Electron-impact-ionization cross sections of inner shells measured by Auger-electron spectroscopy

Vrakking, J.J.A.M.; Meyer, Frank

doi:10.1103/physreva.9.1932

Cited by 59 publications

(28 citation statements)

References 18 publications

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“…At the present time, procedures analogous to those in EPMA to convert a measured Auger-electron intensity to an elemental concentration have not been a.s extensively developed (Scab, 1973;Palmberg, 1973;Riviere, 1973;Chang, 1974;Staib and Kirschner, 1974;. Chang, 1975;Morabito, 1975;Vrakking and Meyer, 1975). This situation is due in part to the novelty of AES compared to EPMA and in part to the lack of knowledge of the relevant physical parameters needed for quantitative AES. '…”

Section: Introductionmentioning

confidence: 89%

“…Meyer and Vrakking (1973) and Vrakking and Meyer (1974) have measured cr~for Si, P, S, Cl, Ti, Br, and Sn in molecules containing these elements and C or Cl. All Auger-electron yields were measured relat Pockman et al (1947) Hink and Ziegler (1969) Glupe andMehlhorn (1967, 1971) and Glupe (1972) Cl and these results are shown in Figs.…”

Section: The Bethe Theory Of Inner-shellmentioning

confidence: 99%

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Cross sections for ionization of inner-shell electrons by electrons

1976

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A survey is given of the available cross-section data for ionization of inner-shell electrons by incident electrons in the range of interest for electron-probe microanaiysis and for Auger-electron spectroscopy of solid surfaces. Owing to the paucity of data, the bulk of the discussion is limited to K-shell and I.-shell ionization of light atoms. Calculated, semiempirical, and experimental cross-section data have been intercompared graphically and through fits to the linearized Bethe equation for inner-shell ionization (the Fano plot). Almost all of the data could be satisfactorily fitted over the range 4 5 U", 5 30, where U", = Eo/E", , Eo is the incident electron energy, and E", the binding energy of electrons in the nl shell.From these fits, values could be obtained of the "effective" Bethe parameters b"I and c"&. Values of the parameter b", have also been derived from photoabsorption data and were found to be generally consistent with the ionization data if account was taken of the distribution of differentia oscillator strength with respect to excitation energy and the consequent expected variation of b", with incident electron energy. The derived "effective" Bethe parameters should not therefore be used outside the range of each fit.

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Section: Introductionmentioning

confidence: 89%

Section: The Bethe Theory Of Inner-shellmentioning

confidence: 99%

Cross sections for ionization of inner-shell electrons by electrons

1976

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“…In the energy range considered here, 1 ± 50 keV, experimental measurements have been mostly carried out for Kshell ionization; cross section data for L-and M-shells are, unfortunately, very scarce. As far as we know, absolute L-shell ionization cross sections have been reported only for the elements P, S and Cl [1], Ar [2 ± 5], Kr [6], Xe [6,7] and Au [8 ± 11] (see also refs. [12,13]).…”

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confidence: 99%

Relative Cross Sections for L- and M-Shell Ionization by Electron Impact

et al. 2000

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Results from measurements and calculations of relative L-and M-shell ionization cross sections by electron impact are presented. Measurements were performed for elements Te, Au and Bi on an electron microprobe with specimens consisting of extremely thin ®lms of the studied element deposited on thin, self-supporting, carbon layers. The relative variation of the ionization cross section was obtained by counting the number of characteristic X-rays from the considered element and shell, for varying incident electron energies, from the ionization energy up to 40 keV. Measured data were corrected to account for the energy-dependent spread of the electron beam within the active ®lm and for the ionization due to the electrons backscattered from the carbon layer, using Monte Carlo simulation. Cross sections were evaluated in the Born approximation using an opticaldata model with numerically evaluated dipole photoelectric cross sections. Calculated ionization cross section were converted to vacancy production cross sections, which can be directly compared with our experimental data.Reliable cross sections for inner-shell ionization by impact of keV electrons are required for quantitative Auger electron spectroscopy (AES), electron probe microanalysis (EPMA) and electron energy loss spectroscopy (EELS). In spite of this need, simple systematic methods to calculate ionization cross sections from ®rst principles remain to be found. The usual practice consists in using semi-empirical formulae, which have limited ranges of validity and normally lead to signi®cantly different results. In the energy range considered here, 1 ± 50 keV, experimental measurements have been mostly carried out for Kshell ionization; cross section data for L-and M-shells are, unfortunately, very scarce. As far as we know, absolute L-shell ionization cross sections have been reported only for the elements P, S and Cl [1], Ar [2 ± 5], Kr [6], Xe [6,7] and Au [8 ± 11] (see also refs. [12,13]). Comprehensive reviews of experimental measurements (as well as theoretical calculations and semi-empirical formulae) of inner-shell ionization cross sections have been published by Powell [14,15,16]. Most of the reported cross sections were based on the measurement of characteristic X-rays which are emitted in the de-exitation of ionized atoms in the gas phase. Because of the lack of knowledge of the corresponding¯uorescence yields and CosterKronig decay yields, experimental results are affected by large uncertainties. Measurements using thick solid samples have also been performed, but the results are obscured by multiple scattering within the target. It is thus dif®cult to establish the reliability of semiempirical formulae and theoretical calculations by comparison with the available experimental data. This dif®culty is found not only regarding the absolute value of the cross section, but also for its energy dependence.The determination of the (relative) energy dependence of the ionization cross section is of interest for

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“…Additionally, the Coulomb's force exerted by the nucleus on these incident electrons affects the ionization cross-sections (Robert and Ducharme, 1972), which control the interaction of the incident electrons with the target atoms (Davis et al, 1972). It has been reported that the ionization cross-sections of the inner-shell electrons are lower than those of the outer-shell electrons at low incident electron energies (Yakking and Mcycr, 1974). However, the inner-shell ionization cross-section increases when the incident electron energy increases.…”

Section: Resultsmentioning

confidence: 99%

“…Thus, the flux of Kα 1 is increased when the incident electron energy is increased. Several researchers have experimentally estimated the ionization cross-sections as a function of the energy of the incident electrons (Dangerfield and Spicer, 1975;Davidovic and Moiseiwitsch, 1975;and Yakking and Mcycr, 1974).…”

Section: Resultsmentioning

confidence: 99%