Plasmon Satellites in Auger Spectra

A theory of Auger spectra in light metals, in which a nonequilibrium formalism is used to handle the aspects of the problem associated with energy loss of the fast electrons and decay of the excited core hole, is presented. The Auger electrons are assumed to reach the surface a time τ after the initial excitation. This time is determined by the decay characteristics of the initial core hole, the geometry, and the velocity of the Auger electrons. After τ, it is assumed that no interactions occur. Electron gas correlations are approximated by a bulk plasmon model. The initial excitation may be due to either X-ray or electron bombardment, although we concentrate on the former. Plasmon production by the primary ejected electrons and the suddenly created core hole is considered. The formalism is based on a perturbation expansion in the electron–plasmon interaction after extraction of the energy shifts, and this procedure is justified by comparison with a simple soluble model. It is applied to third-row (K; LL) Auger transitions. The plasmon gain satellite is compared to the main line, and the entire spectrum is computed in detail for the limiting case of a long lived core hole.

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Cross-Sections for K-Shell Excitation by Fast Electrons

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010007878x ◽

1977 ◽

Vol 35 ◽

pp. 252-253

Author(s):

R. F. Egerton ◽

D. C. Joy

Keyword(s):

Cross Section ◽

Cross Sections ◽

Unit Volume ◽

Direct Method ◽

Specimen Thickness ◽

Thin Specimen ◽

Auger Electrons ◽

Fast Electrons ◽

X Ray ◽

Image Position

The cross-section for excitation of an electron from the innermost shell of a given atom can be determined directly by measuring the proportion of fast incident electrons which have suffered an appropriate energy loss, or (if the X-ray or Auger yields are known) from the number of X-ray quanta or Auger electrons emitted as a result of de-excitation.In the direct method, this cross-section is obtained as a function of α, the maximum scattering angle allowed into the detector, and for a thin specimen it is given by:where n is the number of atoms per unit volume of specimen, t is the specimen thickness, Ik(α) represents the number of K-loss electrons reaching the detector and It represents the total number of fast electrons entering the detector,1 for the same value of α. Equation (1) can also be used12 for microanalysis of low-atomic-number elements in order to measure n or nt if σK(α) is known.

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Auger Electron?Ion Coincidence Studies to Determine the Pathways in Soft X-ray Induced Fragmentation of Isolated Molecules

Australian Journal of Physics ◽

10.1071/ph860633 ◽

1986 ◽

Vol 39 (5) ◽

pp. 633 ◽

Cited By ~ 35

Author(s):

W Eberhardt ◽

EW Plummer ◽

In Whan Lyo ◽

R Reininger ◽

R Carr ◽

...

Keyword(s):

Auger Electron ◽

Core Hole ◽

Final State ◽

Auger Electrons ◽

X Ray ◽

Fragment Ions ◽

Valence Electrons ◽

Molecular Bond ◽

Doubly Charged ◽

Insight Into

We report a coincidence .experiment between energy selected Auger electrons and the ions produced in the events following the absorption of a soft X-ray photon by a CO molecule. This study allows us to correlate specific double hole final state configurations of the Auger decay of a core hole in this molecule with the production of fragment ions, thus giving new experimental insight into the potential energy curves of the doubly charged molecular ion and the involvement of individual valence electrons into the molecular bond in general.

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X-ray photoemission spectroscopy of the 90 K superconductor Ba2YCu3O7−δ

Journal of Materials Research ◽

10.1557/jmr.1987.0768 ◽

1987 ◽

Vol 2 (6) ◽

pp. 768-774 ◽

Cited By ~ 48

Author(s):

Z. Iqbal ◽

E. Leone ◽

R. Chin ◽

A. J. Signorelli ◽

A. Bose ◽

...

Keyword(s):

Core Level ◽

Band Spectrum ◽

Full Potential ◽

Electronic Density ◽

Augmented Plane Wave ◽

X Ray ◽

Superconducting Material ◽

Auger Spectra ◽

Linearized Augmented Plane Wave

The x-ray photoemission spectroscopie (XPS) data from different pelletized samples of the 90 K superconductor Ba2YCu3O7−δ (where δ∼0.2) have been obtained. The valence band spectrum (recorded at 300 and 170 K), which is composed of contributions from both the Cu 3d and O 2p levels, is compared with the full potential linearized augmented plane wave (FLAPW) calculated electronic density-of-states (DOS) reported by Massidda et al. and Mattheiss and Hamann. The experimental data indicate a relatively low DOS at the Fermi level. Detailed measurements of the core level Cu 2p, O 1s, Ba 3d, 4d, and Y 3d spectra of the superconducting and related standard materials, are presented. Data for the superconducting material were recorded in the freshly prepared form as well as after scraping in situ. The Cu 2p core level, satellite, and Auger spectra for the various samples were carefully examined in order to assess the possibility of the presence of Cu3+ ions in Ba2YCu3O7-δ. It is observed that surface reaction in air to form carbonates and hydroxides occurs readily in the superconducting material.

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X-ray investigation of polypropylene and poly(ethylene-co-vinyl acetate) blends irradiated with fast electrons

Radiation Physics and Chemistry ◽

10.1016/s0969-806x(97)00292-2 ◽

1999 ◽

Vol 56 (5-6) ◽

pp. 581-589 ◽

Cited By ~ 8

Author(s):

M Mihailova ◽

M Kresteva ◽

N Aivazova ◽

V Krestev ◽

E Nedkov

Keyword(s):

Vinyl Acetate ◽

Fast Electrons ◽

X Ray ◽

Poly Ethylene

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Satellite X-Ray Lines and KLL Auger Electrons from Fluorine Compounds

Inner-Shell and X-Ray Physics of Atoms and Solids ◽

10.1007/978-1-4615-9236-5_158 ◽

1981 ◽

pp. 811-814

Author(s):

G. Deconninck ◽

S. van den Broek

Keyword(s):

Auger Electrons ◽

X Ray ◽

Fluorine Compounds

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Core-hole effects in x-ray-absorption spectra of fullerenes

Physical Review B ◽

10.1103/physrevb.60.7956 ◽

1999 ◽

Vol 60 (11) ◽

pp. 7956-7960 ◽

Cited By ~ 98

Author(s):

Mats Nyberg ◽

Yi Luo ◽

Luciano Triguero ◽

Lars G. M. Pettersson ◽

Hans Ågren

Keyword(s):

Absorption Spectra ◽

Core Hole ◽

X Ray ◽

X Ray Absorption

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Auger Spectroscopy and Surface Analysis

Australian Journal of Physics ◽

10.1071/p96075 ◽

1997 ◽

Vol 50 (4) ◽

pp. 745 ◽

Cited By ~ 6

Author(s):

S. M. Thurgate

Keyword(s):

Short Distance ◽

Auger Spectroscopy ◽

Low Energy ◽

Simultaneous Occurrence ◽

X Rays ◽

Auger Process ◽

Surface Layers ◽

Auger Electrons ◽

Low Energy Electrons ◽

Auger Spectra

Abstract In 1925 Pierre Auger reported on his observations of low energy electrons associated with core-ionised atoms in cloud chamber experiments. He was able to correctly identify the mechanism for their production, and such electrons are now known as Auger electrons. Typically Auger electrons have energies in the range 10 eV to 2 keV. The short distance that such low energy electrons travel in solids ensures that Auger electrons come from the surface layers. The data generated by the AES technique are complex. There are at least three electrons involved in the process, and there are many possible configurations for the atom. These possibilities led to spectra that are not readily interpreted in detail. Theory lags behind experiment in this area. In principle, it should be possible to find information about the chemical environment of atoms from Auger spectra. While there are clear changes in spectral lineshapes, there is no simple way to go from the spectra to an understanding of the chemical bonding of the atom. There are a number of experiments currently underway which aim to improve our understanding of the Auger process. Synchrotron experiments with tunable energy x-rays are providing new insight. Experiments that use positrons to excite Auger emission have also produced further recent understanding. Coincidence experiments between photoelectrons and Auger electrons have also made recent advances. Auger photoelectron coincidence spectroscopy reduces the complexity of Auger spectra by only counting those electrons that occur as a consequence of selected ionisations. The effect is to reduce the complexity of the spectra, and to isolate processes that are often clouded by the simultaneous occurrence of other effects.

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VUV and Soft X-ray Spectroscopy of Actinides

MRS Proceedings ◽

10.1557/proc-802-dd2.5 ◽

2003 ◽

Vol 802 ◽

Author(s):

Clifford G. Olson ◽

John J. Joyce ◽

Tomasz Durakiewicz ◽

Elzbieta Guziewicz ◽

Martin Butterfield

Keyword(s):

Cross Section ◽

Cross Sections ◽

Spectral Characteristics ◽

Electronic States ◽

Momentum Dependence ◽

Auger Electrons ◽

X Ray ◽

Relative Cross Section ◽

Initial States ◽

Valence Bands

ABSTRACTOptical and photoelectron spectroscopies using VUV and Soft X-ray photons are powerful tools for studies of elemental and compound actinides. Large changes in the relative atomic cross sections of the 5f, 6d and sp electrons allow decomposition of the character of the valence bands using photoemission. Resonant enhancement of photoelectrons and Auger electrons at the 5d core threshold further aids the decomposition and gives a measure of elemental specificity. Angle-resolved photoemission can be used to map the momentum dependence of the electronic states. The large changes in relative cross section with photon energy yields further details when the mapping is done at equivalent points in multiple zones. Spectra for well understood rare earth materials will be presented to establish spectral characteristics for known atomic character initial states. These signatures will be applied to the case of USb to investigate f-d hybridization near the Fermi level.

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