Energy-spin spectroscopy of state-selective electron capture for multiply charged Ar recoil ions

Abstract

Cross sections for capture into specific states are measured for 1 keV Arq+ (6<or=q<or=10) ions colliding with neon, argon and xenon. The information is obtained by energy-gain spectroscopy with an energy resolution of about 0.25q eV. The measurements clearly differentiate between capture to individual radiative and autoionising states and in some cases even give information about metastable projectile ions. The energy dependence of the state-selective cross sections is discussed, as is the q dependence of total cross sections for single capture and transfer ionisation. Within a simple two-state Landau-Zener curve-crossing model, a universal plot of the coupling elements is attempted.