Charge-state dependence ofK-shell x-ray production in aluminum by 2–12-MeV carbon ions

Abstract

Charge-state dependence for K-shell x-ray production cross sections in 13 Al bombarded by 2-12-MeV 6 C ions with charge states from 2ϩ to 6ϩ was measured using a Si͑Li͒ detector. A thin Al target was used to ensure single collision conditions. Contributions of the electron capture as well as direct ionization to the inner-shell ionization were determined by an analysis of the charge-state dependence of the target x-ray production. The measurements are compared with the prediction of the ECPSSR theory using a single-hole fluorescence yield. The ECPSSR theory is based on the perturbed stationary state ͑PSS͒ formalism and relativistic effects ͑R͒ for the target electrons, and energy loss ͑E͒ and Coulomb deflection ͑C͒ of the projectile. In general, this theory gives reasonable agreement with the data for carbon ions without K vacancies while it overpredicts the data for carbon ions with K vacancies. The significant underprediction of the data at the lowest energy is likely associated with the molecular-orbital effect that is not accounted for in the ECPSSR theory.

K X-ray production by 12C4+ ion impact on selected elements

“…Incident ions for the K X-ray production cross sections measurements were 12 C 4+ with energies ranging from 6 to 9 MeV, in 0.5 MeV steps. When higher charge states are used, like 12 C 5+ or 12 C 6+ , there is a noticeable effect due to electron capture by the incoming ion (Sun et al, 1996). There is also a growth in the X-ray production cross sections with increasing projectile charge, which is most significant when ions carry one or two K-shell holes.…”

“…In particular, the production of K X-rays by heavy ions (such as 12 C or 16 O) was studied by several authors (Gray et al, 1976;Wheeler et al, 1976;Knaf et al, 1977;Zelazny and Hornshoj, 1984;Paul and Muhr, 1986;Geretschla¨ger and Benka, 1986;Geretschla¨ger et al, 1990;Geretschla¨ger et al, 1992;Fazinic et al, 1996;Tong et al, 1996;Sun et al, 1996;Mitra et al, 1997;Kubala-Kukus et al, 1999;Ozafra´n et al, 2003). Nevertheless, the development of theoretical models that describe and predict the X-ray production cross sections by heavy ion impact has not seen a strong advancement in the past 10 years, at least (Montenegro and Sigaud, 1985;Benka et al, 1987).…”

Double effects of projectile charge state on Nb L-shell ionization by slow highly ionized Xe ions

“…In ion-atom collision, inner-shell ionization following the heavy ion-solid surface interaction usually shows a strong monotonic increase with the projectile charge state. The charge state effect has attracted much attention [2][3][4][5][6][7][8][9][10]. For slow nearly symmetric or fully symmetric collisions, electron promotion with coupling molecular orbitals allows a successful qualitative description of this effect [11][12].…”

Pre-equilibrium stopping and charge capture in proton-irradiated aluminum sheets

“…3,16 Similarly, the response of aluminum foils to ion irradiation has been shown to depend on both ion charge and foil thickness. 17,18 Such studies inferred projectile charge equilibration time scales smaller than 10 fs and length scales shorter than 10 nm. 14,16,[18][19][20] Sensitivity of electron emission to incident ion charge was shown even for ∼ 100 nm thick carbon foils and attributed to preequilibrium stopping and projectile charge.…”