Three-body-fragmentation dynamics ofCO24+investigated by electron collisions at an impact energy of 500 eV

Abstract

Fragmentation of ${\text{CO}}_{2}{}^{4+}$ induced by electron impact at the energy of 500 eV is studied using a momentum imaging spectrometer. It is found that ${\text{CO}}_{2}{}^{4+}$ decays mainly through two three-body-fragmentation channels: ${\mathrm{CO}}_{2}{}^{4+}\ensuremath{\rightarrow}{\mathrm{O}}^{+}+{\mathrm{C}}^{2+}+{\mathrm{O}}^{+}$ (121) and ${\mathrm{CO}}_{2}{}^{4+}\ensuremath{\rightarrow}{\mathrm{O}}^{2+}+{\mathrm{C}}^{+}+{\mathrm{O}}^{+}$ (211). The fragmentation dynamics of these two channels are analyzed using Dalitz plots and Newton diagrams. In channel (121) ${\text{CO}}_{2}{}^{4+}$ dissociates mainly through linear and molecular bending fragmentation, while the asynchronous breakup mechanism dominates channel (211). The distributions of momentum correlation angles between ionic fragments and the kinetic energy releases are obtained. Based on the Coulomb explosion model, the bond angle and the bond length of ${\text{CO}}_{2}{}^{4+}$ before fragmentation are reconstructed. The experimental most probable values of the O-C-O bond angle are ${172}^{\ensuremath{\circ}}$ and ${171}^{\ensuremath{\circ}}$ for channel (121) and (211), which agree quite well with that of the neutral ${\text{CO}}_{2}$ molecule $(172.{5}^{\ensuremath{\circ}})$. The reconstructed values of C-O bond length, $1.20 \text{\AA{}}$ and $1.13 \text{\AA{}}$ from channel (121) and channel (211), are also inconsistent with the equilibrium value of the neutral ${\text{CO}}_{2}$ molecule (1.16 \AA{}).