Vibrational excitation of hydrogen molecules by two-photon absorption and third-harmonic generation
Vibrational excitation of hydrogen molecules by two-photon absorption and third-harmonic generation
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双光子吸收和三次谐波产生氢分子的振动激发
DOI：
10.1088/1361-6455/aa9782
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发表时间：
2017
期刊：
影响因子：
--
通讯作者：
Yoshimura Motohiko
中科院分区：
文献类型：
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作者：
Miyamoto Yuki;Hara Hideaki;Hiraki Takahiro;Masuda Takahiko;Sasao Noboru;Uetake Satoshi;Yoshimi Akihiro;Yoshimura Koji;Yoshimura Motohiko
本文报道了双光子吸收对氢分子振动态的相干激发和由此产生的三次谐波（THG）。用4.8 μm的中红外纳秒脉冲辐照液氮冷却的对氢分子，其线宽接近傅立叶变换限制。准氢的第一激发态由中红外光子的双光子吸收填充。由于中红外脉冲的线宽较窄，基态和激发态之间的相干性足以诱发高阶过程。在1.6 μm处观察到THG的近红外光子。确定了近红外辐射强度与中红外脉冲能量、靶压和细胞长度的关系。我们在考虑实际实验条件的情况下，使用了一个简单的THG公式来解释观测结果。
We report the coherent excitation of the vibrational state of hydrogen molecules by two-photon absorption and the resultant third-harmonic generation (THG). Parahydrogen molecules cooled by liquid nitrogen are irradiated by mid-infrared nanosecond pulses at 4.8 μm with a nearly Fourier-transform-limited linewidth. The first excited vibrational state of parahydrogen is populated by two-photon absorption of the mid-infrared photons. Because of the narrow linewidth of the mid-infrared pulses, coherence between the ground and excited states is sufficient to induce higher-order processes. Near-infrared photons from the THG are observed at 1.6 μm. The dependence of the intensity of the near-infrared radiation on mid-infrared pulse energy, target pressure, and cell length is determined. We used a simple formula for THG with consideration of realistic experimental conditions to explain the observed results.