Deep inner-shell multiphoton ionization by intense x-ray free-electron laser pulses

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

[BibTeX][pdf]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.

Tags: Xe, Ar, ionization dynamics, multiphoton, multiple ionization, inner-shell, decay cascade, x-ray, SACLA, experiment, XATOM, XFEL, CFEL, DESY