The TRIXS end-station for femtosecond time-resolved resonant inelastic x-ray scattering experiments at the soft x-ray free-electron laser FLASH

• Main Authors: S. Dziarzhytski, M. Biednov, B. Dicke, A. Wang, P. S. Miedema, R. Y. Engel, J. O. Schunck, H. Redlin, H. Weigelt, F. Siewert, C. Behrens, M. Sinha, A. Schulte, B. Grimm-Lebsanft, S. G. Chiuzbăian, W. Wurth, M. Beye, M. Rübhausen, G. Brenner
• Format: Article
• Language: English
• Published: AIP Publishing LLC and ACA 2020-09-01
• Series: Structural Dynamics
• Online Access: http://dx.doi.org/10.1063/4.0000029

We present the experimental end-station TRIXS dedicated to time-resolved soft x-ray resonant inelastic x-ray scattering (RIXS) experiments on solid samples at the free-electron laser FLASH. Using monochromatized ultrashort femtosecond XUV/soft x-ray photon pulses in combination with a synchronized optical laser in a pump-probe scheme, the TRIXS setup allows measuring sub-picosecond time-resolved high-resolution RIXS spectra in the energy range from 35 eV to 210 eV, thus spanning the M-edge (M1 and M2,3) absorption resonances of 3d transition metals and N4,5-edges of rare earth elements. A Kirkpatrick–Baez refocusing mirror system at the first branch of the plane grating monochromator beamline (PG1) provides a focus of (6 × 6) μm2 (FWHM) at the sample. The RIXS spectrometer reaches an energy resolution of 35–160 meV over the entire spectral range. The optical laser system based on a chirped pulse optical parametric amplifier provides approximately 100 fs (FWHM) long photon pulses at the fundamental wavelength of 800 nm and a fluence of 120 mJ/cm2 at a sample for optical pump-XUV probe measurements. Furthermore, optical frequency conversion enables experiments at 400 nm or 267 nm with a fluence of 80 and 30 mJ/cm2, respectively. Some of the first (pump-probe) RIXS spectra measured with this setup are shown. The measured time resolution for time-resolved RIXS measurements has been characterized as 287 fs (FWHM) for the used energy resolution.