Fragmentation dynamics of CO4+2: Contributions of different electronic states

Abstract

Fragmentation of CO4+2, created by the impact of slow, highly charged ions (96 keV Arq+; 8≤q≤14) on CO2, has been studied by recoil ion momentum spectrometry. CO4+2 was found to dissociate into three ionic fragments through two channels: CO4+2→O++C2++O+ [the (1,2,1) channel] and CO4+2→O2++C++O+[the (2,1,1) channel]. The kinetic energy of each fragment ion and the total kinetic energy release (KER) distributions for these channels were derived. Ab initio quantum chemical calculations at the multiconfiguration self-consistent-field configuration-interaction level of theory were carried out to obtain the potential energy curves of CO4+2, from which the expected KER values were derived. A comparison of the experimental KER distributions with the expected KER values for different excited states enabled the estimation of the relative probabilities of accessing different electronic states of CO4+2. These probabilities were found to depend on the projectile charge q. The fragmentation was visualized using the Dalitz plots, which revealed that the (1,2,1) channel arises exclusively via concerted fragmentation, while the (2,1,1) channel also has a small contribution from sequential fragmentation.