Resonant electron capture by the metastable C V and O VII ions

Dielectronic recombination rates and cross sections for the metastable C V and O VII ions are calculated and found to be extremely large, with cross sections of the order of 10 −15 cm 2 and rates of the order of 10 −9 cm 3 s −1 for individual resonances. Electric field enhancement and composition of the metastable 1 s 2 s ion beams in terms of ( 1 S ) and ( 3 S ) are used to reproduce the recent experimental data of Andersen et al. [Phys. Rev. Lett. 62 , 2656 (1989)] for O VII and unpublished data for C V. The overall features are well explained in the case of carbon, while the features for oxygen are well explained except for the broad prominent peaks at 2.5 and 6.8 eV, which are only partially explained.