Measurement and calculation of absolute single- and multiple-charge-exchange cross sections for Feq+ions impacting CO and CO2

Abstract

Absolute cross sections are reported for single, double, and triple charge exchange of Fe${}^{q}$${}^{+}$ ($q=5--13$) ions with CO and CO${}_{2}$. The highly charged Fe ions are generated in an electron cyclotron resonance ion source. Absolute data are derived from knowledge of the target gas pressure, target path length, and incident and charge-exchanged ion currents. Experimental results are compared with new calculations of these cross sections in the $n$-electron classical trajectory Monte Carlo approximation in which the ensuing radiative and nonradiative cascades are approximated with scaled hydrogenic transition probabilities and scaled Auger rates. The present data are needed in astrophysical applications of solar- and stellar-wind charge exchange with comets, planetary atmospheres, and circumstellar clouds.