基于强激光场调控的关联电子动力学操控研究

Double ionization (DI) of atoms and molecules is one of the most interesting phenomena in strong-field physics as it involves the correlated motion of two electrons. Detailed understanding of the correlated electron dynamics driven by the strong laser field is essential to extend people’s knowledge on laser-matter interaction and the concepts of attosecond physics to many-body microscopic systems. The recent research has demonstrated that, the emitted electronic signal carries abundant structural information about the structure of the target. Therefore, the ultrafast dynamics control of correlated electrons from DI and the structural detection of the target can be achieved by analyzing and manipulative electron dynamics. In this project, we choose the typical and relatively stable atoms of inert gases and diatomic molecules as the target, and investigate the correlated electron dynamics in strong-field DI of atoms and molecules by solving the time-dependent Schrödinger equation. Firstly, we investigate the atto-second collision dynamics of correlated electrons from strong-field DI of the atoms and the homonuclear and heteronuclear diatomic molecules，analyze the difference of the atto-second collision dynamics of correlated electron from DI for different target structures. Then we explore the influences of the laser pulse duration, intensity, wavelength and carrier-envelope phase on the dynamics of the two correlated electrons from strong-field DI. We evaluate the contribution of the different ionization channels to DI, and analyze the relevant physical nature. Finally, on the basis of preceding researches, we can determine the suitable laser parameters to manipulate and control the dynamics of the correlated electron using the tailored laser fields via the phase of ionization time and recollision probability of the returned electronic wave packet.

强激光场原子分子非次序双电离中的电子对表现出很强的关联效应，因而强场双电离研究对人们进一步认识强场物理过程，深入了解微观世界中阿秒时间尺度的电子关联动力学的物理本质有重要意义。最新的研究结果显示，强场双电离发射电子信号携带丰富的靶核结构信息，通过裁剪激光场，对双电离电子信号进行分析和调控，不但有望实现对关联电子动力学的操控，还能够实现对靶核结构的探测。因此，本项目拟选用具有代表性的原子和双原子分子为研究对象，利用数值求解含时薛定谔方程量子理论方法，开展强场原子分子双电离过程中电子关联动力学研究。首先研究靶核结构对电子对关联动力学的影响，分析不同靶核双电离过程中电子关联特性的差异。随后探索激光脉宽、强度、波长和载波包络相位等可控激光参数对关联电子动力学细节的影响，并评估不同电离通道对双电离产率的贡献及其物理本质。最后通过调控电离时间相位和回复电子波包，实现对关联电子超快动力学的精确操控。

强激光场中原子分子非次序双电离是强场物理学的一个基础且重要的非线性现象。由于电子表现出很强的电子关联，因而开展强场原子分子双电离研究有助于人们更加直观和深入的认识微观动力学过程的物理本质。项目按照预定计划和目标开展，我们重点进行了三个方面的研究：1）研究了椭圆偏振激光脉冲驱动下原子非次序双电离。指出椭偏光下总的双电离概率几乎不随载波包络相位的增大而改变；关联电子沿激光偏振平面长轴方向和短轴方向的动量谱均强烈的依赖于载波包络相位；关联电子沿激光偏振平面长轴方向的动量谱呈现出明显的V型结构，进一步的研究表明，该结构是由母核离子与电子以及电子与电子之间的库仑作用共同导致。2）提出鉴别非次序双电离中短轨道贡献和长轨道贡献的两种可行实验方案。方案一：利用非次序双电离对few-cycle激光脉冲载波包络相位的依赖鉴别短轨道和长轨道的贡献；方案二：利用不同脉宽的few-cycle的椭偏光，测量非次序双电离对载波包络相位的依赖。这两种方案在实验上都是容易实现，从而为人们从实验上研究关联电子微观动力学过程提供了重要途径。3）探索并解释了中红外激光脉冲驱动的原子非次序双电离的微观动力学过程。通过比较近红外激光和中红外激光的结果，发现中红外激光下，有效的再碰撞过以第二次返回轨迹为主，而在近红外激光下，有效的再碰撞主要发生在第一个电子的第一次返回轨迹。提出中红外激光下两电子再碰撞过程中能量不均匀共享行为是非常普遍的现象，并且这种不均匀共享程度强烈的依赖于激光强度，从而导致关联电子沿激光偏振方向的动量谱强烈的依赖于激光强度。