Angle dependence of dissociative tunneling ionization of NO in asymmetric two-color intense laser fields
Angle dependence of dissociative tunneling ionization of NO in asymmetric two-color intense laser fields
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DOI：
10.1103/physreva.100.053422
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发表时间：
2019-11-27
影响因子：
2.9
通讯作者：
Hishikawa, Akiyoshi
中科院分区：
文献类型：
--
作者：
Endo, Tomoyuki;Fujise, Hikaru;Hishikawa, Akiyoshi
利用三维离子动量成像技术研究了线偏振锁相双色飞秒强激光场（45 fs，λ = 800和400 nm，总场强I = 1 × 10 ~（14）W/cm ~ 2）中一氧化氮（NO）的解离隧穿电离.解离电离产生的N+碎片NO -> NO+ e（-）-> N+ + O + e（-），在与激光偏振方向成有限角度处呈现出蝴蝶状的动量分布。此外，还观察到了两个激光场之间的相对相位的明显依赖关系，表明当电场从N指向O时，隧道电离有效地发生。对于最高的动能分量，所观察到的取向依赖性很好地解释与理论计算的2 π最高占据分子轨道（HOMO）的弱场渐近理论。另一方面，峰值角向激光偏振方向移动的动能减少，表明从HOMO的直接电离以外的途径有助于解离电离。
Dissociative tunneling ionization of nitric oxide (NO) in linearly polarized phase-locked two-color femtosecond intense laser fields (45 fs, lambda = 800 and 400 nm, total field intensity I = 1 x 10(14) W/cm(2)) has been studied by three-dimensional ion momentum imaging. The N+ fragment produced by the dissociative ionization, NO -> NO+ e(-) -> N+ + O + e(-), exhibits a butterflylike momentum distribution peaked at finite angles with respect to the laser polarization direction. In addition, a clear dependence on the relative phase between the two laser fields is observed, showing that the tunneling ionization occurs efficiently when the electric field points from N to O. For the highest kinetic energy component, the observed orientation dependence is well explained with theoretical calculations by the weak-field asymptotic theory for the 2 pi highest occupied molecular orbital (HOMO). On the other hand, the peak angle shifts toward the laser polarization direction as the kinetic energy decreases, indicating that pathways other than direct ionization from the HOMO contribute to the dissociative ionization.