Observation of two sequential pathways of(CO2)3+dissociation by heavy-ion impact

Abstract

An experimental investigation of the breakup of ${(\mathrm{C}{\mathrm{O}}_{2})}^{3+}$ induced by $\mathrm{N}{\mathrm{e}}^{4+}$ ion impact at incident energies of 1.12 MeV was performed. By analyzing the momentum distributions and the kinetic energies of the three fragment ions, the nonsequential and sequential dissociation mechanisms are verified. In contrast to highly charged ion impact, two different sequential decay pathways were observed in the present experiment. One pathway originates from the primary cation ${(\mathrm{C}{\mathrm{O}}_{2})}^{3+}$ populated into $^{4}\mathrm{\ensuremath{\Sigma}}^{+}$ states by collision charge exchange and its daughter cation ${(\mathrm{CO})}^{2+}$ populated into the two excited states ($^{3}\mathrm{\ensuremath{\Pi}}$ and $X{\phantom{\rule{0.16em}{0ex}}}^{1}\mathrm{\ensuremath{\Pi}}$) by the first fragmentation step, resulting in a lower KER peak. The other pathway originates from the primary cation ${(\mathrm{C}{\mathrm{O}}_{2})}^{3+}$ locating at $^{6}\mathrm{\ensuremath{\Pi}}$ state, and its daughter cation ${(\mathrm{CO})}^{2+}$ populated into the metastable excited states $^{3}\mathrm{\ensuremath{\Pi}}$, $X{\phantom{\rule{0.16em}{0ex}}}^{1}\mathrm{\ensuremath{\Pi}}$, and $^{3}\mathrm{\ensuremath{\Sigma}}^{+}$, leading to the higher KER peak. Our work is a breakup experiment of ${(\mathrm{C}{\mathrm{O}}_{2})}^{3+}$ presenting the initial states of the parent cation ${(\mathrm{C}{\mathrm{O}}_{2})}^{3+}$ and the metastable states of $\mathrm{C}{\mathrm{O}}^{2+}$ ion simultaneously.