Femtosecond Reduction of Atomic Scattering Factors Triggered by Intense X-Ray Pulse
Ichiro Inoue, Jumpei Yamada, Konrad Jerzy Kapcia, Michal Stránský, В. И. Ткаченко, Zoltán Jurek, Takato Inoue, Taito Osaka, Yuichi Inubushi, Atsuki Ito, Yuto Tanaka, Satoshi Matsuyama, Kazuto Yamauchi, Makina Yabashi, Beata Ziaja
Abstract
X-ray diffraction of silicon irradiated with tightly focused femtosecond x-ray pulses (photon energy, 11.5 keV; pulse duration, 6 fs) was measured at various x-ray intensities up to 4.6×10^{19} W/cm^{2}. The measurement reveals that the diffraction intensity is highly suppressed when the x-ray intensity reaches of the order of 10^{19} W/cm^{2}. With a dedicated simulation, we confirm that the observed reduction of the diffraction intensity can be attributed to the femtosecond change in individual atomic scattering factors due to the ultrafast creation of highly ionized atoms through photoionization, Auger decay, and subsequent collisional ionization. We anticipate that this ultrafast reduction of atomic scattering factor will be a basis for new x-ray nonlinear techniques, such as pulse shortening and contrast variation x-ray scattering.