He Lixin, Sun Siqi, Lan Pengfei, He Yanqing, Wang Bincheng, Wang Pu, Zhu Xiaosong, Li Liang, Cao Wei, Lu Peixiang, Lin C D
Wuhan National Laboratory for Optoelectronics and School of Physics, Huazhong University of Science and Technology, 430074, Wuhan, China.
Optical Valley Laboratory, 430074, Hubei, China.
Nat Commun. 2022 Aug 6;13(1):4595. doi: 10.1038/s41467-022-32313-0.
Electron migration in molecules is the progenitor of chemical reactions and biological functions after light-matter interaction. Following this ultrafast dynamics, however, has been an enduring endeavor. Here we demonstrate that, by using machine learning algorithm to analyze high-order harmonics generated by two-color laser pulses, we are able to retrieve the complex amplitudes and phases of harmonics of single fixed-in-space molecules. These complex dipoles enable us to construct movies of laser-driven electron migration after tunnel ionization of N and CO molecules at time steps of 50 attoseconds. Moreover, the angular dependence of the migration dynamics is fully resolved. By examining the movies, we observe that electron holes do not just migrate along the laser polarization direction, but may swirl around the atom centers. Our result establishes a general scheme for studying ultrafast electron dynamics in molecules, paving a way for further advance in tracing and controlling photochemical reactions by femtosecond lasers.
分子中的电子迁移是光与物质相互作用后化学反应和生物功能的起源。然而，追踪这种超快动力学过程一直是一项长期的努力。在此，我们证明，通过使用机器学习算法分析双色激光脉冲产生的高次谐波，我们能够获取固定在空间中的单个分子谐波的复振幅和相位。这些复偶极矩使我们能够以50阿秒的时间步长构建N和CO分子在隧道电离后激光驱动电子迁移的动态图像。此外，迁移动力学的角度依赖性也得到了充分解析。通过观察这些动态图像，我们发现电子空穴并不只是沿着激光偏振方向迁移，而是可能围绕原子中心旋转。我们的结果建立了一种研究分子中超快电子动力学的通用方案，为利用飞秒激光进一步追踪和控制光化学反应铺平了道路。
