Electron Diffuse Reflectance Spectroscopy Research Articles

Solid-Phase Synthesis of Nickel-Molybdenum Catalysts for Metathesis of Propylene under Mechanical Action

The solid-phase synthesis of model aluminum-molybdenum (Al-Mo) and aluminum-nickel-molybdenum (Al-Ni-Mo) compositions constituting the catalysts for metathesis of propylene was carried out under mechanical action. The structure of model Al-Mo and Al-Ni-Mo compositions was studied using X-ray diffraction analysis, high-resolution transmission electron microscopy, infrared spectroscopy, and diffuse reflectance electron spectroscopy (UV-vis DRS). The latter method revealed the presence of isolated monomeric and oligomeric molybdate compounds in the model Al-Ni-Mo compositions. Granulated catalysts for metathesis were obtained by molding the model Al-Mo and Al-Ni-Mo compositions with aluminum hydroxide followed by calcination. Most active in the metathesis of propylene was the aluminum-molybdenum catalyst containing 2.6 wt.% Ni, 13.0 wt.% Mo and 32.7 wt.% Al. At the process temperature of 200 °С, pressure 0.1 MPa, and weight space velocity of propylene 1 h–1, the conversion of propylene on this catalyst reached 33.7 %, which makes the catalyst promising for practical application. Therewith, the weight fraction of ethylene in the reaction products was 17.5 %, and butenes – 71.3 %.

Morphotropic Phase Boundary Enhanced Photocatalysis in Sm Doped BiFeO3.

This paper presents the results of the synthesis of samarium-doped bismuth ferrite (BFO) nanoparticles by the solution combustion method. The dependence of BFO properties on the amount of the samarium (Sm) in the composition was studied. The synthesized nanocomposites were characterized by scanning electron microscopy SEM), X-ray diffractometry (XRD), Raman, Electron Diffuse Reflectance Spectroscopy (EDRS) and Electron Magnetic Resonance (EMR). The photocatalytic (PC) measurements showed the absence of a strict correlation between the PC activity and the crystallite size and band gap. An increase in the PC activity of BFO samples with 10 and 15% doping was observed and it was concluded that in controlling the PC properties in doped BFO, the processes of interfacial polarization at the boundaries of the morphotropic phase transition are of decisive importance. It was supposed that the internal electric field formed at these boundaries contributes to the efficient separation of photogenerated charge carriers.

Sorption-photocatalytic performance of NbOx nanocrystals synthesized via heat-stimulated oxidation of niobium carbide

In this work, nano-sized niobium oxides with different crystal structures can be produced by thermal treatment of nonstoichiometric nanocrystalline niobium carbide (NbCy) and serve as effective sorbents and photocatalytic materials. Differential thermal analysis of initial NbCy powder was carried out, and temperatures of thermal treatment for the were chosen. The nanopowders were studied using powder X-ray diffraction, scanning electron microscopy, low-temperature N2 adsorption–desorption, X-ray photoelectron spectroscopy and diffuse reflectance electron spectroscopy methods. The specific surface area of samples annealed at 100, 200, 300, 400, 500 °C was about 224, 255, 273, 224 and 47 m2/g, respectively. The photocatalytic activity of the obtained nanopowders was analyzed during the oxidation of an aqueous solution of methyl orange on exposure to visible light. The photocatalytic activity of nanopowders grows with the annealing temperature increasing from 100 to 500 °C and reaches the maximum value for the higher niobium oxide Nb2O5. The time of complete decoloration of dye was 165 min. The tests performed to establish the sorption equilibrium between catalyst and dye in the dark revealed that the nanopowder produced during annealing at 300 °C possesses a high sorption capacity of 76.5%, which allows it to be considered as an effective sorbent.

SPECTROSCOPIC STUDY OF SALT MELTS OF THE SmF3-CeF3-NaCl-KCl SYSTEM

Redox interactions between the components of the SmF3-CeF3 and SmF3-CeF3-NaCl-KCl systems have been established by IR transmission spectroscopy, diffuse reflectance electron spectroscopy and luminescence spectroscopy. A significant decrease in the transparency in the IR range of the spectrum was found when passing from the first of the systems to the second, which is explained by an increase in scattering by ultramicrodispersed particles of fluorides in the salt melt. In both systems, the formation of a significant amount of Sm (II) and a decrease in the content of Sm (III) are observed. The change in the valence state of Samarium both during solid-phase heat treatment (1100 °C) and during holding in a salt melt at 700 °C is manifested in the disappearance of some absorption bands, the appearance of new bands, and a gypsochromic shift of the remaining bands. The luminescence spectra exhibit high-intensity emission bands in the 640–740 nm range, which correspond to 5d‑4f electronic transitions in Sm2+ ions. At the same time, the highest intensity is observed in the band corresponding to intracenter 5d‑4f electronic transitions in Ce3+ ions. Apparently, the Ce(IV) compound, formed as a result of the exchange reaction of complex fluoride with a salt melt, volatilizes with subsequent decomposition and does not affect the character of luminescence. On the whole, the luminescence intensity after treatment in the molten salt increases by several tens of times, which indicates a significant change in the radiation mechanism. The mechanism of redox reactions in the solid-phase state, as well as exchange processes in the salt melt and after its crystallization, is discussed. A significant role of solvation shells around particles of lanthanide fluorides in luminescence processes is assumed.

Synthesis, Crystal Structure, Spectroscopic Characterization, DFT Calculations and Cytotoxicity Assays of a New Cu(II) Complex with an Acylhydrazone Ligand Derived from Thiophene

A new Cu(II) complex is synthetized by the reaction of copper nitrate and a N-acylhydrazone ligand obtained from the condensation of o-vanillin and 2-thiophecarbohydrazide (H2L). The solid-state structure of [Cu(HL)(H2O)](NO3)·H2O, or CuHL for simplicity, was determined by X-ray diffraction. In the cationic complex, the copper center is in a nearly squared planar environment with the nitrate interacting as a counterion. CuHL was characterized by spectroscopic techniques, including solid-state FTIR, Raman, electron paramagnetic resonance (EPR) and diffuse reflectance and solution UV-Vis electronic spectroscopy. Calculations based on the density functional theory (DFT) assisted the interpretation and assignment of the spectroscopic data. The complex does not show relevant antioxidant activity evaluated by the radical cation of 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) method, being even less active than the free ligand as a radical quencher. Cytotoxicity assays of CuHL against three human tumor cell lines, namely MG-63, A549 and HT-29, revealed an important enhancement of the effectiveness as compared with both the ligand and the free metal ion. Moreover, its cytotoxic effect was remarkably stronger than that of the reference metallodrug cisplatin in all cancer cell lines tested, a promissory result in the search for new metallodrugs of essential transition metals.

Experimental studies of optical properties of hard tissues of anterior teeth and modern synthetic filling materials

The article data on the study of reflection spectra of hard tooth tissues and dental restoration materials are presented. The method of investigation of dental hard tissues and dental restoration materials — the method of diffuse reflection electron spectroscopy is defined. The relevance of the work, since a high level of restoration aesthetics in therapeutic dentistry is important is shown. Reflection spectra of the studied samples on an automated spectrofluorometer “SDL-2” were performed. Spectral dependences of the reflection coefficient of enamel and dentin sections, as well as intact teeth of patients of different ages, were obtained. The spectral dependences of the reflection coefficient of various dental restoration materials were analyzed.

Structural and Morphological Features of Polycrystalline Aluminum Oxide Surface after Nanocoating with Titanium Oxide of Different Thickness

Using the molecular layering method, titanium oxide coatings were synthesized on the surface of polycrystalline aluminum oxide plates by alternating treatment with titanium tetrachloride and water vapors. It was shown by means of diffuse reflection electron spectroscopy that at different nanocoating thickness, surface complexes differing in structure are formed: distorted octahedral (alumotitanate), those with tetrahedral titanium coordination, and polyhedra with anatase-like environment of the central atom. The surface morphology changes during the synthesis and after 600 layering cycles the titanium oxide coating covers the entire surface of the initial substrate.

Diffuse reflection electron spectroscopy in study of blood serum with multiple myeloma

Diffuse reflection electron spectroscopy in study of blood serum with multiple myeloma

Effect of Modification of Supported V2O5/SiO2 Catalysts by Lanthanum on the State and Structural Peculiarities of Vanadium

Using the methods of diffuse reflectance electron spectroscopy, Raman spectroscopy and temperature-programmed reduction with hydrogen, the formation of surface phases in supported lanthanum-modified V2O5/SiO2 catalysts was studied. It is shown that the order of depositing the active component has a significant effect on the phase composition and catalytic properties of the samples in the reaction of propane oxidative dehydrogenation.

Метод электронной спектроскопии диффузного отражения в исследовании мышечной ткани диких и домашних животных

The aim of the work was to study the application of diffuse reflection electron spectroscopy (DRES) method for obtaining the optical surface characteristics of slices and chopped muscle tissue, muscle fibre and sarcoplasmic protein extracts of wild (wild boar, elk, deer, freshwater and marine fish) and domestic (pork, beef, lamb) animal tissue depending on the following processing conditions: freezing, water extraction, lyophilisation and enzyme-microbial exposure. Electronic spectra of transverse sections of whole-piece material, ground muscle tissue, muscle fibre and aqueous extracts were recorded using a Specord M-200 spectrophotometer (AIZ Engineering GmbH, Germany) having a vertical pathway relative to the Spectralon standard in the wavelength range of 200-700 nm. During testing of biological tissues of animal origin in solid and liquid state, the high sensitivity, resolution and analytical features of the express DRES method was shown to allow the acquisition of factual information concerning changes in the spectral characteristics of their main components under experimental conditions. Regardless of the species and type of animal organism, proteins, mucopolysaccharides, lipids, pigment protein and various oxidised forms demonstrate absorption bands in four clearly differentiated regions of the electromagnetic spectrum: 200-300, 400-425, 300-380, 540-580 and 635 nm, respectively. A comparative study of the pork and beef muscle tissue demonstrated significant differences in the nature of changes in the spectral characteristics of the main components and components of muscle tissue and muscle fibre, depending on the degree of oxidation, mechanical destruction, strength of myofibrils and pigment protein myoglobin associated with them.

Effect of lyophilization and various treatments on spectral characteristics of beef muscle tissue and its main components

Native and lyophilized shredded muscle tissue of beef and its main ingredients (muscle fibers, stroma, stroma proteins) prepared via consecutive treatment with water, saline (Weber solution ) and alkaline (0.6 M NaOH) solutions as well as colloidal solutions-extracts of sarcoplasmic substances, actomyosin and mucopolysaccharide complexes are comparatively studies by attenuated total internal reflection infrared (ATIR) and diffuse reflectance electronic spectroscopy. A high sensitivity, efficiency, extended options and advanced prospects of diffuse spectroscopy are considered in respect of the characterization of the component composition of complex solid-state and liquid biological systems in medical and veterinary practice.

Formation of Active Structures in Monolith Copper–Manganese Oxide Catalysts for Air-Heating Devices

Impregnation catalysts based on CuO, MnOx, and CuO–MnOx with different Cu/Mn ratios supported on ceramic monoliths of alumina and silica are studied by BET, mercury porosimetry, X-ray diffraction analysis, transmission and scanning electron microscopy, temperature-programmed reduction with H2, diffuse reflectance electron spectroscopy, and differential dissolution. It is found that, in the butane oxidation reaction, CuO–MnOx catalysts exert a synergistic effect, which is attributed to the formation of highly defective phases of complex oxides of the nonstoichiometric spinel type with a large number of interparticle boundaries in the near-surface layers of the support.

OPTICAL PROPERTIES OF OIL EXTRACTS AND RESIDUES OF MEDICINAL AND AROMATIC HERBS

The purpose of this work is to conduct a comparative study of attenuated total reflection infrared spectroscopy, diffuse-reflection electron spectroscopy and refractometry of the optical characteristics of a series of oil extracts, residues and dry-milled ( -1 ), valency (3008 cm -1 ) and deformation (722 cm -1 ) vibrations of the CH-groups with a double bond (CH = CH) when compared with the spectra of residues and dry raw materials.

A study of muscular tissue of animal origin by reflection-spectroscopy methods

A comparative analysis of the spectral characteristics of the surface of muscular tissue of animal origin (pork) and its main components has been performed by the methods of diffuse reflection electronic spectroscopy (DRES) and frustrated total internal reflection IR spectroscopy. The experiments have shown that the application of the DRES method makes it possible to detect more pronounced changes in the surface optical characteristics of muscular tissue and obtain electronic spectra containing information about the component composition of its main parts under successive extraction of sarcoplasmic materials, myofibrillar proteins of the actomyosin complex, and stroma mucopolysaccharides.

Sol–gel synthesis of 2D and 3D nanostructured YSZ:Yb3+ ceramics

This paper presents results of a detailed study of fundamental aspects of the formation of 2D and 3D nanostructured YSZ:Yb3+ ceramics with a cubic structure through a key synthesis step in aqueous solutions of zirconium-containing hydroxy nanoparticles (1–2 nm) modified by Y3+ and Yb3+ ions, with the use of a sol–gel method and subsequent calcination of the resultant xerogels at temperatures above 350°C. As starting chemicals for the synthesis of ceramic powders, we used zirconyl, yttrium, and ytterbium nitrates and chlorides and aqueous ammonia. Using mixed solutions of these salts and a procedure developed by us, we synthesized sols, gels, and xerogels. To examine the effect of temperature on solid-state transformations, the xerogels were calcined according to a predetermined program in a muffle furnace at temperatures in the range from 350 to 1350°C (rarely, up to 1650°C). We focused primarily on ceramic powders close in composition to 0.86ZrO2 · 0.10Y2O3 · 0.04Yb2O3. The ceramics were characterized by high-resolution transmission electron microscopy, electron microdiffraction, electronic diffuse reflectance spectroscopy, energy dispersive X-ray microanalysis, and X-ray fluorescence analysis.

Quantum-chemical approach to optimization of the synthesis conditions of two-component phosphorus-titanium oxide structures on silica surface

The features of formation of a two-component phosphorus-titanium oxide coating on the silica surface by sequential treatment of the substrate with POCl3 and TiCl4 vapors were analyzed with application of quantum-chemical approaches. An experimental synthesis of two-component coatings under conditions selected on the basis of theoretical calculations yielded coatings whose composition corresponded to the model predictions. The structure of the resulting coatings was studied by Fourier-transform IR spectroscopy, electronic diffuse reflectance spectroscopy, and chemical analysis.

Role of PdAg interface in Pd-Ag/SiO2 bimetallic catalysts in low-temperature oxidation of carbon monoxide

An approach to the development of bimetallic nanoparticles with the separated but interacting phases of silver and palladium was proposed to effectively separate the active sites of silver, which possess high activity in activation of molecular oxygen, and the sites of palladium-containing phases, which are responsible for CO adsorption. The structure of PdAg particles was determined using X-ray diffraction analysis, electronic diffuse reflectance spectroscopy, and temperature-programmed reduction. It was found that the introduction of silver led to easier reduction of palladium from oxidized states in an atmosphere of CO. The activity of the bimetallic PdAg catalysts in the oxidation of CO increased, as compared with that of the Pd/SiO2 catalyst. The oxidized bimetallic catalyst, in which palladium occurred in an oxide state, was even more effective in the oxidation of CO; this can be related to the better cooperation of the active sites of silver and palladium oxide, which are responsible for the activation and conversion of CO and oxygen at the Ag-PdO interfacial boundary.

Study of the interaction in the ZnS (ZnO)-Dy2S3 system

The exchange reactions of the impurity ZnO in zinc sulfide produced by self-propagating high-temperature synthesis with the additive Dy2S3 were studied by IR spectroscopy and diffuse reflectance electron spectroscopy. It was found that the main products of the interaction in the ZnS (ZnO)-Dy2S3 system are ZnS and Dy2O2S. The exchange character of the interaction was modeled by the systems ZnO-Dy2S3 (2: 1) and Dy2S3-Dy2O3 (1: 2). The possibility of estimating the ZnO impurity content of zinc sulfide was demonstrated, which allows one to optimize the zinc sulfide synthesis conditions.

Active states of gold in small and big metal particles in CO and methanol selective oxidation

Role of small and big gold particles in CO oxidation and methanol selective oxidation to formaldehyde has been studied by the methods of diffuse reflectance electron spectroscopy, XRD, XPS, HRTEM and catalytic testing. By comparison of catalytic and spectroscopic data it was concluded that states Auδ+ with certain effective charge (δ<1) are active sites in low-temperature CO oxidation as well as in alcohol partial oxidation. These states can be formed under the action of different factors, such as metal–support interaction, redox treatments, and modifying additives. Modifiers stabilizing the ionic states of gold (Ce and Zr oxides) increase the selectivity of the catalyst in alcohol partial oxidation, whereas electron-releasing additions (La and Cs oxides) impair the catalyst properties.

Deactivation and oxidative regeneration of modern catalysts for deep hydropurification of diesel fuel: Oxidative regeneration of IK-GO-1 catalyst

Oxidative regeneration of a deactivated IK-GO-1 catalyst was studied in removal of carbonaceous deposits and sulfur from the catalyst composition. Elemental analysis data, texture characteristics, and catalytic activities of fresh and regenerated samples were compared. Raman spectroscopy, X-ray phase analysis, electronic diffuse reflectance spectroscopy, and X-ray photoelectron spectroscopy were used to examine the structure of cobalt and molybdenum compounds entering into the composition of the catalysts.