Stability of single-layer islands on a flat substrate in vacuum deposition processes

Conditions of unstable equilibrium of single-layer islands of the adsorbate and empty adsorption vacancies are studied. An analog of the Kelvin-Thomson effect for these islands is found. Appropriate corrections are made in the classical theory of nucleation.     

Complexes of neodymium and dysprosium triiodides with amines. Molecular structures of the {Dy[Me2N(CH2)3NH2]8}I3, NdI3(PriNH2)4, and NdI3(PriNH2)5 complexes

The dissolution of DyI₂ in diamine Me₂N(CH₂)₃NH₂ (DMDA) is accompanied by the disproportionation of the salt, hydrogen evolution, and oxidation of Dy^II to Dy^III. The [Dy(DMDA)₈]I₃ complex (1) was isolated from the solution. The neodymium amide amine complex (PrⁱNH)NdI₂(IPA)₄ was produced by the reaction of NdI₂ with isopropylamine (IPA). The recrystallization of this complex from IPA afforded the NdI₃(IPA)₄ complex (2). The recrystallization of (PrⁱNH)NdI₂(IPA)₄ from a toluene-IPA mixture gave the complex with five amine ligands, NdI₃(IPA)₅ (3). The structures of compounds 1, 2, and 3 were established by X-ray diffraction. Dedicated to Academician G. A. Abakumov on the occasion of his 70th birthday. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1674–1679, September, 2007.     

Formation of dibenzenevanadium by the reaction of dysprosium diiodide with vanadocene in benzene

Russian Chemical Bulletin -     

Cyclometallated iridium(III) complex with 1-phenylisoquinoline and norbornene-substituted pyrazolonate ligands and related electroluminescent polymers

A new cyclometallated iridium(III) complex NBEpzIr(Piq)₂ (I) (NBEpzH is 1-phenyl-3-methyl- 4-(5-bicyclo[2.2.1]hept-5-en-2-yl)-5-pyrazolone, PiqH is 1-phenylisoquinoline) is synthesized. The structure of the compound is determined by X-ray diffraction analysis (СIF file CCDC no. 1521037). Copolymers with the carbazole and iridium-containing fragments in the side chains (P1–P3) are prepared from monomer I by the ring-opening metathesis polymerization method. Their photoluminescence and electroluminescence properties are studied. Copolymers P1–P3 exhibit an intense photoluminescence and electroluminesce of red color. The maximum luminance (3010 cd/m²) and current efficiency (15.1 cd/A) are achieved for emitter P2.     

Multifragmentation of gold nuclei by light relativistic ions: Thermal breakup versus dynamical disintegration

The multiple emission of intermediate-mass fragments (IMF) is studied for collisions of p, ⁴He, and ¹²C on Au with the 4π FASA setup. The mean multiplicities of IMF saturate at a value of around 2 for incident energies above 6 GeV. An attempt at describing the observed IMF multiplicities in the two-stage scenario, a fast cascade followed by a statistical multifragmentation, fails. Agreement with the measured IMF multiplicities is obtained by introducing an intermediate expansion phase and modifying empirically the excitation energies and masses of remnants. The angular distributions and energy spectra from p-induced collisions are in agreement with the scenario of “thermal” multifragmentation of a hot and expanded target spectator. In the case of ¹²C + Au(22.4 GeV) and ⁴He (14.6 GeV) + Au collisions, deviations from a pure thermal breakup are seen in the fragment energy spectra, which are harder than those both from model calculations and from the measured ones for p-induced collisions. This difference is attributed to a collective flow with the expansion velocity at the surface of about 0.1c (for ¹²C + Au collisions).     

Study of reactions of some halides, cyclopentadienyl dichlorides, and bis(cyclopentadienyl) chlorides of lanthanides withtrans-stilbene adducts with alkali metals [PhCHCHPh]·−M+ (M=Li, Na)

Reaction of Sml₂(THF)₂ with metallic lithium andtrans-stilbene in 1:2:2 ratio in DME gives the stilbene complex of divalent samarium (PhCHCHPh)Sm(DME)₂. This complex reacts with hydrogen in THF to give SmH₂(THF)₂ and 1,2-diphenylethane. The reaction with (Me₃Si)₂NH gives the amide [(Me₃Si)₂N]₂Sm(DME)₂ and the reaction with triphenylgermane yields Ph₃GeGePh₃. Reaction of CpLuCl₂(THF)₂ with 2 equivalents of [PhCHCHPh]·⁻Na⁺ in DME results in the dimerization of stilbene fragments to give anate-complex {Cp₂Lu[μ-CH (Ph)CH(Ph)CH(Ph)CH(Ph)]}Na(DME)₃. In the reaction of Cp₂GdCl with [PhCHCHPh]·⁻Na⁺, the known complex Cp₃Gd(THF) was isolated as the only lanthanidecontaining product. Published inIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1442–1446, August, 2000.     

Alkyl(aryl)oxy derivatives of thulium(III)

The reactions of Tml₂(DME)₃ with phenol andtert-butyl alcohol afforded thulium(III)-alkoxyiodides ROTmI₂(DME)₂ (R=Ph and Bu^t, respectively). Their structures were determined by X-ray analysis. Monoiodides (RO)₂ TmI(THF)₂ were synthesized from TmI₃ (THF)₂ and ROH (taken in a ratio of 1∶2). Triphenoxides (RO)₃Tm (R=Ph or 2,4,6-Bu^t ₃C₆H₂) were prepared by the reactions of the naphthalene thulium complex [C₁₀H₈Tm(DME)]₂C₁₀H₈, with an excess of the corresponding phenol. The iodide catechoxide complex 3,6-Bu^t ₂C₆H₂O₂TmI(DME)₂ was prepared by the reaction of TmI₂(DME)₃ with 3,6-di-tert-butylbenzoquinone-1,2 or 3,6-di-tert-butylpyrocatechol. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1804–1807, September, 1999.     

The geometric series method for constructing exact solutions to nonlinear evolution equations

It is proved that, for the majority of integrable evolution equations, the perturbation series constructed based on the exponential solution of the linearized problem is geometric or becomes geometric as a result of changing the variable in the equation or after a transformation of the series. Using this property, a method for constructing exact solutions to a wide class of nonintegrable equations is proposed; this method is based on the requirement for the perturbation series to be geometric and on the imposition of constraints on the values of the coefficients and parameters of the equation under which the sum of the series is the solution to be found. The effectiveness of using the diagonal Padé approximants the minimal order of which is determined by the order of the pole of the solution to the equation is demonstrated.     

Connection of Gibbs layer gatherings with rate of mass transfer upon deposition of thin films with presence of impurity

The Gibbs layer gatherings on the condensation front of silver vapor in the presence of water vapor are analyzed. The front of condensation for analyzing the Gibbs concentration excess is calculated with the use of the modified Langmuir’s model of sorption. At a fixed flow of silver vapor and temperature of the substrate, the water-vapor pressure varies. Calculations have shown that the change of the water-vapor pressure changes the structure of the silver condensate, the structure of Gibbs layers, and microroughness on the condensation front. As a consequence, the efficiency of mass transfer varies. With growth of the water-vapor pressure, the condensation efficiency of both vapor components decreases. For obtaining the most equal surface of condensed silver film there is an optimum water-vapor pressure. The results allow the influence of noncondensed gas impurity on growth of thin films to be understood in greater detail and help to choose optimum modes for vacuum deposition. A general conclusion regarding the connection of the Gibbs layers and microroughness of the condensation surface with the intensity of mass transfer, leaving a framework of vacuum deposition processes, is drawn.