Ionic fragmentation of the CO molecule by impact of 10-keV electrons: Kinetic-energy-release distributions

Abstract

The ionic fragmentation of a multiply charged CO molecule is studied under impact of 10-keV electrons using recoil-ion momentum spectroscopy. The kinetic-energy-release distributions for the various fragmentation channels arising from the dissociation of CO${}^{q+}$ ($q$ = 2--4) are measured and discussed in light of theoretical calculations available in the literature. It is observed that the present kinetic-energy-release values are much smaller than those predicted by the Coulomb explosion model. The kinetic-energy-release distribution for the C${}^{+}$+O${}^{+}$ channel is suggested to arise from the tunneling process. It is seen that the peak of kinetic-energy-release distribution is larger for that dissociation channel that arises from the same molecular ion which has higher charge on the oxygen atom. Further, the relative ionic fractions for seven ion species originating from ionization and subsequent dissociation of the CO molecule are obtained and compared with the existing data reported at low energy of the electron impact. The precursor-specific relative partial ionization cross sections are also obtained and shown to be about 66.4$%$ from single ionization, 29.9$%$ from double ionization, 3.3$%$ from triple ionization, and about 0.4$%$ from quadruple ionization of the precursor CO molecule contributing to the total fragment ion yield.