He Lixin, Zhang Qingbin, Lan Pengfei, Cao Wei, Zhu Xiaosong, Zhai Chunyang, Wang Feng, Shi Wenjing, Li Muzi, Bian Xue-Bin, Lu Peixiang, Bandrauk André D
Wuhan National Laboratory for Optoelectronics and School of Physics, Huazhong University of Science and Technology, 430074, Wuhan, China.
State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, 430071, Wuhan, China.
Nat Commun. 2018 Mar 16;9(1):1108. doi: 10.1038/s41467-018-03568-3.
Molecules constituted by different isotopes are different in vibrational modes, making it possible to elucidate the mechanism of a chemical reaction via the kinetic isotope effect. However, the real-time observation of the vibrational motion of isotopic nuclei in molecules is still challenging due to its ultrashort time scale. Here we demonstrate a method to monitor the nuclear vibration of isotopic molecules with the frequency modulation of high-order harmonic generation (HHG) during the laser-molecule interaction. In the proof-of-principle experiment, we report a red shift in HHG from H and D. The red shift is ascribed to dominant HHG from the stretched isotopic molecules at the trailing edge of the laser pulse. By utilizing the observed frequency shift, the laser-driven nuclear vibrations of H and D are retrieved. These findings pave an accessible route toward monitoring the ultrafast nuclear dynamics and even tracing a chemical reaction in real time.
由不同同位素构成的分子在振动模式上存在差异，这使得通过动力学同位素效应阐明化学反应机制成为可能。然而，由于分子中同位素原子核振动运动的时间尺度极短，对其进行实时观测仍然具有挑战性。在此，我们展示了一种在激光与分子相互作用过程中，通过高阶谐波产生（HHG）的频率调制来监测同位素分子核振动的方法。在原理验证实验中，我们报道了来自氢（H）和氘（D）的HHG出现红移。这种红移归因于在激光脉冲后沿伸长的同位素分子产生的主导HHG。通过利用观测到的频移，我们获取了氢和氘的激光驱动核振动。这些发现为监测超快核动力学乃至实时追踪化学反应铺平了一条可行之路。
