X-ray production by electron excitation, ionization, and capture forFq+(q=1−9) ions in collisions with a He gas target

Abstract

$K$ x-ray transitions resulting from collisions between F projectiles, with charge states ranging from ${1}^{+}$ to ${9}^{+}$, and He atoms have been observed. Production mechanisms leading to projectile $K$ x rays include $K$-shell electron excitation, single $K$-shell multiple $L$-shell vacancy production, and electron capture. The measured F $K$ x-ray production cross sections range from ${10}^{\ensuremath{-}22}$ ${\mathrm{cm}}^{2}$ for low charge states to ${10}^{\ensuremath{-}17}$ ${\mathrm{cm}}^{2}$ for incident bare ions. Using calculated average fluorescence yields, the $K$-shell electron excitation, single $K$-shell, single $K$-shell + single $L$-shell, single $K$-shell + double $L$-shell ionization, and electron-capture cross sections have been determined. The measured ionization cross sections are found to decrease with the increase in projectile charge state, whereas single-$K$-shell electron-excitation cross sections increase with the increase in projectile charge state.