We report an experimental investigation of three-body fragmentation of ${{\mathrm{CO}}_2}^{2+}$ into ${\mathrm{C}}^{+}+{\mathrm{O}}^{+}+\mathrm{O}$ induced by 1 MeV/u ${\mathrm{C}}^{4+}$ ions using a cold-target recoil-ion momentum spectroscopy. With ion-ion coincidence measurement, the ${\mathrm{C}}^{+}+{\mathrm{O}}^{+}$ ion pair is identified. By taking advantage of the differences in momentum correlations among fragments from ${{\mathrm{CO}}_2}^{2+}$ and those from ${{\mathrm{CO}}_2}^{q+}$ $(q\ge 3)$, we are able to disentangle the contributions from ${{\mathrm{CO}}_2}^{2+}$. Consequently, the kinetic energy release (KER) distribution for the channel ${{\mathrm{CO}}_2}^{2+}\to {\mathrm{C}}^{+}+{\mathrm{O}}^{+}+\mathrm{O}$ is determined and compared with the available experimental and theoretical data. By filtering the events using an energy correlation map, the linear and molecular bending concerted fragmentation mechanisms, as well as the sequential fragmentation mechanism with ${\mathrm{CO}}^{+}$ as the intermediate, are identified with the aid of the kinetic energy distributions of the fragments and the Dalitz plots, and their relative branching ratios are evaluated. The linear concerted fragmentation with higher KER values was not observed in previous study of slow ion collisions. This difference indicates that the projectile velocity has a strong influence on the molecular fragmentation dynamics.

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• Atomic & molecular collisions