Dissociative recombination dynamics of the ozone cation

The dissociative recombination of the ozone cation has been studied at the heavy-ion storage ring CRYRING. The total cross section and branching fractions have been measured. The cross section from 0 eV to 0.2 eV follows a nearly E-1 dependence, which was theoretically predicted to be a characteristic of the direct dissociative recombination mechanism. The thermal rate coefficient has been deduced from the cross section to be 7.37× 10-7 (T/300) -0.55 cm3 s-1. The branching fraction analysis carried out at 0 eV interaction energy has shown a strong propensity (94%) to dissociate through the three-body channel. Due to the overwhelming dominance of this channel it has been investigated in more detail. Of the six energetically available three-body pathways only three are significantly populated, such that the production of O (S1) is highly unfavored and all atomic oxygen fragments are predominantly formed in P3 and D1 states. Analysis of the breakup geometries has been performed by means of the Dalitz plot. It is observed that the molecules dissociating through the O (P3) +O (P3) +O (P3) and O (P3) +O (P3) +O (D1) channels have an open linear geometry where the cleavage of two valence bonds occurs preferentially in unison, while the O (P3) +O (D1) +O (D1) breakup might proceed partly through a sequential mechanism.