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Main Authors: Ma, Yongzhe, Liu, Qingcao, Ni, Hongcheng, Wu, Jian
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2509.02026
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author Ma, Yongzhe
Liu, Qingcao
Ni, Hongcheng
Wu, Jian
author_facet Ma, Yongzhe
Liu, Qingcao
Ni, Hongcheng
Wu, Jian
contents Tunneling and over-barrier ionization are the primary processes of strong-field ionization of atoms and molecules. While the dynamics of tunneling ionization have been extensively studied, exploration of over-barrier ionization dynamics has remained a significant challenge. In this study, we investigate the dynamics of over-barrier ionization using the backpropagation method specifically adapted for this context. By analyzing the topology of the backpropagating trajectories, we differentiate the contributions of tunneling and over-barrier ionizations to the distributions of photoelectron momentum and ionization time. While the transition from tunneling to over-barrier ionization is known to depend on the field strength, our results reveal that it is also influenced by the initial transverse momentum of the outgoing electron. We clarify how ionization probabilities vary with intensity for each mechanism, highlighting a competitive relationship between them. We further find that accounting for the Stark shift is essential for accurately determining the threshold field strength for over-barrier ionization. Our work provides a detailed understanding of the dynamics of over-barrier ionization and lays the groundwork for exploring new mechanisms in intense laser-matter interactions.
format Preprint
id arxiv_https___arxiv_org_abs_2509_02026
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Over-Barrier Ionization Dynamics Studied by Backpropagation
Ma, Yongzhe
Liu, Qingcao
Ni, Hongcheng
Wu, Jian
Atomic Physics
Tunneling and over-barrier ionization are the primary processes of strong-field ionization of atoms and molecules. While the dynamics of tunneling ionization have been extensively studied, exploration of over-barrier ionization dynamics has remained a significant challenge. In this study, we investigate the dynamics of over-barrier ionization using the backpropagation method specifically adapted for this context. By analyzing the topology of the backpropagating trajectories, we differentiate the contributions of tunneling and over-barrier ionizations to the distributions of photoelectron momentum and ionization time. While the transition from tunneling to over-barrier ionization is known to depend on the field strength, our results reveal that it is also influenced by the initial transverse momentum of the outgoing electron. We clarify how ionization probabilities vary with intensity for each mechanism, highlighting a competitive relationship between them. We further find that accounting for the Stark shift is essential for accurately determining the threshold field strength for over-barrier ionization. Our work provides a detailed understanding of the dynamics of over-barrier ionization and lays the groundwork for exploring new mechanisms in intense laser-matter interactions.
title Over-Barrier Ionization Dynamics Studied by Backpropagation
topic Atomic Physics
url https://arxiv.org/abs/2509.02026