Scientific Instrument FXE
The FXE instrument enables ultrafast pump–probe experiments on ultrafast timescales—below 100 femtoseconds—for a broad scientific user community.
The instrument comprises two independent secondary X-ray emission spectrometers next to a 1-Mpx detector for scattering studies. Its main research is devoted to dynamic studies of chemical and biochemical reactions in liquids next to different solid-state applications. With a powerful laser as pump source, it permits studies with femtosecond time resolution exploiting different observables via a suite of hard X-ray tools (which may be further expanded over time):
- X-ray diffraction (XRD)
- X-ray diffuse scattering (XDS), or wide-angle X-ray scattering (WAXS)
- X-ray emission spectroscopies (XES): non-resonant, or resonant inelastic X-ray scattering (RIXS)
- X-ray absorption spectroscopies: X-ray absorption near-edge structure (XANES), or extended X-ray absorption fine structure (EXAFS)
The FXE scientific instrument serves a broad scientific community and embraces several fields of ultrafast X-ray science and their applications. State-of-the-art femtosecond instrumentation and techniques, both for X-rays and optical lasers, delivers new information about geometric and electronic structures serving applications in many fields, and particular in the areas of
- Chemical dynamics
- Photovoltaic applications
- Photosynthesis
- Catalytic processes
- Material physics
Operation of the FXE instrument started in September 2017. A more detailed description of the science case of FXE can be found in the FXE TDR and CDR.
The main specifications and beam parameters of FXE are summarized in table 1 below. Further technical details about the available equipment at FXE is available here and in the TDR and CDR or by contacting the FXE group.
|
Bandwidth ΔE/E |
1x10-3 (natural FEL source) , 1x10-4 (standard Si(111) 4-bounce mono) |
|---|---|
|
Photon energy range |
5–20 keV |
|
Polarization |
Linear (horizontal), circular (future option) |
|
X-ray pulse duration |
50 fs FWHM |
|
Beam size |
8–200 µm adjustable (via several Be lenses) |
|
Special optics |
1 primary 4-bounce Si(111) mono 2 secondary (von Hamos, Johann) spectrometers |
|
Optical laser wavelengths |
Pump–probe (0.1–1 mJ) 800 nm (15–100 fs) Pump–probe (200 µJ) 800 nm (50 fs, 15fs possible), harmonics, TOPAS adjustable UV-vis-NIR Pump–probe (>20 mJ) 1030 nm (850 fs) Pump–probe (>50 µJ) 1 mm (=0.3 THz) generated via optical rectification |
|
X-ray detectors |
APD (0D, full rep. rate with MHz DAQ) Gotthard (1D, 1280 px, 50 µm pixel pitch, 0.9 MHz) Jungfrau (2D, 1024 x 1024 px, 75 x 75 µm pixel size, 10Hz) LPD (2D, 1 Mpx, (500 µm)2 pixel size, 512 frames at 4.5 MHz, 3-fold dynamic gain covering 1 (SP at 12keV) to 1x104 per pixel) |