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Dichroic electron emission patterns from oriented helium ions

Niclas Wieland1,*, Klaus Bartschat2, Filippa Dudda1, René Wagner3,1, Philipp Schmidt3, Carlo Callegari4, Alexander Demidovich4, Giovanni De Ninno4, Michele Di Fraia4 et al.

Jiri Hofbrucker5, Michele Manfredda4, Valerija Music3,6,7, Oksana Plekan4, Kevin C. Prince4, Daniel E. Rivas3, Marco Zangrando4,8, Nicolas Douguet9, Alexei N. Grum-Grzhimailo10, Michael Meyer3, and Markus Ilchen1,7,3

  • *Contact author: niclas.wieland@uni-hamburg.de
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Phys. Rev. A 113, 043110 – Published 7 April, 2026

DOI: https://doi.org/10.1103/3z51-5g8k

Abstract

We report a joint experimental and theoretical study using a combination of polarization-controlled free-electron-laser (FEL) and near-infrared (NIR) pulses in a synchronized two-color photoionization scheme. Excited He+ ions, created by extreme ultraviolet (XUV) circularly polarized radiation from the XUV-FEL FERMI in the oriented 3p(m=+1) state, are exposed to circularly polarized 784-nm NIR radiation with peak intensities from 1012 to 1013W/cm2. The angular distribution of the ejected electrons exhibit a strong dichroism depending on the NIR intensity. While the corotating case is defined by a single path, for the counterrotating case, there are two dominant pathways whose relative strength and phase difference are determined.

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Phys. Rev. A 113, 043110– Published 7 April, 2026
  • Received 6 August 2025
  • Revised 2 December 2025
  • Accepted 19 February 2026
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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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