共查询到20条相似文献,搜索用时 46 毫秒
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Kai Siegbahn 《Journal of Electron Spectroscopy and Related Phenomena》1985,36(2):113-129
A discussion of factors related to improved resolution in electron Spectroscopy for different modes of excitation is given. Some examples are presented from recent studies of solids, gases and liquids, together with some aspects on angular distributions. A new type of time-of-flight instrument is described where the electrons drift in a strong magnetic field with a dependence. A ‘modular’ instrument for different modes of excitation of gases, liquids and solids is presented. A symbiosis of ESCA and lasers concerns studies of excited or fragment molecules (free radicals) and excited surfaces. 相似文献
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Yan Wang Xiao-Yuan Fu Ruo-Zhuang Liu Yaoming Xie Henry F. Schaefer Iii III 《Molecular physics》2013,111(13):879-890
Bromine oxides are of significant interest due to their importance in atmospheric chemistry. Density functional theory (DFT) methods have been used in conjunction with a DZP++ (double-ζ plus polarization with diffuse functions) basis set to study the molecular geometries and total energies of BrOn and BrO- n (n = 1-4). The adiabatic electron affinity (EAad), the vertical electron affinity (EAvert) of the bromine oxide and the vertical detachment energy (VDE) of each anion are reported. Harmonic vibrational frequencies and zero point energies are also reported. Five different DFT methods were employed for comparison. Among these, the BHLYP method predicts the geometries and the vibrational frequencies in best agreement with available experimental data, while the the other methods do better in predicting the limited number of energetic quantities determined observationally. The predicted adiabatic electron affinities are 2.38 eV (BrO, experiment 2.35 eV), 2.36 eV (BrO2), 3.35 eV (BrOO), 4.32 eV (BrO3), 2.91 eV (BrOOO) and 5.28 eV (BrO4). The electronic ground state of BrOO- is a triplet (3A") state. Predicted Br–;O bond distances range from 1.61 (BrO3) to more than 2 Å for Br...O2 for the neutral molecules; and from 1.61 Å for BrO- to 1.82 Å for BrO- to more than 2 Å for Br-...O3 among the anions. The BrOO isomer (Cs symmetry) is predicted to lie 17–18 kcal mol-1 below the C2v symmetry OBrO structure. The asymmetric 3A" anion BrOO- analogously lies below OBrO-, in this case by 40–41 kcalmol-1. BrOOO (Cs symmetry) is predicted to lie 42-45 kcalmol-1 below the symmetric C3v BrO structure. Finally the asymmetric BrOOO- anion (C1 symmetry) is predicted to lie 10-13kcal mol-1 below symmetric C3v BrO- 3. 相似文献
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WU Ji-Min 《中国物理C(英文版)》1992,16(6):518-526
By Mellin transformation,we solve the QED evolution equation for electron,positron distribution function analytically:Aseries expression for electron,positron distribution function is given.It approaches rapidly to the precise result required.The comparison with some other approximate results is also given.Our result greatly benefits the discussion of radiative correction in e+e- collision process. 相似文献
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Experimental conductivity measurements made during highly stable tensile deformation of Au nanowires show a rich variety of behaviors, including noninteger quantum conductance plateaus, transitions, and slopes. Using tight binding conductance calculations on simulated nanowires previously deformed using density functional theory, we demonstrate that all of these phenomena arise from structural transitions between deeply metastable ordered atomic configurations that self-organize during tensile deformation. 相似文献
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新型电子束源—虚火花放电室设计 总被引:1,自引:0,他引:1
提出一种新型的脉冲线加速器驱动的高功率,强流密度,低发射率,高亮度电子束源-虚火花放电室的初步设计。基于空心阴极效应和虚火花放电经验公式,确定了空心阴极,多隙阴-阳极,取及工作气压范围,最后提出关于虚火花产生高亮度电子束源的总体实验方案。 相似文献
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Nonplanar electron-acoustic shock waves having superthermal hot electrons are investigated with two temperature electrons model in unmagnetized plasma. Using reductive perturbation method, Korteweg-de Vries-Burgers (KdVB) equation is obtained in the cylindrical/spherical coordinates. Dissipation effect is introduced in the model by means of kinematic viscosity term. On the basis of the solutions of KdVB equation, variation of shock waves features (amplitude, velocity and width) with different plasma parameters are analysed. KdV-Burgers equation always leads to monotonic solitons and no oscillatory peak may appear. The combined effect of particle density (α), superthermal parameter (κ), electron temperature ratio (??) and kinetic viscosity (η0) is numerically studied, and it is observed that these parameters significantly change the properties of the shock waves in nonplanar geometry especially in spherical coordinates. Results could be helpful to analyse the soliton features in laboratory as well as in the space environments. 相似文献
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S. Jaksch I. M?hr S. Denifl A. Bacher O. Echt T. D. M?rk P. Scheier 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,52(1-3):91-94
Helium nanodroplets, formed in a supersonic expansion, are doped with C60 in a pickup cell. In some experiments, they are co-doped with water. Electrons are attached to the doped droplets; the yield of anions is recorded as a function of electron energy. The C60 - yield extends to much higher energies than in experiments involving isolated, hot fullerenes; we attribute the difference to the low temperature of the neutral precursors and the efficient cooling of the nascent anions by the helium droplet, which quench thermally activated autodetachment. The yields of (C60)2 - and C60D2O- anions reveal another important factor, namely depletion of the anion signal by dissociation which is energetically more facile than autodetachment. 相似文献