Three-body fragmentation dynamics of CH3CCH3+ investigated by 50-keV/u Ne8+ impact: Comparison with its isomer ion CH2CCH23+

Abstract

The three-body fragmentation dynamics of propyne $({\mathrm{CH}}_{3}\mathrm{C}\mathrm{C}\mathrm{H})$ to ${\mathrm{H}}^{+}$ $+$ $\mathrm{C}{\mathrm{H}}^{+}$ $+$ ${\mathrm{C}}_{2}{\mathrm{H}}_{2}{}^{+}$ and ${\mathrm{H}}^{+}$ $+$ ${\mathrm{CH}}_{2}{}^{+}$ $+$ ${\mathrm{C}}_{2}{\mathrm{H}}^{+}$ is investigated by 50-keV/u ${\mathrm{Ne}}^{8+}$ ion impact. Employing the reaction microscope, all three ionic fragments are detected in coincidence, and the momentum vector as well as kinetic energy of each fragment is obtained. By analyzing the momentum and kinetic energy correlation between different fragments, various fragmentation mechanisms are identified, and the relative ratio of each mechanism is determined. We find that the concerted fragmentation with CH and CC bonds breaking simultaneously and the sequential pathway with CH breakage prior to the CC breakage are the major contributions to both channels. In contrast, the sequential pathway with CC breakage prior to CH breakage was found to make a minor contribution only to the ${\mathrm{H}}^{+}$ $+$ $\mathrm{C}{\mathrm{H}}^{+}$ $+$ ${\mathrm{C}}_{2}{\mathrm{H}}_{2}{}^{+}$ channel. In addition, we compare the present results for ${\mathrm{CH}}_{3}\mathrm{C}\mathrm{C}\mathrm{H}$ with ${\mathrm{CH}}_{2}{\mathrm{CCH}}_{2}$ published in Ma et al. [C. Ma, S. Xu, D. Zhao, D. Guo, S. Yan, W. Feng, X. Zhu, and X. Ma, Phys. Rev. A 101, 052701 (2020)]. The location of the CH and CC bonds' breakage, either from distinct C atoms or from the same C atom, leads to similar dissociation mechanisms but different ionic fragments for the two isomers.