Fragmentation Dynamics of a Carbon Dioxide Dication Produced by Ion Impact
Hang Yuan, Shenyue Xu, Enliang Wang, Jiawei Xu, Yue Gao, Xiaolong Zhu, Dalong Guo, MA Bing-hui, Dongmei Zhao, Shaofeng Zhang, Shuncheng Yan, Ruitian Zhang, Yong Gao, Zhongfeng Xu, X. Ma
Abstract
The response of carbon dioxide to radiolysis is crucial for understanding the atmospheric chemistry of planets. Here, we present a combined experimental and theoretical investigation of the three-body fragmentation dynamics of CO22+ to C+ + O+ + O initiated by 1 keV/u Ar2+ impact. Taking advantage of the kinematic complete measurement employing a reaction microscope, three dissociation mechanisms are distinguished, and their branching ratios are determined. The concerted fragmentation with two C–O bonds breaking simultaneously is dominant, while the sequential pathway with CO+ as the intermediate also makes a significant contribution. Also, a novel isomerization pathway with transitory formation of O2+ is identified. The identified mechanisms can contribute to O+ and O escaping from the Martian atmosphere, since the kinetic energies of most of the fragments are observed to be higher than the escape energy of oxygen.