Tong Aihong, Li Qianguang, Ma Xiaomeng, Zhou Yueming, Lu Peixiang
Opt Express. 2019 Mar 4;27(5):6415-6425. doi: 10.1364/OE.27.006415.
Using the classical ensemble method, we have investigated the alignment dependence of the correlated electron dynamics in strong-field nonsequential double ionization (NSDI) of diatomic molecules driven by linearly polarized laser pulses. Our numerical results show that the correlated electron pairs are more likely to emit into the same hemisphere (side-by-side emission) for the parallel aligned molecules at the small internuclear distance, in agreement with previous experimental results. Surprisingly, as the internuclear distance increases, this side-by-side emission is more prevalent for the perpendicularly aligned molecules. Back analyzing of the classical trajectories shows that a considerable part of the NSDI events for the parallel aligned molecules at the large internuclear distances occur through an internal collision, not the well-known recollision. In the internal collision induced NSDI, the first electron tunnels through the inner barrier from the up-field core, moves directly towards the other core, and kicks out the second electron. For this type of NSDI events, the electron pairs are more likely to emit into the opposite hemispheres and thus the correlated electron momentum spectrum exhibits a more dominant back-to-back behavior in the parallel aligned molecules.
利用经典系综方法，我们研究了线性偏振激光脉冲驱动下双原子分子强场非序列双电离（NSDI）中关联电子动力学的取向依赖性。我们的数值结果表明，对于小核间距的平行取向分子，关联电子对更有可能发射到同一半球（并排发射），这与先前的实验结果一致。令人惊讶的是，随着核间距增加，这种并排发射在垂直取向分子中更为普遍。对经典轨迹的反向分析表明，大核间距时平行取向分子的NSDI事件相当一部分是通过内部碰撞发生的，而非众所周知的再碰撞。在内部碰撞诱导的NSDI中，第一个电子从上场核心隧穿内层势垒，直接向另一个核心移动，并踢出第二个电子。对于这类NSDI事件，电子对更有可能发射到相反半球，因此关联电子动量谱在平行取向分子中表现出更占主导的背对背行为。
