Correlation between core level chemical shifts obtained by ultrasoft X-ray emission and ESCA

High resolution C:K X-ray emission spectra have been recorded from six molecules in the gas phase. The spectra are interpreted by comparing the relative X-ray energies with the vertical ionization energies of the valence orbitals and comparing the intensities predicted by the C 2p populations from CNDO calculations with the measured intensities. The obtained C 1s binding energy shifts are found to be in excellent agreement with shifts measured with ESCA.     

Vapour phase M4,5N4,5N4,5 Auger electron spectra of antimony and tellurium

High resolution M_4,5N_4,5N_4,5 Auger electron spectra from Sb₄ and Te₂ vapours have been measured using electron impact excitation. The spectra have been decomposed into line components and relative intensities and energies of the components are compared with calculated intensities and energies. The calculations have been done for these molecular samples using the free-atom calculation model involving initially filled shells. The calculations have been treated in the mixed coupling scheme using jj coupling for initial state and intermediate coupling for the final state. The experimental results agree well with the calculated values, indicating that the molecular effects on the relative intensities and energies are very small for these core level transitions. The clear molecular effects are found in the broadening of lines and in the kinetic energy shifts due to extra-atomic relaxation effects.     

Potassium and titaniumKX-ray de-excitation induced by ion bombardment

KX-ray de-excitation spectra have been produced for K and Ti by proton, alpha and oxygen ion beam bombardment. These spectra have been measured with a crystal spectrometer of resolution (FWHM) of 10 and 13 ev for theKα_1,2 line in K and Ti respectively. The additional lines not found in the normal X-ray spectra are attributed to multiple inner shell ionization. The energy shifts and relative intensities of these lines are compared to theoretical predictions.     

A study of KαL1 X‐ray satellite spectrum of the elements 27 ≤ Z ≤ 31 by photon excitation

K _α X‐ray satellite spectra of Co, Ni, Cu, Zn, and Ga generated by photon excitation are analyzed using a wavelength dispersion spectrometer. Spectra of Ni, Cu, Zn, and Ga are studied for the first time using a LiF420 crystal. Spectrum of Co was studied with LiF200 crystal in second order. K_αL¹ X‐ray satellite energies and relative intensities are measured. The energy shifts relative to diagram line are computed and are compared with theoretical and semi‐empirical values. Dependence of energy shifts and relative intensities on Z and mode of excitation is analyzed.     

Near edge X-ray absorption fine structure (NEXAFS) of model compounds for the humic acid/actinide ion interaction

To understand spectral features of humic acid (HA) C 1s-near edge X-ray absorption fine structure (NEXAFS) with and without metal ion complexation, a set of model compounds is investigated. Halogenated benzoic acids and anthranilic acid are examined to demonstrate the effect of electron withdrawing groups on the C 1s-NEXAFS spectra of complex organic acids, including HA. The peak positions for aromatic and carboxylic groups in these spectra are in agreement with common assignments. The spectral position of the peak for substituted aromatic carbon shifts with increasing electronegativity of the substituent to higher photon energies. Polyacrylic acid (PAA) and different PAA metal ion complexes are investigated as model substances for metal cation complexation by HA. Tb(III)-, Zr(IV)- and U(VI)–PAA exhibit general spectral signatures previously observed for the PAA/Eu(III)–PAA system. For these different metal cations, similar spectral changes and distinct variations in peak intensities are observed going from the uncomplexed to the metal-loaded macromolecules. These spectral changes are comparable to those for U(VI)- and Th(IV)–HA systems.     

Prompt γ-rays from Pb following neutron emission from muonic Pb

We have measured the energies and intensities of prompt γ-rays from ²⁰⁶Pb that follow neutron emission from muonic ²⁰⁷Pb. For the levels at 803, 1704 and 2648 keV we deduce muonic isomer shifts. By comparing the relative and absolute yields of the γ-rays with the intensities of neutron groups observed in (γ, n) reactions, we find that roughly 50% of the prompt neutrons from muonic ²⁰⁷Pb result from radiationless deexcitation of atomic levels with .     

Photoelectron spectra of chromium tetranitrosyl

The ultraviolet and X-ray-excited photoelectron spectra of Cr(NO)₄ are reported. The electron binding energies, shake-up spectra, relative peak intensities and the Auger peak kinetic energies have been measured, and are compared to the spectra from gas-phase NO, from NO adsorbed on a transition metal surface, and to SCF-MS calculations. The theoretical calculations are utilized to obtain ionization energies and charge distributions, and consequently to discuss the bonding in nitrosyl complexes.     

X-ray spectra from highly ionized dense plasmas produced by ultrashort laser pulses

Hydrogen-like and helium-like X-ray spectra (between 7.1 and 8.2 , i.e., 1500 to 17.50 eV, respectively) from solid aluminium targets irradiated with high intensity (up to 10¹⁷ W/cm²) subpicosecond (0.7 ps) laser pulses have been measured. The spectra show that the resonance lines are very broad and very asymmetric. Evidence for a Doppler-shifted reabsorption of the resonance line emission has been found. The spectra have been simulated by a computer code for the calculation of spectral-line intensities and linewidths. Electron densities exceeding the critical density have been estimated for different laser intensities by comparing the observed and simulated intensity ratio of different dielectronic satellite lines. From the X-ray spectra generated byp- ands-polarized radiation fat different laser intensities, the thresholds for the formation of hydrogen-like and helium-like ions have been determined.     

Chemical Effect Analyses of 3dElements by Study of X-Ray Fluorescence Spectra

Spectra of K X-rays emitted from pure 3d transition metals and their oxide and sulfate compounds were measured using a single crystal wavelength dispersive X-ray spectroscopy (WDXRF). The measurements were performed using a ZSX-100e sequential spectrometer equipped with an Rh X-ray tube operated. An accurate analytical representation of each line was obtained by a fit to a Lorentz function. The spectra were analyzed in order to examine the K X-ray peak parameters such as asymmetry index, peak energy and relative intensity ratios. The energy shifts and relative intensities weredetermined tobetter understand the chemical effect.     

Photoluminescence of charged magneto-excitons in InAs single quantum dots

We calculated the photoluminescence spectra of charged magneto-excitons in single two-dimensional parabolic quantum dots, using an unrestricted Hartree–Fock method. The calculated luminescence spectra explain well the observed red shifts of transition energies of InAs/GaAs single quantum dot by additional electron capture in a dot. The magnetic-field-induced transition of the ground state configuration of trapped electrons causes drastic change in the photoluminescence spectra. The dependence of photoluminescence intensities of charged excitons on the excess energies of photogenerated carriers above the bulk GaAs energy gap is studied phenomenologically, by calculating the steady state electron population probability in a dot.     

The local electronic structure of tin phthalocyanine studied by resonant soft X-ray emission spectroscopies

The electronic structure of thin films of the organic semiconductor tin phthalocyanine (SnPc) has been investigated by resonant and non-resonant soft X-ray emission (RXES and XES) at the carbon and nitrogen K-edges with excitation energies determined from near edge X-ray absorption fine structure (NEXAFS) spectra. The resultant NEXAFS and RXES spectra measure the unoccupied and occupied C and N 2p projected density of states, respectively. In particular, RXES results in site-specific C 2p and N 2p local partial density of states (LPDOS) being measured. An angular dependence of C 2p and N 2p RXES spectra of SnPc was observed. The observed angular dependence, the measured LPDOS and their correspondence to the results of density functional theory calculations are discussed. Observed differences on the same site-specific features between resonant (non-ionising) and non-resonant (ionising) NXES spectra are attributed to symmetry selection and screening.     

X-ray emission spectra of small molecules

An instrument for X-ray emission studies of free molecules is described and electron and fluorescence excitations are discussed. The application of X-ray emission spectroscopy to free molecules is exemplified by the spectra of N₂, CO, NO and CO₂. From the spectra the core level binding energies of the molecules are deduced. For the diatomic molecules vibrational fine structure is resolved and analyzed in terms of different bond lengths in the initial and final states. The change in bond length, when the initial 1s vacancy is formed, is also discussed. The influence of the X-ray selection rules and molecular localization properties on the band intensities are discussed and exemplified by the O1s and C1s spectra of CO and CO₂. In the spectra about ten satellites are found.     

Determination of effective atomic charge,extra-atomic relaxation and madelung energy in chemical compounds on the basis of X-ray photoelectron and auger transition energies

A new method is proposed for the determination of effective atomic charge, extra-atomic relaxation, and Madelung energy in chemical compounds, based on the experimentally measured energies of X-ray photoelectron and Auger transitions. The method has been applied to solid compounds of the elements from Na to Cl, and to a number of free sulfur-, phosphorus-, silicon-, and chlorine-containing molecules. The experimental energies are represented as consisting of two parts. The first part is determined by the ionization energy of a free ion with a given effective charge, and includes the intra-atomic relaxation. The second part is determined by the Madelung energy and the extra-atomic relaxation. The first contribution is calculated by using the Hartree-Fock method. The effective atomic charges required have been found from the shifts of Kα-lines in the X-ray spectra. The extra-atomic relaxations are obtained as the differences between experimental and theoretical Auger parameters, and the values calculated are the additive functions of ligands of the atom studied. The increments of the additive scheme correlate with the ligand refractions. The effective charges, extra-atomic relaxation energies and Madelung potentials obtained from ESCA and AES data agree well with both calculated and direct experimental results.     

不同动能的~(129)Xe~(26+)与Au表面作用产生的X射线谱

测量了动能为350—600 keV和1.8—3.9 MeV的129Xe26+入射Au表面产生的X射线谱.结果表明,350—600 keV的Xe26+仅激发出了Au的Mα特征X射线,而1.8—3.9 MeV的Xe26+可激发出Au的Mζ,Mα,Mγ和Mδ特征X射线.分析了X射线强度和产额比与入射离子动能的关系,并估计了Xe26+激发Xe的L-X射线的动能阈值.     

Yb2.75C60同步辐射光电子能谱

在超高真空系统中制备了Yb275C60薄膜.对样品进行了同步辐射光电子能谱研究.在费米能级以下约5 eV范围内的谱数据由Yb275C60价带（C60分子轨道LUMO，HOMO和HOMO 1导出的能带）和芯态（Yb 4f7/2，4f5/2）能级构成.用紫外能区不同能量的入射光子，用C 2p和Yb 4f光电离截面随光子能量的不同变化规律，通过定量拟合，得到了对谱线有贡献的上述各个组分的峰位、峰宽和强度.结果表明，光子能量高于约300 eV时，芯态4f的贡献使得实验结果远远偏离价带的本征态密度分布.因此，研究Yb275C60价态时，应使用能量低于300 eV的光子.对实验和拟合结果分析，发现了类似纯C60的光电离截面振荡现象.振荡幅度相对于纯C60较小，反映了化合物中C60分子的化学环境对光电离截面振荡现象起着不可忽略的作用. 关键词： Yb275C60 同步辐射光电子能谱 光电离截面振荡     

Study of Langmuir-Blodgett polydiacetylene polymer films by surface enhanced Raman scattering

Large shifts (～50 cm^-1) to lower energies in the C=C and C≡C stretching modes of the Raman spectra of Langmuir-Blodgett deposted thin films of 15-8 polydiacetylene polymer are observed as the film thickness changes from a monolayer or one bilayer to two or more bilayers. The spectra of two or more bilayers are found to be identical to bulk material. These large shifts, observed by surface enhanced Raman scattering from the silver island substrate on which the films are deposited are attributed to delocalization of the electronic states in the backbone of the polydiacetylene polymer.     

Kα X-ray satellite spectra of Ti, V, Cr and Mn induced by photons

K X-ray emission spectra of Ti, V, Cr and Mn generated by photon excitation have been studied with a crystal spectrometer. The measured energy shifts of K_α satellite relative to the diagram line are compared with values obtained by electron excitation and with different theoretical estimates. The present experimental values of K_αL¹/K_αL⁰ relative intensities are compared with values obtained by electron excitation.      

Photoelectron spectroscopy of sulfur heterocycles adsorbed onto a Cu(110) surface

Photoelectron spectra of Cu(110) after exposure to thiacyclobutane, thiacyclopentane, and thiacyclohexane, as well as of the clean Cu(110) surface, have been obtained using He(I) radiation. Comparison of the spectra of the absorbates with gas-phase spectra suggests a strong sulfur-to-copper dative bond. Sulfur lone-pair orbital stabilization energies were obtained for thiacyclobutane (1.4 eV), thiacyclopentane (1.1 eV), and thiacyclohexane (0.6 eV), and these stabilization energies are correlated with the dative sulfur-to-surface bond energies. Ring-strain changes are suggested as the reason for additional small shifts of absorbate-bond energies in the thiacyclobutane spectrum. Relaxation energies were found to decrease in the order 4- > 5- > 6-membered ring. An empirical linear relation was found between relaxation shifts and lone-pair orbital stabilization energies for monoheteroatom heterocycles bonded to Cu(110) by a lone-pair dative bond. All adsorbates studied showed marked angular dependence, suggesting nonrandom orientation on the surface. Al Kα X-ray data were used to calculate percentage surface coverages. Other sulfur-containing adsorbates are discussed, including thiophene, allyl mercaptan, and thiacyclopropane. Thiacyclopropane was found to decompose upon exposure to copper.     

Ab initio calculations for XPS chemical shifts of poly(vinyl-trifluoroacetate) using trimer models

X-ray photoelectron spectra (XPS) of the polymer poly(vinyl-trifluoroacetate) show C(1s) binding energy shifts which are unusual because they are influenced by atoms which are several bonds away from the probed atom. In this work, the influence of the trifluoroacetate substituent on the 1s ionization potential of the carbon atoms of the polyethylene chain is investigated theoretically using mono-substituted, diad and triad models of trimers representing the polymer. Carbon 1s ionization energies are calculated by the Hartree–Fock theory employing Koopmans' theorem. The influence of the configuration and conformation of the functional groups as well as the degree of substitution are found to be important determinants of XPS spectra. It is further found that the 1s binding energy correlates in a linear fashion, with the total electrostatic potential at the position of the probe atom, and depends not only on nearest neighbor effects. This may have implications for the interpretation of high-resolution XP spectra.     

核衰变产生的X射线和俄歇电子数据计算

核衰变过程中,内转换电子发射和电子俘获能在原子电子壳层内留下空穴.其他原子电子壳层的电子将填补这些空穴,其原子电子位置将重排,并发射X射线和俄歇电子.X射线和俄歇电子的能量由原子电子结合能计算得到,X射线和俄歇电子的强度分别由内转换电子发射和电子俘获在原子电子壳层内留下的空穴数,X射线荧光产额,和空穴转移系数计算得到.本文简要介绍核衰变产生的X射线和俄歇电子数据的计算方法、计算程序与工作流程,并以核衰变为例说明其具体应用和简要讨论与总结.