We have calculated dielectronic recombination (DR) cross sections from the ground state (1 'S) and excited states (2'S, 2'S, and 2'P) of the He-like ions C + and 0 + 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 C +, we obtain excellent agreement when we choose the 2'S to 2 'S population ratio to be 18. For the case of 0 +, we obtain good agreement with experiment with a 2'S to 2 'S population ratio of 70, except in the 6to 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'S term to be 70%%uo in C + and 20% in 0 +. The reason for this large difference is not understood.

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We report on the first time-dependent close-coupling calculation of dielectronic capture into a doubly excited state of a two-electron atom. An incoming electron is represented by a Gaussian wave packet which collides with singly ionized helium in its ground state. The close-coupling equations describe the propagation of the total compound wave function on a two-dimensional radial lattice. By projecting this wave function onto a doubly excited state of neutral helium, we can determine the probability amplitude for dielectronic capture into one of these states and the subsequent autoionization from it.