激光场中锂原子发射的电离阈值以下低阶谐波的研究  

Study on the low-order harmonics generation for below ionization threshold of lithium atom in laser field

作　　者：张启迪 李鹏程[1] 赵松峰[1] 周效信[1] ZHANG Qi-Di;LI Peng-Cheng;ZHAO Song-Feng;ZHOU Xiao-Xin(College of Physics and Electronic Engineering,Northwest Normal University,Lanzhou 730070,China)

机构地区：[1]西北师范大学物理与电子工程学院,兰州730070

出　　处：《原子与分子物理学报》2020年第4期581-586,共6页Journal of Atomic and Molecular Physics

基　　金：国家自然科学基金(11764038,11664035)。

摘　　要：利用单电子近似下锂原子精确的模型势,通过数值求解三维含时薛定谔方程的方法,研究了锂原子在激光场中发射低阶谐波的性质,研究结果表明,对于锂原子电离阈值以下的低阶谐波,除了通常的奇次谐波外,还有侧峰结构出现,运用同步压缩变换技术(SST)分析这些低阶谐波的辐射特性,我们发现这些侧峰是由原子在激光场中的缀饰态之间的跃迁和无场下激发态到基态的跃迁组成的,如果当激光脉冲结束后,仍有发射的侧峰,其位置与主峰之间的能量差可以用来估算原子激发态在激光场中的最大Stark移动.By using the precise model potential of lithium atom with the single-active-electron approximation,the properties of low-order harmonics below ionization threshold emitted by lithium atoms in the laser field are studied by numerically solving the three-dimensional time-dependent Schr dinger equation.Our results show that for the low-order harmonics below the ionization threshold of lithium atom,in addition to the usual odd harmonics,there are also side-peak structures.The radiation characteristics of these low-order harmonics are analyzed by using the synchronous squeezing transform(SST)techniques.We found that these side-peaks are composed of the transition between the dressed states of atoms in the laser field and the transition from the excited state to the ground state in field-free case.If there is still a radiation for the side-peak after the laser pulse ends,the energy difference between the side-peak position and the main peak can be used to estimate the maximum Stark shift for the excited state of atom in laser field.

关 键 词：锂原子 低阶谐波 激发态最大Stark移动 

分 类 号：O561.4[理学—原子与分子物理]