional lattice gas approximation for multilayer adsorbates is substantiated on the basis of statistical physics. In addition, some problems of equilibrium thermodynamics and kinetics are formulated, and a number of approximations are derived. A detailed kinetic theory of thin film growth, which is complementary to the applied approaches based on phenomenological models, thermodynamics of nonequilibrium processes, and solid medium and lattice gas models, is developed.Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 105, No. 1, pp. 130–148, October, 1995.     

Surface layering in ionic liquids: an X-ray reflectivity study

The surface structure and thermodynamics of two ionic liquids, based on the 1-alkyl-3-methylimidazolium cations, were studied by X-ray reflectivity and surface tensiometry. A molecular layer of a density approximately 18% higher than that of the bulk is found to form at the free surface of these liquids. In common with surface layering in liquid metals and surface freezing in melts of organic chain molecules, this effect is induced by the lower dimensionality of the surface. The concentrations of the oppositely charged ions within the surface layer are determined by chemical substitution of the anion. The temperature-dependent surface tension measurements reveal a normal, negative-slope temperature dependence. The different possible molecular arrangements within the enhanced-density surface layer are discussed.     

Oriented crystalline monolayers and bilayers of 2 x 2 silver(I) grid architectures at the air-solution interface: their assembly and crystal structure elucidation

Oriented crystalline monolayers, approximately 14 A thick, of a 2 x 2 Ag+ grid complex, self-assembled at the air-solution interface starting from an water-insoluble ligand 3,6-bis[2-(6-phenylpyridine)]pyridazine spread on silver-ion-containing solutions, were examined by grazing-incidence X-ray diffraction and specular X-ray reflectivity using synchrotron radiation. The monolayer structure was refined, including a determination of the positions of the counter-ions, with the SHELX-97 computer program. The monolayers were transferred from the interface onto various solid supports and visualized by scanning force microscopy, and characterized by X-ray photoelectron spectroscopy in terms of molecular structure. On surface compression, the initial self-assembled monolayer undergoes a transition to a crystalline bilayer in which the two layers, almost retaining the original arrangement, are in registry. Such a phase transition is of relevance to the understanding of crystal nucleation.     

Synthesis and properties of optically active ferrocenylethylindazoles

The stereochemistry of two processes, viz., -ferrocenylalkylation of indazole with optically active S-(+)-1-ferrocenylethanol and the thermal rearrangement of S-(+)-2-N-(ferrocenylethyl)indazole into S-(+)-1-N-(ferrocenylethyl)indazole, was studied. Both reactions proceed stereoselectively.     

Pair Correlations and Magnetic Susceptibility of Small Al-Grains

Pair correlations and the magnetic susceptibility of electrons in a spherical cavity are studied both for grand canonical and the canonical ensemble. The coupling constant of the BCS Hamiltonian is adjusted to experimental values of the gap parameter. The gap parameter is found to increase for small grains as a consequence of the pronounced shell structure in the spectrum of the spherical cavity. The sharp phase transition at Tc is smeared out for the canonical ensemble. The strong paramagnetic susceptibility of the normal electrons in the cavity is reduced by the superconductivity, but it remains positive.     

The Stability of Mononuclear and Binuclear Complexes of Silver(I) with Thiosemicarbazide in an Aqueous Solution

Moscow University Chemistry Bulletin - The complexation process of silver(I) ions with thiosemicarbazide (Tsc) in a wide range of concentrations of silver(I) and thiosemicarbazide at T =...     

Сyclization of 1-amino-2-hydrazinobenzimidazole treated with carbon disulfide. Synthesis of 9-amino-2,9-dihydro-3<Emphasis Type="Italic">Н</Emphasis>-[1,2,4]triazolo[4,3-<Emphasis Type="Italic">а</Emphasis>]benzimidazole-3-thione and its derivatives

1-Amino-2-hydrazinobenzimidazole when treated with carbon disulfide underwent a regioselective cyclization involving the hydrazino group to form 9-amino-2,9-dihydro-3Н-[1,2,4]triazolo[4,3-а]benzimidazole-3-thione. Being an N-amine this compound gives Schiff bases with aromatic aldehydes, and as thione in DMF at a temperature not exceeding 60°С it is successfully alkylated, particularly by functionalized alkylating agents, affording the corresponding sulfanylmethyl derivatives. In boiling DMF, as it is demonstrated by an example of benzyl chlorides, NNH₂ group also undergoes alkylation that unexpectedly results in 4-benzylidenamino-3-benzylsulfanyltriazolobenzimidazoles.     

Flare angle changes antenna of the millimeter wave band

A pyramidal horn with flare-angle changes was designed at millimeter wave band with using of the S.Cohn's method of antenna pattern shaping. Results of the investigation show an assemblage of good properties are rest-ricted to this kind of antennas (if take into account such parameters as: form of beam, level of sidelobe and crosspolarization, microwave loss and radiation coefficient away from main lobe).     

Synthesis and some conversions of N-substituted benzimidazole-2-sulfonic acids

A series of N-substituted benzimidazole-2-sulfonic acids was synthesized in good yield by the N-alkylation of benzimidazole-2-sulfonic acids by alkylation with simple and functionalized alkylating agents under mild conditions. The corresponding N-substituted benzimidazolones and also primary, secondary, and tertiary amines were obtained by the action on the obtained compounds of alkali, ammonia, ammonium acetate, and amines. __________ Translated from Khimiya Geterotsiklicheskikh, No. 4, pp. 528–534.