Abstract
We have calculated dielectronic recombination (DR) cross sections from the ground state (1 ) and excited states (2 , S, and 2 ) of the He-like ions and in the LS-coupling and intermediate-coupling approximations, using the program autostructure. We find the effects of configuration interaction, intermediate coupling, and external electric fields to be small. We compare our results with the recent high-resolution measurements of DR from the excited states of these ions by Andersen et al. [Phys. Rev. Lett. 62, 2656 (1989) and Phys. Rev. A 41, 1293 (1990)] by convoluting our cross sections with their electron velocity distribution. For the case of , we obtain excellent agreement when we choose the 2 to 2 population ratio to be 18. For the case of , we obtain good agreement with experiment with a 2 to S population ratio of 70, except in the 6- to 8-eV energy region, where a model calculation indicates that coupling between resonances via the continuum may be important. By comparing experiment with theory, we have also estimated the metastable fraction of the 2 term to be 70% in and 20% in . The reason for this large difference is not understood.
- Received 21 August 1989
DOI:https://doi.org/10.1103/PhysRevA.41.2422
©1990 American Physical Society