Schedule Aug 06, 2010
Core-Level Photoexcitation of Metals by Intense XFEL: Quantum Kinetics and Nonlinear Photonics
Hikaru Kitamura (Kyoto Univ.)

On the basis of the quantum-statistical density-matrix equation [H.K., J. Phys. B 43, 115601 (2010)], we simulate ultrafast kinetics of electron excitation and relaxation in a metallic target irradiated by an intense X-ray free-electron laser (XFEL) pulse. Numerical results for metallic lithium demonstrate that a near-edge multiple photoexcitation of core electrons to the conduction band gives rise to a lowering of core energy levels, which induces a blue shift of the absorption edge and a reduction of the absorption coefficient within approximately 10 fs; the Auger decay and Coulomb explosion can safely be neglected during such a short timescale. In light of these observations, we investigate the possibility of nonlinear transmission of an XFEL pulse through a thin solid target, which was detected in recent VUV laser experiments [H. Yoneda et al., Opt. Express 17, 23443 (2009)].

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