华东师范大学孙真荣团队近日实现了利用多周期椭圆偏振飞秒激光脉冲探测H₂和D₂解离双电离中的超快核动力学。这一研究成果于2025年5月5日发表在《物理评论A》期刊上。

由于难以区分相邻光学周期中释放的电子，因此使用多周期椭圆偏振飞秒激光脉冲研究激光诱导H₂解离双电离中的超快核动力学颇具挑战性。在这项研究中，课题组通过使用相同的激光技术并通过与D₂的同位素对应物进行比较来克服这一局限性，从而实验性地揭示了这些动力学。

通过分析离子碎片的核间距相关总动量，研究组以亚周期时间分辨率重建了含时核运动。 此外还观察到，随着核间距的增加，第二个释放电子的动量幅度减小，这是由于瞬时激光场强和电离时刻分子离子的库仑引力的共同作用。该研究结果强调了同位素效应在阐明激光诱导分子碎裂中的超快核动力学中的关键作用。

附：英文原文

Title: Probing ultrafast nuclear dynamics in dissociative double ionization of H2 and D2 using a multicycle elliptically polarized femtosecond laser pulse

Author: Junyang Ma, Shuqi Li, Fan Yang, Yan Yang, Zhenrong Sun

Issue&Volume: 2025/05/05

Abstract: Ultrafast nuclear dynamics in laser-induced dissociative double ionization of H2 is challenging to investigate with a multicycle elliptically polarized femtosecond laser pulse due to the difficulty of distinguishing electrons released in neighboring optical cycles. In this study we experimentally reveal these dynamics by employing the same laser technique and overcoming this limitation through comparison with the isotopic counterpart of D2. By analyzing the internuclear-distance-dependent sum momentum of the ionic fragments, we reconstruct the time-dependent nuclear motions with subcycle temporal resolution. Furthermore, we observe a decrease in the momentum magnitude of the second released electron with increasing internuclear distance, attributed to the combined effects of the instantaneous laser field strength and the Coulomb attraction of the molecular ion at the moment of ionization. Our findings highlight the critical role of isotope effects in elucidating ultrafast nuclear dynamics in laser-induced molecular fragmentation.

DOI: 10.1103/PhysRevA.111.053102

Source: https://journals.aps.org/pra/abstract/10.1103/PhysRevA.111.053102