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  • Letter
  • Open Access

Decoding strong-field ionization of H2 via photoelectron momentum torus

Daimu Ikeya1, Hikaru Fujise1, Minami Takahashi1, Kyoichiro Yasui1, Akitaka Matsuda1, Mizuho Fushitani1, Hirokazu Matsui2, Hiroka Hasegawa2, Oleg I. Tolstikhin3 et al.

Toru Morishita4,2 and Akiyoshi Hishikawa1,5,*

  • *Contact author: hishikawa.akiyoshi.z6@f.mail.nagoya-u.ac.jp
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Phys. Rev. Research 7, L032059 – Published 12 September, 2025

DOI: https://doi.org/10.1103/g7g6-mm4z

Abstract

Strong-field ionization of H2 in circularly polarized laser fields (1035 nm, 35 fs, ∼1×1014W/cm2) has been studied by three-dimensional electron-ion coincidence momentum imaging. Both the effective ionization potential and the applied laser electric field amplitude are simultaneously determined from the parameters characterizing the tunnel-electron torus in momentum space, using the adiabatic theory of strong-field ionization extended to include higher-order nonadiabatic effects as a reference. The effective ionization potential of H2, obtained with an accuracy and precision of 10−2 a.u., reveals a clear shift from the field-free value. Dependence on both the field amplitude and the ionization pathways to H2+ and H++H is also resolved. These findings demonstrate that the target-specific properties can be quantitatively decoded from the structure of the photoelectron momentum torus, thus establishing a basis for quantitative ultrafast tunnel-electron spectroscopy.

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Information

Phys. Rev. Research 7, L032059– Published 12 September, 2025
  • Received 19 April 2025
  • Accepted 18 August 2025
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

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