The Heisenberg-RIXS instrument at the European XFEL

Area of Science:

• X-ray spectroscopy
• Materials science
• Quantum optics

Background:

• Resonant inelastic X-ray scattering (RIXS) offers high energy and time resolution.
• Core-hole lifetime broadening affects RIXS resolution and pump-probe experiment times.
• High-repetition-rate pulsed X-ray sources are crucial for photon-hungry RIXS.

Purpose of the Study:

• To present the Heisenberg RIXS instrument designed for soft X-ray experiments.
• To achieve energy resolution approaching Fourier and Heisenberg limits.
• To utilize the European XFEL for advanced RIXS studies.

Main Methods:

• Utilized a spherical grating with variable line spacing and a 2D position-sensitive detector.
• Employed two gratings to cover a wide photon energy range.
• Integrated with the SCS instrument at the European XFEL, allowing continuous adjustment of scattering angles (65-145°).

Main Results:

• Achieved energy resolution better than 40 meV (high-resolution grating) and 90 meV (high-transmission grating) below 1000 eV.
• Demonstrated compatibility with liquid jet and solid sample chambers, including optical laser pumping.
• Measured performance closely matches design expectations for energy resolution and detector count rate.

Conclusions:

• The Heisenberg RIXS instrument successfully meets its design goals for high-resolution soft X-ray spectroscopy.
• It provides a powerful new capability for studying material dynamics at unprecedented resolution.
• The instrument has been available to users since summer 2022.