强激光场诱导负离子中电子重碰撞激发及相关物理过程

Due to the significant differences in structure and character between anion and neutral atom and molecule, such as the short-range Coulomb potential and the low binding energy of the additional electron and the strong electron-electron correlations, the interaction between anion with intense fields is quite different from that with neutral atom and molecule, of which the physical mechanism are still currently unclear, requiring to perform further studies to reveal it. This proposal is aimed at the electron rescatter excitation and the related physical processes of anions which are induced by the strong laser fields. Using the fluorescence spectrum, we will detect the neutral excited atoms which are produced by anions from electron rescatter excitation, thus to measure the yield and dependence on laser parameters of atoms in different excited states, , and to analyse the influence factors of the electron rescatter process in strong laser field, and further to control the electron rescatter excitation; We will study the anionic detachment and double ionization by the time of flight mass spectrum, and compare it with fluorescence spectra. The purpose of the proposal is to study the dynamics and mechanism of electron rescatter excitation of anions in strong laser field, and then compared with other strong field physical processes, to clarify the important role and status of electron rescatter in these anionic strong field physical processes, therefore to add more understanding about the characteristics of anions in strong laser field, and to advance development of relevant theoretical methods, and further to improve the cognition of complex atomic and molecular processes in strong laser field.

负离子具有与中性原子分子显著不同的结构和特性，如额外电子的短程库伦势，较低的电子亲和能以及不可忽略的电子关联作用等，使得负离子的强场物理过程与中性原子分子明显不同，其内在的物理机制还不清楚，亟需进一步的研究予以揭示。本项目针对激光诱导的负离子中电子重碰撞激发及其相关物理过程进行研究。利用荧光光谱检测负离子在强激光场中所形成的中性激发态原子，测量不同量子态的产率及其对激光参数的依赖关系，分析影响强激光场中负离子电子重碰撞几率的因素，进而调控负离子的碰撞激发过程；使用飞行时间质谱研究负离子的强场解吸附和双电离，并与荧光光谱比对研究。项目旨在研究负离子在强激光场中的碰撞激发的机制及其动力学过程，并与其它强场物理过程相比较，明确电子重碰撞过程在负离子强场物理中的作用和地位，加深对负离子强场特性的理解，推动相关理论的发展，提升对强场中复杂的原子分子过程的认知。

负离子在飞秒激光场中的强场物理过程，是当前原子分子光物理的研究前沿和热点之一。项目执行期间，我们搭建并优化了一套负离子飞行时间质谱，并研究了电子与分子的碰撞过程，制备了纯净、高效的负离子源；在计算分子负离子的几何结构、稳定性和势能曲线等方面开展了一些工作。同时，还实验研究了原子分子在飞秒激光场下的电离，双电离，激发及其辐射等强场物理现象，分析了光电子重散射在其中的重要地位和作用，加深了对飞秒光场中强场物理过程的理解。研究成果在包括The Journal of Physical Chemistry A，Chemical Physics Letters, Chinese Physics B 等原子与分子物理和化学物理领域知名学术期刊上发表 SCI 收录论文6篇。项目负责人多次在国内学术会议上做学术报告，受到了国内外同行的关注。项目执行期间，协助培养获博士学位研究生1名，协助培养硕士学位研究生6名。项目研究提升了我们对强场物理现象的理解，也为进一步的深入研究打下坚实的基础。.项目取得的主要成果如下：.1，搭建了一套负离子飞行时间质谱，研究了电子与分子的碰撞过程，优化了负离子的产率，获得了高效、纯净的负离子源。.2，理论计算了分子负离子的几何结构、光谱常数、电子亲合能以及势能曲线等，指认了负离子中特殊存在的偶极束缚态，研究了负离子的稳定性。.3，实验研究了原子分子在飞秒激光场下的电离、双电离、激发及其辐射等，分析了准直效应、分子结构效应在强场过程中的影响，通过改变激光波长，发现了双电离机制的反常变化，研究了激光参数对电子重散射的影响，明确了光电子重散射在强场物理过程中的重要地位和作用。