We report on an investigation on the fragmentation dynamics of $\mathrm{C}{{\mathrm{F}}_4}^{q+}$ $(q=2,3)$ induced by 1-keV electron collisions utilizing an ion momentum imaging spectrometer. From the time-of-flight correlation maps five dominating dissociation channels of $\mathrm{C}{{\mathrm{F}}_4}^{2+}$ as well as one three-body fragmentation channel of $\mathrm{C}{{\mathrm{F}}_4}^{3+}$ are identified. The kinetic energy release (KER) distributions for these channels are obtained and compared with the data available in the literature. The Dalitz-like momentum diagram and the Newton diagram are employed to analyze the breakup mechanism in the three-body fragmentation channel. We found that, for $\mathrm{C}{{\mathrm{F}}_4}^{2+}$ dissociation into ${\mathrm{F}}^{+}+\mathrm{C}{{\mathrm{F}}_2}^{+}+\mathrm{F}$, ${\mathrm{F}}^{+}+\mathrm{C}{\mathrm{F}}^{+}+2\mathrm{F}$, and ${\mathrm{F}}^{+}+{\mathrm{F}}^{+}+{\mathrm{CF}}_2$, the concerted breakup is the dominating process. Channel ${\mathrm{C}}^{+}+{\mathrm{F}}^{+}+3\mathrm{F}$ is dominated by the initial charge separation, i.e., $\mathrm{C}{{\mathrm{F}}_4}^{2+}\to {\mathrm{F}}^{+}+\mathrm{C}{\mathrm{F}}^{+}+2\mathrm{F}\to {\mathrm{C}}^{+}+{\mathrm{F}}^{+}+3\mathrm{F}$. With the help of the native frame method, we assigned one sequential pathway and two concerted pathways for channel $\mathrm{C}{{\mathrm{F}}_4}^{3+}\to {\mathrm{F}}^{+}+{\mathrm{F}}^{+}+\mathrm{C}{{\mathrm{F}}_2}^{+}$. The branching ratios of these pathways are determined. The momentum correlation of the fragments and the deduced KER distribution indicate that different excited states of $\mathrm{C}{{\mathrm{F}}_4}^{3+}$ with different geometries are responsible for these three pathways. The Coulomb explosion model simulation shows that most of the events in this channel are produced by $\mathrm{C}{{\mathrm{F}}_4}^{3+}$ ions that have deformed geometries from the neutral ${\mathrm{CF}}_4$ molecule.

中文翻译：

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1-keV电子碰撞引起的CF4q+(q=2,3)碎裂

我们报告了关于碎片化动态的调查 $\mathrm{C}{{\mathrm{F}}_4}^{q+}$ $(q=2,3)$由使用离子动量成像光谱仪的 1-keV 电子碰撞引起。从飞行时间相关图可以看出五个主要的解离通道$\mathrm{C}{{\mathrm{F}}_4}^{2+}$ 以及一个三体碎片通道 $\mathrm{C}{{\mathrm{F}}_4}^{3+}$被识别。获得这些通道的动能释放 (KER) 分布，并与文献中可用的数据进行比较。采用类Dalitz动量图和牛顿图分析三体碎裂通道中的破裂机制。我们发现，对于$\mathrm{C}{{\mathrm{F}}_4}^{2+}$ 分解成 ${\mathrm{F}}^{+}+\mathrm{C}{{\mathrm{F}}_2}^{+}+\mathrm{F}$, ${\mathrm{F}}^{+}+\mathrm{C}{\mathrm{F}}^{+}+2\mathrm{F}$， 和 ${\mathrm{F}}^{+}+{\mathrm{F}}^{+}+{\mathrm{CF}}_2$，协同分手是主导过程。渠道${\mathrm{C}}^{+}+{\mathrm{F}}^{+}+3\mathrm{F}$ 由初始电荷分离支配，即， $\mathrm{C}{{\mathrm{F}}_4}^{2+}\to {\mathrm{F}}^{+}+\mathrm{C}{\mathrm{F}}^{+}+2\mathrm{F}\to {\mathrm{C}}^{+}+{\mathrm{F}}^{+}+3\mathrm{F}$. 在原生框架方法的帮助下，我们为通道分配了一个顺序路径和两个协调路径$\mathrm{C}{{\mathrm{F}}_4}^{3+}\to {\mathrm{F}}^{+}+{\mathrm{F}}^{+}+\mathrm{C}{{\mathrm{F}}_2}^{+}$. 确定这些途径的支化率。碎片的动量相关性和推导出的 KER 分布表明不同激发态的$\mathrm{C}{{\mathrm{F}}_4}^{3+}$不同的几何形状负责这三种途径。库仑爆炸模型模拟表明，该通道中的大部分事件是由$\mathrm{C}{{\mathrm{F}}_4}^{3+}$ 具有中性变形几何形状的离子 ${\mathrm{CF}}_4$ 分子。