H2+在椭圆/圆偏振强激光场中光电子能谱低能结构研究

Observation and steering of electronic dynamics by ultrashort intense laser pulse is one of the frontier scientific issues. The research of interaction between H2+ and elliptically or circularly polarized laser is an important part of strong field physics, however, because of the complexity of molecule potential and diversification of laser polarization direction, this examination is very hard in either experiment or theory. In this project, we will study the interaction using accurate quantum method, and choose the H2+ as the target molecule. First, the model is established with accurate H2+ potential, the wave function is described by Sine-DVR basis functions and propagated by second-order split-operator, and the Wigner rotation technique is introduced. Then, the electronic dynamics are investigated. Including: the mechanism and property of low energy structure; the influence of resonance states to ionization; the mechanism of tunneling and multiphoton ionization. Then we can understand the process of electronic dynamics, and this research gives the fundamental basis for understanding the ionization of complex molecules.

用超短强激光脉冲探测和控制原子分子中电子的运动是当前的科学前沿问题之一，其中H2+与椭圆/圆偏振强激光场相互作用的研究是强场物理领域的重要原型物理体系。但是，分子势的复杂性和椭圆/圆偏振激光偏振方向的引入，使得分子与激光场的相互作用变为一个高维的复杂体系，其光电子能谱低能结构的精确量子力学计算非常困难。本项目拟引入H2+的精确三维势能面，用Sine-DVR基描述波函数，采用二阶分裂算符传播波函数，传播过程中引入Wigner旋转技术加速三维动力学演化计算时间，由演化波函数得到在精确分子势条件下的光电子能谱低能结构性质，即椭圆/圆偏振强激光场作用下H2+中光电子能谱低能结构的产生机理与特性，共振电子态对电离的影响，以及分子中隧穿电离与多光子电离的机理。本项目为研究更为复杂分子的强场电离过程特别是光电子能谱低能结构提供准确的物理机制。

本项目研究了原子或分子在椭圆/圆偏振强激光场中的电离现象。研究内容包括光电子的能谱结构与特征，电子隧穿电离动力学性质等。依托该项目，我们首先建立了原子或分子在椭圆/圆偏振强激光场作用下全维度电离模型，其中引入了Wigner旋转技巧，使理论计算程序高效进行。并通过该理论模型，（1）完成了原子分子体系在圆偏振激光作用下隧穿电离过程中，有关电离几率的研究，发现电离几率与初始电子密度分布以及激光场条件有明显的依赖关系；(2) 完成了原子分子体系隧穿电离过程中，有关隧穿时间的研究，分别通过实时电离几率和电子波包的含时变化建立理论模型，定义了隧穿时间，其中避免了经典物理的概念。受项目经费资助，我们完成了三篇科研论文分别发表在了Optics Express（两篇）和Journal of Physics B: Atomic, Molecular and Optical Physics（一篇）上面。