The influence of relaxation and nondipole effects on the intensity of X-ray photoelectron spectra

The photoionization cross sections; dipole and nondipole parameters of the angular distribution of photoelectrons; and the spectroscopic factors for the main X-ray photoelectron lines, which are used in quantitative analysis of the surface and most of atoms, have been calculated. It is shown that consideration of nondipole effects leads to a significant (up to 10%) change in the photoelectron angular distribution. Therefore, neglect of nondipole transitions may lead to an error above 10% when MgK _α and AlK _α X-ray lines are used for surface analysis. Consideration of the spectroscopic factors leads to a decrease in the absolute line intensity by about 20%. Calculations showed that this value weakly depends on the atomic number and quantum shell numbers.     

Photoelectron spectroscopic study of Li oxides on Li over-deposited V2O5 thin film surfaces

The Li oxides species formed on Li over-deposited V₂O₅ thin film surfaces have been studied by using X-ray and UV induced photoelectron spectroscopy (XPS and UPS). The photoelectron spectroscopic data show that the Li over-deposited V₂O₅ system itself is not stable. Further chemical decomposition reactions are taken place even under UHV conditions and lead to form Li₂O and Li₂O₂ compounds on the surface. The formation of Li₂O₂ causes to arise an emission line at about 11.3 eV in the valence band spectra.     

Many-body effect in the coincidence L3 and M3 photoelectron spectroscopy spectra of Cu metal

The coincidence L₃ and M₃ photoelectron spectroscopy (PES) main lines of Cu metal are calculated by a many-body theory. There is no peak-energy shift between the singles PES main line and the coincidence one. The asymmetric narrowing of the coincidence PES main line on the low kinetic energy (KE) side is very small. This is in accord with recent experimental findings. In Cu metal, the shakeup satellite intensity is small and the main-line satellite separation energy is much larger than the core–hole lifetime width. The interference via the final-state interaction is negligible. In the PES main line, the imaginary part of the self-energy by shakeup excitations, which is very small compared to the core–hole lifetime width, decreases very slowly in linear with photoelectron KE. The branching ratio of Auger decay of a single hole state then increases very slowly in linear with photoelectron KE so that the deviation of the coincidence PES main line from the singles one is very small. The 939 eV structure seen only in the coincidence L₃ PES spectrum of Cu metal is attributed to the enhancement of the inelastic peak of a smaller energy loss due to electrons of a smaller average emission depth measured in coincidence with the elastic Auger peak. The structure will not be enhanced in the singles PES spectrum. The background subtraction in the coincidence spectrum cannot be the same as that in the singles one. Such consideration is necessary before we can conclude about the asymmetric narrowing on the low KE side. A unique capability of APECS by which one can determine the photoelectron KE dependent part of the imaginary part of the self-energy is pointed out.     

Analysis of the Auger-photoelectron coincidence spectroscopy (APECS) spectra of metallic Pd,Ag, and Sn

The M45-level photoelectron spectrum of Ag metal measured in coincidence with the M45–VV(¹G) Auger-electron line is analyzed by taking into account the possibility of the M4–M5–VV Coster–Kronig (CK)-transition preceded Auger transition. We denote the atomic shells Mx(Mxy) and Nxy (x, y = 4,5) by MX(MXY) and V, respectively. The M4–M5 CK-transition rate is very small. The M45–VV Auger-electron spectra of metallic Pd and Sn measured in coincidence with the M4 (or M5)-level photoelectron line are analyzed. The M4–M5 CK-transition rates are also very small in metallic Pd and Sn. The coincidence Auger-electron line previously interpreted as the M4–M5–VV (or M4–M5V–VVV) Auger-electron line is largely due to the inelastically scattered M5-level photoelectron background beneath the M4-level photoelectron line. The APECS spectrum of Pd metal shows the first evidence of the M5V–VVV transition of the localized M5V shakeup two-hole state. The intensity ratio of the inelastically scattered Auger-electron background to the M5–VV Auger-electron main line of Ag metal measured in coincidence with the inelastically scattered M5-level photoelectron background beneath the M4-level photoemission line increases, as compared to that measured in coincidence with the M5-level photoelectron main line. This is because when the probability of the photoelectron being inelastically scattered increases, that of the Auger electron emitted by the same ionized atom, being inelastically scattered increases. In other words the photoelectrons and the Auger electrons are originated from the deeper atomic sites (longer pathlength).     

Photoelectron spectroscopy of brominated derivative of pyrimidine: 2-bromopyrimidine

In this study the brominated derivative of pyrimidine, 2-bromopyrimidine, was investigated by photoelectron spectroscopy. Outer valence photoelectron spectra recorded at 21.22, 45 and 100 eV photon energy for this compound are presented. The recorded spectra have a higher resolution than that previously reported in the literature. The bromine 3d and 3p edge photoelectron spectra have also been recorded in a photon impact experiment at 100 and 225 eV. All measurements were performed using Double Toroidal Coincidence Spectrometer showing its potential as a versatile apparatus for spectroscopic studies.     

同步辐射光电子能谱光束线控制系统

同步辐射光电子能谱光束线控制系统是根据设计和使用要求对构成该光束线主要部件进行可靠控制。该控制系统除了满足在线光路部件、机械部件和真空部件等安全精密工作的要求外 ,还要求能使光束线能够以良好的性能为实验站服务。由于系统工作的电磁环境比较恶劣 ,在调试过程中经常发现电子器件、接口电路及电子设备等时常由于强电磁干扰及辐射干扰而损坏。经过多次现场分析和模拟实验之后 ,采用辐射屏蔽和不同形式的抗强电磁干扰措施 ,最终使系统和设备能长期可靠的工作     

X-ray photoelectron and Raman studies of microwave Plasma Assisted Chemical Vapour Deposition (PACVD) diamond films

X-ray photoelectron and Raman spectroscopies were used to investigate the chemical and the structural properties of thin diamond films synthesised by Plasma Assisted Chemical Vapour Deposition (PACVD). Continuous polycrystalline diamond films were grown under different plasma conditions and based on the combination of detailed XPS and Raman spectroscopic analysis two main topics are highlighted (i) the stress measurements were discussed by distinguishing clearly the chemical effects from the mechanical effects; (ii) an electronic gap at 2.7 eV probed by Raman resonance that corresponds to an energy loss peak on the XPS carbon signal, was related to the surface hydrogenation.     

Proton radioactivity — spherical and deformed

The proton drip line defines one of the fundamental limits to nuclear stability. Nuclei lying beyond this line are energetically unbound to the emission of a constituent proton from their ground states. For near-spherical nuclei in the region of the drip line between Z=69 (Tm) and Z=81 (T1), proton decay transition rates have been shown to be well reproduced by WKB calculations using spectroscopic factors derived from a low-seniority shell model calculation [2]. Another approach using spectroscopic factors obtained from the independent quasiparticle approximation has also proved successful in this region [3]. These interpretations have allowed the extraction of nuclear structure information from nuclei well beyond the proton drip line.     

Alpha-spectroscopic factors in the DWBA

The analysis of α-transfer experiments in the frame of the Distorted Wave Born Approximation (DWBA) yields experimental values for the spectroscopic factors. We show that a consistent reaction theory leads to a theoretical formula for these spectroscopic factors which is different from the one conventionally used. The main point is that we take into account properly the effects of the antisymmetrization.     

Intramolecular dynamics due to electron transitions: from photoelectron spectroscopy to Femtochemistry

Select spectroscopic and chemical physics problems associated with atomic motion triggered by electronic transitions are the topics of this paper. The story starts with the initial stimulation provided by Dick Brundle's photoelectron spectroscopy studies of adsorbed molecules and continues to contemporary examples in photoelectron spectroscopy and Femtochemistry, all of which are theoretically modelled within a unified framework of time-dependent, driven oscillators and decaying states.     

A comparison of molecular orbital methods for the analysis of the He(I) photoelectron spectra of n-alkenes

The two highest vertical ionization potentials are calculated by the Fenske-Hall, MINDO/1, and MINDO/3 molecular orbital methods for an extensive series of n-alkenes. It is found that the Fenske-Hall method gives a better correlation with the corresponding experimental photoelectron spectral data and is the most useful for the interpretation and understanding of these results. When MINDO/3 was used for calculations by the ΔSCF method, it was not possible to obtain satisfactory agreement with the photoelectron spectroscopic measurements. Finally, the relevant findings of other calculational procedures such as ab initio and SPINDO are given.     

Hönl-London factors for multiplet transitions in Hund’s case a or b

Hönl-London factors are the factors that give the dependence of spectroscopic line intensities on the rotational quantum numbers. Recently it has been shown that most tabulations of Hönl-London factors for singlet-singlet transitions do not allow for the special cases of Π-Σ and Σ-Π transitions, where a consideration of the parity symmetrisation shows that an extra factor of 2 is required. The present paper extends these considerations to multiplet transitions, in either pure Hund’s case a or pure Hund’s case b.     

减压氩气环境下激光微区发射光谱分析精度的研究

依据数理统计理论,对减压氩气环境下,利用CCD数据采集处理系统所获取的激光微区发射光谱数据进行筛选,用以减弱样品表面激光蚀坑变化、样品不均匀性、激光波动性等因素的影响,探讨了激光微区发射光谱定量分析精度的改善方法。实验中以铝合金标样为分析样品,对Cu,Zn,Mg分析表明：分析谱线相对强度RSD分别为1.80%,4.35%,6.29%,定量分析相对标准偏差RSD分别为10.1%,6.98%,8.17%,分析结果平均值的相对误差为-3.76%,3.62%,-1.62%。     

Ray tracing studies of a complete plane grating monochromator beam line

Optical design of a plane grating monochromator beam line for X-ray spectroscopic studies to be installed on INDUS-1 is studied using ray tracing technique. The main components of the beam line are pre- and post-elliptical mirrors and the plane mirror-grating dispersing system. The ideal positions of the optical components are decided by using our analytical formulation of the Riemer’s kinetic principle for reflecting synchrotron radiation onto the same spot of the dispersing grating. The program is developed indigenously and can be used on a PC. The tangent error and microroughness of the mirrors is explicitly accounted for in the program. The wavelength dependent absorption of radiation at the different reflecting surfaces is also included for calculations of the optical throughput. The dependence of the final image line shape and resolution on various beam line parameters is calculated. The results are useful in deciding the tolerances of the various beam line components and their positions.     

Evidence for the short-period oscillations in spin-resolved photoemission of thin Cr(110) films

The spin-resolved electronic structure of thin Cr overlayers on top of the Fe(110) surface was investigated by means of spin- and angle-resolved photoelectron spectroscopy. The initial fast drop of photoelectron spin-polarization at the Fermi level, followed by weak oscillatory behavior with the period of about 2 ML, can give an evidence for the first time spectroscopic observation of the short period oscillations in (110)-oriented thin Cr films.     

Valence-level structure of phosphides of 3d-metals on the basis of XRS and ESCA data

For the first time, comprehensive X-ray spectroscopic and X-ray photoelectron data have been obtained on the energy spectra of valence electrons in phosphides of the transition metal series: TiP, CrP, MnP, FeP, NiP.Analysis of the experimental data on the electronic structure of phosphides of 3d-metals in the TiPNiP series indicates that the mechanism of interaction of the M 3d-states occurring near the top of the valence band with the s,p-states of phosphorus in the following sub-bands resides in the latter being induced near the d-sub-band as a result of the M 3d—P 3s,p interaction with the density maximum of the nearest P 3p-states being oppositely shifted as the number of d-electrons of the metal increases. Analysis of X-ray spectroscopic and X-ray photoelectron data on phosphides of transition metals along with those of metals of groups I(Cu, Ag) and II(Zn, Cd), and comparison of these data with the results of similar studies involving sulphides and silicides of the same metals indicate that the occupancy and the associated position of the d-shell of the metal within the valence band are the determining factors as far as the mutual arrangement of energy sub-bands and the symmetry of respective states are concerned.     

X-ray photoelectron spectroscopic,electrical and magnetic studies on Mg2NiH4

X-ray photoelectron and X-ray induced Auger spectroscopic (XPS and XAES) investigations show that, in Mg₂NiH₄, both Mg and Ni are in the metallic state. Support for this observation has been obtained from thermopower and magnetic measurements.     

Electron momentum spectroscopy of valence satellites of neon

Electron momentum spectroscopy (EMS) study of the neon valence satellites is reported. The experiments were performed at impact energies of 1250, 1450 and 1670 eV using a multichannel spectrometer that features high sensitivity. Binding energy spectra up to 100 eV and momentum profiles for the 2p⁻¹ and 2s⁻¹ primary transitions as well as the satellites are presented. The results are used to examine impact energy dependence of the relative intensities and shapes of the satellite momentum profiles. The results are also used to determine symmetries and spectroscopic factors of the satellites, and are compared with the previous experiments by EMS and photoelectron spectroscopy and sophisticated theoretical calculations. The present study has largely resolved controversies in the previous studies.     

Auger rates of second-row atoms calculated by many-body perturbation theory

Many-body perturbation theory is applied to calculate the KLL Auger rates of all terms of atoms C, N, F and Ne. Theoretical rates are compared with experiment and other theories for Ne and O. A new set of the Auger satellites, corresponding to the main photoelectron line binding energy is proposed. The intensities of these satellites are calculated and some of these satellites are identified in experimental KLL Auger spectra of Ne.