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