Imaging multiphoton ionization dynamics of CH3I at a high repetition rate XUV free-electron laser

Yu Chen Cheng, Bart Oostenrijk, Jan Lahl, Sylvain MacLot, Sven Augustin, Georg Schmid, Kirsten Schnorr, Severin Meister, Dimitrios Rompotis, Bastian Manschwetus, Harald Redlin, Cédric Bomme, Benjamin Erk, Daniel Rolles, Rebecca Boll, Pavel Olshin, Artem Rudenko, Michael Meyer, Per Johnsson, Robert MoshammerMathieu Gisselbrecht

Research output: Contribution to journalArticlepeer-review

Abstract

XUV multiphoton ionization of molecules is commonly used in free-electron laser experiments to study charge transfer dynamics. However, molecular dissociation and electron dynamics, such as multiple photon absorption, Auger decay, and charge transfer, often happen on competing time scales, and the contributions of individual processes can be difficult to unravel. We experimentally investigate the Coulomb explosion dynamics of methyl iodide upon core-hole ionization of the shallow inner-shell of iodine (4d) and classically simulate the fragmentation by phenomenologically introducing ionization dynamics and charge transfer. Under our experimental conditions with medium fluence and relatively long XUV pulses (∼75 fs), we find that fast Auger decay prior to charge transfer significantly contributes to the charging mechanism, leading to a yield enhancement of higher carbon charge states upon molecular dissociation. Furthermore, we argue for the existence of another charging mechanism for the weak fragmentation channels leading to triply charged carbon atoms. This study shows that classical simulations can be a useful tool to guide the quantum mechanical description of the femtosecond dynamics upon multiphoton absorption in molecular systems.

Original languageEnglish
Article number014001
JournalJournal of Physics B: Atomic, Molecular and Optical Physics
Volume54
Issue number1
DOIs
Publication statusPublished - 2020

Subject classification (UKÄ)

  • Atom and Molecular Physics and Optics

Free keywords

  • Auger decay
  • charge transfer
  • methyl iodide dissociation
  • recoil-ion momentum spectroscopy
  • sequential ionization

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