Theoretical study of X-ray photoelectron spectra of BN and SiC crystals

The tight-binding method has been used to calculate the density of states and X-ray photoelectron spectra of valence electrons in BN and SiC cubic crystals. It is shown that s- and p-states of atoms of various components contribute differently to the spectrum.     

硝酰自由基光电子能谱的理论研究

本文采用谐振子模型,考虑Duschinsky效应,推得计算三维Franck-Condon因子的代数表示,且应用于研究硝酰自由基的光电子能谱的强度分布及振动结构。对于HNO((?)~3A″)-HNO~-((?)~2A″)光脱附过程,通过Franck-Condon因子计算,得到光电子能谱的谱线相对强度,理论上计算的光电子能谱与实验观测到的光电子能谱达到较好的一致;另外,在光谱模拟过程中,通过迭代Franck-Condon分析,拟合实验能谱得到阴离子HNO~-自由基(?)~2A″电子态的几何结构:键长R(NO)是0.1335±0.0005 nm,键角∠(HN())是106.3±0.5°.     

硝酰自由基光电子能谱的理论研究

本文采用谐振子模型, 考虑Duschinsky效应，推得计算三维Franck-Condon因子的代数表示，且应用于研究硝酰自由基的光电子能谱的强度分布及振动结构。 对于HNO（ 3A″）– HNO‾（ 2A″）光脱附过程，通过Franck-Condon 因子计算，得到光电子能谱的谱线相对强度，理论上计算的光电子能谱与实验观测到的光电子能谱达到较好的一致；另外，在光谱模拟过程中，通过迭代Franck-Condon分析，拟合实验能谱得到阴离子HNO‾自由基 2A″电子态的几何结构：键长R(NO)是0.1335 ± 0.0005 nm，键角(HNO)是106.3 ± 0.5o 。     

X-ray photoelectron spectra and structure of iron polynuclear complexes

Iron trimethylacetate complexes with different ligands have been investigated by X-ray photoelectron spectroscopy (XPS). The Fe 2p, Fe 3p, C 1s, O 1s, and N 1s spectra obtained at successive replacement of the Fe-O coordination bonds with Fe-N bonds have been analyzed. A satellite component is found in the spectra of iron trimethylacetate complexes, which is indicative of the high-spin state of Fe^II and Fe^III iron atoms. The XPS data made it possible to determine the degree of covalence of the metal-ligand bonding and reveal two nonequivalent states for iron atoms.     

Theoretical study of X-ray photoelectron spectra of mono- and polycrystalline samples

Recently Sixl and Sanwald¹ reported on measurements of fluctuation conductivity in very thin superconducting Al films. We reinterpret their data and find good agreement with the Aslamazov-Larkin and Maki-Thompson theories with a thickness dependent pairbreaking parameter.     

X-ray photoelectron spectra of hexavalent iron

Binding energies of Fe 3p and Fe 2p electrons for K₂FeO₄ were measured and compared with those for γ-FeOOH, α-Fe₂O₃, and for metallic iron.     

X-ray photoelectron spectra of cobalt compounds

The X-ray photoelectron spectra of a variety of cobalt(II) and cobalt(III) complexes have been investigated. Intense satellite lines were observed for the 2p, 3s and 3p peaks in the case of the high spin cobalt(II) compounds, but not for low spin cobalt(III) complexes. The satellites of the 2p levels are best explained as arising from shake-up processes, whereas those of the 3s and 3p levels are thought to arise largely from multiplet (exchange) splitting of the levels. Multiplet splitting of the 2p level is small and responsible for an increase in the doublet separation of the 2p_1/2, 2p_3/2 spin-orbit levels of the high spin cobalt(II) compounds. The chemical shifts for cobalt differ for the 2p, 3s and 3p levels of the high spin cobalt(II) compounds. Those of the 2p and 3p levels of diamagnetic cobalt(III) and low spin cobalt(II) complexes are equal. The difference in the case of the high spin cobalt(II) compounds is thought to be due to the presence of unpaired 3d electrons.     

Relative intensities in X-ray photoelectron spectra

An experimental determination of the relative intensities of X-ray photoelectron lines corresponding to the inner levels of elements with Z ? 20, and calculations of the total photo-ionization cross-sections for all shells of these elements with the Hartree—Fock—Slater potential are reported. The experimental and theoretical values agree well for the 1s levels while marked discrepancies are revealed for the 2p levels. The theoretical values of the cross sections for the atomic valence levels are used to calculate the relative intensities of molecular levels in CF₄, BF₄^?, BeF₄^2?, LiF, NO₃^?, CO₃^2?, CO, N₂, CO₂, H₂O and C₄H₅N. The results of the calculations agree satisfactorily with experiment.     

二氧化铬阴离子光电子能谱的理论研究

凭借密度泛函理论,采用不同基组对中性分子CrO2的基态((X)3B1)以及阴离子CrO1-的基态((X)4B1)进行几何优化和振动频率分析;应用量化计算得到的力常数及结构和光谱参数,基于推得的两维四模Franck-Condon重叠积分的代数表示,对CrO2((X)3B1)-CrO2-((X)4B1)的光脱附过程进行Franck-Condon分析和光谱模拟,理论上得到光电子能谱的谱线相对强度及振动结构分布,理论谱与实验测得的二氧化铬阴离子光电子能谱达到一致,并对光电子能谱的振动结构进行归属及热带分析;另外,在光谱模拟过程中通过迭代Franck-Condon分析过程,推得CrO2-((X)4B1)与CrO2((X)3B1)平衡几何结构之差:△R(Cr-O)=0.05A,△∠(O-Cr-O)=12°.     

Electronic structure of LiMnO : X-ray emission and photoelectron spectra and band structure calculations

The electronic structure of LiMnO₂ and Li₂MnO₃ was studied by means of X-ray photoelectron and soft X-ray emission spectroscopy. For LiMnO₂, LSDA and LSDA+U calculations were carried out. The LSDA+U calculations are in rather good agreement with the measured valence-band structure as well as with the magnetic and electrical properties of LiMnO₂. It is shown that the band gap in LiMnO₂ is determined by the charge-transfer effect. Received 15 March 1999 and Received in final form 14 July 1999     

Electronic structure,chemical bonding and X-ray photoelectron spectra of light rare-earth oxides

The electronic structure of the light RE oxides CeO₂, Pr₂O₃ and Nd₂O₃ has been studied by the cluster discrete variational DV-X method and X-ray photoelectron spectroscopy. The interpretation of XPE spectra basing on the MO model is given. The various electronic states contributions to the chemical bonding in the oxides are investigated.     

X-ray and UV photoelectron spectra of the metal sesquioxides

He(I,II) and MgKα valence region photoelectron spectra of polycrystalline Ti₂O₃, V₂O₃, Cr₂O₃, Mn₂O₃, Fe₂O₃ and Rh₂O₃ have been recorded. The method of sample preparation employed gave rise to UV-PE spectra which are significantly different from those previously reported. While clear changes are observed in the spectra accompanying the semiconductor-to-metal transition of V₂O₃ at 150 K, there is no apparent modification of the Ti₂O₃ spectra accompanying its second order transition at 500 K. The remaining first row transition metal sesquioxides exhibit spectra indicative of localised 3d electrons.     

Electronic structure,chemical bonding and X-ray photoelectron spectra of heavy rare-earth oxides

The electronic structure of the heavy RE sesquioxides from Sm₂O₃ to Lu₂O₃ has been studied by the cluster discrete variational X method and X-ray photoelectron spectroscopy. The interpretation of XPS spectra basing on the MO model is given. An analysis of the dependence of Ln 4f orbitals contribution to chemical bonding on the lanthanide atomic number and bond lengths is made.     

X-ray photoelectron spectra of halogens in coordination compounds

X-ray photoelectron data on C12p energies for more than 200 coordination compounds of transition metals have been analysed. The effects of the central atom, other ligands, and the geometrical location of the chlorine atom on the C12p energy have been considered and certain regularities have been observed. The data on Br3d and F1s lines in coordination compounds have also been considered.     

Electronic structure and X-ray photoelectron spectra of TiC and ZrC: Cluster and band structure approaches

The electronic structure for titanium and zirconium monocarbides have been calculated with the SCF MS X_α-cluster method. The results are compared with the experimental X-ray photoelectron spectra and augmented plane wave (APW) calculations.     

三态K2分子飞秒含时光电子能谱的理论研究

利用三态模型和含时波包法, 研究了K₂分子在强飞秒抽运-探测激光场中延时、脉宽以及抽运波长对光电子能谱和波包动力学过程的影响. 研究结果表明, 激光场强较弱或者脉宽较短都可能不发生Autler-Townes分裂, 光电子能谱呈现出单峰结构; 延时和抽运波长的改变影响能峰结构、位置和相对峰高; 对于不同的抽运波长, 波包的振动周期是相同的, 波包振荡幅度随脉宽增大而减小; 光电子能谱反映了波包动力学信息. 研究结果可以为实验上实现分子的光控制以及量子调控过程提供一定的参考, 并为进一步研究K₂分子的动力学性质提供有用的信息.     

Theoretical and experimental investigation of X-ray O- and N-emission spectra of tungsten

The experimental investigation of the O_IIIN_{VI, VII}-emission spectrum of pure tungsten and tungsten in W₂C is carried out. The experimental data are compared with the theoretical calculation of the intensity in the O_IIIN_{VI, VII}-emission spectrum of tungsten. A good agreement is obtained between the theoretical and experimental spectra. The conclusion was drawn, that the earlier published experimental data on the O_IIIN_VI,VII- spectrum of tungsten referred to carbide of tungsten.     

Satellite phenomena in the X-ray photoelectron spectra of lanthanide trihydroxides

Using the direct CI method perturbation corrections to the Koopmans ionization energies have been obtained up to order 10 for the molecules CN^? and H₂O. The results are compared with those from the fully converged CI and B_k-type calculations. The convergence of the perturbation series is found to be quite slow although substantial improvement is possible using a variation-perturbation method.