Resonant electron impact ionization and recombination of Li-like Cl14+ and Si11+ at the Heidelberg Test Storage Ring

Abstract Absolute cross sections for dielectronic recombination and electron-impact ionization of Li-like Cl 14+ and Si 11+ ions have been measured with high energy resolution at the Heidelberg heavy ion storage ring TSR, using the electron cooler as a free electron target. Recombination and ionization rates were recorded simultaneously for the whole energy range from 0 up to the second ionization threshold. We discuss excitation-autoionization steps, dielectronic ionization and dielectronic recombination resonances associated with 1s → 2 l and 1s → 3 l excitations. The results agree well with theory, but the distorted wave calculations overestimate direct ionization by ∼ 20%.