Effect of the Crystal Face Orientation and Alloying with Gold on the Properties of Thin Anodic Films of Ag(I) Oxide: I. Photocurrent

D. A. Kudryashov, S. N. Grushevskaya, S. V. Ganzha, and A. V. Vvedenskii

Voronezh State University, Universitetskaya pl. 1, Voronezh, 394006 Russia

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Received September 5, 2008

Abstract — The anodic formation of nano-size anodic films of Ag(I) oxide on polycrystalline silver and Ag–Au  alloys, as well as on low-index monocrystalline silver faces in 0.1 M KOH, is studied. Based on the data of photocurrent measurements, the n-kind of the oxide film conductivity is determined. Replacing the polycrystalline silver with monocrystals, as well as adding a small amount of gold atoms to its lattice (X_[Au] <= 4 at. %), results in substantial structure ordering of the oxide due to the decrease in the deviation from the stoichiometric composition. The structure-dependent parameters of Ag(I) oxide (the optical absorption coefficient , the concentration of donor defects N_D, the width of the spatial charge region W, and the Debye screening length L_D) are determined by the silver crystal face orientation, the gold content, and the film formation potential. At E = 0.52V, the series of changes in these characteristics correlate with the series of reticular density. An increase in E breaks the series and increases the deviation of the composition from the stoichiometric Ag₂O composition.

Selective Adsorption of Organic Sulfur-Containing Compounds from Diesel Fuel Using Type-Y Zeolite and -Aluminum Oxide

A. M. Voloshchuk^a*, O. K. Krasil’nikova^a, N. V. Serebryakova^a, S. D. Artamonova^a,
A. D. Aliev^a, E. V. Khozina^a, and V. P. Kiselev^a,b,c

^a Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences,
Leninskii pr. 31, Moscow, 119991 Russia

^b Institute of Bioorganic Chemistry and Petrochemistry, National Academy of Sciences of Ukraine;

^c Plus Radio Scientific-Technical Center, Murmanskaya ul. 1, Kiev-94, 02660 Ukraine

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Received November 25, 2008

Abstract — Samples based on type-Y zeolite and aluminum oxide (-Al₂O₃) with immobilized Cu(I) ions used
as adsorbents of molecules of thiophene derivatives during the desulfurization of diesel fuel were investigated. An analysis of diesel fuel after the desulfurization process showed that a decrease in sulfur content caused by contacting adsorbents amounts to 40–80%. Porous structure parameters of the adsorbents before and after contacting diesel fuel were determined using adsorption isotherms of nitrogen vapor at 77K. Desulfurization processes are shown to influence the porous adsorbent structure; therefore, the specific surface and pore size decrease. According to X-ray diffraction, the data on changing the porous adsorbent structure in the desulfurization process are stipulated by the deposition of sulfur and carbon. It was ascertained that the samples based on HY/Cu(I) zeolite better adsorb sulfur-containing compounds than -Al₂O₃/Cu(I) do. An analysis of the IR spectra of adsorbent samples after desulfurization indicates the possibility of chemisorbing aromatic components of diesel fuel, most notably sulfur-containing compounds on the surfaces of all investigated samples with the simultaneous transformation of these compounds mainly into aliphatic-type structures.

PACS numbers:

Effect of Temperature on Adsorption of Phenol on Microporous Activated FAS-Type Carbons

O. K. Krasil’nikova, N. S. Kazbanov, and V. V. Gur’yanov

Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences,
Leninskii pr. 31, 119991 Moscow, Russia

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Received November 13, 2007

Abstract — Phenol adsorption from aqueous solutions is studied on activated FAS-type carbons. It is shown that the limiting adsorption value grows at an increase in the temperature from 293 to 318 K. The anomalous character of the temperature dependence of adsorption is related to competition between two simultaneous processes, i.e., activated and physical adsorption. The obtained adsorption isotherms are well described by the Dubinin–Radushkevich (DR) equation with an exponent of 2. It is shown that, in the case of phenol adsorption on FAS microporous carbons of different porosity, temperature invariance of the characteristic curve of the DRmodel is observed. Parameters of the DR equation are determined for the studied systems. Isosteric adsorption heat is calculated based on the temperature dependence of adsorption.

Formation of Nanoislands on the Surface of Thin Dipeptide Films under the Effect of Vaporous Organic Compounds

I. G. Efimova^a, M. A. Ziganshin^a, V. V. Gorbatchuk^a, D. V. Soldatov^b, S. A. Ziganshina^c,
A. P. Chuklanov^c, and A. A. Bukharaev^c

^a Butlerov Institute of Chemistry, Kazan State University, Kremlevskaya ul. 18, Kazan, 420008 Russia

^b University of Guelph, 50 Stone Road East, Guelph, Ontario, N1G 2W1 Canada

^c Zavoisky Physical-Technical Institute, Kazan Scientific Center, Russian Academy of Sciences,
Sibirskii trakt 10/7, Kazan 420029 Russia

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Received March 12, 2009

Abstract — Sorption properties of a thin L-alanyl-L-valine dipeptide film for vapors of organic compounds, i.e., methanol and toluene, were studied. Compositions of the inclusion compounds formed in the systems are determined using quartz microbalances. The surfaces morphology of of thin dipeptide films before and after the interaction with organic sorbate was studied with atomic force microscopy. The dipeptide was found to have a larger sorption capacity for methanol than for toluene. As a result of the interaction between a thin L-alanyl-L-valine dipeptide layer with toluene vapor, nanoislets appear on the film surface, and the receptor ability of dipeptide inactivated.

PACS numbers: 81.16.Rf

Synthesis of meso-Substituted Porphyrins as Precursors in Creating Highly Ordered Electroluminescent Polymer Materials

E. V. Vinogradova, Yu. Yu. Enakieva, Yu. G. Gorbunova*, and A. Yu. Tsivadze

Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Leninskii pr. 31, Moscow, 119991 Russia

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Received March 13, 2009

Abstract — Methods of obtaining porphyrin-containing polymer materials that have electroluminescent properties are analyzed. Based on the data, a strategy for producing the most effective porphyrin precursors for the further synthesis of highly ordered polymer materials is developed. Synthetic approaches are found and twomeso-substituted porphyrins, i.e., 5,15-diphenyl-10,20-dibromoporphyrin (1a) and 5,15-diethynylphenylpor-phyrin (2a), are synthesized.

PACS numbers: 78.60.Fz

Photorefractive Polymer Composites Based on Ruthenium (II) Tetra-15-Crown-5-Phthalocyanate Axially Coordinating Ethylisonicotinate Molecules Photosensitive in Telecommunication Range

A. D. Grishina, Yu. G. Gorbunova, L. Ya. Pereshivko, A. A. Nekrasov, Yu. Yu. Enakieva,
T. V. Krivenko, V. V. Savel’ev, A. V. Vannikov*, and A. Yu. Tsivadze

Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Leninskii pr. 31, Moscow, 119991 Russia

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Received February 27, 2009

Abstract—Polyvinylcarbazole layers containing ruthenium (II) tetra-15-crown-5-phthalocyanate axially coordinating ethylisonicotinate molecules are found to have photoelectric and photorefractive sensitivity at 1550nm. The effect is determined by the formation of supramolecular ensembles with the electronic optical absorption and photoelectric sensitivity in the near IR range up to 1600 or 1700 nm and nonlinear optical properties. A photorefractive two-beam coupling gain coefficient measured at 1550 nm increases with an increase in the Ru(II) complex content in the polymer layer and equals 25 cm^–1 at 6 wt %. The difference between the coupling gain and absorption coefficients (the actual gain coefficient) is – = 19 cm^–1. Additionally introducing 3 wt % C₆₀ fullerene into the layer does not change the characteristics, but the subsequent preirradiation (irradiation of the whole layer with a 633-nm laser beam in a range of the optical absorption of C₆₀ before recording photorefractive curves) results in an increase in the gain coefficient at 1550 nm up to = 48.3 cm^–1 and, hence, in – = 42.3 cm^–1 . A time constant of the diffraction grating formation is about = 0.8 s. PACS numbers: 42.70.Nq

A Model of Dissipative Energy Transfer in Natural and Artificial Photosystems

A. S. Belov and V. V. Eremin

Chemical Faculty, Moscow State University, Moscow, 119992 Russia

Received March 15,2009

Abstract — Within the Redfield theory, a model is proposed that describes dissipative dynamics of electronic excitation energy migration in natural and artificial photosystems. The model explicitly takes into account physicochemical properties of the protein environment, which allows the fitting parameters to be completely excluded from calculations. The model is used to calculate the dynamics of energy transfer in a photosystem of purple bacteria and eight model photosystems, which helped to reveal the main factors that determine the rate and efficiency of energy transfer.

Peculiarities of Polyaniline Matrix Synthesis in the Presence of Mixtures of Different Types of Matrices and Investigation of Properties of Formed Interpolymer Complexes

V. F. Ivanov^a, A. A. Isakova^a, O. L. Gribkova^a, A. A. Nekrasov^a, A. N. Bogdanov^a,
A. V. Vannikov^a, and V. A. Tverskoi^b

^a Frumkin Institute of Physical Chemistry and Elecrochemistry, Russian Academy of Science,
Leninskii pr. 31, Moscow, 119991 Russia

^b Lomonosov State Academy of Fine Chemical Technology, pr. Vernadskogo 86, Moscow, 119571 Russia

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Received March 13, 2009

Abstract — In the present work, the existence of a matrix domination effect in the formation process in polyaniline interpolymer complex solutions under aniline oxidation in the presence of rigid and flexible poly(amidosulfonic acid)s was demonstrated for the first time.

PACS numbers: 82.35.-x

Formation of Pyramidal Shaped Single Crystal Diamonds in Chemical Vapor Deposition

P. G. Kopylov, A. N. Obraztsov, M. A. Dolganov, and S. S. Abramchuk

Physics Faculty, Moscow State University, Moscow, 119899 Russia

Received March 12, 2009

Abstract — The work demonstrates the possibility of obtaining material containing micron-size diamond single crystals with a regular pyramidal shape surrounded by a low-order diamond fraction by plasma-enhanced deposition (CVD). To study the morphology of these films, the selective oxidation technique followed by an analysis of its results by electron microscopy and Raman spectroscopy is applied. We propose a model that describes the formation of these films. The possibilities to use the materials of this type are also discussed.

PACS numbers: 81.05.Vw, 52.77.Dq

Topology of Nanometric Graphite Films

A. V. Tyurnina*, D. V. Serov, and A. N. Obraztsov

Physical Faculty, Lomonosov Moscow State University, Moscow, 119992 Russia

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Received on March 12, 2009

Abstract — This work submits the results of a study in which the combinational scattering (CS) spectroscopy and electronic and optical microscopy of nanometric single-crystal graphite films obtained by precipitating in gas phase were used. It is shown the graphite material samples synthesized in this manner are fine, highly streamlined films that grow alongside of the substrate surface. The films feature a fairly smooth surface and thicknesses of 100–1 atomic layers. The study of the topologic properties of the material, such as the formation of folds along the entire surface and the occurrence of waveform ripples on some surface areas, showed that they may appear due to large differences in the carbon film and nickel substrate thermal expansion factors. The film thickness was assessed for the observed parameters of the periodic structures and the results comply with data obtained using other techniques. In some areas of the material in study, the graphene layers spontaneously split and form bubbles. The results of the CS analysis of various bubbles on studied film surfaces are evidence that, similar to the film itself, the walls of bubbles are composed of different numbers of graphite layers. It is shown that transparent bubbles in which meshlike topology is observed are formed with a single atomic layer.

PACS numbers: 81.16.Rf