Yu. M. Nikolenko

Phase transitions and incommensurate states in GIC C5nHNO3

Abstract ESR data of graphite intercalation compounds C 5 n HNO 3 ( n = 2, 4) point at change of quantity and mobility of spin carriers in compounds of different stages and at intercalate crystallization ( T

The Fluorescent Properties of Heteroligand Europium Cinnamates

Heteroligand europium cinnamates with nitrogen- and phosphorus-containing neutral ligands were studied by luminescent and X-ray electron spectroscopy. A tendency toward an increase in the electron density on Eu3+ was observed when neutral ligands were coordinated by donor nitrogen atoms. The Δν0, ΔF1, and I(F0)/I(F2) values monotonically decreased as the donor properties of neutral ligands increased because of strengthening of the interaction of Eu3+ with the ligands.

Atomic force microscopy and X-ray photoelectron spectroscopy study of chitosan-carbon fiber materials

Chitosan-carbon materials produced by electrochemical deposition of chitosan on an activated carbon fiber (ACF) as an electrode have been studied by atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). AFM data demonstrate that the microstructure of the coating depends on whether chitosan is deposited in soluble or insoluble form. XPS data are used to evaluate the state of chitosan in the composites in relation to the deposition conditions.

Synthesis and characterization of nanographites with chemically modified edges

Nanographites, the structural blocks of activated carbon fibers in which the predominant part of edge carbon atoms forms covalent bonds with a chosen halogen (fluorine or chlorine), were synthesized and studied using X-ray photoelectron spectroscopy, X-ray diffraction analysis, and electron paramagnetic resonance. It was found that the formation of these bonds leads to changes in the density of states at the Fermi level and also in the values of some parameters of the spin system of current carriers of the boundary π-electron states of nanographites.

Study by X-ray photoelectron spectroscopy of rice husk and the products of its processing

The rice floral glume (husk) and its processing products were studied using X-ray photoelectron spectroscopy. We established that the rice husk contained silica in two non-equivalent forms in 1:3 ratio. The predominating form is silicon dioxide, while the minor component contains the silicon bound with the organic component which is stable up to ∼350°C.

Hexamethylenetetrammonium dodecahydro-closo-dodecaborate: Synthesis and study

The reaction of dodecahydro-closo-dodecaboric acid with hexamethylenetetramine (urotropin) was studied by potentiometric titration, chemical and X-ray diffraction analyses, thermogravimetry, and IR and X-ray photoelectron spectroscopy. The donor-acceptor bond with acid H+ cations involves only one of the nitrogen donor atoms of hexamethylenetetramine. The product (C6H12N4H)2B12H12 is isolated as a finely crystalline, easily filterable, and poorly soluble precipitate. A saturated solution of the product contains no more than 0.4 g of the salt per 100 g.

Thermal conversions of chitosanium dodecahydro-closo-dodecaborate

The thermal behavior of chitosanium dodecahydro-closo-dodecaborate, (C6O4H9NH3)2B12H12, was studied by thermal analysis, X-ray diffraction, and IR and X-ray photoelectron spectroscopy. As this compound is heated at a rate above 10–20 K/min, it ignites at a temperature of about 300°C. As the compound is heated to 1000°C at a rate below 10 K/min in an inert atmosphere, it yields a mixture of carbon and amorphous boron and/or boron carbides. The presence of a small amount of boron oxide in the product is explained by the formation of a partially oxidized hydroborate anion at the early stages of (C6O4H9NH3)2B12H12 decomposition via the interaction between oxygen of the chitosanium cation and the B12H122− anion. Heating the initial compound in air at a rate below 10 K/min yields carbon and boron oxide as the main products. Molten boron oxide protects boron and/or boron carbides and boron nitride forming in small amounts in the particle bulk from oxidation.

Fluorescence properties of mixed-ligand europium carboxylates

Mixed-ligand binuclear and mononuclear europium carboxylate complexes with nitrogen-and phosphorus-containing neutral ligands have been studied by luminescence and X-ray photoelectron spectroscopy. The coordination of neutral ligands through the nitrogen donor atom leads to an increase in electron density at the Eu3+ atom. In groups of carboxylates of the same type, the coordination of neutral donor ligands leads to an increase in the relative intensity of the 5D0-7F4 electric dipole transition. Analysis of the luminescence excitation spectra points to the presence of two excitation energy transfer channels for mixed-ligand europium trifluoroacetate and toluate complexes and of one channel for europium cinnamate complexes with neutral ligands.

Semi-Ionic Type Bonds in Fluorinated Carbon Compounds

Abstract Fluorinated graphite oxides (FGO) and fluorinated lignin (FL) have been investigated by X-ray photoelectron spectroscopy (XPS). In the F1s spectra of both compounds a peak with the energy being intermediate between the value in a typical ionic compound LiF and covalent compounds of type (CF)n and-(CF2-CF2)n- was extracted. The substances under study, even at high oxidizer content, contain structure fragments with carbon having sp2-hybridized orbitals. The bond formed between fluorine and these fragments is of semi-ionic type. The temperature, which allows the semi-ionic fluorine-carbon bond formation, is found to be between the room temperature and 100°C. The registration of semi-ionic state of fluorine in the FL allows to assume that the layered structure of initial substance is not necessary for the formation of semi-ionic bond between fluorine and carbon.

Organic-Mineral Composites Copper Oxide/Chitosan/Carbon Fiber Obtained by the Electrodeposition Method

The methods of the coprecipitation of chitosan and copper-containing particles on a carbon fiber used as a cathode and also of the precipitation of copper(II) on a carbon-fiber electrode preliminarily modified by chitosan were studied for feasibility of obtaining composites containing copper oxide/copper in a chitosan matrix. The composition, morphology, structure of the organic-mineral composites were studied by the methods of X-ray phase analysis, scanning electronic microscopy, X-ray photoelectron spectroscopy, and ESR spectroscopy.