超短强激光脉冲激励甲烷团簇的内电离机理

采用三维粒子动力学模拟方法研究了甲烷团簇在超短强激光脉冲激励下的爆炸动力学行为,重点讨论了几种典型的内电离机理对团簇爆炸过程中离子的价态和动能的影响.研究表明,在激光脉冲强度比较小的情况下,团簇中的原子主要是在光场作用下通过隧道电离的方式发生电离.当激光场进一步增强时,势垒压低电离是电离的主要方式.在相同的较高激光强度下,团簇更容易通过势垒压低电离达到高的电离价态.团簇发生电离后,其内部库仑电场的点火电离效应和内部滞留自由电子的碰撞电离效应也将增强团簇的再次电离过程. 关键词： 超短强激光脉冲 甲烷团簇 内电离

Inner ionization mechanisms of methane clusters driven by an ultrashort intense laser pulse

By use of three-dimensional particle dynamics simulations, the explosion dynamics of methane clusters driven by an ultrashort intense laser pulse has been analyzed. Especially the influences of some classical inner ionization mechanisms on the charged state and kinetic energy of the ions produced in the laser-cluster interaction process have been discussed in detail. It is presented that when the laser intensity is low, the atoms are ionized by the laser field mainly through the tunnel ionization while the barrier suppression ionization dominates for the inner ionization as the laser intensity increases. Under the irradiation of the same laser pulse with high intensity, the cluster can attain highly-ionized charged states by the barrier suppression ionization rather than by the tunnel ionization. After the cluster is ionized, the ignition ionization effect from the inner Coulomb field of the cluster and the electron impact ionization effect from the free electrons resided inside the cluster will facilitate the process that the cluster can be ionized further.