双原子分子多光子电离强场效应的含时波包动力学研究

强激光非线性条件下分子的多光子电离过程呈现出较为明显的强场效应.由于这种效应不能用传统的量子微扰论来处理,“缀饰态”模型方法提供了物理图象清晰的处理光与物质相互作用的方案.本文基于含时波包动力学的基本理论,将激光场看作经典场,利用“缀饰态”模型研究了强场下双原子分子(NO、RbI等)的多光子电离过程.研究表明,激光场的强度、泵浦-探测脉冲延迟时间等对多光子电离光电子能谱的形状有着重要的影响,而这种影响是由光诱导势引起的.另外,在研究具有两个连续态的RbI体系时,自电离现象的发生也与势能面的交叉密切相关,并受外场强度的影响.本文计算模拟外场中分子的光电子能谱时所得到的强场效应对理解和实现原子分子过程的激光操控具有重要的意义.

Time-dependent wavepacket dynamical approach to intense field effect of multiphoton ionization for diatomic molecules

The process of multiphoton ionization in strong laser fields takes on obvious intense field effect.Since this effect can not be interpreted by a simple quantum perturbation theory,the "dressed-states" model provides a clear scheme to investigate light-matter interaction.Based on the time-dependent wavepacket dynamics,this paper regards the laser field as a classical one,and employs the "dressed-states" model to study multiphoton ionization processes of some diatomic molecules(such as NO,RbI,etc.) in strong laser fields.The investigation shows that the intensity and pump-probe delay time of the laser pulses have significant influence on the shape of photoelectron spectrum,which can be interpreted by the so-called "light-induced potential".It is also shown that for the system with more than two continua such as RbI,the occurrence of autoionization phenomenon has some relation with potential crossing,and the strength of the cross-coupling is influenced by the external field,too.The intense field effect obtained by simulating the photoelectron spectrum of molecules in external fields has important meaning for understanding and realizing the laser manipulation of atomic-molecular processes.