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arXiv · 2501.11144

Low-energy photoelectron structures for arbitrary ellipticity of a strong laser field

Q. Z. Lv·M. Klaiber·P. -L. He·K. Z. Hatsagortsyan·C. H. Keitel
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Abstract

Previous attoclock experiments measuring the photoelectron momentum distribution (PMD) via strong-field ionization in an elliptically polarized laser field have shown anomalously large offset angles in the nonadiabatic regime with large Keldysh parameters ($γ$). We investigate the process theoretically in the complete range of ellipticity ($ε$) and large range of $γ$, employing numerical solutions of time-dependent Schrödinger equation and nonadiabatic classical-trajectory Monte Carlo simulations matched with the under-the-barrier motion via the nonadiabatic strong field approximation. We show the formation of low-energy structures (LES) at any ellipticity value when the Keldysh parameter is sufficiently large. Three regimes of the interaction in the ($ε$-$γ$)-space of parameters are identified via the characteristic PMD features. The significant modification of the recollision picture in the nonadiabatic regime, with so-called anomalous and hybrid slow recollisions, is shown to be behind the LES, inducing extreme nonlinear Coulomb bunching in the phase-space in the polarization plane. Our findings elucidate subtle features of the attosecond electron dynamics in strong-field ionization at extreme conditions and indicate limitations on attosecond imaging.

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Q. Z. Lv, M. Klaiber, P. -L. He, K. Z. Hatsagortsyan, C. H. Keitel. 2025-01-19. Low-energy photoelectron structures for arbitrary ellipticity of a strong laser field. https://arxiv.org/abs/2501.11144

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