Experimental derivation of Auger transition probabilities from X-ray excited Auger electron spectra in XPS

Auger transition probabilities were experimentally derived from dominant XAES and related XPS peaks observed in XPS spectra. Some values of derived probabilities were higher than 1, because of addition or subtraction of background signal from the XAES or/and XPS peak intensity. However, the probabilities obtained are recognized to be useful for practical quantification by XAES and AES.     

ESCA studies on copper-cobalt based catalysts

The copper-cobalt catalysts for alcohol synthesis were prepared and studied by ESCA techniques (XPS and XAES) and TPR. The valence states of the surface elements were investigated for Co–Cu–Y based catalysts, and it was found that there were some reoxidation during the reaction. From the XPS and XAES results, strong interactions between copper and cobalt in the samples were presented, in agreement with the TPR experiments. The interacted copper-cobalt units could be the active sites for higher alcohol synthesis.     

用XPS和XAES分析电化学沉积的DLC膜

采用电化学沉积方法，以甲醇溶剂作碳源，直流电压作用下在单晶硅表面沉积得到碳薄膜。通过研究石墨、金刚石和样品薄膜的XPS和XAES谱图特征，证明了此方法沉积得到的是DLC薄膜;利用曲线拟合技术在C_1s电子能谱图中拟合出sp³峰与sp²峰，并计算出样品薄膜中sp³碳的相对含量为55%;研究石墨、金刚石和样品薄膜的一阶微分XAES谱图，用线性插入法估算出样品薄膜中sp³碳的相对含量为60%。     

Quantitative surface analysis by Auger and x-ray photoelectron spectroscopy

Recent developments in quantitative surface analysis by Auger (AES) and x-ray photoelectron (XPS) spectroscopies are reviewed and problems relating to a more accurate quantitative interpretation of AES/XPS experimental data are discussed. Special attention is paid to consideration of elementary physical processes involved and influence of multiple scattering effects on signal line intensities. In particular, the major features of core-shell ionization by electron impact, Auger transitions and photoionization are considered qualitatively and rigorous approaches used to calculate the respective transition probabilities are analysed. It is shown that, in amorphous and polycrystalline targets, incoherent scattering of primary and signal Auger and photoelectrons can be described by solving analytically a kinetic equation with appropriate boundary conditions. The analytical results for the angular and energy distribution, the mean escape depth, and the escape probability as a function of depth of origin of signal electrons as well as that for the backscattering factor in AES are in good agreement with the corresponding Mote Carlo simulation data. Methods for inelastic background subtraction, surface composition determination and depth-profile reconstructions by angle-resolved AES/XPS are discussed. Examples of novel techniques based on x-ray induced photoemission are considered.     

C 1s and Au 4f7/2 referenced XPS binding energy data obtained with different aluminium oxides, -hydroxides and -fluorides

A number of partially catalytically active aluminium compounds characterised by powder XRD have been investigated by XPS and XAES using a new method for static charge referencing [1, 2]. In detail, α-Al₂O₃, γ-Al₂O₃, boehmite γ-AlO(OH), bayerite α-Al(OH)₃, hydrargillite γ-Al(OH)₃, α-AlF₃, β-AlF₃, and AlF_2.3(OH)_0.7· H₂O and a hexa-fluoropropylene oxide (HFPO) modified γ-Al₂O₃ are examined. Well defined and chemically inert 20 nm gold particles are deposited as a nearly statistical distribution on the sample surface avoiding large coagulation effects. This procedure allows a determination of gold referenced XPS and XAES data sets. Binding energies (BE) of Al 2p, Al 2s, O 1s and F 1s photoelectron peaks as well as kinetic energies (KE) of Al KLL and F KLL Auger electron emission peaks are presented in relation to the Au 4f_7/2 BE reference. XPS and XAES data found in literature are, in most cases, C 1s referenced and scatter in a broad range. BE differences Δ between the C 1s charge reference BE and Au 4f_7/2 charge reference BE obtained with our samples are monitored by using the Al 2p orbital. These BE differences Δ clearly suggest that the chemical state of carbon observed in this study is not as uniform as required for reliable static charge referencing. Received: 24 June 1996 / Revised: 12 December 1996 / Accepted: 14 December 1996     

CO2加H2合成甲醇Cu－Zn－O催化剂表面化学态研究

应用XRD、ESR、URDS、XPS及XAES等手段研究了CO₂加H₂合成甲醇Cu-Zn-O催化剂在还原后和反应状态下的表面化学状态,结果表明,在还原及反应状态下,催化剂表面仅能检测到Cu⁰,而未发现稳定的Cu²⁺和Cu⁺存在;ZnO被部分还原产生低价锌Zn^2-δ(0<δ<2).关联活性测试结果认为,Cu⁰/Zn^(2-δ)+O构成CO₂加H₂合成甲醇反应的活性中心。     

Electronic structure of the doped SnO_2

SnO2 doped with La, Ce, Sm, Zn, Ca, Al and Sb was prepared by sol-gel technique and characterized by TEM, BET, XPS and XAES. The effect of the dopants on the grain sizes of SnO2 was described and especially the effect of dopants on the distribution of the electronic state density (DESD) of Sn4d orbital was studied deeply by using X-ray-induced Auger electron spectros-copy (XAES). It was observed that the dopants could influence not only the grain sizes of SnO2 but also electronic structure of SnO2, as well as the stability of the doped SnO2 samples. The experiment results indicated that the structure and stability of SnO2 film could be improved by the chemical modification of the dopants.     

AMT在铜表面形成保护膜的STM研究

5一氨基七一流基一1、3、各喀二隆（AMT不仅是一种有效的感光材料和分析试剂，同时作为重要的中间体被广泛应用于农药、医药生产中间，但作为铜腐蚀抑制剂的应用还远不如苯并三氯哩．实验表明［'－'l，AMT在酸性、中性及碱性介质中对铜及其合金均具有较好的缓蚀作用，经AMT处理     

掺氮石墨烯-铜基催化剂的制备及催化性能

采用水热法合成掺氮石墨烯(N/GN),通过超声辅助等体积浸渍法制备掺氮石墨烯-铜基催化剂(Cu-N/GN)。通过XRD、SEM、TEM、N2吸附脱附、XPS和XAES对催化剂的微观结构、形貌及元素组成进行表征,并考察Cu-N/GN对乙炔氢氯化反应的催化性能。结果表明:在催化剂中铜颗粒尺寸较小、均匀分布于N/GN片层上,且铜含量较低(3.6%);Cu-N/GN对乙炔氢氯化反应的催化效果良好,乙炔转化率为68%,氯乙烯选择性为99%。     

XPS and XAES of polyethylenes aided by line shape analysis: The effect of electron irradiation

X-ray photoelectron spectroscopy (XPS) and X-ray induced Auger electron spectroscopy (XAES) have been used to investigate different polyethylene surfaces, i.e. low density polyethylene (PELD), high density polyethylene (PEHD) and polyethylene of ultra high molecular weight (PEUHMW). The ratio of Csp²/sp³ was evaluated from (i) fitting of XPS C 1s spectra, (ii) the width of XAES C KLL spectra (parameter D) and (iii) line shape analysis by the pattern recognition (PR) method using the fuzzy k-nearest neighbors (fkNN) rule. The proposed approaches investigate: (i) the differences between various polyethylene surfaces, (ii) their surface changes and degradation due to electron irradiation under various doses and (iii) their stability under electron beam irradiation.The results of proposed approaches, i.e. C 1s fitting, C KLL width evaluation and PR line shape analysis applied to C 1s and C KLL transitions, are qualitatively consistent. The unirradiated polyethylenes indicate nearly Csp³ hybridizations. Under an electron dose a rapid decrease of Csp³ is observed, starting at a dose of 100 Cm⁻². The quantitative differences observed between results obtained from analyses using the C KLL and C 1s spectra, can be explained with a smaller average information depth of C KLL transition. However, quantitative discrepancies between results of various approaches using the same electron transition, i.e. C KLL or C 1s, are smaller. The surface degradation due to X-ray irradiation was negligible in comparison to electron beam irradiation. The PR method was efficient in identifying the polyethylene surfaces under various electron doses. The largest stability under an electron beam is exhibited by the PEUHMW.     

Oxidation‐induced nanostructures on Cu{100}, Cu(Ag) and Ag/Cu{100} studied by photoelectron spectroscopy

Initial surface oxidation and nanoscale morphology on Cu{100}, Cu(Ag) and Ag/Cu{100} have been investigated in situ by X‐ray photoelectron spectroscopy (XPS), X‐ray induced Auger electron spectroscopy (XAES) and the inelastic electron background analysis as a function of oxygen exposure at 3.7 × 10^?2 and 213 mbar pressures at a surface temperature of 373 K. Relative Cu₂O concentrations have been quantified by analysis of the peak shape of the XAES Cu LMM transition. The surface morphology of Cu₂O islands and the Ag layer has been characterized by inelastic electron background analysis of XAES O KLL and Ag 3d transitions. Oxygen‐induced segregation of Cu, as well as the subsequent Cu₂O island formation on Cu(Ag) and Ag/Cu{100} surfaces, has been investigated quantitatively. Our results indicate that Ag has a clear inhibitive effect on the initial oxidation and Cu₂O island formation on Cu(Ag) and Ag/Cu{100} surfaces. The Cu₂O islands are also observed to remain highly strained on Ag/Cu{100} even at higher O₂ exposures. The results suggest that strained Cu₂O islands eventually penetrate through the buried Ag layer, and in conjunction with segregating Cu atoms enable the oxidation to proceed at a similar rate to or even faster than on the unalloyed Cu surface. Copyright © 2007 John Wiley & Sons, Ltd.     

Effect of phosphorus concentration on the electronic structure of nanocrystalline electrodeposited Ni–P alloys: an XPS and XAES investigation

A surface analysis has been conducted on a series of electrodeposited nickel‐phosphorus (Ni–P) alloys containing from 6 to 29 at.% phosphorus, using X‐ray photoelectron spectroscopy (XPS) and X‐ray excited Auger electron spectroscopy (XAES). No changes in core‐level binding energies, Ni2p3/2 and Ni2p1/2, P2p, P2s, or X‐ray excited NiLMM and PKLL Auger lines were observed regardless of phosphorus concentration. The only systematic differences observed concerned: (i) the binding energy of the Ni2p satellite peak, (ii) the fine structure of the NiLMM Auger lines, (iii) the percentage of the satellite in the total Ni2p3/2 spectrum and (iv) the valence band density of states in the Ni3d electrons region, all related to the electronic structure of the Ni–P alloys. For the first time, it has been possible to describe and rationalise the influence of (phosphorus) ligand concentration on the electronic structure of nickel‐based alloys, using a screening model proposed in the literature for clarifying the role of substituents on the electronic structure of conductor compounds of nickel. As the phosphorus content increases, the number of non‐bonding Ni3d electrons decreases. Thus the d‐type core‐hole screening is less pronounced and the binding energy of the satellite for the final state with a filled Ni4s shell increases. Copyright © 2008 John Wiley & Sons, Ltd.     

Land-ocean interaction in modern delta formation and development: A case study of the Pearl River delta,China

SnO₂ doped with La, Ce, Sm, Zn, Ca, Al and Sb was prepared by sol-gel technique and characterized by TEM, BET, XPS and XAES. The effect of the dopants on the grain sizes of SnO₂ was described and especially the effect of dopants on the distribution of the electronic state density (DESD) of Sn4d orbital was studied deeply by using X-ray-induced Auger electron spectroscopy (XAES). It was observed that the dopants could influence not only the grain sizes of SnO₂ but also electronic structure of SnO₂, as well as the stability of the doped SnO₂ samples. The experiment results indicated that the structure and stability of SnO₂ film could be improved by the chemical modification of the dopants.     

Land-ocean interaction in modern delta formation and development: A case study of the Pearl River delta,China

SnO₂ doped with La, Ce, Sm, Zn, Ca, Al and Sb was prepared by sol-gel technique and characterized by TEM, BET, XPS and XAES. The effect of the dopants on the grain sizes of SnO₂ was described and especially the effect of dopants on the distribution of the electronic state density (DESD) of Sn4d orbital was studied deeply by using X-ray-induced Auger electron spectroscopy (XAES). It was observed that the dopants could influence not only the grain sizes of SnO₂ but also electronic structure of SnO₂, as well as the stability of the doped SnO₂ samples. The experiment results indicated that the structure and stability of SnO₂ film could be improved by the chemical modification of the dopants.     

A study on properties and morphological structure of ferrocene-filled PVC

The crystallization, special interaction, rheological behavior, and mechanical properties of PVC/ferrocene blends were studied through WAXD, FTIR, XPS, capillary rheometry, and mechanical property tests. The experimental results showed that the tensile strength of PVC/ferrocene (100/10) amounts to 82 MPa, 1.3 times as high as that of PVC. In the presence of a small amount of ferrocene, the processability of PVC is also improved. Crystallization of ferrocene in the blend is inhibited. The FTIR characteristic peaks of ferrocene shift or disappear. A new peak appears in the C1s XPS spectra and the Cl (2p) XPS spectra of PVC/ferrocene blends, and most of the ferrocene in the blends cannot be extracted by solvent alcohol, indicating the existence of some intermolecular interactions between PVC and ferrocene which cause the mechanical strength of the blends to increase. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 2828–2834, 1999     

XPS光电子峰和俄歇电子峰峰位表

在长期从事XPS分析测试的经验基础上,搜集了有关文献中的大量数据,编制了XPS光电子峰和俄歇电子峰峰位表,用于正确识别各种样品XPS谱图中的电子峰,达到快速、正确分析各种样品元素组成和化学组成的目的．本峰位表对于从事XPS测试的分析人员和应用XPS的科技人员具有很好的实用价值．     

Studies of the Auger spectrum from the (100) surface of GaAs using positron annihilation induced Auger electron spectroscopy

Measurements of the first high-resolution positron annihilation induced Auger spectrum from GaAs(100) are presented. The spectrum displays six As and three Ga Auger peaks below 110 eV, including a strong As M_4,5VV peak at 28 eV and a less intense Ga M_2,3M_4,5M_4,5 peak at 53 eV. The Auger peak intensities are used to obtain experimental annihilation probabilities for relevant core-level electrons. Experimental results are compared with first-principles calculations of positron surface states and annihilation characteristics of surface trapped positrons.     

Mixed metal fluorides as doped Lewis acidic catalyst systems: a comparative study involving novel high surface area metal fluorides

MF₃-doped/MgF₂ systems with enhanced Lewis acidity are reported, which are obtained either by the conventional aqueous route of co-precipitation or, by a novel non-aqueous soft chemistry route. The latter gives outstanding high surface areas and exhibits potent Lewis acid catalyst behaviour. The doped solid metal fluorides with dopant metals such as Ga, In, Fe, V are discussed in terms of the modified Tanabe model, which is adopted for metal fluoride systems. The two doped but differently prepared systems are analysed according to their surface characteristics by BET surface area, pore-size distribution and XPS/XAES as well as for the solid state structure by scanning electron microscopy (SEM), XRD and -MAS-NMR. The surface properties were evaluated by photoacoustic IR-spectroscopy of pyridine adsorbates and selected catalytic reactions.The exemplarily investigated GaF₃-doped/MgF₂ system reveals modified intrinsic properties of the solid mixture culminating in very high surface areas of a structurally distorted mesoporous solid and electrostatic charge rearrangements causing increased Lewis acid sites.     

Microchemical investigation of early iron metallurgy slags

A group of slags, dating back to Iron Age II (Aramean period, 800-720 B.C.), that appeared to be iron-smelting by-products, have been found at Tell Afis (North-Western Syria). The microchemistry of these materials has been studied by means of small-area X-ray photoelectron spectroscopy (XPS), X-ray induced Auger electron spectroscopy (XAES), scanning electron microscopy (SEM), electron-probe microanalysis (EPMA) and optical microscopy (OM). The results indicate that the slags can be associated with an iron-smelting process and show the presence of large amounts of Fe(II) and Fe(III) oxides and hydroxides mixed with different glassy and crystalline silicon compounds. The latter consist essentially of quartz and various silicates, such as wollastonite, melilite, Mg[SiO₄] or Mg[SiO₆] compounds and other complex aluminosilicates. This chemical information is used to elucidate some aspects of the early ironmaking process.     

Analysis of XPS valence band spectra of polymers using a density‐functional theory based calculation of model oligomers

XPS valence band spectra of 10 polymers (PE, PcI, PPG, PVME, PVA, PVMK, PAA, PMA, PMMA, and PGMA) were measured and simulated with the DMol ab initio molecular orbital program. We performed the calculations with model compounds such as trimers, pentamers, or hexamers of the polymers. The theoretical spectra of the oligomers show a good accordance with the experimental data. With the analysis of the calculated partial densities of states it is possible to assign the spectral features to specific atomic groups of the polymers. This gives a new detailed insight into the XPS valence band structure of the investigated polymers. The presented method could also be useful to obtain informations about the chemical structure of polymers with an unknown structure from the XPS valence band spectra. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 95–103, 1999