Mobilities of ground-state and metastable O+, O2+, O2+, and O22+ ions in helium and neon

The ionic mobilities of O+, O2+, O2+, and O2+2 in helium and neon have been measured using a selected-ion drift apparatus (SIDA). It is found that the mobilities of both O+ and O+2 ions in the metastable states (2D or 4Πu) are measurably smaller than those of the same ions in their ground states. The detection and identification of metastable ions was carried out by using known, state-selective ion–molecule reactions. A similar mobility differentiation of ground-state and metastable ions was not observed for the O2+ and O2+2 ions.