Speaker
Description
The Spectroscopy and Coherent Scattering (SCS) Instrument of the European X-ray Free Electron Laser (European XFEL) offers a wide range of measurement techniques and sample environments for ultrafast studies in solids and liquids. In this talk I will introduce the instrument and its capabilities with an emphasis on applications in magnetism.
The soft X-ray branch of the European XFEL delivers highly energetic femtosecond X-ray pulses at high repetition rates in the photon energy range from 400 eV to 3 keV. A grating monochromator provides tuning over absorption edges with high energy resolution. The photon energy range covers the L- and M-edges of transition metals and rare earth respectively, allowing ultrafast time resolved studies of all magnetic materials of technical relevance. The femtosecond X-ray pulses are complemented by optical lasers spanning from ultraviolet to mid infrared and terahertz for pump-probe experiments.
The experimental techniques offered at the instrument currently include X-ray absorption spectroscopy (XAS), small angle X-ray scattering (SAXS), X-ray diffraction (XRD) and resonant inelastic X-ray scattering (RIXS). Our implementation of XAS is based on a beam splitting scheme using transmission zone plates and an area detector to reach the shot noise limit [1]. With the newly installed elliptical undulators, XAS has been extended to include X-ray magnetic circular dichroism. Magnetic SAXS and coherent diffractive imaging (CDI) can be performed on thin film samples in a transmission geometry using a dedicated end station equipped with fast sample scanning and an out-of-plane electromagnet. Single pulse scattering data can be collected on the DSSC detector at up to 4.5 MHz [2]. The Heisenberg RIXS spectrometer is optimized for solid and liquid jet samples [3]. An end station for solid samples offers X-ray diffraction studies from e.g. spin- or charge ordered systems in combination with RIXS with continuous angle tuning. A liquid jet end station can be coupled to the RIXS spectrometer at fixed angles.
References
[1] L. Le Guyader et al., “Photon-shot-noise-limited transient absorption soft X-ray spectroscopy at the European XFEL,” Journal of Synchrotron Radiation, vol. 30, no. 2. International Union of Crystallography (IUCr), pp. 284–300, Feb. 20, 2023. https://doi.org/10.1107/s1600577523000619.
[2] N. Zhou Hagström et al., “Megahertz-rate ultrafast X-ray scattering and holographic imaging at the European XFEL,” Journal of Synchrotron Radiation, vol. 29, no. 6. International Union of Crystallography (IUCr), pp. 1454–1464, Sep. 29, 2022. https://doi.org/10.1107/s1600577522008414.
[3] J. Schlappa et al., “The Heisenberg-RIXS instrument at the European XFEL,” Journal of Synchrotron Radiation, vol. 32, no. 1. International Union of Crystallography (IUCr), pp. 29–45, Jan. 01, 2025. https://doi.org/10.1107/s1600577524010890.
