共查询到20条相似文献,搜索用时 15 毫秒
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X-Ray and X-ray Photoelectron Spectroscopy Studies of the Electronic Structure of Borane Derivatives
V. D. Yumatov E. A. Il'inchik L. N. Mazalov O. V. Volkov V. V. Volkov 《Journal of Structural Chemistry》2001,42(2):281-295
This paper reviews the results of electronic structure studies of a number of typical members of borane series by X-ray and X-ray photoelectron spectroscopy using quantum chemical calculations. Fragment analysis of the molecular orbital structure is given. The nature of chemical interaction in boron cluster compounds is studied on models: simple molecules NH3, BH3, and BF3 and their adducts NH3BH3 and NH3BF3. The electronic structure of B10H12L2 type compounds with Lewis bases L = NH3, (CH3)2S, (C6H5)3P is analyzed. The complexes are considered in terms of the concept of donor–acceptor interactions between the fragments. The donor–acceptor bond has contributions from both occupied and vacant acceptor orbitals. X-ray photoelectron data on the charged states of atoms in the compounds are overviewed. Electron distribution in complex compounds with transition metals [(1,2-B9C2H11)2M]–, M = FeIII, CoIII, NiIII, and NiIV and chain type polycobaltocarborane anions {[(3)-1,2-B9C2H11]2Co
n
[(3,6)-1,2-B8C2H10]n-1}
n–
, n = 2-7, is considered. 相似文献
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X-Ray Photoelectron Spectra and Electronic Structure of Solid Solutions Based on Cubic Boron Nitride
The electronic energy structure of substitution solid solutions based on boron nitride B
1-x
NR
x
and BN
1-x
Rx (R = C, O) (x=0.25) in a diamond-like modification of ZnS type has been investigated by the local coherent potential method in terms of multiple-scattering theory. The total and partial densities of states were calculated for each element in a solid solution. The crystalline potential was calculated using an MT approximation. The lattice parameter was chosen based on X-ray diffraction data for c-BN: 0.3615 nm. The electronic energy structures of the solid solutions and binary c-BN are compared in the framework of a single approximation. The calculated partial densities of states are compared with the experimental X-ray emission and photoelectron spectra of boron, nitrogen, and oxygen in these compounds. The calculated partial charges of electrons at the top of the valence band show that charge transfer from boron to nitrogen takes place in the solid solutions. An analysis of the electronic structures of the solid solutions of boron nitride indicates that the quasicore resonances inherent in binary c-BN are delocalized and that chemical bonding in the solid solutions of boron nitride is weakened. 相似文献
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钌—钛金属氧化物涂层电极的电子能谱分析 总被引:1,自引:0,他引:1
用X-光电子能谱分析了Ru-Ti金属氧化物电极的组成、结构和元素价态。结果表明,电极表面不同于体内,讨论了表面和体内Ti的价态区别对Ru-Ti阳极活性和寿命的影响,指出掺杂Ir和Pd后会提高电极活性。 相似文献
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Jan Brunvoll Rgine Guidetti-Grept Istvan Hargittai Reinhart Keese 《Helvetica chimica acta》1993,76(8):2838-2846
The efficient synthesis of all-cis-[5.5.5.5]fenestrane ( 2 ) from the readily available intermediate 3 allowed the electron-diffraction analysis of 2 . This structure analysis revealed long C? C bonds in the central C(C)4 fragment and a twist-envelope conformation for the four cyclopentane substructures. The four bridgehead H-atoms are in a synclinal rather than an ecliptic position with an approximate D2 symmetry of 2 . Planarizing distortions are evident from the opposite bond angles at the central C-atom being 116.2 ± 0.5° with the remaining four being 103.7 ± 0.2°. 相似文献
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Yu. V. Shchapova S. L. Votyakov M. V. Kuznetsov A. L. Ivanovskii 《Journal of Structural Chemistry》2010,51(4):657-662
X-Ray photoelectron spectroscopy (XPS) is used to study the electronic structure of radiation damaged samples of ZrSiO4 zircon mineral at early and middle stages of its radiation destruction. The effects of radiation induced atomic disordering
are found to be most distinctly manifested in the spectra of O1s states and to a smaller extent in the spectra of Si2p states, and also in the zircon valence band. Based on the quantum chemical calculation results the conclusion is drawn that
the observed changes in XPS lines are caused by the formation of oxygen vacancy defects and an increase in the covalency of
interatomic bonds near oxygen vacancies. For zircon samples with a low/moderate degree of radiation damage these changes reflect
the initial stage of the polymerization of the ZrSiO4 structure due to the formation of Si—O—Si chain fragments. 相似文献
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砷化镓半导体表面自然氧化层的X射线光电子能谱分析 总被引:1,自引:0,他引:1
用X射线光电子能谱(XPS),测量了Ga3d和As3d光电子峰的结合能值,指认了砷化镓(GaAs)晶片表面的氧化物组成,计算了表面氧化层的厚度,定量分析了表面的化学组成;比较了几种不同的砷化镓晶片表面的差异。结果表明:砷化镓表面的自然氧化层主要由Ga2O3、As2O5、As2O3和单质As组成,表面镓砷比明显偏离理想的化学计量比,而且,氧化层的厚度随镓砷比的增大而增加;溶液处理后,砷化镓表面得到了改善。讨论了可能的机理。 相似文献
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I. N. Shabanova 《Journal of Structural Chemistry》2000,41(6):959-964
This paper reports on the results of an XPS study and FP–LMTO and TB–LMTO band structure calculations of the electronic structure of transition metal systems in the crystalline and disordered (amorphous, liquid, and quasicrystalline) states. Valence band structure is modeled in relation to the occupation of the valence d- and p-shells of the alloy components, chemical bonding, concentration, and temperature. 相似文献
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Ariza MJ Rodríguez-Castellón E Rico R Benavente J Muñoz M Oleinikova M 《Journal of colloid and interface science》2000,226(1):151-158
Surface chemical characterization of activated composite membranes, which consist of a polyamide/polysulfone support containing different amounts of di-(2-ethylhexyl) phosphoric acid as carrier, was performed by X-ray photoelectron spectroscopy (XPS) in order to obtain information about the nature of the chemical bonding between the carrier and the membrane top layer. XPS spectra of the top layer of the polymeric support (polyamide) show bands in the C 1s, N 1s, O 1s, and P 2p regions. The N 1s and O 1s signals of the polyamide layer were asymmetric and could be deconvoluted in two peaks that correspond to the coexistence of free and hydrogen bonded polyamide. To support this assignment, primary amides such as benzamide and n-butyramide, which can associate themselves forming hydrogen bonding, and a tertiary amide, N-benzoyl morpholine, unable to form hydrogen bonding, were also studied by XPS. The N 1s asymmetric signals of benzamide and n-butyramide were deconvoluted in two peaks due to the coexistence of free and hydrogen bonded species, while the N 1s signal of N-benzoyl morpholine is symmetric and corresponds to the existence of free amide alone. As a result of the addition of di-(2-ethylhexyl) phosphoric acid to the polymeric matrix, the N 1s signal intensities decrease, while the P 2p signal intensities increase with carrier concentration to a maximum corresponding to surface site saturation. Upon acid addition, the polyamide was protonated and an expected chemical shift of the N 1s signal to higher binding energies was observed due to the increase of the positive charge of the nitrogen atom. This type of chemical interaction allows to fix the carrier in the membrane without its complete immobilization. On the other hand, the surface concentration of N and P, determined by XPS, indicates that a concentration of 400 mM of the carrier in the casting solution is sufficient to saturate the surface of the membrane. Copyright 2000 Academic Press. 相似文献