ABSTRACT

We studied the dynamic evolution of the rotational states by measuring the laserlike narrow-bandwidth coherent radiation of ${\mathrm{N}}_2^{+}$ from ${\mathrm{N}}_2^{+}\left({\mathrm{B}}^2{\mathrm{\Sigma }}_{\mathrm{u}}^{+}\right)$ to ${\mathrm{N}}_2^{+}\left({\mathrm{X}}^2{\mathrm{\Sigma }}_{\mathrm{g}}^{+}\right)$. The coexistence of radiation and absorption was observed when the ratio of population in the ${\mathrm{N}}_2^{+}\left({\mathrm{B}}^2{\mathrm{\Sigma }}_{\mathrm{u}}^{+}\right)$ and ${\mathrm{N}}_2^{+}\left({\mathrm{X}}^2{\mathrm{\Sigma }}_{\mathrm{g}}^{+}\right)$ states is around unity. The absorption turns up on the blue side of the radiation with a time delay of 250 fs. Based on a semiclassical radiation and absorption model, it was found that the fast rotational temperature evolution, determining the population distribution on the rotational states, holds the key to understand this behaviour.

中文翻译：

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旋转激发氮分子离子中辐射和吸收的意外共存

摘要

我们通过测量类似激光的窄带宽相干辐射来研究旋转状态的动态演化。 ${\mathrm{ñ}}_{\mathrm{2个}}^{+}$ 从 ${\mathrm{ñ}}_{\mathrm{2个}}^{+}（{\mathrm{乙}}^{\mathrm{2个}}{\mathrm{\Sigma }}_{\mathrm{ü}}^{+}）$ 至 ${\mathrm{ñ}}_{\mathrm{2个}}^{+}（{\mathrm{X}}^{\mathrm{2个}}{\mathrm{\Sigma }}_{\mathrm{G}}^{+}）$。当人体中的人口比例时，观察到了辐射与吸收共存。${\mathrm{ñ}}_{\mathrm{2个}}^{+}（{\mathrm{乙}}^{\mathrm{2个}}{\mathrm{\Sigma }}_{\mathrm{ü}}^{+}）$ 和 ${\mathrm{ñ}}_{\mathrm{2个}}^{+}（{\mathrm{X}}^{\mathrm{2个}}{\mathrm{\Sigma }}_{\mathrm{G}}^{+}）$国家是团结的。吸收在辐射的蓝色面上以250 fs的时间延迟打开。基于半经典的辐射和吸收模型，发现旋转温度的快速演变决定了旋转状态下的总体分布，这是理解这种行为的关键。