双激光场调控Be2+离子动力学的研究

为了研究高电荷态Be2+离子在强激光中的超快动力学过程，采用求解系统的密度矩阵的方法，进行了理论分析，获得了Be2+离子系统的光谱响应。结果表明，由于强激光场会导致激发态能级的瞬态斯塔克效应进而引起电子运动状态的改变，对应于Be2+离子系统跃迁偶极子的相位改变量为0.5π；当两束红外激光强度为0.94×1012W/cm2时，Be2+离子吸收光谱向高、低频端延伸，谱线形状由单个孤立的洛伦兹线型转化为“波浪式”结构；改变入射激光场的强度以及激光脉冲的持续时间和相对延迟时间可以控制吸收谱线型。此研究结果说明调控双激光的参量可以实现对高电荷态离子中核外电子运动的控制，也指明了软X射线脉冲整形的一个可行性方案。

The study of ultrafast dynamics of highly changed Be2+ ion in double strong laser fields

In order to study the ultrafast dynamic process of highly charged state Be2+ ions in a strong laser, the spectral response of Be2+ ions was analyzed by solving the system's density matrix. It is found that the strong laser field causes a change of the electron motion in the excited state due to the transient Stark effect, corresponding to a phase change of 0.5π to the Be2+ system's dipole; the spectral response of Be2+system extends to the high and low frequencies and the line shape is changed from an isolated Lorentz line to a "wave-like" structure with the intensities of both near infrared laser pulses set to be 0.94×1012 W/cm2; the absorption spectral line depends on the intensity of the incident laser field, pulse duration, and relative delay time, which indicates that the movement of electrons outside the nucleus in highly charged ions can be controlled by adjusting the parameters of the pump laser fields. It also find us a possible pulse-shaping scheme for soft X-rays.