Enhanced Ionization of Molecules in Intense Laser Fields
Enhanced Ionization of Molecules in Intense Laser Fields
复制标题
DOI：
10.1007/978-3-642-28726-8_2
复制
发表时间：
2012
期刊：
影响因子：
--
通讯作者：
A. Bandrauk;F. Légaré
中科院分区：
文献类型：
--
作者：
A. Bandrauk;F. Légaré
暴露于强超短激光脉冲的分子在临界大核间距离处经历快速电离，需要非微扰模型来解释高度非线性非微扰响应。简单的准静态模型可以预测这些临界核间距离。结果表明，增强电离的机制是由于对称双原子和三原子分子中斯塔克位移 LUMO（最低未占分子轨道）的过势垒电离。在非对称分子中，永久偶极矩有助于电子轨道的强烈斯塔克位移，并且通过 HOMO（最高占据分子轨道）和 LUMO 的共振而增强电离，对应于电荷转移。双电离也在某些临界距离处增强，但涉及中间电子态的相当大的激发。
Molecules exposed to intense ultrashort laser pulses undergo rapid ionization at critical large internuclear distances requiring nonperturbative models to explain the highly nonlinear nonperturbative response. Simple quasistatic models allow for the prediction of these critical internuclear distances. It is shown that the mechanism for enhanced ionization is due to overbarrier ionization of the Stark-shifted LUMO (lowest unoccupied molecular orbital) in both symmetric diatomic and triatomic molecules. In nonsymmetric molecules, permanent dipole moments contribute to the strong Stark-shifts of electron orbitals and enhanced ionization occurs through resonances of the HOMO (highest occupied molecular orbital) and LUMO, corresponding to charge transfer. Double ionization is also enhanced at certain critical distances but involves considerable excitations of intermediate electronic states.