Atomic-number dependence of the secondary-electron cascade from solids

Greenwood, J. C.; Prutton, M.; Roberts, R. H.

doi:10.1103/physrevb.49.12485

Cited by 17 publications

(12 citation statements)

References 26 publications

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“…The values of m lie outside the range of 0.5 to 1.5 for electron bombardment [3,7], although their energy dependence suggests that a high-energy asymptotic value close to the 1.1 reported by Greenwood et al [7] for Cu at 20 keV might be approached. (This premise cannot be tested with the present system, for which the maximum incident projectile energy is 2 keV.…”

mentioning

confidence: 57%

“…Differences in the probabilities for inner shell ionization and Auger electron generation will also lead to some differences between the present m values for low-energy positron impact and those from earlier higher energy ͑ϳ20 keV͒ incident electron beam measurements [3,7]. Ichimura et al [15] postulated that broad features are introduced into the emitted electron spectrum N͑E͒ by the inner-shell ionization of target atoms by backscattered and secondary electrons, and Auger electrons create their own cascades of secondary electrons, modifying N͑E͒ and thus the value of m [4].…”

mentioning

confidence: 81%

“…The parameter m was found to be typically ϳ1; log 10 N͑E͒ has linear segments sometimes bounded by regions with Auger electron peaks (the Auger electrons being regarded here as secondary electrons of fixed initial energies). Further measurements of m by Matthew et al [3] and Greenwood et al [7], both for primary electron energies of about 20 keV, yielded values falling between 0.5 and 1.5. m showed a dependence on atomic number Z reflecting the number of valence electrons in the target atom. More recently Matthew et al [8] performed Monte Carlo simulations, for a primary energy of 5 keV, yielding similar results.…”

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confidence: 94%

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Measurement of the Energy Spectrum of Secondary Electrons Ejected from Solids by Positron Impact

Overton

Coleman

1997

Phys. Rev. Lett.

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Energy distributions of fast secondary electrons ejected from Cu and Si bombarded by positrons of energies in the range 50 to 2000 eV, incident at glancing angles ͑#5 ± ͒ and at 35 ± , have been fit to the form AE 2m proposed by E. N. Sickafus. The absence of electron backscattering and the reduction of cascade effects common in electron-stimulated secondary electron spectra allow the direct determination of m for comparison with theory. The values obtained rise from 1.5 at 2000 eV to about 2.5 at 50 eV, and are all higher than those found for electrons incident at higher energies (0.5 -1.5). No significant dependence of the value of m on target species or angle of incidence was observed. [S0031-9007(97)03544-8] PACS numbers: 79.20.Hx

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confidence: 57%

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confidence: 81%

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confidence: 94%

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Measurement of the Energy Spectrum of Secondary Electrons Ejected from Solids by Positron Impact

Overton

Coleman

1997

Phys. Rev. Lett.

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“…Division of the Auger signal with a high-energy background was first proposed by Mischler and Bi~hop,'~ who used the background at 2000 eV and a 10 keV primary beam to compensate for both topographical and subsurface composition variations because they observed that such a high-energy background was relatively weakly dependent upon the atomic number of the substrate. This has since been verified experimentally by Greenwood et a1., 22 whose results display a monotonic increase of the high-energy background, B,, with 2. In a recent paper Crone et a1. "…”

Section: New Ratio Techniquementioning

confidence: 88%

New technique for the simultaneous correction of topographical and backscattering artefacts in electron‐excited Auger spectroscopy and microscopy

Crone

Barkshire

Prutton

1994

Surface & Interface Analysis

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In order to relate an Auger signal to the atomic concentration in the surface of a solid, it is well known that corrections have to be made for matrix effects. Also, corrections may be needed to compensate for the effects of artefacts caused by properties of the sample other than the concentration of different elements. Large artefacts can be caused by the surface topography and subsurface composition variations often present in 'real' samples. This paper reports a new correction scheme that enables the quantitative analysis of samples with a structure for which no prior knowledge exists. The scheme uses the ratio of the Auger peak height to a background count rate above the energy of all significant Auger features, combined with a linear correction involving the atomic number of the substrate and the Auger backscattering factor. Inhomogeneous samples with angle of incidence variations from 0 O to 45" and an arbitrary atomic number can be analysed with an accuracy of -5 at.% using this method. Limitations exist for thin unsupported films.

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“…21 the characterization of the energy analyser itself in order to understand the transmission function and the effects of internally scattered electrons; 22 the use of this information to interpret the shape of the secondary electron cascade that is seen added to the Auger spectrum; 23 and the use of multivariate statistics in the interpretation and analysis of spectra revealing the composition-depth profiles. 24 An example from the work concerning the shape of the secondary electron cascade is shown in Fig.…”

Section: Electron Spectroscopymentioning

confidence: 99%

From LEED to MULSAM

Prutton

2000

Surf. Interface Anal.

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This account gives an outline of the work done in the Department of Physics, University of York since 1965. The Surface Physics Group has been particularly active in the development and application of electron probes of solid surfaces with strong emphasis upon low‐energy electron diffraction and scanning electron microscopy using Auger electrons to form images. A scanning Auger microscope using multi‐imaging (MULSAM) has been particularly fruitful for the study of a variety of heterogeneous materials. Examples are given of the application of MULSAM to the minimization of topographic contrast artefacts, to the study of multilayers of magnetic materials, to the characterization of very rough PtRh catalyst surfaces, to the interpretation of the shapes of electron spectra and to the angular dependence of both Auger electron and energy‐dispersive x‐ray signals. Copyright © 2000 John Wiley & Sons, Ltd.

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Atomic-number dependence of the secondary-electron cascade from solids

Cited by 17 publications

References 26 publications

Measurement of the Energy Spectrum of Secondary Electrons Ejected from Solids by Positron Impact

Measurement of the Energy Spectrum of Secondary Electrons Ejected from Solids by Positron Impact

New technique for the simultaneous correction of topographical and backscattering artefacts in electron‐excited Auger spectroscopy and microscopy

From LEED to MULSAM

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