Coincidence measurement of two-photon double ionization of argon through an autoionizing resonance

We present coincidence measurements of two-photon double ionization (TPDI) of argon driven by femtosecond pulses tunable around 26.5eV photon energy, which are obtained from a high-harmonic generation source. The measured photoelectron spectra are interpreted with regard to three TPDI mechanisms. Th...

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Bibliographic Details
Main Authors: Sebastian Hell, Julian Späthe, Morten Førre, Robert Klas, Jan Rothhardt, Jens Limpert, Robert Moshammer, Christian Ott, Gerhard G. Paulus, Stephan Fritzsche, Matthias Kübel
Format: Article
Language:English
Published: American Physical Society 2025-08-01
Series:Physical Review Research
Online Access:http://doi.org/10.1103/f63d-4hrh
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Summary:We present coincidence measurements of two-photon double ionization (TPDI) of argon driven by femtosecond pulses tunable around 26.5eV photon energy, which are obtained from a high-harmonic generation source. The measured photoelectron spectra are interpreted with regard to three TPDI mechanisms. Theoretical predictions are obtained by an approximate model for direct TPDI and atomic structure calculations, which are implemented into a Monte Carlo simulation. The prevailing mechanism involves the excitation and prompt photoionization of an autoionizing resonance in neutral argon. We provide evidence for pronounced electron-electron interaction in this ultrafast ionization process. Furthermore, we show that the dominant TPDI mechanism can be altered by slight tuning of the photon energy. The present work paves the way for scrutinizing and controlling nonlinear photoionization in the extreme ultraviolet using table-top sources.
ISSN:2643-1564