近日，华中科技大学的陆培祥&周月明及其研究小组与瑞士苏黎世联邦理工学院的Meng Han等人合作并取得一项新进展。经过不懈努力，他们揭示阿秒分辨非偶极子光电离动力学。相关研究成果已于2024年1月10日在国际知名学术期刊《自然—光子学》上发表。

该研究团队将阿秒时间分辨光谱学引入非偶极相互作用体系。研究人员利用氦原子的自参考阿秒光电子干涉测量法，研究了在近红外激光场磁分量驱动下，氦原子在15pm范围内的电子亚周期运动。此外，他们还测量了电偶极子和电四极子跃迁之间的时间延迟为15±10as，并以阿秒分辨率解析了光电子正反向产率的不对称性。这些基本发现得到了基于非偶极子时变薛定谔方程的从头计算的支持。

据悉，光与物质之间的相互作用通常在电偶极子近似中描述。这种方法忽略了磁场分量和光电场在相关电子长度尺度上的空间变化。从红外到软X射线域，光电离过程中的非偶极子效应相对较小。迄今为止，所有关于非偶极子的观测都局限于单脉冲、单色测量。

附：英文原文

Title: Attosecond-resolved non-dipole photoionization dynamics

Author: Liang, Jintai, Han, Meng, Liao, Yijie, Ji, Jia-bao, Leung, Chung Sum, Jiang, Wei-Chao, Ueda, Kiyoshi, Zhou, Yueming, Lu, Peixiang, Wrner, Hans Jakob

Issue&Volume: 2024-01-10

Abstract: Light–matter interactions are usually described within the electric-dipole approximation, where the magnetic-field component and the spatial variation of the light electric field over the relevant electronic length scales are both ignored. Non-dipole effects in photoionization were revealed to be tiny from the infrared to the soft X-ray domains, and all non-dipole observations reported so far were limited to single-pulse, single-colour measurements. Here we advance attosecond time-resolved spectroscopy into the non-dipole interaction regime. Using a self-referenced attosecond photoelectron interferometry on helium atoms, we resolve the electron subcycle motion along the light propagation direction in the 15pm range driven by the magnetic component of a near-infrared laser field. Furthermore, we measure a time delay of 15±10as between the electric-dipole and electric-quadrupole transitions by resolving the asymmetry of the photoelectron forward–backward yields with attosecond resolution. These fundamental findings are supported by ab initio calculations based on the non-dipole time-dependent Schrdinger equation.

DOI: 10.1038/s41566-023-01349-z

Source: https://www.nature.com/articles/s41566-023-01349-z