Influence of the metastable ion content in the initial beam in C2++H, H-2 and O2++H collisions

We present ab initio calculations of cross sections for electron capture by C2+ ions in their ground (S-1) and metastablee (P-3) states, from H and H- 2. We explain the difference between C2+-H-2 collisions, where the content of metastable ions is critical, and C2+-H collisions, where it is less impo rtant. We also present preliminary results for electron capture by O2+ in g round (P-3) and metastable (D-1, S-1) states from H.