Tong Jihong, Liu Xiwang, Dong Wenhui, Jiang Wenyu, Zhu Ming, Xu Yidan, Zuo Zitan, Lu Peifen, Gong Xiaochun, Song Xiaohong, Yang Weifeng, Wu Jian
State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200241, China.
School of Science and Center for Theoretical Physics, Hainan University, Haikou 570288, China.
Phys Rev Lett. 2022 Oct 21;129(17):173201. doi: 10.1103/PhysRevLett.129.173201.
Attosecond time-resolved electron tunneling dynamics have been investigated by using attosecond angular streaking spectroscopy, where a clock reference to the laser field vector is required in atomic strong-field ionization and the situation becomes complicated in molecules. Here we reveal a resonant ionization process via a transient state by developing an electron-tunneling-site-resolved molecular attoclock in Ar-Kr^{+}. Two distinct deflection angles are observed in the photoelectron angular distribution in the molecular frame, corresponding to the direct and resonant ionization pathways. We find the electron is temporally trapped in the Coulomb potential wells of the Ar-Kr^{+} before finally releasing into the continuum when the electron tunnels through the internal barrier. By utilizing the direct tunneling ionization as a self-referenced arm of the attoclock, the time delay of the electron trapped in the resonant state is revealed to be 3.50±0.04 fs. Our results give an impetus to exploring the ultrafast electron dynamics in complex systems and also endow a semiclassical presentation of the electron trapping dynamics in a quantum resonant state.
通过阿秒角条纹光谱法研究了阿秒时间分辨电子隧穿动力学，在原子强场电离中需要一个相对于激光场矢量的时钟参考，而在分子中情况变得复杂。在此，我们通过在Ar-Kr⁺中开发一种电子隧穿位点分辨的分子阿秒时钟，揭示了一种通过瞬态的共振电离过程。在分子坐标系中的光电子角分布中观察到两个不同的偏转角，分别对应直接电离和共振电离路径。我们发现，当电子隧穿通过内部势垒时，它会暂时被困在Ar-Kr⁺的库仑势阱中，最终释放到连续态中。通过将直接隧穿电离用作阿秒时钟的自参考臂，发现被困在共振态的电子的时间延迟为3.50±0.04 fs。我们的结果为探索复杂系统中的超快电子动力学提供了动力，也为量子共振态中的电子俘获动力学提供了半经典描述。
