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Description
The relaxation processes in atomic xenon following core ionization of the 4d and 4p subshells by extreme ultraviolet (XUV) pulses from a free-electron laser (FLASH: FL26 beamline) are investigated using ion time-of-flight spectroscopy (see [1] for detailed description of the experimental setup). We compare the dynamics following ionization and Auger-Meitner decays at 90-eV photon energy, i.e., near the giant resonance, with those at 160 eV, near the Cooper minimum, where cross sections for photoionization of the 4d and 4p subshells are similar. Final states with charges higher than 4 show signatures of sequential absorption of two XUV photons, followed by subsequent Auger-Meitner decay. The averaged lifetimes of some important excited states are measured in a two-color XUV-pump–near-infrared-probe experiment (XUV pulse duration is (2010) fs and 800 nm NIR pulse duration is (153) fs). A transient enhancement in the ion yield of Xe5+ with an average lifetime of (49 ± 3) fs is obtained, attributed to transient intermediate states following the decay of 4d double-core-hole states [2]. This lifetime for Xe5+ is twice as short as observed earlier. A different decay channel of Xe6+ was observed, most likely arising from NIR-induced double ionization of doubly excited states of Xe4+. This work demonstates that utilizing intense XUV and x-ray sources, such as FEL, enables the selective population of core-hole states and with NIR pulses allows studying decay dynamics in atoms and molecules.
References
[1] Atia-Tul-Noor et al. 2024 Opt. Express 32 6597
[2] Kumar S et al. 2024 Phys Rev A 110 063104
