Angular momentum distribution in strong-field frustrated tunneling ionization

Using the classical-trajectory Monte Carlo model, we have theoretically studied the angular momentum distribution of frustrated tunneling ionization(FTI) of atoms in strong laser fields. Our results show that the angular momentum distribution of the FTI events exhibits a double-hump structure. With this classical model, we back traced the tunneling coordinates, i.e., the tunneling time and initial transverse momentum at tunneling ionization. It is shown that for the events tunneling ionized at the rising edge of the electric field,the final angular momentum exhibits a strong dependence on the initial transverse momentum at tunneling.While for the events ionized at the falling edge, there is a relatively harder recollision between the returning electron and the parent ion, leading to the angular momentum losing the correlation with the initial transverse momentum. Our study suggests that the angular momentum of the FTI events could be manipulated by controlling the initial coordinates of the tunneling ionization.     

正交双色场中氢分子非次序双电离的研究

利用经典系综模型,研究了正交双色场作用下氢分子非次序双电离中双电离电子的相关特性.结果表明,双电离电子相关动量谱强烈地依赖于正交双色场的相对相位.通过改变正交双色场的相对相位,相关动量可以从反相关模式转变为相关模式.向后分析表明,相关电子动量谱对双色场相对相位的依赖关系起源于碰撞过程中碰撞电子碰撞角和碰撞动量对相对相位...     

Electron Correlation in Nonsequential Double Ionization of Helium by Two-Color Pulses

We investigate the momentum and energy correlations between the two electrons from nonsequential double ionization （NSDI） of helium by strong two-color pulses with the classical three-dimensional ensemble model. The correlated momentum distribution in the direction parallel to the laser field exhibits an arc-like structure and the sum-energy spectrum shows a sharp peak for the NSDI of helium in the two-color fields. Back analysis reveals that the narrow time interval during which recollisions occur, the low returning energy and the short time delay between recollision and double ionization lead to the novel momentum and energy correlations.     

Classical Effects of Carrier--Envelope Phase on Nonsequential Double Ionization

A classical microcanonical 1＋1-dimensional model is used to investigate the ion momentum distributions in nonsequential double ionization with linearly polarized few-cycle pulses. We find that the ion momentum distribution has a strong dependence on the carrier-envelope phase of the few-cycle pulse, which is consistent with the experimental results qualitatively. Back analysis shows that the ionization probability of the first electron at different phases and its returning kinetic energy play the main role on the ion momentum distributions.     

不同分子取向下氢分子非次序双电离对核间距的依赖关系

利用三维经典系综模型研究了氢分子非次序双电离对核间距的依赖性.在不同分子取向下,氢分子双电离率随核间距的增大而先增大后减小,在核间距为4a.u.时取最大值.氢分子非次序双电离对核间距的依赖性随分子轴与激光偏振方向间夹角φ的增大而减弱.φ=0时,氢分子非次序双电离包含丰富的相关模式,对核间距有强烈的依赖性φ=π/2时,不同核间距下的相关模式相似,重碰撞在双电离过程中发挥更重要的作用.这些结果表明分子结构对双原子分子非次序双电离有重要影响. 关键词： 非次序双电离 核间距 关联动量分布     

Taking snapshots of a moving electron wave packet in molecules using photoelectron holography in strong-field tunneling ionization

Coherent superposition of electronic states induces attosecond electron motion in molecules. We theoretically investigate the strong-field ionization of this superposition state by numerically solving the time-dependent Schrödinger equation. In the obtained photoelectron momentum distribution, an intriguing bifurcation structure appears in the strong-field holographic interference pattern. We demonstrate that this bifurcation structure directly provides complete information about the status of the transient wave function of the superposition state:the horizontal location of the bifurcation in the momentum distribution reveals the relative phase of the involved components of the superposition state and the vertical position indicates the relative coefficient. Thus, this bifurcation structure takes a snapshot of the transient electron wave packet of the superposition state and provides an intuitive way to monitor electron motion in molecules.