亚周期非偶极隧穿电离超快动力学研究

Recent applications of novel light sources and advances in coincident detection technology makes it possible to clearly observe the transfer of photon momentum to the departing electron in the ultrafast ionization process due to the breakdown of dipole approximation. As such, nondipole atomic ionization has become a heated topic lately. However, present studies are limited to the integral effect of the entire ionizing pulse, lacking a subcycle resolution of the ultrafast photon momentum transfer dynamics. The current project aims to study the nondipole transfer of photon momentum on the subcycle scale using the mid-infrared attoclock technique and the backpropagation method, as well as the relative contribution of different Hamiltonian terms to the nondipole effect. This project represents the first in the field to resolve the photon momentum transfer on the subcycle scale. We aim to establish the corresponding theory, which promises to illustrate more clearly the principle of photon momentum transfer in the laser field.

得益于新光源的应用以及电子离子符合探测分辨率的不断提高，超快电离过程中由非偶极效应引起的光子动量传递已经可以清晰分辨，于是非偶极电离成为最近的研究热点。然而，目前对于光子动量传递的研究仅限于电离脉冲的整体效应，而缺乏亚周期超快动力学过程研究。本项目拟采用反向演化方法结合中红外阿秒钟技术在亚周期时间尺度下研究非偶极隧穿电离超快动力学过程，并探索不同哈密顿项对于非偶极效应的贡献。本项目是首个对非偶极光子动量传递效应亚周期超快动力学过程的研究，将建立相应理论，有望更清晰地阐述激光场中光子动量传递物理过程的基本原理。

在光与物质相互作用的过程中，光不仅传递能量给物质，还同时传递动量给物质，而其传递动量的过程是由非偶极效应引起的。在传统的非偶极强场隧穿电离研究中，人们往往仅考虑整个光脉冲的线性动量传递，而缺乏在光场亚周期尺度上细致的光场动量传递过程研究。本项目围绕亚周期超快时间尺度上的非偶极隧穿电离动力学过程，开展了一系列相关研究，包括：建立了非偶极光场动量传递过程的亚周期尺度理论，发现了隧穿电离过程中非偶极非绝热耦合效应，分离了电子在不同运动阶段的光场动量传递，分离了不同非偶极哈密顿项贡献的动量传递，系统研究了包括非偶极效应在内的多种效应对阿秒钟信号的影响，发现了由大角度散射引起的高阶阈上电离信号中的非常规非偶极动量传递极小值等。在本项目资助下发表论文10篇，包括3篇Physical Review Letters，1篇Physical Review X，1篇Journal of Physical Chemistry Letters，1篇Advanced Photonics等。