Workshop information: 19.05.2015 - Non-linear experiments with hard X-rays at SwissFEL

• Bill Francesco Pedrini (Paul Scherrer Institut)

Overview SwissFEL hard X-ray experimental stations (ES-A, ES-B, ES-C)

• Bill Francesco Pedrini (Paul Scherrer Institut)

SwissFEL operation modes (+ Discussion)

• Sven Reiche (Paul Scherrer Institut)

X-ray nonlinear processes in solid Fe with hard X-ray free-electron laser pulses (+ Discussion)

• Joanna Hoszowska (University of Fribourg, Department of Physics)

Nonlinear interaction of solid Fe with intense femtosecond hard x-ray free-electron laser (XFEL) pulses will be reported. The experiment was performed at the CXI end-station of the Linac Coherent Light Source (LCLS) by means of high-resolution x-ray emission spectroscopy. Extreme fluences reaching ~10^5 photons/Å^2 allowed for x-ray nonlinear two-photon absorption. Double-K-hole formation via sequential two-photon absorption, and the direct two-photon absorption leading to single K-shell ionization was observed. The cross-sections for the nonlinear x-ray photon absorption processes were derived from the x-ray fluence dependence of the measured x-ray emission rates. I will present the obtained results as well as the different aspects of the experimental setup, the beam parameters and diagnostic in view of future needs.

X-ray nonlinear absorption and emission processes (+ Discussion)

• Kenji Tamasaku (RIKEN SPring-8 Center)

I will present our recent results on nonlinear absorption and emission processes obtained at SACLA. As for the absorption, I will present two-photon absorption experiment and discuss requirements to perform X-ray two-photon absorption spectroscopy. In the emission process, I will show that the fluorescence decay channel is controllable with intense X-rays, and discuss the theoretical background. Finally, I will explain our requests for the XFEL beam to perform more advanced X-ray nonlinear experiments.

Nonlinear X-Ray Wave-Mixing (+ Discussion)

• Sharon Shwartz (Bar Ilan University)

I will describe recently performed experiments demonstrating nonlinear x-ray wave-mixing including x-ray and visible wave mixing [1], x-ray second harmonic generation [2], and x-ray parametric down-conversion [3]. I will present theoretical studies of difference-frequency generation of optical radiation from two-color x-ray pulses [4], and x-ray-pulse characterization by spectral shearing interferometry [5]. I will discuss future directions of exploring nonlinear and quantum effects in the x-ray regime. For example, x-ray parametric down-conversion may be developed into a very powerful method to study fundamental effects in quantum optics. X-ray and visible mixing may lead to atomic scale resolution techniques to study chemical bonds. Nonlinear techniques are expected to be useful in the inspection of sub-femtosecond temporal pulses. [1] T. E. Glover et al., Nature 488, 603 (2012). [2] S. Shwartz et al. Phy. Rev. Lett. 112, 163901 (2014). [3] S. Shwartz et al. Phy. Rev. Lett. 109, 013602 (2012). [4] E. Shwartz and S. Shwartz, Opt. Exp. 23, 7471 (2015) [5] S. Yudovich and S. Shwartz, Phys. Rev. A 90, 033805 (2014).

Implications of Stimulated Resonant X-ray Scattering for Spectroscopy with X-Rays (+ Discussion)

• Alexander Foehlisch (Helmholtz-Zentrum Berlin)

Stimulated electronic x-ray Raman scattering and perspectives for nonlinear optical spectroscopy at XFELs (+ Discussion)

• Nina Rohringer (Max Planck Institute for the structure and dynamics of matter)

Non-linear experiments with soft X-rays at the SwissFEL

Further discussions / Conclusions

Invited dinner for speakers

Workshop information: 20.05.2015 - Nanoscale Material Science at SwissFEL

• Bill Francesco Pedrini (Paul Scherrer Institut)

Overview SwissFEL hard X-ray experimental stations (ES-A, ES-B, ES-C)

• Bill Francesco Pedrini (Paul Scherrer Institut)

Participant contributions

Participant contributions / Discussions

Participant contributions / Discussions

Conclusion