Speaker
Description
At the European XFEL, two-color pump-probe experiments offer crucial insights into chemical reactions and molecular dynamics. High-intensity X-ray pulses with extremely high repetition rates enable researchers to observe sequential ionization. By adjusting the time delay between pump and probe pulses and tuning their wavelengths, researchers capture the sequence of events. To achieve this an x-ray optical delay line (ODL) in combination with a magnetic chicane inside of the undulator section is being developed. The ODL, consisting of four B4C coated silicon mirrors, provides a fixed delay of 200 fs, allowing new possibilities as the zero and negative delay between the two colors. The existing undulator set-up allows tuning of the X-ray photon energy in the range of 250-3000 eV, with single pulse energies up to several mJ.
Since the ODL mirrors are located very close to the source point of the radiation, the resulting small beam footprint on the mirrors is prone to cause severe damage to the mirror coating. In order to check the feasibility of the set-up, a dedicated experiment at the EuXFEL facility had been carried out at the SQS beamline. The objective of this investigation was to determine the damage threshold of B4C coating on silicon substrate when exposed to soft X-ray radiation at a grazing incidence angle of 9mrad. The corresponding damage threshold was determined to be 0.34 $\mu J/{\mu m}^2$.
| I plan to submit also conference proceedings | Yes |
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