Mainz 2017 – scientific programme
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A: Fachverband Atomphysik
A 34: Atoms in Strong Fields I
A 34.6: Talk
Friday, March 10, 2017, 12:30–12:45, N 2
Laser-driven recollisions under the Coulomb barrier — •Thomas Keil1, Sergey Popruzhenko2, and Dieter Bauer1 — 1Institut für Physik, Universität Rostock, 18051 Rostock, Germany — 2National Research Nuclear University MEPhI, Kashirskoe shosse 31, 115409, Moscow, Russia
Photoelectron spectra obtained from the ab initio solution of the time-dependent Schrödinger equation can be in striking disagreement with predictions by the strong-field approximation (SFA) not only at low energy but also around twice the ponderomotive energy where the transition from the direct to the rescattered electrons is expected. In fact, the relative enhancement of the ionization probability compared to the SFA in this regime can be several orders of magnitude. We show for which laser and target parameters such an enhancement occurs and for which the SFA prediction is qualitatively good. The enhancement is analyzed in terms of the Coulomb-corrected action along analytic quantum orbits in the complex-time plane, taking soft recollisions under the Coulomb barrier into account. These recollisions in complex time and space prevent a separation into sub-barrier motion up to the "tunnel exit" and subsequent classical dynamics. Instead, the entire quantum path up to the detector determines the ionization probability [1].
[1] Th. Keil, S.V. Popruzhenko, D. Bauer, Phys. Rev. Lett. (accepted), preprint arXiv:1608.03844