Ionization, charge exchange, and excitation in F + Ar and F + Kr collisions

Hopkins, Forrest; Brenn, R.; Whittemore, Anthony R; Cue, N.; Dutkiewicz, Vincent A.; Chaturvedi, Rishabh

doi:10.1103/physreva.13.74

Cited by 45 publications

(6 citation statements)

References 36 publications

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“…This value is in excellent agreement with a measurement by Winters et al [19] of 4,100 b. 'Cross sections of Ar and Kr measured by Hopkins et al [24] at overlapping energies are not directly comparable since these measurements were done with higher (q> 7 § charge states and therefore significant deviations are to be expected [19,23]. For 19 MeV F 5+ Tawara et al [25] measured a Si K Xray cross section of (1.63_+0.16).…”

Section: A K-shell Ionisation Of the Target Atomsupporting

confidence: 89%

“…The dependence of the X-ray cross sections on the projectile energy is quite satisfactorily reproduced by the BEA calculations, indicating the dominance of direct ionization as vacancy production mechanism. This ionization process seems also to prevail at still higher energies for ion charge states __>7 § [24]. Especially at low projectile velocities, ionization of the Kr L-shell by electron promotion from orbitals connected with the projectile K-shell (3da orbital for example) and the target atom L-shells could be important.…”

Section: B L-and M-shell Ionization Of Target Atomsmentioning

confidence: 94%

“…4. Cross sections measured for projectiles with q=7 + at 26MeV are higher by about a factor of 4 for Ar and a factor of 2 for Kr [24]. The cross sections were obtained from measurements at 135 ~ assuming isotropic X-ray emission.…”

Section: Emission Of Projectile X-raysmentioning

confidence: 99%

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Inner-shell ionization created by fluorine ions in nearly symmetric collisions

1980

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We have measured projectile and target X-ray cross sections for F + Si, S, Ar and Kr collisions at projectile energies from 1 to 25 MeV. The experiments were performed under single collision conditions using a differentially pumped gas target. X-rays were measured by a Si(Li) detector and a proportional counter. The experimental cross sections are compared to predictions of theoretical models for direct and quasi-molecular ionization. Effects of multiple ionization that influence the K-shell fluorescence yields were examined using experimental information from line energy shifts and intensity ratios.

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Section: A K-shell Ionisation Of the Target Atomsupporting

confidence: 89%

Section: B L-and M-shell Ionization Of Target Atomsmentioning

confidence: 94%

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Inner-shell ionization created by fluorine ions in nearly symmetric collisions

1980

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“…The cross section values measured using the two detectors agreed with one another to within 5-10% at all the measured energies and charge states of the incident projectile. For absolute normalization, the Ar K x-ray yields were measured, in the same geometry, using 56 and 77 MeV F ion beams in different charge states for which the x-ray cross sections are known (Hopkins et al 1974). It was found that the cross sections derived from the present measurements were slightly lower (by a factor of 1.3) than those obtained by Hopkins et al However, we have used the existing data of Hopkins et al (1974) to normalize our cross section data.…”

Section: Data Analysis Results and Discussionmentioning

confidence: 99%

Strong double K-K transfer channel in near symmetric collision of Si+Ar at intermediate velocity range

Dhal

Tribedi

Tiwari

et al. 2000

J. Phys. B: At. Mol. Opt. Phys.

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We present a combined study of single and double K-K electron transfer cross sections along with the single and double K-shell ionization of Ar induced by Si projectiles in the energy range 0.9-4.0 MeV u −1. The charge-state dependence of the normal and hypersatellite x-rays was used to derive the cross sections for the one-and two-electron processes, respectively. The enhancement in the fluorescence yields due to multiple vacancies was measured from the energy shifts and intensity ratios of the characteristic x-ray lines to derive K-shell vacancy production cross sections from x-ray production cross sections. The ratio of double to single K-K transfer cross sections is found to be quite large for this nearly symmetric collision system, whereas the ratio of double to single ionization cross sections is quite small. The measured single K-K transfer cross sections are reproduced very well by the two-centre close-coupling calculations whereas the double K-K transfer data are underestimated by the theory based on the independent-electron approximation (IEA). The K-shell ionization cross sections are found to deviate strongly from the calculations based on the continuum distorted wave eikonal initial state (CDW-EIS) and ECPSSR models. The CDW-EIS calculations along with the IEA model grossly underestimate the double ionization cross sections. It is stressed that in the case of two-electron processes the independentelectron model breaks down and the possible role of correlations between K-electrons is discussed.

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“…The strong effects of projectile charge state on inner-shell ionization [1][2][3][4] have been reported by a number of groups for gas targets.…”

Section: Introductionmentioning

confidence: 84%