Electron migration in molecules is crucial for chemical reactions and biological functions after light-matter interaction. This study demonstrates the retrieval of complex amplitudes and phases of harmonics from single fixed-in-space molecules using machine learning analysis of high-order harmonics generated by two-color laser pulses. This allows for the construction of movies of laser-driven electron migration in N2 and CO2 molecules at 50-attosecond time steps, resolving angular dependence. The observed electron hole migration shows swirling patterns around atom centers, not just along the laser polarization direction. This work establishes a general scheme for studying ultrafast electron dynamics in molecules and controlling photochemical reactions.

Lixin He, Siqi Sun, Pengfei Lan, Yanqing He, Bincheng Wang, Pu Wang, Xiaosong Zhu, Liang Li, Wei Cao, Peixiang Lu, C. D. Lin