Temporal coherent control of resonant two-photon double ionization of the hydrogen molecule via doubly excited states
Temporal coherent control of resonant two-photon double ionization of the hydrogen molecule via doubly excited states
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DOI：
10.1103/physreva.103.053110
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发表时间：
2021-05-11
影响因子：
2.9
通讯作者：
Starace, Anthony F.
中科院分区：
文献类型：
--
作者：
Djiokap, J. M. Ngoko;Starace, Anthony F.
利用延迟反转的几周期阿秒非重叠脉冲，研究了脉冲传播方向沿着（k）平行或垂直于帽上分子轴（R）时，氢分子双光子双电离（TPDI）共振过程的时间相干控制.对于与（R）overcap平行的（k）overcap和36 eV的脉冲载波频率共振地填充Q（2）（1）Pi（+）（u）（1）双激发态以及其他（1）Pi（+）（u）双激发态，我们发现通过这些双激发态的间接电离路径改变了运动学涡旋的性质，形状的动量分布产生的两个直接电离路径从四重到二重旋转对称。该结果类似于在涉及P-1（+/- 1）o双激发态的He原子的TPDI中发现的结果[Ngoko Mokokap和Starace，J. Opt. 19，124003（2017）];但是，在此情况下，在He原子的基态和双激发态之间表现出量子拍频效应的角分布在这里被观察到，其分子对应物具有异常的形状，频率，而不是频率。在光电子对的方位角上积分的六次微分概率表明，这种异常是由于自电离衰减和双激发态之间的量子拍频。对于（k）over cap垂直于（R）over cap和30 eV的宽带脉冲载波频率，填充Q1（1）Pi（+）（u）（1），Q（1）（1）Sigma（u+）（1），Q（2）（1）Pi（+）（u）（1）和Q（1）（1）Sigma（u+）（2）双激发态，动量分布显示出具有四个旋臂的动态电子涡旋，其源自（1）Delta（+）（g）、（1）Pi（+）（g）和（1）Sigma（+）（g）动态电离幅度之间的相互作用。无论是绝热核近似或固定核近似内我们的治疗表明，后者提供了一个很好的帐户，这相关的过程。
We use time-delayed, counter-rotating, circularly polarized few-cycle attosecond nonoverlapping pulses to study the temporal coherent control of the resonant process of two-photon double ionization (TPDI) of hydrogen molecule via doubly excited states for pulse propagation direction along (k) over cap either parallel or perpendicular to the molecular axis (R) over cap. For (k) over cap parallel to (R) over cap and a pulse carrier frequency of 36 eV resonantly populating the Q(2) (1)Pi(+)(u)(1) doubly excited state as well as other (1)Pi(+)(u) doubly excited states, we find that the indirect ionization pathway through these doubly excited states changes the character of the kinematical vortex-shaped momentum distribution produced by the two direct ionization pathways from fourfold to twofold rotational symmetry. This result is similar to what found in TPDI of the He atom involving P-1(+/- 1)o doubly excited states [Ngoko Djiokap and Starace, J. Opt. 19, 124003 (2017)]; however, angular distributions exhibiting a quantum beat effect between the ground state and a doubly excited state seen for the He atom are observed here for its molecular counterpart with an anomaly in shape and magnitude, not in frequency. The sixfold differential probability integrated over the azimuthal angle of the photoelectron pair shows that this anomaly is due to autoionization decays and quantum beats between doubly excited states. For (k) over cap perpendicular to (R) over cap and a broadband pulse carrier frequency of 30 eV populating the Q1 (1)Pi(+)(u)(1), Q(1) (1)Sigma(u+) (1), Q(2) (1)Pi(+)(u)(1), and Q(1) (1)Sigma(u+) (2) doubly excited states, the momentum distribution is shown to exhibit dynamical electron vortices with four spiral arms, which originates from the interplay between the (1)Delta(+)(g), (1)Pi(+)(g), and (1)Sigma(+)(g) dynamical ionization amplitudes. Our treatment within either the adiabatic-nuclei approximation or fixed-nuclei approximation shows that the latter provides a very good account for this correlated process.