Search

The problem of using octanometers for the rapid control of the octane number of compounds in the production of commercial gasoline is considered, and the factors forming it are indicated. Error spectra of a multidimensional absorption spectral analytic signal of commercial gasolines and compounds of their individual fractions (components) were studied in measurements in the mid-IR region. The effect of a change of the proportion of the main constituents (aromatic hydrocarbons, benzene catalysate, isomerizate, methyl tert-butyl ether, and isopentane) in the compound on the spectra of commercial gasolines was evaluated. Multidimensional measurements of light absorption by gasolines in a wide spectral region and difference spectra were used. It was shown that spectral noise does not form limitations in spectroscopic measurements, while uncontrollable variations in the process conditions can form significant deviations in the absorption spectra, leading to problems in using calibration characteristics based on commercial gasoline samples. [ABSTRACT FROM AUTHOR]

To assess a possibility of the measurement of the relative concentration of main gasoline components under varied conditions, we studied the absorption of electromagnetic radiation by these components in the mid-IR region. The results for the absorbance of gasoline with varying concentrations of components, obtained using Fourier-transform IR spectroscopy are presented. The use of multidimensional difference spectra of gasoline is the most effective and informative way to perform measurements. The high sensitivity of the difference spectra to changes in the composition and concentrations of the main gasoline components is demonstrated. [ABSTRACT FROM AUTHOR]

Resonance dipole-dipole interactions are shown to strongly manifest themselves in fundamental and overtone band shapes of low-temperature systems consisting of polar and nonpolar molecules as well with a relatively large first derivatives (P′>0.3 D) of the dipole moment. A rough model on the basis of the interaction between two non-degenerate, doubly degenerate, and triply degenerate oscillators was developed to study pairs of interacting molecules and clusters in low-temperature condensed systems. The concentration dependences of second- and third-order spectral band moments made it possible to estimate the number of molecules in clusters. [ABSTRACT FROM AUTHOR]

IR spectra of the solution of SF6 molecules in liquid NF3 at 84 K have been recorded. In a solvent transmission window of 1500–1750 cm−1, two wide absorption bands with pronounced peaks in the high-frequency part are observed. The profile of these bands is explained by the influence of the resonance dipole-dipole (RDD) interaction of the states of the simultaneous transition ν1(SF6) + ν3(NF3) and ν2(SF6) + ν3(NF3) with the states (ν1 + ν3) and (ν2 + ν3) of the SF6 molecules, respectively. The use of three isotopic modifications 32SF6, 33SF6, and 34SF6 has allowed us to vary the resonance detuning and thus to change the strength of the RDD interaction. With the liquid near the melting point being represented as a close-packed cubic crystal, the profile was calculated and its spectral characteristics were determined. The frequencies of the main peaks coincide with the experimental values accurate to the error. [ABSTRACT FROM AUTHOR]

The IR absorption spectra of liquid OCS ( T = 135(1) K) and of the following solutions—OCS + Ar ( T = 90 K), OCS + N2 ( T = 90 K), OCS + Kr ( T = 130 K), and OCS + Xe ( T = 163 K)—are measured in the range 800–7000 cm−1. From 16 to 40 bands corresponding to transitions to vibrational states up to the third order inclusive are interpreted for basic isotope modification and for the isotopically substituted molecules 18O12C32S, 16O13C32S, and 16O12C34S. In the spectra of the liquids, the spectral moments M(1) and M(2) of all the observed bands are determined. The harmonic frequencies ω i and the anharmonicity constants x ik are calculated for all the systems, including the liquid. The anharmonicity is found to be constant within the experimental error. A large shift Δω3 is primarily determined by the dipole-induced dipole interaction. [ABSTRACT FROM AUTHOR]

It is shown that the integrated absorption coefficients of strong fundamental bands of some gaseous substances can be determined with an accuracy of 5–10% using experimental data on the spectral moments of bands in the overtone spectral range of these substances in the liquid phase near the melting point. The absorption coefficients are calculated within the framework of the cell model of the liquid state from the contributions of the resonance dipole-dipole interaction to the second spectral moment. The combination and overtone absorption bands of the SF6, CF4, SiF4, NF3, CHF3, CC1F3, CBrF3, OCS, N2O, and CO2 molecules in the liquid state and in solutions in liquefied Xe, Kr, and O2 are recorded. The data in the literature on the intensity of strong IR bands in the gas phase are analyzed. Using an improved experimental technique, additional measurements are performed. It is found that the absorption coefficients determined from the spectral characteristics of the liquids agree well with the coefficients measured in the gas phase. [ABSTRACT FROM AUTHOR]

Spurrite from Negra Mine, Queretaro, Mexico is characterized by a complex chemical composition. Its empirical formula derived based on electron microprobe, wet chemical analyses and gas chromatography of annealing products is H0.18Ca5.01Na0.05[(SiO4)1.91(SO4)0.08)][(CO3)0.71(BO3)0.28]O11. The mineral was studied by single-crystal X-ray diffraction (SCXRD) as well as infrared (IR), Raman and nuclear magnetic resonance (NMR) spectroscopy. According to spectroscopic data, boron has three-fold coordination and sulfur occurs in the mineral in the sulfate form. A significant portion of carbonate groups is substituted by BO33– anions. Charge compensation is achieved due to the substitution of a part of SiO44– anions by SO42– groups, as well as to the admixture of sodium. SCXRD shows that sodium occurs in its own site with a low occupancy. The studied sample is isotypic with the synthetic NaCa5(SiO4)2(BO3) compound. The IR spectrum shows possible partial protonation of the SiO4 tetrahedra whereas bands of H2O molecules and isolated OH– anions are not observed. Thermal behavior of B,S,Na-bearing spurrite from Negra Mine has been studied using powder high-temperature X-ray diffraction (HTXRD) together with boron poor and S-free spurrite from Fuka Area (Japan). The studied samples are stable up to ~ 1200 °C and ~ 1100 °C, respectively, whereas synthetic B,S-free spurrite decomposes at about 900 °C. The thermal expansion is significantly anisotropic and is observed mainly in the direction perpendicular to the ac plane which is coplanar with the layers of calcium polyhedra and anionic pseudo-layers formed by (C,B)O3 triangles and (Si,S)O4 tetrahedra. Isomorphism and a similarity of the thermal, baric and compositional (C-B substitution) deformations of spurrite-like structures are discussed. [ABSTRACT FROM AUTHOR]

Sergeysmirnovite, MgZn2(PO4)2 · 4H2O, is a new mineral from the oxidation zone of the Kester mineral deposit, Sakha-Yakutia, Russia. This mineral forms tabular colorless crystals growing on quartz and fluorapatite aggregates in association with pseudomalachite, libethenite, native copper, a Na-analogue of batagayite, arsenolite, tobermorite, epifanovite, and batagayite. The mineral is orthorhombic, with the space group Pnma. The unit cell parameters refined from powder X-ray diffraction data are the following: a = 10.5957(6) Å, b = 18.365(1) Å, c = 5.0320(4) Å, V = 979.16 (8) Å3. The eight most intense powder X-ray diffraction lines are the following (I-d[Å]-hkl): 100-5.28-200; 33-4.576-040; 24-3.999-230; 24-3.877-031; 22-3.387-221; 44-3.015-250; 57-2.854-311; 34-2.647-400. Sergeysmirnovite belongs to the hopeite group and is dimorphous with reaphookhillite. The mineral is named in honor of famous Soviet geologist, Academician Sergei Sergeevich Smirnov (1895–1947), a renowned specialist in the mineralogy of ore deposits. [ABSTRACT FROM AUTHOR]

The possibility of the application of high-uranium self-irradiation-damaged metamict zircon for U-Pb geochronological studies (ID-TIMS) after preliminary high-temperature annealing and acid treatment was demonstrated using zircon from the Li–F granites of the Turga massif (Eastern Transbaikalia). Optimal conditions of high-temperature annealing and acid treatment of zircon with high self-irradiation α-dose can be selected to remove completely a metamict phase and preserve sufficient quantities of the mineral for U-Pb (ID-TIMS) studies. [ABSTRACT FROM AUTHOR]

Microporous silicate tiettaite from the Khibiny alkaline massif (Kola Peninsula, Russia) has been studied using X-ray diffraction analysis, electron probe microanalysis, and Raman spectroscopy of single crystals and powders. Its chemical formula is refined to be K4Na12Fe3+Si16O41(OH)4⋅ 2H2O. The Raman spectrum of tiettaite contains lines at 3650, 3450, 1097, 1066, 980, 920, 681, 635, 569, 499, 458, 404, 272, 144 cm–1. The orthorhombic unit-cell parameters are a = 28.866(7) Å, b = 10.707(3) Å, c = 17.425(7) Å, V = 5385(3) Å3, Z = 4, sp. gr. Cmcm. The tiettaite crystal structure has been solved for the first time from single crystal and refined by the Rietveld method to the final Rwp = 2.47% and RBragg = 1.38%. The structure based on a new-type microporous heteropolyhedral framework formed by one-dimensional modules [Si28Na16Fe4K4O110]76– elongated along the c axis. Each module consists of complex ribbons with compositions of [Si14O39]22– and [Fe2K2Na6O32]50– compose a framework via shared vertices of half-occupied silicon–oxygen tetrahedra Si5 and Si6. Tiettaite structure contains a three-dimensional system of crossed channels with effective channel widths of 2.61 × 7.50, 2.46 × 2.92, and 3.60 × 3.90 Å2, running along the [100], [010], and [001] directions, respectively. The presence of a system of broad channels allows one to consider tiettaite as promising ion exchanger. Regarding the information complexity parameters, tiettaite can be assigned to minerals with very complex structure. [ABSTRACT FROM AUTHOR]

Evolution of the electronic absorption and photoluminescence spectra of the fullerene C[sub 60] solutions with various concentrations in a polar solvent (N-methylpyrrolidone) was studied. Comparison with the electrooptical properties of these solutions shows that a slow (associative) fullerene-solvent interaction mechanism is operative at large (nearly saturating) concentrations (1 × 10[sup -3] g/cm³), whereas the solutions of relatively low concentration (less than 5 × 10[sup -4] g/cm³) exhibit fast complex formation between fullerene and the solvent molecules. The latter interaction significantly changes the electronic structure of fullerene. [ABSTRACT FROM AUTHOR]