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

Abstract

We have measured projectile and target x-ray cross sections for F + Ar and F + Kr collisions using fluorine beams of charge states 7 +, 8 +, and 9+ with energies from 20 to 76 MeV. Pronounced enhancements for the Ar $K$ and Kr $L$ vacancy cross sections using ${\mathrm{F}}^{9+}$ ions compared to those for the 7+ projectile can be explained by charge exchange as described by an empirically scaled Brinkman-Kramers theory. The Ar $L$, Kr $K$ and Kr $M$ cross sections are found to exhibit features expected for Coulomb ionization. The projectile $K$ x-ray production for the 9+ ion is accounted for by charge exchange processes. Predictions of the first Born approximation for direct single-step excitation to bound states by the target nucleus overestimate the observed cross sections for ${\mathrm{F}}^{7+}$ and ${\mathrm{F}}^{8+}$.