Russian Journal of Physical Chemistry A最新文献

Our current study employs the spin-polarized density functional theory (DFT) using the all-electron full potential linear augmented plane-wave method (FP-LAPW) to examine the structural, electronic, and magnetic properties of InSb doped with Tungsten (In(_{{1 - x}})W_xSb with x = 0.125, 0.25) in the zinc blende crystal structure. We used, for the electronic exchange and correlation energy, the generalized gradient approximation (GGA) with the Wu-Cohen (WC) functional, improved with the Tran–Blaha modified Becke–Johnson (TB-mBJ) approach for the electronic properties. The obtained results show that this calculation method allows for reliable band gap values. The estimated structural properties match well with existing experimental results. The value of the total magnetic moment is around 3.00 µB for the investigated compounds, and because of their half-metallic ferromagnetic properties, they are regarded prospective candidates for spintronic applications.

The authors analyze temperature dependences of the retention of derivatives of quinoline, 1,2,3,4-tetrahydroquinoline, and pyridazino[4,5-c]quinoline under conditions of reversed-phase high-performance liquid chromatography on octadecyl silica gel. The thermodynamic characteristics of sorption of these compounds are calculated. The change in the enthalpies of sorption are found to depend on the content of acetonitrile in the water–acetonitrile eluent.

The authors continue their set of studies on the separation of boron isotopes by means of chemical exchange in liquid–liquid systems using tri-n-octylamine as the main component of the organic phase. Degree of separation K = 1.0961 ± 0.0016 was obtained using experimental modeling of the operation of a rectangular cascade for separating boron isotopes in a 30-h long period of separation in the mode of product extraction. The obtained data are used to determine period τ = 19–21 h of concentration needed to reach a steady state when operating with product extraction at maximum degree of separation K_m = 1.109. The time needed to reach a steady state is τ = 130–160 h when operating in the mode without product extraction, which corresponds to maximum degree of separation K_m = 1.131.

Composite catalyst (CC) Ni/HMOR/({text{SO}}_{4}^{{2 - }})–ZrO₂ is used to study the hydroconversion of benzene and toluene at atmospheric pressure, a temperature of 180°C, WHSV = 2 h⁻¹, and Н₂/ArH = 8. The conversion of benzene is as high as 58.2%. Adding an alkyl substituent raises conversion to 78.5%. It is shown that the primary conversion of toluene is similar to the conversion of benzene through selective aromatic ring hydrogenation with its subsequent isomerization, ring reduction, and hydrocleavage. Components of the catalytic system are inactive in the hydroconversion of aromatic hydrocarbons. Synergism emerges in the hydrogenating CC activity due to the cojoint effect which individual inactive ({text{SO}}_{4}^{{2 - }})–ZrO₂ and Ni/HMOR components of this system have on the reaction. The probable mechanism of the hydrogenation of aromatic hydrocarbons is discussed. It is hypothesized that hydrogenating activity synergism results from the radical reaction becoming one of an ion radical.

The non-exchangeable sorption of tryptophan by the AV-17-2P anion exchanger from solutions of different compositions was studied. The sorption of the amino acid was shown to be independent of the nature of the accompanying component. This was explained by quantum-chemical modeling, which gave variants of attachment and energy characteristics of the bonds formed in the sorbent phase during non-exchangeable sorption of tryptophan by a highly basic anion exchanger in the salt form. The polar interactions play the major role, and π–π interactions produce an additional effect during the non-exchangeable sorption of amino acids on highly basic aromatic anion exchangers.

Results are presented from measuring optical density in the ultraviolet (UV) and visible ranges of polymer films made of polysulfone (PSF), polymethyl methacrylate (PMMA) and polyvinyl alcohol (PVA) with embedded CNTs, produced by mixing solutions. It is found that adding CNT increases the optical density of polymers, and the efficiency of absorption depends on the choice of polymer. Coefficients of extinction are calculated for CNT in PSF, PMMA, and PVA. The results can be used to develop a way of monitoring the homogeneity of CNT distribution in polymer films.

A comparatively simple method for estimating the mixing enthalpy of melts by differential scanning calorimetry using standard equipment is proposed. The enthalpies of mixing of CsX–PbX₂ (X = Cl, Br) melts are determined by this method. The measured values of mixing enthalpy in the CsCl–PbCl₂ system are in good agreement with those obtained by means of independent measurements. For the CsBr–PbBr₂ system, the enthalpy of mixing was measured for the first time. The similar values of mixing enthalpy were found for both studied systems.

The parameters of boron isotope-selective IR multiphoton (MP) dissociation of 2-chloroethenyl dichloroborane molecules (HClC=CHBCl₂) under the action of pulsed CO₂ laser radiation were measured. The laser radiation frequencies were tuned in resonance with the low-frequency wing of the IR absorption band of HClC=CH¹⁰BCl₂ molecules. The dependences of the dissociation yields and selectivity of HClC=CH¹⁰BCl₂ and HClC=CH¹¹BCl₂ molecules on the intrinsic gas pressure, laser radiation intensity and frequency, and N₂ inert buffer gas and BCl₃ resonance buffer gas pressures were obtained. At sufficiently high intrinsic pressures of HClC=CBCl₂ (66.5−266 Pa) and moderate laser radiation intensity (2–3 J/cm²), high MP dissociation parameters are achieved: dissociation yields of HClC=CH¹⁰BCl₂ molecules of up to 6–9% and selectivity from 30 to 100.

The densities of solutions of ammonium halides in N-methylpyrrolidone (MP)–water mixtures were studied over the entire range of compositions of the mixed solvent at 298.15 K. The standard partial molar volumes (bar {V}_{2}^{0}) of the electrolytes were calculated. The standard partial molar volume of the ammonium ion (bar {V}_{i}^{0}) in the mixtures was determined. The contributions to (bar {V}_{i}^{0}) due to electrostriction, specific ion–solvent interactions, and structural changes in solution were calculated. The dependence of the obtained values on the composition of the mixture is discussed in connection with the structure of the mixed solvent.

This work is devoted to the kinetic analysis and modeling of patterns of the formation of nanoforms of metallic gold and mechanisms of the formation of metal macroparticles. The kinetics of the process in a steady state in solution and in a flow simulating the processes of deposit formation is considered. The autocatalytic nature of the synthesis of gold nanoparticles is shown, where the reverse oxidation of Au⁰ by strong oxidizer Au³⁺ is of fundamental importance. The kinetic behavior of the system is modeled, depending on the initial concentration of the reagent (Au³⁺), concentrations of autocatalytic seeds (Au¹⁺, Au⁰), and the concentration of the reducing agent. The dependence of the multi-stage process on temperature is analyzed. The formation of a gold placer in a flow is modeled mathematically, based on the theory of ideal displacement reactors. The model includes a zone of dispersed mineral gold (or nanodistributed gold), a zone of the hydroflow, and a zone of coagulation in the formation of macroparticles on a metal nucleus (a zone of precipitation). Calculations are made of the dependence of reagent distribution on the concentration of the reducing component, the rate of hydraulic flow, the concentration of coagulants, and the precipitation of seeds.