Kinetic energy distributions in ion-induced CO fragmentation: Signature of shallow states in multiply charged CO

Ion-induced molecular fragmentation of CO has been studied using time-of-flight mass spectroscopy with position sensitive detectors in multihit coincidence mode. Ar8+ ions having a velocity of 1.1 a.u. were used as projectiles. The features observed in the kinetic energy release (KER) spectra for all the detected fragmentation channels are discussed in light of the existing and calculated ab initio potential energy curves. The preference of the symmetric breakup over the asymmetric one is clearly observed. For fragmentation channels originating from the same parent molecular ion, it is observed that the most probable KER value is higher for the dissociation channel having a higher charge on the oxygen ion. Occurrence of sharp peaks in KER spectra of some of the fragmentation channels hints towards the existence of shallow (possibly metastable) excited states of COq+ (q=4,5) molecular ions and calls for further theoretical investigations.