1. Siddharth Bhardwaj, Sang-Kil Son, Kyung-Han Hong, Chien-Jen Lai, Franz X. Kärtner, and Robin Santra, “Recombination-amplitude calculations of noble gases, in both length and acceleration forms, beyond the strong-field approximation,” Phys. Rev. A 88, 053405 (2013).
  2. 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).
  3. K. Motomura, H. Fukuzawa, Sang-Kil Son, S. Mondal, T. Tachibana, Y. Ito, M. Kimura, K. Nagaya, T. Sakai, K. Matsunami, S. Wada, H. Hayashita, J. Kajikawa, X. -J. Liu, R. Feifel, 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, “Sequential multiphoton multiple ionization of atomic argon and xenon irradiated by x-ray free-electron laser pulses at SACLA,” J. Phys. B: At. Mol. Opt. Phys. 46, 164024 (2013) [special issue on frontiers of free-electron laser science].
  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. Benedikt Rudek, Daniel Rolles, Sang-Kil Son, Lutz Foucar, Benjamin Erk, Sascha Epp, Rebecca Boll, Denis Anielski, Christoph Bostedt, Sebastian Schorb, Ryan Coffee, John Bozek, Sebastian Trippel, Tatiana Marchenko, Marc Simon, Lauge Christensen, Sankar De, Shin-ichi Wada, Kiyoshi Ueda, Ilme Schlichting, Robin Santra, Joachim Ullrich, and Artem Rudenko, “Resonance-enhanced multiple ionization of krypton at an x-ray free-electron laser,” Phys. Rev. A 87, 023413 (2013).
  6. Sang-Kil Son, Henry N. Chapman, and Robin Santra, “Determination of multiwavelength anomalous diffraction coefficients at high x-ray intensity,” J. Phys. B: At. Mol. Opt. Phys. 46, 164015 (2013) [special issue on frontiers of free-electron laser science].
  7. Beata Ziaja, Zoltan Jurek, Nikita Medvedev, Sang-Kil Son, Robert Thiele, and Sven Toleikis, “Photoelectron spectroscopy method to reveal ionization potential lowering in nanoplasmas,” J. Phys. B: At. Mol. Opt. Phys. 46, 164009 (2013) [special issue on frontiers of free-electron laser science].