We experimentally investigated the delayed fragmentation processes of ethylene and allene dications induced by 300-eV electrons with the cold target recoil ion momentum spectroscopy in an observation window up to ∼2 μs. For each molecule, several distinct pathways involving prompt or delayed fragmentations were observed and relative branching ratios among them were analyzed. According to the time-of-flight coincidence measurements of corresponding recoil ionic fragments, the survival times and thus lifetimes from nanoseconds to microseconds of different delayed-dissociative precursor dications were retrieved. Besides the two-body channels, i.e., ${\mathrm{H}}^{+}+{\mathrm{C}}_2{{\mathrm{H}}_3}^{+}$ and ${\mathrm{H}}^{+}+{\mathrm{C}}_3{{\mathrm{H}}_3}^{+}$, the delayed deprotonation was also observed in many-body channels, i.e., $\mathrm{H}+{\mathrm{H}}^{+}+{\mathrm{C}}_n{{\mathrm{H}}_2}^{+}$ ($n=2$, 3) and $2\mathrm{H}/{\mathrm{H}}_2+{\mathrm{H}}^{+}+{\mathrm{C}}_3{\mathrm{H}}^{+}$. The lifetimes of the metastable intermediate diacations ${\mathrm{C}}_n{{\mathrm{H}}_3}^{2+}$ and ${\mathrm{C}}_3{{\mathrm{H}}_2}^{2+}$ were estimated.

中文翻译：

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电子撞击引起的乙烯和丙二烯的延迟裂解

我们通过冷目标反冲离子动量谱在不超过2μs的观察窗内实验性地研究了300 eV电子诱导的乙烯和亚丙基指示剂的延迟裂解过程。对于每个分子，观察到了涉及迅速或延迟断裂的几种不同途径，并分析了其中的相对分支比。根据相应反冲离子碎片的飞行时间重合测量，可以获取不同延迟解离性前体指示物的生存时间，以及从纳秒到微秒的寿命。除了两体通道，即${\mathrm{H}}^{+}+{\mathrm{C}}_2{{\mathrm{H}}_3}^{+}$ 和 ${\mathrm{H}}^{+}+{\mathrm{C}}_3{{\mathrm{H}}_3}^{+}$，在多体通道中也观察到了延迟的去质子化，即 $\mathrm{H}+{\mathrm{H}}^{+}+{\mathrm{C}}_{ñ}{{\mathrm{H}}_2}^{+}$ （$ñ=2$，3）和 $2\mathrm{H}/{\mathrm{H}}_2+{\mathrm{H}}^{+}+{\mathrm{C}}_3{\mathrm{H}}^{+}$。亚稳中间晶状体的寿命${\mathrm{C}}_{ñ}{{\mathrm{H}}_3}^{2+}$ 和 ${\mathrm{C}}_3{{\mathrm{H}}_2}^{2+}$ 被估计。