@article{oai:nagoya.repo.nii.ac.jp:00030436, author = {Fushitani, M. and Sasaki, Y. and Matsuda, A. and Fujise, H. and Kawabe, Y. and Hashigaya, K. and Owada, S. and Togashi, T. and Nakajima, K. and Yabashi, M. and Hikosaka, Y. and Hishikawa, A.}, issue = {19}, journal = {Physical Review Letters}, month = {May}, note = {Ultrafast multiphoton ionization of Xe in strong extreme ultraviolet free-electron laser (FEL) fields (91 eV, 30 fs, 1.6×10^12  W/cm2) has been investigated by multielectron-ion coincidence spectroscopy. The electron spectra recorded in coincidence with Xe^4+ show characteristic features associated with two-photon absorption to the 4d^−2 double core-hole (DCH) states and subsequent Auger decay. It is found that the pathway via the DCH states, which has eluded clear identification in previous studies, makes a large contribution to the multiple ionization, despite the long FEL pulse duration compared with the lifetime of the 4d core-hole states.}, title = {Multielectron-Ion Coincidence Spectroscopy of Xe in Extreme Ultraviolet Laser Fields: Nonlinear Multiple Ionization via Double Core-Hole States}, volume = {124}, year = {2020} }