共查询到20条相似文献,搜索用时 15 毫秒
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Jérôme Lamontagne Lionel Desgranges Christophe Valot Jean Noirot Thierry Blay Ingrid Roure Bertrand Pasquet 《Mikrochimica acta》2006,155(1-2):183-187
The behaviour of gases produced by fission is of great importance for nuclear fuel operation. Within this context, an experimental
method for the characterisation of the fission gas including gas bubbles in an irradiated UO2 nuclear fuel was developed in our laboratory using SIMS, EPMA and SEM results. SIMS and EPMA have been used to measure the
radial distribution of xenon and SEM gives information on bubble formation across the fuel pellet radius. Using SIMS, xenon
concentration can be determined in the matrix and in the bubbles. A quantification method, allowing the determination of the
total inventory of xenon, is proposed and qualified with EPMA results. It is concluded that the complementary micro-analytical
techniques SIMS, EPMA and SEM are very powerful tools for the characterisation of the fission gas bubbles in irradiated nuclear
fuel. 相似文献
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Wang Ya-Feng Lee Wen-Jhy Chen Chuh-Yung Wu Yo-Ping Greg Chang-Chien Guo-Ping 《Plasma Chemistry and Plasma Processing》2000,20(4):469-494
Decomposition of dichlorodifluoromethane (CCl2F2 or CFC-12) in aradiofrequency (RF) plasma system is demonstrated. The CCl2F2decomposition fractions CCl
2
F
2 and mole fractionsof detected products in the effluent gas stream of CCl2F2/O2/Ar andCCl2F2/H2/Ar plasma, respectively, have been determined. The experimentalparameters including input power wattage, O2/CCl2F2 or H2/CCl2F2 ratio,operational pressure, and CCl2F2 feeding concentration wereinvestigated. The main carbonaceous product in the CCl2F2/O2/Arplasma system was CO2, while that in the CCl2F2/H2/Ar plasma systemwas CH4 and C2H2. Furthermore, the possible reaction pathways werebuilt-up and elucidated in this study. The results of the experimentsshowed that the highly electronegative chlorine and fluorine wouldeasily separate from the CCl2F2 molecule and combine with the addedreaction gas. This led to the reactions terminated with the CO2,CH4, and C2H2 formation, because of their high bonding strength. Theaddition of hydrogen would form a preferential pathway for the HCland HF formations, which were thermodynamically stable diatomicspecies that would limit the production of CCl3F, CClF3, CF4, andCCl4. In addition, the HCl and HF could be removed by neutral orscrubber method. Hence, a hydrogen-based RF plasma system provideda better alternative to decompose CCl2F2. 相似文献
4.
István Szilágyi Sándor Dóbé Tibor Bérces 《Reaction Kinetics and Catalysis Letters》2000,70(2):319-324
The rate constant value of k
1 = (6.05 ± 0.20)×109 cm3 mol–1 s–1 (with ± 1 error) has been determined for the reaction OH + CH2F2 (1) by applying the discharge-flow/resonance-fluorescence method at 298 K. 相似文献
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The spin-spin coupling constant 3
J
H,F of the H(CF2)2 group varies within 1.6—3.5 Hz for 5-RF- and 3.8—4.5 Hz for 3-RF-isoxazoles and pyrazoles in CDCl3 and can serve as a reliable criterion for recognition of regioisomeric and tautomeric structures of H(CF2)2-containing heterocyclic compounds. 相似文献
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Andrzej Leś 《Theoretical chemistry accounts》1985,66(6):375-393
Intermolecular potential energy curves for the hydrogen bonded systems H2O·H2S, H2O·H2Se and H2S·H2S were calculated with nonempirical pseudopotentials using optimized-in-molecules basis sets augmented by polarization functions. The H2O·H2O interaction energy curve has been also considered as a test case. The present results for H2O·H2S and H2S·H2S indicate much weaker intermolecular interactions than those found in previous ab initio calculations. The H2O·H2Se interaction was found to be quite similar to H2O·H2S.This work was partly supported by the Polish Academy of Sciences within the Project PAN-09, 7.1.1.1On leave from Quantum Chemistry Laboratory, Dept. of Chemistry, University of Warsaw, Pasteura 1, 02-093. Warsaw, Poland 相似文献
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Jingjing Li Shifu Zhang Jinmiao Wang Xiaomeng Yin Zhenxing Han Guobo Chen Dongmei Zhang Mei Wang 《Molecules (Basel, Switzerland)》2022,27(4)
The process of electrocatalytic CO2 reduction and H2 evolution from water, regarding renewable energy, has become one of the global solutions to problems related to energy consumption and environmental degradation. In order to promote the electrocatalytic reactivity, the study of the role of ligands in catalysis has attracted more and more attention. Herein, we have developed a copper (II) complex with redox-active ligand [Cu(L1)2NO3]NO3 (1, L1 = 2-(6-methoxypyridin-2-yl)-6-nitro-1h-benzo [D] imidazole). X-ray crystallography reveals that the Cu ion in cation of complex 1 is coordinated by two redox ligands L1 and one labile nitrate ligand, which could assist the metal center for catalysis. The longer Cu-O bond between the metal center and the labile nitrate ligand would break to provide an open coordination site for the binding of the substrate during the catalytic process. The electrocatalytic investigation combined with DFT calculations demonstrate that the copper (II) complex could homogeneously catalyze CO2 reduction towards CO and H2 evolution, and this could occur with great performance due to the cooperative effect between the central Cu (II) ion and the redox- active ligand L1. Further, we discovered that the added proton source H2O and TsOH·H2O (p-Toluenesulfonic acid) could greatly enhance its electrocatalytic activity for CO2 reduction and H2 evolution, respectively. 相似文献
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Riccardo d'Agostino Francesco Cramarossa Santolo De Benedictis 《Plasma Chemistry and Plasma Processing》1984,4(1):21-31
Discharges fed with C3F8-H2 mixtures have been studied by means of mass spectrometry in a tubular reactor operated at 0.5 torr and 50 W. Comparison of the results with those obtained with emission actinometry give additional evidence that emission actinometry and mass spectrometry are powerful diagnostic tools to monitor stable and unstable species in discharges utilized for dry etching and polymer depositions. Mechanisms for end product formation and polymer deposition are also discussed. 相似文献
10.
In2O3八面体的碳还原法制备及其发光性能研究 总被引:1,自引:0,他引:1
In2O3 octahedrons were synthesized by carbothermal reduction using In2O3 nanoparticles as the source material. The as-synthesized products were characterized by X-ray powder diffraction (XRD), energy dispersive X-ray(EDX), scanning electron microscopy(SEM), transmission electron microscopy(TEM), high-resolution transmission electron microscopy (HRTEM), selected-area electron diffraction analysis(SAED) and Room-temperature photoluminescence(PL) spectroscopy. The results show that the products are single-crystalline In2O3 octahedrons, the length of the octahedrons is in the range of 400~3 000 nm; the PL patterns display two peaks located at 447nm and 555 nm upon excitation at 380 nm, and the other two peaks located at 444 nm and 550 nm upon excitation at 325 nm; the excitation pattern shows two peaks located at 274 nm and 371 nm, respectively. The growth mechanism of the In2O3 octahedrons is discussed, and the high supersaturation ratio is considered as the key factor. 相似文献
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Akira Nishimura Ryouga Shimada Yoshito Sakakibara Akira Koshio Eric Hu 《Molecules (Basel, Switzerland)》2021,26(10)
The aim of this study is to clarify the effect of doped metal type on CO2 reduction characteristics of TiO2 with NH3 and H2O. Cu and Pd have been selected as dopants for TiO2. In addition, the impact of molar ratio of CO2 to reductants NH3 and H2O has been investigated. A TiO2 photocatalyst was prepared by a sol-gel and dip-coating process, and then doped with Cu or Pd fine particles by using the pulse arc plasma gun method. The prepared Cu/TiO2 film and Pd/TiO2 film were characterized by SEM, EPMA, TEM, STEM, EDX, EDS and EELS. This study also has investigated the performance of CO2 reduction under the illumination condition of Xe lamp with or without ultraviolet (UV) light. As a result, it is revealed that the CO2 reduction performance with Cu/TiO2 under the illumination condition of Xe lamp with UV light is the highest when the molar ratio of CO2/NH3/H2O = 1:1:1 while that without UV light is the highest when the molar ratio of CO2/NH3/H2O = 1:0.5:0.5. It is revealed that the CO2 reduction performance of Pd/TiO2 is the highest for the molar ratio of CO2/NH3/H2O = 1:1:1 no matter the used Xe lamp was with or without UV light. The molar quantity of CO per unit weight of photocatalyst for Cu/TiO2 produced under the illumination condition of Xe lamp with UV light was 10.2 μmol/g, while that for Pd/TiO2 was 5.5 μmol/g. Meanwhile, the molar quantity of CO per unit weight of photocatalyst for Cu/TiO2 produced under the illumination condition of Xe lamp without UV light was 2.5 μmol/g, while that for Pd/TiO2 was 3.5 μmol/g. This study has concluded that Cu/TiO2 is superior to Pd/TiO2 from the viewpoint of the molar quantity of CO per unit weight of photocatalyst as well as the quantum efficiency. 相似文献
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A new reaction of MgCl2·4H2O with CCl2F2 is investigated by DTA and TG from room temperature to 350 °C. It is observed that MgF2 was obtained between 252 and 350 °C, Below the temperature, MgCl2·4H2O dehydrates and hydrolyzes to MgCl2 and Mg(OH)Cl, which are the real reactants of the reaction with CCl2F2. The formation of MgF2 is ascribed to the reaction of MgCl2 and Mg(OH)Cl with HF, which forms by decomposition of CCl2F2 with the taking part in of H2O released from dehydration of hydrated magnesium chloride on the surface of MgCl2 and Mg(OH)Cl, which catalyzes the decomposition of CCl2F2 in this case. Consequently, the reactions are tested in the fluid-bed condition. It is found that MgF2 formed at temperatures down to 200 °C in a fluid-bed reactor. This reaction may be used as a method of disposing of the environmentally sensitive CCl2F2 (rather than release into the atmosphere). It is also a method for the preparation of MgF2. 相似文献
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Nuo Xu Yunjia Jiang Wanqi Sun Jiahao Li Lingyao Wang Yujie Jin Yuanbin Zhang Dongmei Wang Simon Duttwyler 《Molecules (Basel, Switzerland)》2021,26(17)
A highly water and thermally stable metal-organic framework (MOF) Zn2(Pydc)(Ata)2 (1, H2Pydc = 3,5-pyridinedicarboxylic acid; HAta = 3-amino-1,2,4-triazole) was synthesized on a large scale using inexpensive commercially available ligands for efficient separation of C2H2 from CH4 and CO2. Compound 1 could take up 47.2 mL/g of C2H2 under ambient conditions but only 33.0 mL/g of CO2 and 19.1 mL/g of CH4. The calculated ideal absorbed solution theory (IAST) selectivities for equimolar C2H2/CO2 and C2H2/CH4 were 5.1 and 21.5, respectively, comparable to those many popular MOFs. The Qst values for C2H2, CO2, and CH4 at a near-zero loading in 1 were 43.1, 32.1, and 22.5 kJ mol−1, respectively. The practical separation performance for C2H2/CO2 mixtures was further confirmed by column breakthrough experiments. 相似文献
14.
Enthalpies of formation of F2SO, F2SO2, FClSO and FClSO2 molecules have been determined using ab initio molecular orbital theory and density functional theory (DFT) calculations. Different DFT approaches and levels of the Gaussian-3 and the complete basis set (CBS) ab initio model chemistries have been employed to calculate enthalpies of formation from both total atomization energies and isodesmic reaction schemes. The best values at 298 K for F2SO, F2SO2, FClSO and FClSO2 as derived from an average of G3, G3B3, CBS-Q and CBS-QB3 isodesmic energies are −140.6, −181.1, −92.6 and −132.3 kcal mol−1, respectively. The results obtained suggest that the accumulated small component errors found in the DFT-based methods are significantly reduced at the ab initio levels employed. Structural properties, harmonic vibrational frequencies, mode assignations and infrared intensities derived from B3LYP and mPW1PW91 functional with the 6-311+G(3df) basis set are presented. 相似文献
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We have analyzed decay kinetics of CF2 radicals in the afterglow of low-pressure, high-density C4F8 plasmas. The decay curve of CF2 density has been approximated by the combination of first- and second-order kinetics. The surface loss probability evaluated from the frequency of the first-order decay process has been on the order of 10–4. This small surface loss probability has enabled us to observe the second-order decay process. The mechanism of the second-order decay is self-association reaction between CF2 radicals (CF2+CF2C2F4). The rate coefficient for this reaction has been evaluated as (2.6–5.3)×10–14 cm3/s under gas pressures of 2 to 100 mTorr. The rate coefficient was found to be almost independent of the gas pressure and has been in close agreement with known values, which are determined in high gas pressures above 1 Torr. 相似文献
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Molybdovanadophosphoric Acid Catalyzed Oxidation of Hydrocarbons by H2O2 to Oxygenates 总被引:1,自引:0,他引:1
Nirupa A. Alekar S. B. Halligudi R. Rajani S. Gopinathan C. Gopinathan 《Reaction Kinetics and Catalysis Letters》2001,72(1):169-176
Heteropoly acids of the general formula H3+x[PMo12-xVxO40] (where x = 1,2,3) catalyzed the oxidation of aromatic hydrocarbons at 65°C with H2O2 to give oxygenated products. Among the catalysts, H4[PMo11VO40] was found to be a more active catalyst and its activities have been reported in the oxidation of cyclohexane, methyl cyclohexane, naphthalene, 1-methyl naphthalene and biphenyl. 相似文献
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I. M. Issa Y. M. Temerk A. Z. Abu Zhuri M. S. El-Meligy M. M. Kamal 《Monatshefte für Chemie / Chemical Monthly》1980,111(5):1151-1158
The stoichiometry and structure of salicylidenebenzoic-hydrazine (SBH) chelates with UO2(II), Ce(III) and Th(IV) in buffer-ethanol mixtures and in pure ethanol is studied applying conductometric titration, visible spectrophotometry and ir-spectrophotometry. The ir-spectra revealed that coordination takes place through the C=O and C=N groups.Deceased December 1977. 相似文献
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Tetracyanonickelate compounds as sorptive materials and the substitution of their H2O content by D2O
Anna Sopková Katarína Györyová Michal Šingliar 《Journal of inclusion phenomena and macrocyclic chemistry》1986,4(4):369-377
The compounds NiNi(CN)4·3,5H2O and Ni(NH3)2Ni(CN)4·H2O have been studied to examine the possibility of substituting their H2O or NH3 content by D2O. Contact with D2O was performed after heating the compounds to several temperatures. Depending on the degree of decomposition of the original compounds different ranges of substitution were possible. In such manner the compounds NiNi(CN)4·3,5D2O, NiNi(CN)4·5D2O, Ni(NH3)2Ni(CN)4·D2O, and Ni(D2O)2Ni(CN)4·D2O were prepared and thermally they were less stable than the original ones. The substitution by D2O is in agreement with the sorptive properties of the original tetracyanonickelate against different organic compounds using GC, since these could substitute the guest component and sometimes also the ligands during their decomposition. 相似文献
19.
H. Bernhard Schlegel Kurt Mislow Fernando Bernardi Andrea Bottoni 《Theoretical chemistry accounts》1977,44(3):245-256
The energy hypersurface for the attack of fluoride ion on methyl fluoride has been explored with ab initio LCAO-SCF calculations at a split-valence basis set level. Transition states for frontside and backside attack have been located. In addition to transition states, two possible F–-CH3F clusters have been identified. The transition state for the substitution of fluoride with retention of configuration is found to be 56 kcal/mol higher than the transition state for inversion of configuration. The transition state for hydride displacement with inversion is 62 kcal/mol above the transition state for fluoride substitution with inversion. 相似文献