Deep Inner-Shell Multiphoton Ionization by Intense X-Ray Free-Electron Laser Pulses

: Fukuzawa H, Son S, Motomura K, Mondal S, Nagaya K, Wada S, Liu X, Feifel R, Tachibana T, Ito Y, Kimura M, Sakai T, Matsunami K, Hayashita H, Kajikawa J, Johnsson P, Siano M, Kukk E, Rudek B, Erk B, Foucar L, Robert E, Miron C, Tono K, Inubushi Y, Hatsui T, Yabashi M, Yao M, Santra R, Ueda K

: 2013

: Physical Review Letters

: 17

: 110

: 17

: 5

: 0031-9007

DOI: https://doi.org/10.1103/PhysRevLett.110.173005

: http://link.aps.org/doi/10.1103/PhysRevLett.110.173005

We have investigated multiphoton multiple ionization dynamics of xenon atoms using a new x-ray free-electron laser facility, {SPring-8} Angstrom Compact free electron {LAser} ({SACLA)} in Japan, and identified that Xen+ with n up to 26 is produced at a photon energy of 5.5 {keV.} The observed high charge states (n≥24) are produced via five-photon absorption, evidencing the occurrence of multiphoton absorption involving deep inner shells. A newly developed theoretical model, which shows good agreement with the experiment, elucidates the complex pathways of sequential electronic decay cascades accessible in heavy atoms. The present study of heavy-atom ionization dynamics in high-intensity hard-x-ray pulses makes a step forward towards molecular structure determination with x-ray free-electron lasers.