强激光场原子电离过程中库仑势对光电子横向动量分布的影响研究

发布时间：2018-03-08 04:19

本文选题：强场电离　切入点：库仑势　出处：《中国科学:物理学力学天文学》2017年03期 　论文类型：期刊论文

【摘要】：本文研究了强激光场原子电离过程中,库仑势对光电子横向动量分布的影响.通过深入考察强场物理过程的三步模型并且结合所研究问题的特点,使用一种新的简化强场轨道概念,发展了一个解析的(隐式)包含库仑效应的电子运动模型.进而使用此模型研究了光电子横向动量分布在库仑势和激光场联合作用下的演化.研究发现,横向动量分布在库仑势的作用下与初始高斯分布相比非常明显地变窄.深入研究解析(隐式)模型发现,库仑势的作用导致电子横向动量在一类特殊的电子轨道附近发生聚集,这对应隧穿电子的偏折函数(Deflection Function)中存在的一种鞍点结构,这种结构对应着最终电子横向动量分布上奇异结构的出现,即尖峰结构.从物理过程中来说,当隧穿电子返回原子核附近时,鞍点附近的轨道会受到原子核的吸引作用对其横向动量进行补偿使得其向鞍点对应值靠拢,因而最后在动量分布中形成尖峰结构.这里的研究将有助于对强场过程中库仑势的影响进行一定的操控.
[Abstract]:In this paper, the influence of Coulomb potential on the transverse momentum distribution of photoelectrons in the intense laser field atomic ionization process is studied. Using a new concept of simplified strong field orbits, An analytical (implicit) model of electron motion with Coulomb effect is developed. The evolution of the transverse momentum distribution of photoelectrons under the combined action of Coulomb potential and laser field is studied by using this model. The transverse momentum distribution is obviously narrower than the initial Gao Si distribution under the action of Coulomb potential. The analytical (implicit) model shows that the effect of Coulomb potential leads to the accumulation of transverse momentum near a special class of electron orbits. This corresponds to the existence of a saddle point structure in the deflection function of tunneling electrons, which corresponds to the emergence of a singular structure in the final transverse momentum distribution of electrons, that is, the peak structure. When tunneling electrons return to the vicinity of the nucleus, the orbital near the saddle point will be compensated for its transverse momentum by the attraction of the nucleus, so that the orbital orbital near the saddle point will move closer to the corresponding value of the saddle point. Therefore, the peak structure is formed in the momentum distribution. The study here will help to control the influence of Coulomb potential in the strong field process.
【作者单位】：中国工程物理研究院北京研究生部;北京应用物理与计算数学研究所;北京大学应用物理与技术研究中心;
【基金】：国家自然科学基金资助项目(编号:11274051)
【分类号】：O562.4

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