近日，吉林大学的丁大军及其研究小组与海南大学的宋晓红等人合作并取得一项新进展。经过不懈努力，他们发现阿秒角条纹中的库仑聚焦现象。相关研究成果已于2024年9月11日在国际知名学术期刊《光：科学与应用》上发表。

该研究团队通过联合实验观测与改进后的库仑修正强场近似统计模拟，研究人员发现，由于非绝热激光诱导电子隧穿所引发的先前未曾预料的库仑聚焦效应，不同初始电离时刻发射的电子会汇聚到最可能的发射角度。

研究人员揭示了库仑聚焦是导致非绝热隧穿角条纹测量中，观察到的非直观能量依赖趋势的原因，并且经典禁阻势垒下的隧穿动力学能在所得信号上留下特征印记。这项研究发现对于利用阿秒角条纹技术解码复杂的隧穿动力学具有重要意义。

据悉，角条纹技术利用接近圆偏振的激光脉冲，在光电子动量分布中建立起最大电离时刻与最可能发射角度之间的映射关系，从而能够以阿秒级的时间分辨率探测激光诱导的原子和分子中的电子动力学。

附：英文原文

Title: Coulomb focusing in attosecond angular streaking

Author: Li, Xiaokai, Liu, Xiwang, Wang, Chuncheng, Ben, Shuai, Zhou, Shengpeng, Yang, Yizhang, Song, Xiaohong, Chen, Jing, Yang, Weifeng, Ding, Dajun

Issue&Volume: 2024-09-11

Abstract: Angular streaking technique employs a close-to-circularly polarized laser pulse to build a mapping between the instant of maximum ionization and the most probable emission angle in the photoelectron momentum distribution, thereby enabling the probe of laser-induced electron dynamics in atoms and molecules with attosecond temporal resolution. Here, through the jointed experimental observations and improved Coulomb-corrected strong-field approximation statistical simulations, we identify that electrons emitted at different initial ionization times converge to the most probable emission angle due to the previously-unexpected Coulomb focusing triggered by the nonadiabatic laser-induced electron tunneling. We reveal that the Coulomb focusing induces the observed nonintuitive energy-dependent trend in the angular streaking measurements on the nonadiabatic tunneling, and that tunneling dynamics under the classically forbidden barrier can leave fingerprints on the resulting signals. Our findings have significant implications for the decoding of the intricate tunneling dynamics with attosecond angular streaking.

DOI: 10.1038/s41377-024-01600-4

Source: https://www.nature.com/articles/s41377-024-01600-4