Studies of Fe2(CO)9 Formation in the Thermolysis of Fe(CO)5 Using Ab Initio Calculations of Fe(CO)5 and Fe(CO)4

Ab initio calculations using the GAMESS program package in the atomic basis TZV (Fe: (14s, 11p, 6d)/[10s, 8p, 3d]; C, O: (11s, 6p)/[5s, 3p]) were performed with account taken of the correlation with the second-order Möller–Plesset (MP2) perturbation theory to predict a new conformer Fe(CO)₄ (with D _4h symmetry). This conformer has a square planar configuration in the ground singlet electronic state and is a mild electrophile produced by dissociation of Fe(CO)₅ along the axial Fe–C bond. The process of nucleation of iron nanoparticles Fe(CO)₅ + Fe(CO)₄ Fe₂(CO)₉ is supposed to occur in two stages. The first stage is an orbital-controlled reaction which should be monitored as an increase in medium polarity and temperature. It should proceed with participation of only one of the stable conformers of the nucleophile Fe(CO)₅, namely, a mild conformer with square-pyramidal structure (C _4v ) rather than a hard but energetically more advantageous conformer with trigonal–bipyramidal structure (D _3h ). The structure of a prereaction complex was discussed.     

Effect of phosphatidylglycerol depletion on the surface electric properties and the fluorescence emission of thylakoid membranes

To explore the possible effect of phosphatidylglycerol (PG) on the surface electric properties and chlorophyll fluorescence characteristics we used electric light scattering technique and 77 K chlorophyll fluorescence of thylakoid membranes from a cyanobacterium, Synechocystis PCC6803 (wild type) and its pgsA mutant defective in PG synthesis. We found a strong decrease in the permanent and induced electric dipole moments of the mutant thylakoids, following long-term PG depletion parallel with a decrease of the emission peak from PSI and an increase of the emission peak from PSII. Partial recovery of the electric state of thylakoid membranes was observed at re-addition of PG to the mutant cells depleted of PG for 21days. This change in the electric dipole moments is probably due to a decrease in PG content and progressive structural alterations in the macroorganization of the photosynthetic complexes induced by PG deprivation.

Our results suggest that the depletion of a lipid, which carries a negative charge, despite its small contribution to the overall lipid content, significantly perturbs the surface charge of the membranes. These changes are related with the chlorophyll fluorescence emission ratios of two photosystems and may partly explain our earlier results concerning the PG requirement for the function and assembly of photosystems I and II reaction centers.     

Synthesis and investigation of electrolytic sodium-vanadium oxide compounds for cathodes of lithium batteries: The production of compounds with stable initial characteristics

Heterogeneous vanadium oxide compounds are produced by electrolyzing a vanadyl sulfate solution containing sodium ions. Limiting technological parameters ensuring the synthesis of electrolytic products with stable initial electrochemical characteristics are found. As sodium ions enhance adhesion of electrolytic deposits to the substrate, these can be used in the thin-layer cathodes of lithium batteries without inert additives, along with the composite electrodes containing such additives. The deposits’ electrochemical properties depend on the content of sodium ions in the electrolyte and the subsequent thermal treatment. Specific discharge capacity of such deposits may reach 320 A h kg^-1 when discharged to 2.0 V at 100 ΜA cm^-2.     

On the kinetics of GaAs chemical transport and epitaxy in the system GaAs–I2

Kinetic analysis of experimental data on transport and epitaxial growth of GaAs with iodine in closed and in open tube systems has been carried out. The uniformly shrinking core model has been applied to study GaAs transport kinetics in the closed system. The kinetics of GaAs epitaxy in the open one is interpreted according to a model which assumes that in the initial stage of chemical reactions new phase nuclei are formed instantly at a constant number of active centers and that the nuclei grow isotropically.     

Electrolytic composites of iron sulfides with graphite in a prototype lithium battery

Electrolytic composites of iron sulfides FeS and Fe₃S₄ with natural graphites of GAK and EUZ-3 brands and Chinese graphite were synthesized in thin layers and studied in a prototype lithium battery.     

Enhancing the efficiency of using electroplated iron and cobalt sulfides with a sublayer of NiC composite in a lithium battery

The efficiency of using in a lithium battery transition metal sulfides electroplated on a metal support strongly depends on the kind and relief of the support. To make the nickel support rougher for enhancing the adhesion of sulfides, it was electroplated with a nickel–carbon composite, NiC. The discharge capacity and the efficiency of cycling of iron and cobalt sulfides electroplated with a NiC sublayer were higher than in the case when the sulfides were electroplated on a smooth nickel support without composite coating.     

Phonon-assisted normal incidence intersubband absorption in semiconductor quantum wells

In the presence of a normally incident mid-IR pulsed laser field, phonon-assisted photon absorption by both intrasubband and intersubband phonon scattering of conduction electrons in GaAs/AlGaAs quantum wells are predicted. The novel non-resonant and non-linear intersubband absorption is found by including the photon-induced phonon scattering process in a Boltzmann equation for phonon energies smaller than the energy separation between two electron subbands in the quantum well. The predicted phonon-assisted photon absorption by intersubband transitions of electrons from the first to the second subband is a unique feature in quantum-well systems and is expected to have a significant effect on the electron populations in both subbands.     

Joint electrolytic deposition of vanadium(V) and chromium(III) oxides from aqueous sulfate solutions

The conditions of the joint electrolytic deposition of vanadium(V) and chromium(III) oxides from mixed sulfate solutions at different concentration ratios of the main components were studied.Translated from Zhurnal Prikladnoi Khimii, Vol. 77, No. 11, 2004, pp. 1795–1798.Original Russian Text Copyright © 2004 by Nagirnyi, Apostolova, Baskevich, Shembel.     

Chronovoltammetry of electrolytic molybdenum oxides at the electrochemical intercalation/deintercalation of lithium ions

Chemical diffusion coefficients of lithium ions in processes of electrochemical intercalation/deintercalation in electrolytic molybdenum oxides and the parameter of interaction between the intercalated particles (g) have been obtained by the following methods: the galvanostatic intermittent titration technique (GITT), the potential relaxation technique after current interruption (PRT), and the potential intermittent titration technique (PITT). In the potential range 2.40–1.40 V the values of of the order of 10^–11–10^–13 cm²/s have been obtained for Mo₄O₁₁ oxide. Intercalation/deintercalation was realized in one phase when g>4.Presented at the 3rd International Meeting on Advanced Batteries and Accumulators, 16–20 June 2002, Brno, Czech Republic     

Electrolytic iron sulfides in prototype lithium batteries with gel electrolytes based on poly(vinyliden fluoride) and its derivatives

Electrolytic thin-film iron sulfide compounds were studied in prototype lithium batteries with gel electrolytes based on poly(vinyliden fluoride) and its derivatives by the method of galvanostatic cycling at room temperature. A discharge capacity of 200–280 mA h g^?1 in 80–180 cycles was obtained.