Abstract
Recollision is the most important post-tunneling process in strong-field physics, but so far has been restricted to interaction between the first ionized electron and the residual ion in nonsequential double ionization. Here we identify the role of recollision of the second ionized electron in the below-threshold nonsequential double ionization process by introducing a Coulomb-corrected quantum-trajectories method. We will reproduce the experimentally observed cross-shaped and anti-correlated patterns in correlated two-electron momentum distributions, and the transition between them. Both the cross-shaped and anti-correlated patterns are attributed to recolliding trajectories of the second electron. The effect of recollision of the second electron is significantly enhanced by the stronger Coulomb potential of the higher valence residual ion, and is further strengthened by the recapture process of the second electron. Our work paves a potential way to image ultrafast dynamics of atoms and molecules in intense laser field.
Highlights
Recollision is the most important post-tunneling process in strong-field physics, but so far has been restricted to interaction between the first ionized electron and the residual ion in nonsequential double ionization
In the recollision picture[5,6], an electron is liberated from the neutral atom or molecule through tunneling, is driven back by the laser field to collide with the parent ion elastically or inelastically, or recombine with the ion, resulting in high-order above-threshold ionization (HATI), nonsequential double ionization (NSDI), and high harmonics generation (HHG), respectively
By introducing a Coulomb-corrected quantumtrajectories (CCQT) method, we identify the key role played by the recollision between the second ionized electron and the divalent ion in the below-threshold NSDI process
Summary
Recollision is the most important post-tunneling process in strong-field physics, but so far has been restricted to interaction between the first ionized electron and the residual ion in nonsequential double ionization. A semiclassical perspective, in which the recollision process plays a key role, is established with great effort It can well explain many intriguing strong-field phenomena, such as high-order above-threshold ionization (HATI), high harmonics generation (HHG), and nonsequential double ionization (NSDI), and serves as the foundation of attosecond physics (see, e.g., Ref. 1–4 for review and references therein). By introducing a Coulomb-corrected quantumtrajectories (CCQT) method, we identify the key role played by the recollision between the second ionized electron and the divalent ion in the below-threshold NSDI process. Only when this recollision is included, the experimentally observed cross-shaped[22,23] and anti-correlated[24] patterns of correlated electron momentum distribution (CEMD), and the transition between them[25], can be well reproduced
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