SUPPRESSED ELECTRON-CAPTURE IN SLOW O-HE COLLISIONS - COMMENT(((4)S(0),(2)D(0),(2)P(0)))

Electron capture in collisions of O+ ions with He atoms is studied on the basis of a molecular-orbital expansion approach. The cross section for electron capture by metastable O+(2D, 2P) ions is found to be lar ger by an order of magnitude than that for capture by ground-state O+( 4S) ions over the entire energy region studied. The energy dependencie s of cross sections for electron capture by the ground and metastable ions are found to differ considerably below 2 keV. The present result, obtained by combining the cross section of 90% of the ground state an d that of 10% of metastable states, reproduces reasonably well the exp erimental result of Kusakabe et al. [J. Phys. Soc. Jpn. 59, 1987 (1990 )], who reported using the mixture of the ground and metastable O+ ion s. The present finding clearly contradicts another experimental result of Wolfrum et al. [Phys. Rev. A 45, R4218 (1999)], who reported no ef fect from the metastable states.