1. Gilles Doumy, C. Roedig, Sang-Kil Son, C. I. Blaga, A. D. DiChiara, Robin Santra, N. Berrah, C. Bostedt, J. D. Bozek, P. H. Bucksbaum, J. P. Cryan, L. Fang, S. Ghimire, J. M. Glownia, M. Hoener, E. P. Kanter, B. Krässig, M. Kuebel, M. Messerschmidt, G. G. Paulus, D. A. Reis, N. Rohringer, L. Young, P. Agostini, and L. F. DiMauro, “Nonlinear atomic response to intense ultrashort x rays,” Phys. Rev. Lett. 106, 083002 (2011).
2. Sang-Kil Son, Henry N. Chapman, and Robin Santra, “Multiwavelength anomalous diffraction at high x-ray intensity,” Phys. Rev. Lett. 107, 218102 (2011).
3. 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, “Deep inner-shell multiphoton ionization by intense x-ray free-electron laser pulses,” Phys. Rev. Lett. 110, 173005 (2013).
4. L. Müller, C. Gutt, B. Pfau, S. Schaffert, J. Geilhufe, F. Büttner, J. Mohanty, S. Flewett, R. Treusch, S. Düsterer, H. Redlin, A. Al-Shemmary, M. Hille, A. Kobs, R. Frömter, H. P. Oepen, B. Ziaja, N. Medvedev, Sang-Kil Son, R. Thiele, R. Santra, W. Schlotter, B. Vodungbo, J. Lüning, S. Eisebitt, and G. Grübel, “Breakdown of the x-ray resonant magnetic scattering signal during intense pulses of extreme ultraviolet free-electron-laser radiation,” Phys. Rev. Lett. 110, 234801 (2013).
5. Yoshiaki Kumagai, Zoltan Jurek, Weiqing Xu, Hironobu Fukuzawa, Koji Motomura, Denys Iablonskyi, Kiyonobu Nagaya, Shin-ichi Wada, Subhendu Mondal, Tetsuya Tachibana, Yuta Ito, Tsukasa Sakai, Kenji Matsunami, Toshiyuki Nishiyama, Takayuki Umemoto, Christophe Nicolas, Catalin Miron, Tadashi Togashi, Kanade Ogawa, Shigeki Owada, Kensuke Tono, Makina Yabashi, Sang-Kil Son, Beata Ziaja, Robin Santra, and Kiyoshi Ueda, “Radiation-induced chemical dynamics in Ar clusters exposed to strong x-ray pulses,” Phys. Rev. Lett. 120, 223201 (2018).
6. Aaron C. LaForge, Sang-Kil Son, Debadarshini Mishra, Markus Ilchen, Stephen Duncanson, Eemeli Eronen, Edwin Kukk, Stanislaw Wirok-Stoletow, Daria Kolbasova, Peter Walter, Rebecca Boll, Alberto De Fanis, Michael Meyer, Yevheniy Ovcharenko, Daniel E. Rivas, Philipp Schmidt, Sergey Usenko, Robin Santra, and Nora Berrah, “Resonance-enhanced multiphoton ionization in the x-ray regime,” Phys. Rev. Lett. 127, 213202 (2021).
7. Xiang Li, Ludger Inhester, Seyyed J. Robatjazi, Benjamin Erk, Rebecca Boll, Kota Hanasaki, Koudai Toyota, Yajiang Hao, Cedric Bomme, Benedikt Rudek, Lutz Foucar, Stephen H. Southworth, Carl S. Lehmann, Bertold Krässig, Tatiana Marchenko, Marc Simon, Kiyoshi Ueda, Ken R. Ferguson, Maximilian Bucher, Tais Gorkhover, Sebastian Carron, Roberto Alonso-Mori, Jason E. Koglin, Jonathan Correa, Garth J. Williams, Sébastien Boutet, Linda Young, Christoph Bostedt, Sang-Kil Son, Robin Santra, Daniel Rolles, and Artem Rudenko, “Pulse energy and pulse duration effects in the ionization and fragmentation of iodomethane by ultraintense hard x rays,” Phys. Rev. Lett. 127, 093202 (2021).