IR Spectra Of Samples Research Articles

In English

It is known that titanium dioxide as photocatalyst has significant drawback - limited absorption spectrum in the ultraviolet region makes it impossible to use solar energy. To expands the absorption spectrum of TiO2, the doping of impurities (metal, non-metal, etc.) were used. They affected the electronic structure and spectral characteristics of TiO2. The aim of our work was to investigate the influence of tin impurities on spectral characteristics of titanium dioxide using experimental and theoretical methods. The TiO2 powders modified by different amount of tin (Sn/TiO2) were synthesized by sol-gel method. The samples were characterized by SEM, EDX, FT-IR and UV-VIS spectroscopy. It has been found that Sn/TiO2 consists of fragmented agglomerates in the range of 5–10 mm. EDX spectroscopy prove that powders include Ti, O and Sn elements. Modification of titanium dioxide with tin leads to band gap narrowing of samples, which explains by insertion of Sn atoms into crystal lattice of titanium dioxide, because Ti4+ and Sn4+ ions radii are close. The band gap values increased with increasing of tin content. The work also analyzes the vibrational spectra of Sn/TiO2 both experimentally and theoretically. In order to interpret the results obtained, quantum chemical calculations on the spatial and electronic structures of cluster models of titanium dioxide (anatase) with inserted tin atoms using the density functional theory B3LYP method and the basis set 6-31G (d, p) were carried out and the corresponding FT-IR spectra have been simulated. By comparing the experimental and theoretical results, the influence has been analyzed of the number and arrangement of impurity tin atoms in clusters on the observed IR spectra of the samples. This makes it possible to forgive the most probable structural motives of titanium dioxide particles doped with tin atoms, as well as to establish the fact of the presence of tin atoms in the samples. Based on the comparison of the IR spectra of samples with different numbers of tin atoms, it is possible to quantify their composition.

Influence of Cereclor on the performance of aged asphalt binder

ABSTRACT Recycling of an asphalt pavement reduces construction cost as well as the environmental degradation. Adding the bitumen emulsion as a rejuvenator in aged and oxidised asphalt binder improves its viscosity and stiffness without significantly decreasing the carbonyl index. This results in a high aging rate of such asphalt materials. This study proposes Cereclor as an alternate rejuvenator in the replacement of conventional bitumen-based emulsion. The main objectives of this study were to investigate the effect of Cereclor on aged asphalt binder’s characteristics, aging resistance and on the durability of Reclaimed Asphalt Pavement (RAP) modified asphalt mixtures. Carbonyl index was calculated from IR spectra of samples before and after laboratory aging to evaluate the aging resistance. It was observed that a 9% by weight of Cereclor rejuvenates 40/50 pen grade aged asphalt binder to the level of 60/70 pen grade bitumen. For durability assessment of RAP and rejuvenated mixes, fatigue, rutting and moisture susceptibility tests were performed. Four-point beam fatigue test showed that a 9% dose of Cereclor has increased the fatigue life of RAP by almost two times as compared to emulsion. Rut depth for all samples was in the range of 3–4 mm satisfying the rutting failure criteria. Overall, this study revealed that Cereclor has higher rejuvenation potential as compared to bitumen-based emulsion and thus it can potentially be used in pavement recycling.

Thermodynamics of PrPO4 whiskers

The heat capacity of PrPO4 whiskers, up to 1000–1500 nm in length and 45 ± 15 nm in diameter, was measured in the temperature range 1.93–1173.2 K. The heat capacity was measured by three methods: in the low temperature region by relaxation and adiabatic methods, and in the high temperature region by the DSC method. Based on the data obtained, values of thermodynamic functions were calculated. The heat capacity of a PrPO4 sample with isometric particles was measured in the range 325.2–1173.2 K. A comparative analysis of the thermodynamic data and IR spectra for samples with different particle habits was carried out. The influence of morphology on the enthalpy and entropy contributions to the total energy of the system was estimated. According to these data, the predominance of the entropy contribution raises the thermodynamic stability of the PrPO4 structure with whisker particles as the temperature rises.

Structural and spectroscopic studies on lead germanate glasses doped with V2O5

Vanadium doped lead germanate glasses were synthesized by melt quenching technique. The samples were characterised by XRD and DSC patterns. Optical absorption and ESR studies of the samples indicated that a considerable proportion of vanadyl ions exist in V4+ and V5+states due to substitution of germanate ions with vanadium. The IR spectra of samples have proved the existence of various conventional germanium and vanadium structural units. The variations observed as a function of mol% of dopant in all these studies were analysed keeping in view of different oxidation states and environment of vanadium ions in the glass network.

Thermostatting of condensed samples in the spectrometer when using the attenuated total reflectance method

The created external thermostatting system of condensed samples in the cell of a MIDAC M4000 infrared Fourier spectrometer is described. A thermostabilized metal bar that was worked out by the authors is the basic element of the system. The system is intended for investigating the IR spectra of samples using the attenuated total reflectance method (ATR spectroscopy method). When the ATR method is used, the standard range of thermostatting of samples in this spectrometer model is from room temperature to 100°C with an accuracy of ±1°C. The desired temperature of the bar is set by the flow of a cooling fluid, which is supplied from an external thermostat, and it is registered with two thermometers (contact for the cell and infrared for a sample). The proposed approach allows samples to be thermostatted in the temperature range from −12 to 80°C with an accuracy of ±0.5°C.

Carbohydrates from Solidago caucasica herb

Solidago caucasica Kem.-Nath. is a goldenrod of the family Asteraceae and is an unstudied species endemic to the Caucasus although other species of the genus Solidago are widely used worldwide to treat diseases of the urogenital system. We previously detected in S. caucasica herb flavonoids (rutin, vicenin, hesperidin), coumarins (umbelliferone, esculetin, dihydrocoumarin), phenolcarboxylic acids (gallic, chicoric, chlorogenic, and caffeic acids) [1], organic acids (citric, malic, and succinic) [2], 15 amino acids, 5 macroelements, and 16 microelements [3]. We studied the carbohydrate composition of S. caucasica herb collected in subalpine meadows of the western Caucasus (Daut Gorge of Karachay-Cherkessia Republic). Raw material (30.0 g of S. caucasica herb) was extracted with CHCl 3 (2 100 mL) and dried. The remaining raw material was extracted twice with refluxing EtOH (82°C) in order to isolate sugars soluble in alcohol (SSA). The resulting extracts were evaporated and chromatographed on Filtrak FN 7,12 paper (PC) using BuOH–Py–H 2 O (6:4:3). SSA according to PC were glucose, galactose (anilinium biphthalate detector), fructose, and sucrose (5% urea detector). Next, polysaccharides were isolated by successive extraction of water-soluble polysaccharides (WSPS) with H 2 O, pectinic substances (PS) with oxalic acid and ammonium oxalate solutions (0.5%), and hemicellulose (HMC) with base solution (5%). The monosaccharide composition of the carbohydrates was established by acid hydrolysis [4]. Neutral sugars were identified by GC. Samples were analyzed by GC on a Chrom-5 chromatograph with a flame-ionization detector, glass column (1.5 m 0.3 m) with 5% Silicone XE-60 on Chromaton NAW (0.200–0.250 mesh), 210°C, He carrier gas at 30 mL/min, and aldononitrile acetates [4]. Table 1 presents the results. The isolated WSPS and PS were assigned according to the amount of component monosaccharides as galactans; HMC, xylans. The greatest amount of galactose was observed in PS fractions. The PS and HMC fractions were the main ones with respect to content. Uronic acids were identified in all fractions. The amount of uronic acids was determined by a photoelectrocolorimetric method using the reaction with carbazole in H 2 SO 4 solution [5]. The greatest amount of uronic acids was detected in PS. The accumulation of these components was responsible for the prospective pharmaceutical use of the carbohydrates. WSPS were a dark-brown powder with relative viscosity 3.0 (c 1%, H 2 O). The content of free carboxylic acids (Cf) was established by titration as 1.98%; of esterified carboxylic acids (Ce), 4.6%; the degree of esterification (), 69.9%. Therefore, WSPS were highly esterified compounds. This allowed them to be recommended for use as excipients for manufacturing drug forms as gel-formers, thickeners, stabilizers, etc. PS were a dark-brown powder that dissolved in H 2 O with heating to form viscous solutions of relative viscosity 10.17 (c 1%, H 2 O). The content of Cf was 6.75%; Ce, 3.78%; 35.89%. Therefore, PS were low-esterified compounds. The rather high content of free carboxylic acids made this plant a promising subject for isolating PS with pronounced sorption properties, especially with respect to metal ions. HMC was a friable light-brown powder that dissolved in base. IR spectra of samples were taken in pressed KBr pellets on a Model 2000 IR-Fourier spectrometer (PerkinElmer) using 100 scans. The following conclusion could be made based on an analysis of the found characteristic IR absorption bands of the carbohydrates.

Studies of physicochemical properties of modified carbon nanomaterials for sorption extraction of radionuclides. III. The effect of oxidizing treatment on sorption of Am(III) from aqueous solutions

The purpose of this work was to develop a method of manufacturing a new sorption material by soft oxidation of initial carbon materials with effective sorption characteristics with respect to americium. A technique of oxidation of FAS and VSK carbons is developed. Physicochemical properties of the obtained materials are studied, the micropore size and volume are determined, and IR spectra of samples are studied. Sorption of Am (III) is studied under various conditions. It is established that oxidizing treatment of FAS increases its sorption ability in respect to Am(III).

The Good Vibrations of Beer. The Use of Infrared and UV/Vis Spectroscopy and Chemometry for the Quantitative Analysis of Beverages

Infrared spectroscopy in combination with a specially developed attenuated total reflection (ATR) flow cell and multivariate analysis was used for the quantitative analysis of beer and other beverages. IR spectra of samples were obtained in the range from below 1000 cm-1 to 4000 cm-1 and subjected to a multivariate analysis based on calibration sets with laboratory reference standards. In the case of beer, this calibration set included 240 beer samples spanning the entire range of ethanol content, extract and CO2. Based on this calibration, an infrared and UV/Vis spectroscopy-based sensor for the quick and quantitative quality control of beer was developed and subjected to extensive tests in breweries. This sensor meets and exceeds all requirements from brewers for the routine control in the production and bottling. Its use for other beverages, for example wine, juices or apple wine, requires only another set of calibration data for the specific beverage.

Behavior of suspending and wetting agents in aqueous environment

This work describes the changes in viscosity, conductivity, pH, electrical conductivity, dielectric constant, zeta potential, UV, and IR spectra of aqueous solutions/dispersions of sodium carboxy methyl cellulose (CMC), Tween 80, and sodium lauryl sulphate (SLS) during aging at different temperatures. Significant reduction in viscosity ofh sodium CMC occurred during aging studies, while relatively small decrease in viscosity was seen with Tween 80 and SLS. Increment in specific conductivity was seen with aging of excipients. Significant increase of zeta potential was also seen with aging of samples. Concomitant shift in IR spectra of samples was observed with aging at 40°C.

Effect of intravenous laser irradiation on the molecular structure of blood and blood components

We present the results of a spectral study of the effect of low-intensity laser radiation on the molecular structure of blood and blood components. Analysis of the Fourier transform IR absorption spectra of blood confirmed the changes we observed previously in the oxygen transport characteristics of blood with intravenous exposure to the emission from a He-Ne laser. We show that structural and conformational changes in the hemoglobin tetramer, initiated by laser-induced photoreactions between Hb and oxygen, lead to characteristic changes in the shape and intensity of the IR bands for NH stretching vibrations, and also the amide I and amide II absorption bands. In the IR spectra of irradiated blood samples, we note increased absorption in the bands for stretching vibrations of the phosphate groups (945–1280 cm−1), which is evidence for an increase in the nucleic acid content (DNA, RNA). In the spectra of plasma and erythrocytes prepared from irradiated blood, there are no changes in this region of the IR spectrum. At the same time, in the IR spectra of samples of irradiated plasma, the intensity of the bands for stretching vibrations of the CH2 groups increases substantially.

Vibrations of the Crystal Lattice of Solid Solutions of Lead Zirconate-Titanate

The IR spectra of samples of solid solutions of lead zirconate-titanate with a rhombohedral and a tetragonal structures have been investigated. The frequencies of the vibrational modes of pairs or groups of atoms bound together have been determined in relation to the composition of the solid solutions. It has been established that in the case of lead zirconate-titanate with the rhombohedral structure, the modes with frequencies 150–250 and 450–600 cm−1 are dependent on the ratio between the atoms of zirconium and titanium in the crystal lattice cell. It is shown that with increase in the content of lead titanate in solid solutions of lead zirconate-titanate with a tetragonal structure, the frequency of the ferroelectric-active mode shifts toward higher frequencies.

Cracking catalyst with increased selectivity for coke

are characterized by higher steaming stability and coke selectivity. In preparing the catalyst samples, we used ultrastable Y zeolite in the H form (USY) and Y zeolite in the RE form, as well as a kaolin clay and a binder [8]. The ultrastable zeolite was obtained by steaming NaY zeolite in the NH4 form with 30-50% steam for a period of 3.5 h at temperatures of 550-815~ The characteristics of these zeolites are listed in Table 1. In Fig. 1 we show the IR spectra of samples of domestic and foreign ultrastable zeolites. It will be seen that they are practically identical. The composition of the Prosyanoe kaolin BP-84 is as follows: A1203 46.6%, SiO 2 51.7%, Na20 0.19%, Fe203 0.465%. The binder was obtained by treating aluminum hydroxide with nitric acid. The catalysts were prepared by mixing slurries of the zeolite, clay, and binder, with subsequent molding of the particles, with dimensions 0.05-0.315 mm. The molded catalysts were dried and calcined at 500-750~ for 4 h and then stabilized at 750 ~ and 790~ over a 6-h period in a 100% steam atmosphere. The catalytic activity of the zeolites was determined in a unit that included a flow-type reactor with a fixed bed of catalyst, in the process of cracking a vacuum distillate at a temperature t = 500~ and a feedstock mass velocity w = 7 h -t. The reactor was charged with 1.5 g of the zeolite, diluted with quartz sand to 15 g [7].

Phase transformation of natural titanite: An infrared, Raman spectroscopic, optical birefringence and X-ray diffraction study

Abstract The thermal behaviour of natural titanite has been studied using infrared and Raman spectroscopy, linear birefringence and synchrotron X-ray diffraction. Natural single crystals from Rauris, Austria (Fe 1.8%. Al 3.8%) were investigated and two additional samples from the Smithonian Institute Washington (Fe 2.8%, Al 0.5% and Fe 8.8%, Al 13.9%) served for IR and birefringence measurements. The coupled substitution of Fe and Al for Ti and OH and F for O leads to the formation of long ranging defect fields which are assumed to account for an increased density of antiphase boundaries. Infrared absorption spectra show increased bandwidths with increasing defect concentration. The phase transition near 500 K is clearly seen in the IR spectra of samples with low defect concentrations but not for those with high defect densities. X-ray diffraction shows strong anisotropic diffuse scattering in the Rauris sample leading to the average symmetry A2/a at room-temperature. A second anomaly at ca. 850 K was fou...

Preparation and catalytic activity of titanium pillared montmorillonite

Thermally stable titanium pillared montmorillonite has been prepared by the intercalation of four different titanium alkoxides. X-ray diffraction, BET, chemical analysis, thermogravimetric analysis, differential thermal analysis, temperature-programmed desorption of ammonia and IR spectra of samples allow the determination of the structure. The catalysts prepared from Ti(OEt) 4 present the most interesting structural properties after calcination. The titanium pillared montmorillonite with pillars of ca. 12A˚shows high activity in the dehydration of 1-butanol. The selectivity of the catalyst is directly related to its acidic properties.

Effect of the wedging error in quantitative analysis of flexible polyurethane foams by FT-IR-microscopy

The absorbance errors in IR-spectra of a polyurethane foam produced by wedging are calculated with the help of a mathematical model resulting from the geometrical form of the struts. It can be shown by experiments with struts and membranes of a flexible polyurethane foam, prepared with wide cell dimensions up to 2.5 mm, that the intensity distortions in the IR-spectra are accounted for by the model. A correction function is obtained for errors in IR-spectra of samples with the special geometry of the struts.

Infrared spectroscopy of exfoliated human cervical cells: evidence of extensive structural changes during carcinogenesis.

Infrared spectra were obtained from exfoliated cervical cells from 156 females, of whom 136 were normal, 12 had cervical cancer, and 8 had dysplasia. The spectra of the normal women, essentially identical, differed from those obtained from patients with either cancer or dysplasia. In malignant samples we noted (i) significant changes in the intensity of the glycogen bands at 1025 cm-1 and 1047 cm-1, the bands at 1082 cm-1 and 1244 cm-1, the C--O stretching band at 1155 cm-1, and the band at 1303 cm-1, (ii) significant shifts of the peaks normally appearing at 1082 cm-1, 1155 cm-1, and 1244 cm-1, and (iii) an additional band at 970 cm-1. Further study of several of these bands, including the pressure dependence of their frequencies, revealed that in the malignant cervical tissue there were extensive changes in the degree of hydrogen bonding of phosphodiester groups of nucleic acids and C--OH groups of proteins, as well as changes in the degree of disorder of methylene chains of lipids. The IR spectra of samples with dysplasia demonstrated the same changes with cancer samples, except that the changes were of lesser magnitude and the phosphodiester peak normally appearing at 1082 cm-1 did not shift. These spectroscopic changes appear to progress in tandem with the morphological changes that lead normal cervical epithelium to cancer through the premalignant stage of dysplasia. The diagnostic potential of IR spectroscopy is discussed.

An infrared study of the Na2O-V2O5-Fe2O3 glass system

Structural studies of Na2O-V2O5-Fe2O3 glasses have been made from their IR spectra which show that vibrational bands characteristic of the vanadium-oxygen bonds in V2O5 are maintained in these glasses, but the addition of Na2O to these glasses results in a shifting of the higher frequency peaks towards lower wave number due to structural changes produced in V2O5. It is inferred that Na+ ions make bonds interstitially with isolated V=O bonds and VO5 polyhedra are destroyed, resulting in the formation of VO4 polyhedra through intermediate complexes. The variation of Fe2O3, however, produces an insignificant structural change in these glasses. The IR spectra of samples heated to their temperature of crystallization confirm the formation of a series of complexes with several isolated V=O bonds.

Chemical stability of hydrotreated fuels, and fuel stabilization by means of antioxidants

more susceptible to oxidation than are untreated fuels [1-3], since the treating removes not only the undesirable components, but also natural oxidation inhibitors. Comparative studies are therefore needed on the oxidizability of such fuels, with a view toward finding means to improve oxidation stability. Here we are reporting on a study of oxidizability under artificial aging conditions, with samples of new types of jet fuels produced by means of hydrogenation andhydrotreating ; we also investigated the effectiveness of commercial antioxidants in chemical stabilization of these fuels. The hydrotreated fuels were commercial materials meeting the appropriate specifications. These studies were performed by means of repetitive oxidation of the same fuel sample at 120~ [4]. The tests were run in apparatus used to determine fuel corrosivity (GOST 20449-75). The fuel sample (110 ml) was placed in the beaker of this apparatus and heated to 120~ with the beaker connected to a reflux condenser through a ground glass joint. Four beakers were placed in the apparatus at the same time, with identical fuel samples. The fuel was held at this temperature for four heating periods of 6 h each, the apparatus being shut down between heating periods. After each heating period, the degree of fuel oxidation was rated by determining the peroxide number, optical density, acidity, and existent gtun content. The peroxide number was determined by potentiometric titration (with 0.1 N Na2S203 solution) of a fuel sample in a mixture of isopropyl alcohol and glacial acetic acid, plus a saturated solution of NaI in absolute isopropyl alcohol. The optical density was determined in a photoelectric colorimeter/neph elometer (Model FEK-56) in a cuvette with a light path of 30.085 ram, with a No. 4 filter (maximum transmission of filter at 434 nm) in comparison with an isooctane standard. The acidity was determined by a modernized ASTM D-974 method. In these determinations, the sample was dissolved in a mixture of toluene and isopropyl alcohol containing a small amount of water, and the resulting single-phase solution was titrated at room temperature with 0.1 N KOH solution in the presence of phenol red indicator up to the color change from yellow to rose-red. The existent gum contentwas determined in accordance with GOST 1567-56. The oxidation of the fuel samples was further characterized by IR spectroscopy, through which the kinetics of end-product accumulation could be observed on the basis of the absorption bands for the C-----O, C-O, and O-H bonds [5-7]. The conditions for recording the spectra were described in [7]. Results from these studies are shown in Table 1 and Fig. 1. The severely hydrogenated fuel (T-6 type) and the hydrotreated fuels (T-8 and RT types) are oxidized significantly under these particular conditions. In the first period of oxidation, active oxygen is found in the T-6 and T-8 fuels (respective peroxide numbers 119.6 and 135.4 mg O2/kg); in the subsequent heating periods, the peroxide compounds are transformed into other products, resulting in increases in optical density and in the quantities of organic acids in the fuel. This transformation is indicated both by the results of the chemical analysis (see Table 1) and by the IR spectra of the oxidation products. Under these particular conditions, no insoluble products (sludge) are formed in the fuels. After 24 h of oxidation at 120~ the fuel is oxidized quite severely. The increases in optical density are 1.08 for the T-6, 0.49 for the T-8, and 0.24 for the RT; the respective acidities are 14.8, 6.0, and 8.8 rag KOH/100 ml. The kinetic curves shown in Fig. 1 for the accumulation of the oxidation end-products in the bulk fuel RT or T-6 were obtained by measuring the optical density (log I0/I) of the bands at 1720 cm -1 ( v C ~O ), 1100 cm-1 (VC-O, SO-H *), and 3570 cm -1 (vO_ H) in the IR spectra of samples that had been oxidized at 120~ These data indicate that the course of the fuel oxidation is not the same in the two fuels. In the RT fuel, during the first 6 h of oxidation, hydroperoxides accumulate; by the end of this period, alcohols have appeared, and *As in Russian original - Translator.

Utilization of ir spectroscopy for the study of the mechanism of the cyclization of ?-(2-carboxyarylamino)propionic acids

It was established by IR spectroscopy that the cyclization of Β-(2-carboxylarylamino) propionic acids to 2,3-dihydroquinoline-4(1H)-ones in acetic anhydride in the presence of an alkali metal acetate proceeds through an intermediate step involving the formation of an eight-membered cyclic anhydride. In the case of Β-(2-carboxy-5-chlorophenylamino) propionic acid the presence of an intermediate in the reaction mixture was established by the IR spectra of samples of the mixtures selected at various temperatures and was illustrated by the IR spectrum obtained by differential spectroscopy.

New method for preparation of cyclopentadienylthallium and cyclopentadienylindium by reaction of zero-valent Tl0 and In0 with cyclopentadiene

1. The IR spectra of samples, obtained by the cocondensation of atomic thallium and indium with cyclopentadiene at 77°K, were measured. The atomic thallium and indium react directly with the cyclopentadiene in the obtained matrix to respectively give cyclopentadienylthallium and cyclopentadienylindium. 2. The IR spectrum of cyclopentadienylindium was obtained for the first time.