共查询到20条相似文献,搜索用时 15 毫秒
1.
2.
Zusammenfassung Es werden vier Methoden zur Analyse einer Gasmischung N2–NO–NO2–N2O4–N2O3–HNO2 besprochen und ihre Bedeutung für die Bestimmung der einzelnen Molekelarten kritisch auseinandergesetzt. Nach keiner der Methoden kann man den Gehalt an Salpetriger Säure und Salpetersäure neben den Oxyden des Stickstoffes auffinden. Aus diesem Grunde ist die Analyse der genannten Gasmischung nach den vier Methoden allgemein nicht genau durchführbar.Mit 1 Abbildung.Herrn Prof. Dr.A. Skrabal zum 75. Geburtstag gewidmet. 相似文献
3.
Teng-Teng Chen Ling Fung Cheung Wei-Jia Chen Joseph Cavanagh Prof. Dr. Lai-Sheng Wang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(35):15372-15377
Multiple bonds between boron and transition metals are known in many borylene (:BR) complexes via metal dπ→BR back-donation, despite the electron deficiency of boron. An electron-precise metal–boron triple bond was first observed in BiB2O− [Bi≡B−B≡O]− in which both boron atoms can be viewed as sp-hybridized and the [B−BO]− fragment is isoelectronic to a carbyne (CR). To search for the first electron-precise transition-metal-boron triple-bond species, we have produced IrB2O− and ReB2O− and investigated them by photoelectron spectroscopy and quantum-chemical calculations. The results allow to elucidate the structures and bonding in the two clusters. We find IrB2O− has a closed-shell bent structure (Cs, 1A′) with BO− coordinated to an Ir≡B unit, (−OB)Ir≡B, whereas ReB2O− is linear (C∞v, 3Σ−) with an electron-precise Re≡B triple bond, [Re≡B−B≡O]−. The results suggest the intriguing possibility of synthesizing compounds with electron-precise M≡B triple bonds analogous to classical carbyne systems. 相似文献
4.
For the equilibrium solid phases occurring in the systems: KCl?KBr?H2O, K2SO4?(NH4)2SO4?H2O and KNO3?NH4NO3?H2O, the concentration dependencies of differential solution enthalpies, Δsol H 2 for several crystallization paths, were measured. The limiting differential solution enthalpies, Δsol H 2 0 , were determined by extrapolation of the above dependencies to the ionic strength,I m 0 , corresponding to the appropriate binary solutions. For KCl?KBr?H2O system only, the clear dependence between Δsol H 2 0 andI m 0 values was found and discussed. 相似文献
5.
Uzi Kaldor 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1994,31(4):279-282
The geometries of the Cl–NH3, Cl–H2O, F–NH3 and F–H2O clusters are optimized using the coupled cluster method. The four lowest ionization potentials are then calculated, leading to the ground and low excited states of the neutral species. The first three IPs describe ionization from the externalp state of the halogen atom, whereas the fourth corresponds to ionization from the NH3 or H2O moiety, leading to charge transfer complexes. These complexes were recently observed in the photoelectron spectrum of Cl–NH3, in full accord with our calculations.Supported in part by the U.S.-Israel Binational Science Foundation 相似文献
6.
《Chemical physics letters》1986,124(3):274-278
We have recorded the photoelectron spectra of the gas phase negative ions N2O− and (N2O)2− both of which were prepared in a nozzle ion source. The shift between the maxima of the two spectra is interpreted in terms of the dissociation energy of the dimer ion. 相似文献
7.
《Chemical physics letters》1985,115(3):268-274
A molecular-orbital study, performed using both multiple scattering Xα and ab initio SCF models, is reported for the protonation process of O2, O2− and O22−. The main features of both molecular electrostatic potential and electron deformation density contour maps are compared and discussed. 相似文献
8.
New potassium-conducting solid electrolytes based on potassium monogallate in the K2?2x Ga2?x V x O4 system are synthesized and studied. It is found that an introduction of V5+ ions leads to a considerable increase in the KGaO2 conductivity due to the formation of vacancies in the potassium sublattice. The conductivity for optimal compositions is approximately 10?3 S cm?1 at 400°C and above 10?2 S cm?1 at 700°C. The results are compared with early obtained data for potassium monogallate dopped with four-charged cations. 相似文献
9.
Roman M. Kenzhin Alexander M. Volodin Alexander F. Bedilo 《Research on Chemical Intermediates》2013,39(4):1789-1797
The concentration of O2 ? radical anions generated on the surface of hydrated ZrO2 in an H2O2 solution was found to depend on H2O2 concentration. It was shown that this method can be used for detecting H2O2 in solutions at concentration as low as 0.01 wt%. The radical anions were found to react with organic molecules, even at room temperature. The decomposition kinetics of O2 ? radical anions was double-exponential with two reaction rate constants. The existence of two distinct rate constants suggests that two types of O2 ? radical anions with similar spectroscopic properties but different reactivity are present on the surface of hydrated ZrO2. It is highly likely that different arrangements of hydroxyl groups near the radical anions account for the presence of the two types of O2 ? with different reactivity. The rate constants obtained in the presence of the organic compounds studied were found to conform with the expected order of reactivity: toluene > benzene ? hexane. 相似文献
10.
《Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy》1994,50(6):1153-1159
A careful study of the Raman spectra of aqueous solutions containing X2O7n− anions, where X = P, n = 4; X = Cr or Se, n = 2, has shown for the first time that in all cases the δX-O-X bending mode occurs below 100 cm−1. In addition, further information on the XO3 terminal stretches was obtained from FTIR spectra of the aqueous solutions. Consequently, more realistic vibrational assignments were obtained for these frequently-studied inorganic anions. 相似文献
11.
《Chemical physics letters》1987,136(2):177-180
SO−2, SO2·O− and SO2·SO− are produced by electron attachment to SO2 clusters under single collision conditions. SO−2, which is not produced at all in low-pressure ion sources, is more abundant than SO2·O− and SO2 ·SO−. Measured relative attachment cross sections for these ions show significant differences when compared to O− and SO− produced by attachment to SO2, i.e. the first resonance is very efficiently quenched in favor of SO−2 production. This is in contrast to previous findings in O2, CO2 and N2O. 相似文献
12.
Esra Öztürk Nilgun Kalaycioglu Ozpozan Serkan Dayan 《Journal of Thermal Analysis and Calorimetry》2014,117(2):573-578
Mn4+ doped and Dy3+, Tm3+ co-doped MgAl2Si2O8-based phosphors were prepared by conventional solid state reaction at 1,300 °C. They were characterized by thermogravimetry, differential thermal analysis, X-ray powder diffraction, photoluminescence, and scanning electron microscopy. The luminescence mechanism of the phosphors, which showed broad red emission bands in the range of 600–715 nm and had a different maximum intensity when activated by UV illumination, was discussed. Such a red emission can be attributed to the 2E → 4A2 transitions of Mn4+. 相似文献
13.
The systems NixMn1?xC2O4·2H2O (x = 0.11, 0.34) are characterized by XRD, SEM, TG/DTA, EGA-MS and magnetic measurements. The last confirmed that the studied samples are real solid solutions. The SEM reveals that the morphology depends on both the excess of C2O42? and the initial ratio Ni/Mn. The thermal magnetic investigations (in situ) show that: (i) the presence of Ni in NixMn1?xC2O4·2H2O leads to decreasing in the decomposition temperature in regard to that of the manganese oxalate; (ii) upon increasing the Ni content the temperature of decomposition (in air) is growing up; (iii) the presence of Ni stabilizes the manganese with respect to oxidation, in spite of the occurring process of decomposition. 相似文献
14.
Two types of solid electrolytes have reached technological relevance in the field of sodium batteries: ß/ß”-aluminas and NaSICON-type materials. Today, significant attention is paid to room-temperature stationary electricity storage technologies and all-solid-state Na batteries used in combination with these solid electrolytes are an emerging research field besides sodium-ion batteries. In comparison, NaSICON materials can be processed at lower sintering temperatures than the ß/ß”-aluminas and have a similarly attractive ionic conductivity. Since Na2O−SiO2−ZrO2−P2O5 ceramics offer wider compositional variability, the series Na3Zr3–xSi2PxO11.5+x/2 with seven compositions (0≤x≤3) was selected from the quasi-quaternary phase diagram in order to identify the predominant stability region of NaSICON within this series and to explore the full potential of such materials, including the original NaSICON composition of Na3Zr2Si2POl2 as a reference. Several characterization techniques were used for the purpose of better understanding the relationships between processing and properties of the ceramics. X-ray diffraction analysis revealed that the phase region of NaSICON materials is larger than expected. Moreover, new ceramic NaSICON materials were discovered in the system crystallizing with a monoclinic NaSICON structure (space group C2/c). Impedance spectroscopy was utilized to investigate the ionic conductivity, giving clear evidence for a dependence on crystal symmetry. The monoclinic NaSICON structure showed the highest ionic conductivity with an optimum ionic conductivity of 1.22×10−3 at 25 °C for the composition Na3Zr2Si2PO12. As the degree of P5+ content increases, the total ionic conductivity is initially enhanced until x=1 and then decreases again. Simultaneously, the increasing amount of phosphorus leads a decrease in the sintering temperatures for all samples, which was confirmed by dilatometry measurements. The thermal and microstructural properties of the prepared samples are also evaluated and discussed. 相似文献
15.
The vanadium complex—pyrazine-2-carboxylic acid (PCA) system catalyzes oxidation of styrenes PhRC=CHR′ (R=H, Me; R′=H, Ph), or phenylacetylenes PhC=CR (R=H, Ph) with hydrogen peroxide in air to give aldehydes, ketones, and carboxylic acids. The reaction begins with H2O2 coordination to the vanadium ion followed by the formation of hydroxyl radicals. Catalytic action of PCA facilitates the reduction of the VV complex to the VIV complex and/or the stage of the formation of a peroxide derivative of vanadium. 相似文献
16.
17.
During the heating of YBCO a peritectic reaction takes place at 1020C, which can be described by: 2YBa2Cu3O7–xY2BaCuO5+L+(1-2x)/2O2 (1) whereL = 3BaCuO2 +2CuO is a fluid with limited amount of yttrium.It has been reported, that many parameters can influence the reaction. From one side not only the starting size of grains but also the heating rate have an influence on the resulting Y2BaCuO5-phase. From the other side, there is a change of the peritectical temperature caused by changing of the partial pressure of O2 and the presence of parasitic phase.From general kinetic consideration one can draw the conclusion, that different mechanisms (nucleation, phase-boundary reaction and diffusion) can control the reaction.Using DTA/TG measurements, the peritectic reaction has been examined. Classical kinetic methods (Kissinger and Friedman) has been used. The Friedman method has given the dependence of the activation energy from reaction degree. This suggests many steps reactions. The dependence of the DTA-peaks from the heat rate suggest a parallel steps of reaction. This assumption can be motivated by evaluation of free O2, one solid and liquid phase formation. Amount of this phases depends on the heating rate. Additionally X-ray and microscopic methods has been used. In this way was shown, that the perovskit structure is stable up to peritectical temperature and than is dramatically destroyed. From microscopic observations has been got information about shape and size of solid phase and it's creation as a function of temperature, time and starting grain size.
Die Arbeit wurde BMBF gefördert und durch Land NRW unterschtützt. 相似文献
18.
Rainer Lork Marius Tybislawski Mark Bends Rolf Jürgen Berger Wolfgang Neuwirth 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1994,29(3):213-221
Cross sections for the production of O 2 ? in charge transfer collisions of fast molecular hydrogen ions (H 2 + , D 2 + , H 3 + , and D 3 + of 10 to 140 keV kinetic energy) with O2 molecules have been determined by means of a time-of-flight mass spectrometer analysing the slow negative product ions from the collisions. Within the measuring accuracy equivelocity H 2 + and D 2 + ions have the same cross sections for the generation of O 2 ? . The projectile velocity dependence curve of the cross section passes through a broad maximum with a peak value of about 6.5×10?18 cm2 around the Bohr velocity (25 keV/u) before showing an asymptotic decrease still within the limited energy range under investigation that is in inverse proportion to the square of velocity. Throughout the examined energy range H 3 + ions yield a cross section which is about 1.4 times larger than that of H 2 + ions of the same velocity. The fragment ion O? has been found to appear with cross sections between 10?19 and 10?18 cm2 upon collisional excitation in the energy range under investigation, with ever decreasing intensity when the energy of the positive hydrogen ions, the proton included, was increased. 相似文献
19.