In this paper, we experimentally investigate femtosecond laser-induced nitrogen fluorescence emission at different air pressures (0.1 Pa–100 kPa). The variation of nitrogen molecule ($N_2$) and molecular nitrogen ion ($N_2^{+}$) characteristic fluorescence spectral lines' intensity as a function of air pressure is observed. When the air pressure is between 10 Pa and 100 kPa, the intensity of fluorescence signals from $N_2^{+}$ and $N_2$ shows opposite variation as a function of air pressure. We deduce that dissociative recombination is the main pathway for the production of the $C^3{\prod }_u$ state of $N_2$. This research helps elucidate the physical emission mechanism of femtosecond laser-induced nitrogen fluorescence emission.

中文翻译：

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不同气压下飞秒激光诱导氮荧光发射

在本文中，我们通过实验研究了在不同气压（0.1 Pa-100 kPa）下飞秒激光诱导的氮荧光发射。氮分子的变化（$N_2$) 和分子氮离子 ($N_2^{+}$) 观察到作为气压函数的特征荧光谱线的强度。当气压在 10 Pa 到 100 kPa 之间时，来自$N_2^{+}$ 和 $N_2$显示出作为气压函数的相反变化。我们推断解离重组是产生$C^3{\prod }_{你}$ 的状态 $N_2$. 该研究有助于阐明飞秒激光诱导氮荧光发射的物理发射机制。