强激光场中的原子分子电离及分子高次谐波的理论研究

The interaction between laser and matter is always the current frontier of scientific research. And the interaction between the ultra-fast intense laser and the atom or molecule is the basis of understanding the interaction between strong field and matter. In this project, we will study the regulate and control both the direct-collision-induced ionization and the re-collision excitation sequential ionization (RESI) with the carrier-envelop phase of few-cycle elliptically polarized laser fields by applying the classical method. We will study the effect of the different relative orientation between the initial rotation direction of electrons and the spiral direction of circular polarized laser fields to the ionization process and analyze the non-adiabatic dynamics of the ionization by considering the conservation of energy and angular momentum. Moreover, we will explore the classical ionization dynamics of the tri-atomic molecule. In addition, we will investigate the high-order harmonic generation (HHG) by numerical solution of the non-Born-Oppenheimer time-dependent Schrödinger equation of H2+ molecule in intense laser field. By using the dipole acceleration distribution versus each electronic coordinate, the contribution of each electronic coordinate on HHG can be demonstrated in space coordinates system, and we will have more detailed analysis on HHG. At the same time we will study the recombination probabilities of electron with two nuclei in H2+ molecule and investigate the control of the quantum-path, the super-continuous spectrum of high-order harmonic and the generation of the isolated attosecond pulse by optimizing the laser parameters.

强激光与物质的相互作用研究是重要的前沿科学研究问题，其中超短超强激光与原子和分子的相互作用研究是理解强场与物质作用的基础。本项目我们应用经典理论方法，研究少周期椭圆偏振激光场中载波包络相位对原子直接碰撞电离和重碰撞激发次序电离的调控；考虑能量守恒以及角动量守恒，应用电离过程的非绝热特性，研究电子初始转动方向与圆偏振激光场螺旋方向的不同相对取向对电离的影响；探索强激光场中三原子分子的经典电离；数值求解非玻恩–奥本海默近似下的激光与氢分子离子相互作用的含时薛定谔方程，根据偶极加速度的电子坐标分布，研究空间坐标下分子轴上每一点对高次谐波的贡献，对分子高次谐波发射进行更细致的分析；研究电子与分子中两个核的复合几率变化，通过优化激光场参数，实现量子轨道的控制，得到具有超连续谱的高次谐波发射，获得超强的孤立阿秒脉冲。

本项目应用经典理论方法研究了强场原子分子非次序双电离(NSDI)以及通过数值求解激光原子分子相互作用的含时薛定谔方程研究了原子分子高次谐波的增强和孤立阿秒脉冲的产生。取得了如下创新性研究成果：研究了少周期椭圆偏振激光场作用下Ar原子NSDI对载波包络相位的依赖性；研究了反向旋转双色圆偏振激光场中Ar原子的非次序双电离动力学、椭圆偏振率对Ar原子和Mg原子NSDI过程的影响以及反旋双色椭圆偏振激光场作用下Ar原子NSDI的相对相位效应；研究了双色圆偏振激光场中叠加一个静电场作用下N2分子高次谐波的增强，获得了百阿秒以下的孤立阿秒脉冲；研究了强激光场中不同振动模式下CO2分子的高次谐波发射，结果表明，高次谐波发射谱的强度对分子振动模式是十分敏感的；数值求解麦克斯韦波动方程建立单体的谐波谱与在气体介质中传播后的谐波谱之间的联系，解释实验中所观察到的频谱分裂以及频率移动等现象；研究了高次谐波连续谱发射及高次谐波的光谱红移，利用中红外激光脉冲和太赫兹场的叠加场，分析了分子高次谐波空间分布的不对称性；研究了非均匀场中H2+分子的高次谐波发射，在不对称的非均匀场作用下伴随小的红移的奇数次谐波和偶数次谐波都可以被观察到；研究了掺杂半导体的势阱深度对能带劈裂的带隙间隔的影响；研究了椭圆偏振激光脉冲作用下分子的光电子动量分布及角分布对于分子取向的依赖性；研究了时间延迟、波长和载波包络相位对氢原子电子涡旋结构的影响以及由两束激光脉冲相干效应产生的光电子动量分布。