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1.
Raman and infrared spectra of calcurmolite were recorded and interpreted from the uranium and molybdenum polyhedra, water molecules and hydroxyls point of view. U O bond lengths in uranyl and Mo O bond lengths in MoO6 octahedra were calculated and O H…O bond lengths were inferred from the spectra. The mineral calcurmolite is characterised by bands assigned to the vibrations of the UO2 units. These units provide intense Raman bands at 930, 900 and 868 and 823 cm−1. These bands are attributed to the anti‐symmetric and symmetric stretching modes of the UO2 units, respectively. Raman bands at 794, 700, 644, 378 and 354 cm−1 are attributed to vibrations of the MoO4 units. The bands at 693 and 668 cm−1 are assigned to the anti‐symmetric and symmetric Ag modes of the terminal MO2 units. Similar bands are observed at 797 and 773 cm−1 for koechlinite and 798 and 775 cm−1 for lindgrenite. It is probable that some of the bands in the low wavenumber region are attributable to the bending modes of MO2 units. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

2.
The mineral marthozite, a uranyl selenite, has been characterised by Raman spectroscopy at 298 K. The bands at 812 and 797 cm−1 were assigned to the symmetric stretching modes of the (UO2)2+ and (SeO3)2− units, respectively. These values gave the calculated U O bond lengths in uranyl of 1.799 and/or 1.814 Å. Average U O bond length in uranyl is 1.795 Å, inferred from the X‐ray single crystal structure analysis of marthozite by Cooper and Hawthorne. The broad band at 869 cm−1 was assigned to the ν3 antisymmetric stretching mode of the (UO2)2+ (calculated U O bond length 1.808 Å). The band at 739 cm−1 was attributed to the ν3 antisymmetric stretching vibration of the (SeO3)2− units. The ν4 and the ν2 vibrational modes of the (SeO3)2− units were observed at 424 and 473 cm−1. Bands observed at 257, and 199 and 139 cm−1 were assigned to OUO bending vibrations and lattice vibrations, respectively. O H···O hydrogen bond lengths were inferred using Libowiztky's empirical relation. The infrared spectrum of marthozite was studied for complementation. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

3.
Raman spectra of the uranyl titanate mineral brannerite were analysed and related to the mineral structure. A comparison is made with the Raman spectra of uranyl oxyhydroxide hydrates. The observed bands are attributed to the TiO and (UO2)2+ stretching and bending vibrations, U OH bending vibrations, as well as H2O and (OH) stretching, bending and libration modes. U O bond lengths in uranyls and O H···O bond lengths were calculated from the wavenumbers assigned to the stretching vibrations. Raman bands of brannerite are in harmony with those of the uranyl oxyhydroxides. The mineral brannerite is metamict, as is evidenced by the intensity of the UO stretching and bending modes being of lower intensity than expected and with bands that are significantly broader. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

4.
Raman spectra of the uranyl titanate mineral euxenite were analysed and related to the mineral structure. A comparison is made with the Raman spectra of uranyl oxyhydroxide hydrates. The observed bands are attributed to the Ti O and (UO2)2+ stretching and bending vibrations, as well as lattice vibrations of rare‐earth ions. The Raman bands of euxenite are in harmony with those of the uranyl oxyhydroxides. The mineral euxenite is metamict as is evidenced by the intensity of the U O stretching and bending modes, which are of lower intensity than expected, and with bands that are significantly broader. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

5.
The gaseous standard molar enthalpies of formation of two 2‐R‐3‐methylquinoxaline‐1,4‐dioxides (R = benzoyl or tert‐butoxycarbonyl), at T = 298.15 K, were derived using the values for the enthalpies of formation of the compounds in the condensed phase, measured by static bomb combustion calorimetry, and for the enthalpies of sublimation, measured by Knudsen effusion, using a quartz crystal oscillator. The three dimensional structure of 2‐tert‐butoxycarbonyl‐3‐methylquinoxaline‐1,4‐dioxide has been obtained by X‐ray crystallography showing that the two N? O bond lengths in this compound are identical. The experimentally determined geometry in the crystal is similar to that obtained in the gas‐phase after computations performed at the B3LYP/6‐311 + G(2d,2p) level of theory. The experimental and computational results reported allow to extend the discussion about the influence of the molecular structure on the dissociation enthalpy of the N? O bonds for quinoxaline 1,4‐dioxide derivatives. As found previously, similar N? O bond lengths in quinoxaline‐1,4‐dioxide compounds are not linked with N? O bonds having the same strength. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

6.
The Raman spectrum of the mineral guilleminite Ba[(UO2)3O2(SeO3)2](H2O)3 was studied and complemented by the infrared spectrum of this mineral. Both spectra were interpreted and compared with the spectra of marthozite, larisaite, haynesite and piretite, all of which should have the same phosphuranylite anion sheet topology. The presence of symmetrically distinct water molecules and hydrogen bonds was inferred from the spectra. This is in agreement with the crystal structural analysis of guilleminite. U O bond lengths in uranyl and O H···O hydrogen bond lengths were calculated from the Raman and/or infrared spectra of guilleminite. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

7.
The molecular structure of the uranyl mineral rutherfordine has been investigated by the measurement of the near‐infrared (NIR) and Raman spectra and complemented with infrared spectra including their interpretation. The spectra of rutherfordine show the presence of both water and hydroxyl units in the structure as evidenced by IR bands at 3562 and 3465 cm−1 (OH) and 3343, 3185 and 2980 cm−1 (H2O). Raman spectra show the presence of four sharp bands at 3511, 3460, 3329 and 3151 cm−1. Corresponding molecular water bending vibrations were only observed in both Raman and infrared spectra of one of two studied rutherfordine samples. The second rutherfordine sample studied contained only hydroxyl ions in the equatorial uranyl plane and did not contain any molecular water. The infrared spectra of the (CO3)2− units in the antisymmetric stretching region show complexity with three sets of carbonate bands observed. This combined with the observation of multiple bands in the (CO3)2− bending region in both the Raman and IR spectra suggests that both monodentate and bidentate (CO3)2− units may be present in the structure. This cannot be exactly proved and inferred from the spectra; however, it is in accordance with the X‐ray crystallographic studies. Complexity is also observed in the IR spectra of (UO2)2+ antisymmetric stretching region and is attributed to non‐identical UO bonds. U O bond lengths were calculated using wavenumbers of the ν3 and ν1 (UO2)2+ and compared with data from X‐ray single crystal structure analysis of rutherfordine. Existence of solid solution having a general formula (UO2)(CO3)1−x(OH)2x.yH2O (x, y ≥ 0) is supported in the crystal structure of rutherfordine samples studied. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

8.
Rotational coherent anti‐Stokes Raman spectroscopy (CARS) in fuel‐rich hydrocarbon flames, with a large content of hydrogen in the product gases (∼20%), has in previous work shown that evaluated temperatures are raised several tens of Kelvin by taking newly derived N2 H2 Raman line widths into account. To validate these results, in this work calibrated temperature measurements at around 300, 500 and 700 K were performed in a cell with binary gas mixtures of nitrogen and hydrogen. The temperature evaluation was made with respect to Raman line widths either from self‐broadened nitrogen only, N2 N2 [energy‐corrected‐sudden (ECS)], or by also taking nitrogen broadened by hydrogen, N2 H2 [Robert–Bonamy (RB)], Raman line widths into account. With increased amount of hydrogen in the cell at constant temperature, the evaluated CARS temperatures were clearly lowered with the use of Raman line widths from self‐broadened nitrogen only, and the case with inclusion of N2 H2 Raman line widths was more successful. The difference in evaluated temperatures between the two different sets increases approximately linearly, reaching 20 K (at T ∼ 300 K), 43 K (at T = 500 K) and 61 K (at T = 700 K) at the highest hydrogen concentration (90%). The results from this work further emphasize the importance of using adequate Raman line widths for accurate rotational CARS thermometry. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

9.
Raman at 298 and 77 K and infrared spectra of two samples of sodium‐zippeite were studied and interpreted. U O bond lengths in uranyl were calculated and compared with those inferred from the X‐ray single crystal structure data of a synthetic sodium‐zippeite analogue. Hydrogen‐bonding network in the studied samples is discussed. O H…O bond lengths were calculated and compared with those predicted from the X‐ray single crystal structure analysis. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

10.
Raman spectra of pseudojohannite were studied and related to the structure of the mineral. Observed bands were assigned to the stretching and bending vibrations of (UO2)2+ and (SO4)2− units and of water molecules. The published formula of pseudojohannite is Cu6.5(UO2)8[O8](OH)5[(SO4)4]·25H2O. Raman bands at 805 and 810 cm−1 are assigned to (UO2)2+ stretching modes. The Raman bands at 1017 and 1100 cm−1 are assigned to the (SO4)2− symmetric and antisymmetric stretching vibrations. The three Raman bands at 423, 465 and 496 cm−1 are assigned to the (SO4)2−ν2 bending modes. The bands at 210 and 279 cm−1 are assigned to the doubly degenerate ν2 bending vibration of the (UO2)2+ units. U O bond lengths in uranyl and O H···O hydrogen bond lengths were calculated from the Raman and infrared spectra. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

11.
The ability to transport large quantities of heat by nucleate boiling is reduced for mixtures compared to their pure components. To study the heat and mass transfer during the boiling process, a one‐dimensional Raman spectroscopy setup was applied to measure, for the first time to the best of our knowledge, the composition and temperature gradients in the vicinity of single boiling bubbles of a mixture of acetone and isopropanol. A novel evaluation strategy allowed the simultaneous detection of the mixture composition and temperature from the C H and the O H Raman spectra. The composition gradients arise because of rectification effects, which cause unlike compositions in the gas and liquid phases. Heat transfer from the boiling bubble to the surrounding liquid induces temperature gradients. High temporal and spatial resolution measurements using an imaging spectrograph and an electron multiplying charge‐coupled device camera revealed large composition and temperature gradients with similar shapes. The accuracy of the composition results was validated by a species conservation calculation. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

12.
The Raman spectrum of the uranyl selenite mineral demesmaekerite was studied, complemented by the infrared spectrum and tentatively interpreted. The observed bands were attributed to the stretching and bending vibrations of (UO2)2+, (SeO3)2− and OH groupings. U O bond lengths in uranyl and O H···O hydrogen bond lengths were calculated from Raman and/or infrared spectra and compared with published data. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

13.
Raman spectra of vajdakite, [(Mo6+O2)2(H2O)2As O5]·H2O, were studied and interpreted in terms of the structure of the mineral. The Raman spectra were compared with the published infrared spectrum of vajdakite. The presence of dimolybdenyl and diarsenite units and of hydrogen bonded water molecules was inferred from the Raman spectra which supported the known and published crystal structure of vajdakite. Mo O and O H···O bond lengths were calculated from the Raman spectra. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

14.
Raman spectra of phosphuranylite and yingjiangite were measured and interpreted, and compared with the published infrared spectra of both minerals. U O bond lengths were calculated using the Bartlett–Cooney empirical relations and the O HċO hydrogen bond lengths were inferred on the basis of Libowitzky's empirical relation. The presence of oxonium and (H3O)+ ions, expected from the single crystal structure analysis of phosphuranylite, was not inferred from the Raman spectra. It was assumed that phosphuranylite and yingjiangite are identical and the name yingjiangite should be discarded because the name phosphuranylite has priority. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

15.
Raman and infrared spectra of the uranyl mineral zellerite, Ca[(UO2)(CO3)2(H2O)2]·3H2O, were measured and tentatively interpreted. U O bond in uranyl and O H···O hydrogen bonds were calculated from the vibrational spectra. The presence of structurally nonequivalent water molecules in the crystal structure of zellerite was inferred. A proposed chemical formula of zellerite is supported. Raman bands at 3514, 3375 and 2945 cm−1and broad infrared bands at 3513, 3396 and 3326 cm−1 are related to the ν OH stretching vibrations of hydrogen‐bonded water molecules. Observed wavenumbers of these vibrations prove that in fact hydrogen bonds participate in the crystal structure of zellerite. The presence of two bands at 1618 and 1681 cm−1 proves structurally distinct and nonequivalent water molecules in the crystal structure of zellerite. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

16.
Raman spectra of jáchymovite, (UO2)8(SO4)(OH)14·13H2O, were studied, complemented with infrared spectra, and compared with published Raman and infrared spectra of uranopilite, [(UO2)6(SO4)O2(OH)6(H2O)6]·6H2O. Bands related to the stretching and bending vibrations of (UO2)2+, (SO4)2−, (OH) and water molecules were assigned. U O bond lengths in uranyl and O H· · ·O hydrogen bond lengths were calculated from the Raman and infrared spectra. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

17.
Raman spectra of the uranyl oxyhydroxy‐hydrated mineral compreignacite, K2[(UO2)3O2(OH)3]2·7H2O, were measured and interpreted. Observed bands were attributed to the stretching and bending vibrations of uranyl units, molecular water and hydroxyl ions. U O bond lengths in uranyl and O HO hydrogen bond lengths were inferred from the spectra and compared with those from the X‐ray single crystal structure data. The importance of this spectroscopic study rests with the ability to analyze very small amounts of the mineral. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

18.
Raman and infrared spectra of five uranyl oxyhydroxide hydrates, becquerelite, billietite, curite, schoepite and vandendriesscheite, are reported. The observed bands are attributed to the (UO2)2+ stretching and bending vibrations, U OH bending vibrations and H2O and (OH) stretching, bending and libration modes. The U O bond lengths in uranyls and the O H···O bond lengths are calculated from the wavenumbers assigned to the stretching vibrations. They are close to the values inferred and/or predicted from the X‐ray single‐crystal structure. The complex hydrogen‐bonding network arrangement was proved in the structures of all the minerals studied. This hydrogen bonding contributes to the stability of these uranyl minerals. Copyright © 2006 John Wiley & Sons, Ltd. John Wiley & Sons, Ltd.  相似文献   

19.
The uranyl tellurite mineral moctezumite, Pb(UO2)(TeO3)2, was studied by Raman spectroscopy and complemented with infrared spectroscopy. The presence of the stretching and bending vibrations of uranyl (UO2)2+ and tellurite (TeO3)2− ions was inferred, and the observed bands were assigned to uranyl and tellurite units vibrations. U O bond lengths calculated from the spectra with two empirical relations are close to those inferred from the X‐ray single‐crystal structure of moctezumite. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

20.
Fe-doped CoCr oxide catalysts are prepared by solid-phase mixing method, coprecipitation method, mechanical mixing method, and citric acid method, respectively, and their catalytic activity in the selective catalytic reduction of nitrogen oxides with NH3 (NH3-SCR) is tested. The Fe0.5CoCrOx catalysts prepared by all preparation methods have good water resistance and sulfur resistance when the calcination temperature is 400 °C. Fe0.5CoCrOx prepared by coprecipitation method by calcination at 400 °C (CP-400) is shown to have the optimum catalyst activity. In addition, the catalysts are characterized by a series of characterizations. The characterization results show that CP-400 has the largest specific surface area, which makes the active and acidic sites highly dispersed on the surface of CP-400, resulting in stronger redox and acidity and improved SCR activity. The removal of NO by NH3-SCR over CP-400 at 150 °C follows the Eley-Rideal (E R) and Langmuir-Hinshelwood (L H) mechanisms.  相似文献   

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