Effects of low concentrations of O 2 and CO on the ion-clustering reactions in the lower ionosphere of Mars

Abstract

It is demonstrated that under conditions which approximate those of the Martian ionosphere traces of CO and O 2 can be effectively incorporated in ion clusters via ion-molecule reaction schemes initiated by the CO 2 + ion. For example, when 0.3 % CO is added to CO 2, (CO) 2 + and [(CO) 2CO 2] + appear as the major cations (584 Å radiation, 300°K). In mixtures containing O 2 in addition to CO 2 (CO 2. O 2) + and [(CO 2) 2O 2] + are important species. A recently proposed mechanism to account for the low abundance of CO and O 2 in the Martian atmosphere is discussed in the light of these observations.