Photon-shot-noise-limited transient absorption soft X-ray spectroscopy at the European XFEL

Area of Science:

• Materials Science
• Physical Chemistry
• Spectroscopy

Background:

• Femtosecond transient soft X-ray absorption spectroscopy (XAS) is crucial for understanding out-of-equilibrium dynamics.
• X-ray free-electron lasers (FELs) provide the necessary high-intensity, ultrashort pulses for XAS.
• Investigating material and energy research requires advanced spectroscopic techniques.

Purpose of the Study:

• To present a dedicated setup for soft X-ray transient absorption spectroscopy at the European X-ray Free-Electron Laser (European XFEL).
• To enable precise, shot-by-shot normalized transmission measurements for studying ultrafast dynamics.
• To review the capabilities of the setup and associated analysis tools for researchers.

Main Methods:

• Utilized a beam-splitting off-axis zone plate (BOZ) in transmission to generate three beam copies.
• Simultaneously measured transmitted intensity through excited and unexcited samples, and monitored incoming beam intensity.
• Employed an imaging detector capable of high frame rates (4.5 MHz) for photon detection during FEL bursts.

Main Results:

• Achieved normalized shot-by-shot analysis of transmission, crucial for accurate dynamic studies.
• Approached photon-shot-noise-limited sensitivity due to advanced detection capabilities.
• Demonstrated the functionality of the new setup for soft X-ray XAS experiments.

Conclusions:

• The presented setup enhances the capabilities of soft X-ray XAS at European XFEL.
• This facilitates advanced investigations into ultrafast dynamics in material and energy research.
• The integrated analysis tools support efficient data processing for users.