Mainz 2026 – scientific programme

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A: Fachverband Atomphysik

A 22: Poster – Attosecond Physics (joint session A/MO)

A 22.3: Poster

Wednesday, March 4, 2026, 17:00–19:00, Philo 1. OG

Coulomb-corrected reconstruction of ionization and recombination times in high-order harmonic generation — •Mohammad Monfared and Manfred Lein — Institute for Theoretical Physics, Leibniz Universität Hannover, Hannover, Germany

Accurate attosecond-scale measurement of electron dynamics is fundamental to ultrafast science. The orthogonally polarized two-color (OTC) field technique enables the reconstruction of electron ionization and recombination times from high-order harmonic generation (HHG) spectra. However, established retrieval methods often neglect or utilize an oversimplified treatment of the Coulomb interaction, limiting their precision. In this work, we introduce a refined time-retrieval method that significantly improves the accuracy of reconstructing ionization and recombination times in OTC fields. We identify that one of the main time-retrieval equations, namely the condition used in earlier works to maximize the harmonic intensity as a function of the two-color delay, is only approximate and replace it with a more accurate stationarity equation. In addition, we incorporate Coulomb effects beyond the simple approximation of an instantaneous momentum kick by numerically integrating the Coulomb force and potential along the classical electron trajectories, providing a more physically consistent correction. We benchmark our method against exact time-dependent Schrödinger equation simulations and the analytical R-matrix theory. Our results demonstrate a substantial improvement in the accuracy of the retrieved ionization times, achieving near-perfect agreement with benchmark models especially for high-frequency probe fields.

Keywords: Attosecond time-resolved spectroscopy; High-order harmonic generation; Coulomb-corrected time retrieval; Orthogonally polarized two-color fields; Ionization and recombination times