Saturable absorption of intense hard X-rays in iron

• Published in: Nature communications Vol. 5; no. 1; p. 5080
• Main Authors: Yoneda, Hitoki, Inubushi, Yuichi, Yabashi, Makina, Katayama, Tetsuo, Ishikawa, Tetsuya, Ohashi, Haruhiko, Yumoto, Hirokatsu, Yamauchi, Kazuto, Mimura, Hidekazu, Kitamura, Hikaru
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.10.2014; Nature Publishing Group
• Subjects: 639/624/1075; 639/624/400/1106; Humanities and Social Sciences; multidisciplinary; Science; Science (multidisciplinary)
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/ncomms6080

In 1913, Maurice de Broglie discovered the presence of X-ray absorption bands of silver and bromine in photographic emulsion. Over the following century, X-ray absorption spectroscopy was established as a standard basis for element analysis, and further applied to advanced investigation of the structures and electronic states of complex materials. Here we show the first observation of an X-ray-induced change of absorption spectra of the iron K-edge for 7.1-keV ultra-brilliant X-ray free-electron laser pulses with an extreme intensity of 10 20  W cm −2 . The highly excited state yields a shift of the absorption edge and an increase of transparency by a factor of 10 with an improvement of the phase front of the transmitted X-rays. This finding, the saturable absorption of hard X-rays, opens a promising path for future innovations of X-ray science by enabling novel attosecond active optics, such as lasing and dynamical spatiotemporal control of X-rays. Saturable absorption is a widely used process in optical-wavelength laser technologies that arises when the transmittance of a material increases upon high-intensity light illumination. Here, Yoneda et al. tightly focus free-electron laser light and demonstrate hard X-ray saturable absorption in iron.