强场隧穿电子再碰撞动力学研究

Fundamental and exploratory research on the interaction of intense laser with matter, including ionization of highly charged ions and charged particle acceleration and vacuum polarization in extreme field and electron-positron pair production, become the most significant frontier fields of scientific research in today's physics. Ionization of atoms in intense laser fields is the basic physical processes of the interaction of intense laser with variety of complex physical forms, and show nonperturbative and multibody correlative complex dynamical behavior. In particular, tunneling electron is driven by the intense laser that recollide with its parent ion, the above process can cause many novel phenomenon, for instance, high energy above threshold ionization spectra, nonsequential multiple ionization, recombined stabilization and high-order harmonic generation .etc. The research on this topic has been central to understanding and harnessing strong field physics. This project aims to research many electron correlation effects and Coulomb focusing in the recollision process through combining theories and the latest experiment in quantum theory and semiclassical trajectory simulation. Explore possible way to probe internal electronic motion on the attosecond time scale and structural changes of atoms or molecules via recollisions. The research on recollision physics related issues not only help us understand microscopic dynamics of matter in the extreme light field, but also promote new technical developments, such as attosecond pulse generation, tomographic imaging of orbitals, new radiation sources (X-ray, neutron source) and so on.

强激光与物质相互作用涉及原子的高剥离过程、带电粒子加速乃至超强场中的真空极化及正负电子对产生，是当今物理学的重要前沿研究领域，具有很强的基础性与探索性。强激光中原子的电离过程是研究强激光与各种复杂物质形态相互作用的基础，展现出非微扰、多体关联主导的复杂动力学行为。其中，隧穿电子在强激光驱动下与母核发生再碰撞过程，将导致高能的阈上电离能谱、非序列多重电离、再俘获引起的稳定化以及高次谐波发射等新奇现象，是强场物理研究的核心问题之一。本项目旨在应用量子理论、半经典轨道模拟方法结合最新实验进展，深入研究再碰撞过程中的多电子关联效应及母核的库仑聚焦效应。探讨通过再碰撞过程探索原子分子内部阿秒尺度的电子运动及结构变化的可行方法。对相关问题的深入研究，将有助于了解极端光场中物质微观动力学机理，在阿秒脉冲产生、分子轨道层析成像以及新型辐射源（X光源、中子源）方面也有潜在应用。

隧穿电子在强激光驱动下与母核发生再碰撞过程，将导致高能的阈上电离能谱、非序列多重电离、再俘获和稳定化以及高次谐波发射等新奇现象，是强场物理研究的核心问题之一。本项目围绕这一科研热点，在发展含时薛定谔方程的求解程序，以及团簇与强激光相互作用的分子动力学程序的基础上，综合运用量子散射方法和经典轨道模拟，通过大规模数值计算，结合最新实验发现，探索了隧穿电离中的混沌散射、超低能结构、中性原子加速、库仑不对称性、光子动量分配；非序列双电离中的库仑三体问题、内壳层电子效应、关联电子热化；多聚物中的里德堡电子囚禁；小尺寸原子团簇的电离与膨胀动力学等新物理、新现象，并发展基于奇偶阶高次谐波和阿秒瞬态光吸收谱等强场与物质相互作用效应的原子、分子结构成像新方法。这些结果一方面加深了人们对极端光场中物质微观动力学机理的理解，同时在阿秒物理、精密测量等领域展现了诱人的应用前景。在项目执行期间（2013 - 2016 年），我们共发表相关SCI 论文27篇，其中包括Physical Review Letters 5 篇，Scientific Reports 2 篇，Physical Review A/E 13篇。出版中英文专著各一部 [1. Jie Liu, Classical Trajectory Perspective of Atomic Ionization in Strong Laser Fields: Semiclassical Modeling, Springer (2013); 2. 刘杰、夏勤智、傅立斌，强激光场中的原子、分子与团簇，科学出版社 (2014)]，为相关领域的进一步深入研究奠定了坚实的基础。