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The authors present the first absolute experimental measurement of a finite PCI line shift of Auger electrons at high electron impact energies. The result confirms recent theoretical predictions about the shape of Auger lines after particle impact ionisation. In particular, it proves that Auger lines are never Lorentzians when obtained from non-coincident collisional ionisation experiments.

The authors have measured the energy shifts in of the Ne KL23L23 (1D2) Auger line (ionisation energy EB(Ne K)=870.3 eV, level width Gamma (Ne K)=0.27 eV) and of the Kr L3M45M45 (1G4) Auger line (EB(Kr L3)=1678.4 eV, Gamma (Kr L3)=1.17 eV) in a wide range of excess energies E1 up to an electron impact energy Eo=10 keV. The small experimental error of the authors data reveals a functional behaviour of the post-collision interaction (PCI) shift in (E1) different from in =c Gamma E-n1. The PCI shift does not follow a monotonic decreasing function in (E1) for all excess energies E1 but remains constant above a certain excess energy /E1, with /E1(Ne K) approximately=1 keV and /E1(Kr L3) approximately=3.5 keV. The authors give arguments for a non-vanishing PCI at large excess energies in the electron impact ionisation and give values for the absolute PCI shift in approximately for at energies E1 larger than /E1: in approximately Ne K)=48+or-12 meV, in (Kr L3)=102+or-25 meV and in approximately (Ar L3)=22+or-6 meV for Ar L3, which was studied previously by Graf and Hink (1985).

The XPS valence band structure of MgO, CaO, SrO, and BaO is discussed. It is shown that a correlation might exist between the auto-convolution of these valence bands and the corresponding O (KVV) Auger line shapes. Die XPS-Valenzbandstruktur von MgO, CaO, SrO und BaO wird diskutiert. Es wird gezeigt, das eine Korrelation existieren konnte zwischen der Selbstkonvolution dieser Valenzbander und den korrespondierenden O(KVV) Auger-Linienformen.

We have studied the interface formation between titanium silicide and silicon under ultra-high vacuum. The interface chemical composition and morphology is discussed with the help of surface sensitive techniques. It is shown that a careful analysis of the silicon Si L 23 VV Auger line shape can provide valuable information in order to get an accurate description of the various interfaces.

Tailored modulation techniques (TMT) are applied to depth profiling to eliminate errors in signal strength measurements caused by Auger line shape changes. The application of TMT is illustrated by profiling through Al 2 O 3 Al interfaces. When peak-to-peak heights in first derivative spectra n (1) m ( E ) are used for profiling, the measured Al KL 2,in3 L 2,3 signal strength shows a large decrease near the interface. This artifact is reduced when peak heights in n m ( E ) are used but can be eliminated only when Auger area values are used for profiling. The peak heights in n m ( E ) and Auger area values can both be obtained in real time with TMT and plotted automatically with conventional multiplexing equipment. Some features of Auger spectra obtained using TMT are illustrated, and a comparison of depth profiles obtained using peak-to-peak heights in n 1 m ( E ), peak heights in n m ( E ) and Auger area values demonstrates the usefulness of TMT in depth profiling.

A reduced version of the independent-electron theory of Auger line shapes is given that takes advantage of the general smallness of those components of a solid's local density of states (LDOS) matrix which are off-diagonal in angular momentum. Thus we present approximate formulae which relate the valence-band Auger line shapes of a soslid simply to its angular-momentum projected LDOS near a surface. Using these simplified formulae, we have located and corrected a number of numerical errors in our previous calculations of the Auger line shapes of Si. We present corrected results here, showing that the independent-electron theory, coupled with the use of atomic Auger matrix elements for Si, actually predicts too large a probability of ${L}_{2,3}{M}_{1}{M}_{2,3}$ decay relative to that for ${L}_{2,3}{M}_{2,3}{M}_{2,3}$ decay to give good agreement with measured Si ${L}_{2,3}\mathrm{VV}$ Auger line shapes. Possible reasons for the experimental smallness of the ${L}_{2,3}{M}_{1}{M}_{2,3}$ Auger decay rate are discussed. The Si ${L}_{1}{L}_{2,3}V$ Coster-Kronig line is also recalculated and shown to be in correspondence with the simplified theory of Auger transitions.

A calculation of the Auger spectrum for an initially filled simple-cubic tight-binding $s$ band is presented. The spectra are obtained for various values of the Coulomb correlation energy as compared to the one-electron bandwidth. The results are compared to various approximate Auger line shapes. The Auger line shape is found to be strongly dependent on the Coulomb interaction between the two holes in the final state and deviate strongly from the self-convolution of the density of states even for small Coulomb interactions.

The matrix elements of the spin-free Hamiltonian between two atomic configuration state functions (CSF'S) in the L-S coupling scheme are expressed in terms of the atomic integrals Fk's and Gk's. Using these general expressions, the matrix elements have been obtained for all the atomic configurations with three valence electrons that have not been solved so far by earlier methods. The scope for applying this new approach to obtain the Auger line energies and the promotion energies of metals that involve more than two partially filled shells is indicated. The energy expressions for some of the relevant configurations are tabulated.

Auger line shape analysis of the Si L23 VV peak of hydrogenated amorphous silicon samples has been performed. Both ion-implanted and glow discharge samples were analyzed. Hydrogen concentrations were established by IR and secondary ion mass spectroscopies. The L23 VV peak was deconvoluted into its L23M1M23, L23M23M23 and localized two-hole components. The relative amounts of the L23 VV components were compared with the hydrogen concentration. The results show that Auger line shape analysis may be used as (i) a semiquantitative monitor of the hydrogenation of amorphous silicon and (ii) a probe of the valence band of hydrogenated amorphous silicon.

Different methods are used to obtain both the Auger widths and the relative Auger line intensities of some 2s2p6nln'l' Na terms. If the relative line intensities are expected to be correctly estimated in the distorted-wave method, the widths are overestimated owing to the use of the same 3s and 3p orbitals in the initial and final states.

The Ti L2,3M2,3V Auger line shape has been measured from TiO, Ti2O3, the anatase and rutile forms of TiO2, chromic-acid-anodized Ti-6Al-4V, and reactive sputter-deposited TiO2. The relationship between the positions of the peaks at ∼ 417–420 and ∼ 411–415 eV is shown to be a sensitive indicator of the average stoichiometry of the surface. No sputtered-induced reduction of the crystalline TiO, Ti2O3, and TiO2 was seen, although a significant amount of reduction was observed for the amorphous TiO2 thin films. This effect is attributed to the decreased thermodynamic stability of the amorphous films.

Systematic studies of Auger line shape changes for the silicon LVV transition in refractory metal silicides confirm the homeotypism of these materials. Using this peak for principal component analysis (PCA) the identification of silicide phases is shown for Cr, Mo, W, and Ti disilicides. PCA depth profiling is less influenced by sputter and matrix effects than usual Auger depth profiles using elemental sensitivity factors. The position of the silicon-silicide interface is well defined by the crossover of the components in the PCA profiles. An interface component between MoSi2, and Si is determined. Systematische Untersuchungen der AES-Linienform des Silizium-LVV-Ubergangs an schwer-schmelzenden Metallsiliziden bestatigen den Homeotypismus dieser Materialien. Mit der Prinzipiellen Komponenten-Analyse (PCA) ist anhand dieses Peaks die Silizidphasen-Identizierung fur Cr-, No-, W-und Ti-Disilizide moglich. PCA-Tiefenprofile werden durch Sputter-und Matrix-effekte weniger gestort als die herkommliche AES-Tiefenprofilanalyse mit Reinelement-Empfind-lichkeitsfaktoren. Die Position der Silizium-Silizid-Grenzflache wird durch den Schnittpunkt der Komponenten bei PCA-Tiefenprofilen eindeutig bestimmt. Eine Grenzflachenkomponente zwi-schen MoSi, und Si wird mit PCA gefunden.

The shape of the ${L}_{2,3}\mathrm{VV}$ Auger line has been calculated for a Si(111) surface and found to be in excellent agreement with the data of Houston and Lagally. By contrast, the experimental line shape scarcely resembles the self-fold of the occupied Si density of states, a fact which the calculation shows to be the result of matrix-element angular momentum dependence and not of "many-body" effects.

The shape of the Ne KL 2 L 3 ( 1 D 2 ) Auger line has been investigated in the 5.5 MeV/u N 2+ — and Ne 3+ -Ne collisions. An asymmetric line shape has been found showing a tail on the high-energy side of the line, while the shape of the line due to the 1s2s2p( 4 P)-1s 2 ( 1 S) transition from the Li-like metastable initial state measured in the 5.5 MeV/u Ar 16+ -Ne collision was symmetrical. The line shape calculated according to a postcollision effect due to the slowly receding ejected electrons shows a very good agreement with the measured line shapes.

The lineshapes of the KL2L3(1D2) Auger lines from magnesium and sodium metal have been analysed with a many-body theory. This yields many-body exponents which are about 30% smaller than those obtained from an analysis of the core lines in magnesium and sodium metal.

We report independent-electron model calculations of the L/sub 2/,/sub 3/VV and L/sub 1/L/sub 2/, /sub 3/V Auger line shapes for ideal Si(111), (100), and (110) surfaces and compare the results to data of Houston, Lagally, and Moore. For the L/sub 2/, /sub 3/VV transitions, agreement between experiment and theory is excellent, in contrast to poor agreement between experiment and the self-fold of the occupied Si density of states; this result shows that matrix-element angular momentum dependence and not many-electron effects cause the latter discrepancy. For the L/sub 1/L/sub 2/, /sub 3/V lines our calculated results are less satisfactory. We suggest that the disagreement between theory and data for these ''Coster--Kronig'' transitions is due to the difficulty of calculating accurate Auger matrix elements at low energies and, perhaps, to the use of ''ideal'' (i.e., unreconstructed) surface geometries in modeling actual Si surfaces.

High‐resolution measurements reveal a double‐peak structure in the oxygen KLL main line of ZnO which is absent in MgO. We suggest that part of this fine structure is due to contributions from interatomic transitions and, as such, corresponds to two maxima in the valence‐band density of states of ZnO.

The authors report measured post-collision interaction phenomena following K-shell ionisation of neon by electron impact. At near-threshold impact energy Ei electron spectra taken in the region of the K-L2,3L2,3(1D2) Auger line reveal a high-energy tail and an energy shift Delta E of this line, the latter obeying the Barker-Berry power law Delta E approximately (Ei-EK)-0.5 where EK is the K-ionisation energy. The intensity ratio of diagram Auger-lines changes noticeably with near-threshold impact energy.

Experimental results of sulfur line shape variations observed from various metal–sulfur compounds (Cu5FeS4, Cu2S, FeS) show that Auger fine structure analysis is able to separate chemical states of sulfur. Atomic sulfur presents a single Auger line at 149 eV whereas sulfur in the S2− oxidation state is characterized by a peak at 147 eV.

During the early stages of an overlayer formation the energy of interaction of some substrate and overlayer atoms may change. As a consequence the resultant Auger line may comprise some number of lines, contributions of which change during the overlayer growth. Thus, variability of the line shape may noticeably distort the values of measured Auger peak-to-peak heights. A method has been proposed allowing correction of these distortions.

The effect of electronic correlations on KLL Auger line intensities is investigated for the elements 12⩽ Z ⩽21 by using a simple ansatz for the correlation of the bound state electrons. No correlation is assumed between the K-shell electron and the continuum electron in the final state. Enhancement of the intensities of the 1 S 0 (KL 2 L 2 ) and the 1 D 2 (KL 2 L 3 ) lines is obtained relative to the 1 S 0 (KL 1 L 1 ) line.

Measurements of LVV Auger-electron spectra from a Si(111) surface before and after Ge deposition reveal that atoms at the surface have a qualitatively different Auger line shape than atoms in the bulk. In particular, the redistribution of electron density at the Si(111) surface enhances the ratio of pp to sp contributions to the LVV line shape. This surface effect is expected to be a general property of LVV spectra from all surfaces, which must be considered when comparing theory to experimental data.

A comparison is performed between theoretical and experimental shapes of theXVV (X=M2,3 andL3) Auger spectra of ferromagnetic Fex−Ni1−x alloys forx=0.48 and 0.27 in order to check if recent theories, which take into account the Coulomb correlation between the two final Auger holes, would be able to reproduce shape and position of the experimental peaks in an accurate way. For the case under investigation, it seems that, at least for the low-energy (M2,3VV) spectra and notwithstanding the usual neglecting of matrix element effects, the theory gives results in close agreement with the experimental data. The comparison with the high-energyL3VV spectra is somewhat hampered by an asymmetric broadening of the experimental data on the low kinetic-energy side due to satellite structures, but still gives good agreement on the high kinetic-energy side.

Coal mine dusts were investigated by scanning Auger spectroscopy and by means of a surface sensitive thermoluminescence method in order to determine the influence of uncontaminated quartz surfaces on the pathogenic behaviour. Even in the case of a fibrogenic dust no clean quartz surfaces could be observed during scanning Auger line scans and the Auger analysis of single points at a lateral resolution between 0.2 and 0.5 μm. The intensities of the thermoluminescence at 160 K agreed fairly well with the quartz content. These results indicate that reactive clean quartz surface areas, only of submicroscopic dimensions however, were present.

Using the Auger line shape of Co atoms adsorbed on Si(111) at room temperature, we have been able to deduce detailed information on the development of the Co/Si interface which shows the initial formation of a boundary ${\mathrm{CoSi}}_{2}$-like phase. Simulation of these Auger lines within the Cini-Sawatzky theoretical scheme allows one to estimate the effective Coulomb interaction ${U}_{\mathrm{eff}}$ of the final two-hole state in the Auger process for bulk Co and cobalt silicides. Finally, in order to confirm these spectroscopic results, lattice-imaging micrographs directly suggest the presence of an interfacial ${\mathrm{CoSi}}_{2}$ layer.

In recent papers, we have described a depth profiling method using chemical beveling and Auger line scan measurement, quick and easy to perform, with a sufficient resolution to check the abruptness of chemical interfaces obtained in epitaxial growth of III-V compounds.The variation law of chemical species concentrations at the interfaces is tighly related to the mecanisms of initial growth. We present here a theoretical analysis applied to chemically beveled interfaces with sharply graded concentrations.We show on two examples of LP-MOCVD quantum wells (InP/GaInAs/InP and GaInP/GaAs/GaInP) the good agreement between experimental and theoretical curves, assuming exponentially varying concentrations. Finally, we discuss the correlations with the dynamics of the first steps of the LP-MOCVD growth.

The understanding of surface and interface phenomena is based on a fair correlation between the surface and interface physicochemical and crystallographic properties and their electronic properties. To look at the solid surfaces and interfaces, on a microscopic scale, the physicists and chemists nowadays are using a great variety of very sensitive techniques, which are actually very sophisticated and rather expensive.

Aluminium L 23 VV and KVV Auger spectra are compared for the first time. In spite of the differences in kinetic energy of the escaping electrons and of the core-holes, the two spectra look very similar suggesting that surface effects do not contribute much to the Auger transition. Moreover in both spectra it is visible a high energy structure which is interpreted as an intrinsic plasmon-grain satellite due to the core-hole relaxation.

Quantitative analysis without reference samples means that the correlation between measured data and sample composition is described by a theoretical expression. Thus, neither reference samples nor pure element standards have to be employed. For X-ray photoelectron spectroscopy (XPS) and X-ray induced Auger electron spectroscopy (XAS) these theoretical correlations can be given. Besides, a good knowledge of the “fundamental parameters” is necessary.

The variation of the relative alloy sensitivity factor PPtCu used in the quantitative AES analysis of Pt-Cu alloys as a function of the atomic concentration of Pt was measured for in situ scraped sample surfaces. Through different Auger line combinations, i.e. Cu(105)-Pt(237), Cu(920)-Pt(237), and Cu(920)-Pt(1967), three sets of PPtCu were obtained. It was found that the as-measured PPtCu changes with composition in a complex manner. However, after background slope correction in the low energy range and noise correction in the high energy range, the variation of PPtCu of Cu(105)-Pt(237) and Cu(920)-Pt(237) become blurred while PPtCu of Cu(920)-Pt(1967) still decreases approximately 30% if the composition changes from 19 to 90 at% Pt. The variation of PPtCu of Cu(920)-Pt(1967) with composition is in agreement with that PPtCu should in principle not be constant with composition as it contains factors such as backscattering factor and escape depth, which are functions of composition. But the blurring of the variation of PPtCu of Cu(105)-Pt(237) and Cu(920)-Pt(237) with composition contradict this. If these variations also exist, the present results show that they may be too small to be detected with the present method. Though the change of PPtCu itself does not have a serious effect on the quantitative AES analysis, in view of the difficulty in accurate determination of the background slope and the noise corrections, the calibration curve method is suggested for accurate AES analysis, especially in dilute alloys.

The influence of the “cluster surface” on cluster densities of states (DOS) of small Si, Ge and GaAs clusters is analysed by means of SCF-Xα-SW calculations. The saturation of the “dangling bonds” is simulated by adding hydrogen atoms at the nearest neighbour sites of the outer atoms. This results in the disappearance of a cluster surface state in the local densities of states (LDOS) on the central atom sites. The relation of experimental solid state data with these local densities of states, together with cluster Auger line shapes and cross-relaxation energies, are discussed.