The experimental set-up
Contact: anders.madsen@xfel.eu
The Materials Imaging and Dynamics (MID) instrument [1] provides hard X-ray scattering and imaging capabilities at the European XFEL [2,3] with particular emphasis on applications of the coherence properties of the beam. The setup allows for pumping the samples with an infrared or optical laser and working with nanosized focused X-ray beams. The instrumentation comprises a megapixel area detector, AGIPD, with MHz acquisition speed and an X-ray split-and-delay line (SDL) with delays ranging from -10 to 800 ps. MID can operate with 15 fs SASE pulses (bandwidth ~2×10-3) of within a self-seeded mode with 10-4 bandwidth pulses. The techniques available at MID range from X-ray photon correlation spectroscopy (XPCS) over ultrafast pump-probe diffraction to holographic and phase-contrast imaging and X-ray microscopy. Mössbauer spectroscopy and fluorescence correlation imaging are also possible.
For this water XPCS experiment the SDL and the liquid jet sample environment were essential components and ePix area detectors with a small pixel size (50 µm) were used to record the scattered speckle pattern from the water jet.
Sketch of the MID instrument [1,4] in wide-angle scattering geometry. The detector can be moved up a distance of 8 m from the sample and measure at scattering angles up to 50 deg.
Many experiments at MID utilize the excellent coherence properties of the XFEL beam. This is demonstrated by e.g. Fraunhofer scattering images.
Fraunhofer image from a ~36 x 31 µm slit opening, with the slit placed 49 m upstream of the detector [1]
Nearfield holography is yet another technique pursued at MID. Shown is the break-up of a liquid jet filament.
Break-up of a liquid jet filament, 16 ns after being hit by an infrared laser pulse. The red arrows indicate the fronts of the resulting shockwave. The scale bar is 20 µm [5].
[1] A. Madsen et al., J. Sync. Rad. 28, 637 (2021)
[2] T. Tschentscher et al., Appl. Sci. 7, 592 (2017)
[3] W. Decking et al., Nat. Photon. 14, 391 (2020)
[4] Homepage of the MID instrument
[5] J. Hagemann et al., J. Sync. Rad. 28, 52 (2021)
Homepage of the MID instrument