Extreme ultraviolet resonant inelastic X-ray scattering (RIXS) at a seeded free-electron laser

Abstract

In the past few years, we have been witnessing an increased interest for studying materials properties under non-equilibrium conditions. Several well established spectroscopies for experiments in the energy domain have been successfully adapted to the time domain with sub-picosecond time resolution. Here we show the realization of high resolution resonant inelastic X-ray scattering (RIXS) with a stable ultrashort X-ray source such as an externally seeded free electron laser (FEL). We have designed and constructed a RIXS experimental endstation that allowed us to successfully measure the d-d excitations in KCoF3 single crystals at the cobalt M2,3-edge at FERMI FEL (Elettra-Sincrotrone Trieste, Italy). The FEL-RIXS spectra show an excellent agreement with the ones obtained from the same samples at the MERIXS endstation of the MERLIN beamline at the Advanced Light Source storage ring (Berkeley, USA). We established experimental protocols for performing time resolved RIXS experiments at a FEL source to avoid X ray-induced sample damage, while retaining comparable acquisition time to the synchrotron based measurements. Finally, we measured and modelled the influence of the FEL mixed electromagnetic modes, also present in externally seeded FELs, and the beam transport with ~120 meV experimental resolution achieved in the presented RIXS setup.

McXtrace anno 2020: complex sample geometries and GPU acceleration

“…of SPIE Vol. 11493 114930A-6 RIXS instrumentation exists (see for example 11 ), yet non-direct beam scattering is rarely taken into account. We believe the union concept can provide instrument developers and beamlines scientists a unique handle to understand the sometimes complicated interplay between scattering elements in a beamline.…”

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

“…3 . Many RIXS spectrometers/beamlines all over the world optimized for shorter wavelengths (MERIXS at the Advanced Light Source ( Chuang et al , 2012 ), ADRESS at the Swiss Light Source ( Strocov et al , 2010 ), the commercial Scienta XES 355 RIXS spectrometer at FERMI FEL ( Dell'Angela et al , 2016 ), and AERHA at Soleil ( Chiuzbăian et al 2014 , etc. ), are based on a scheme with a variable line spacing grating, sometimes in combination with an additional focusing mirror.…”

“…Utilizing RIXS within a pump-probe scheme—either optical pump x-ray probe or all x-ray pump-probe—makes it a very powerful technique to study the dynamics of involved states and their interactions. Such experiments have already been performed in the past at FLASH ( Beye et al , 2010 ), at the Linac Coherent Light Source (LCLS) ( Wernet et al , 2015 , Dell'Angela et al , 2013 and Dean et al , 2016 ) as well as at the Center for Free-Electron Laser Radiation for Multidisciplinary Investigations (FERMI) ( Dell'Angela et al , 2016 ) and recently again at the LCLS ( Parchenko et al , 2020 ) on different systems ranging from strongly correlated materials to catalysts. Beye et al clearly demonstrated the first-order nature of the liquid–liquid phase transition in silicon via time-resolved soft x-ray emission spectroscopy.…”

“…Dell'Angela et al have used a commercial RIXS spectrometer at FERMI and measured for the first time high-resolution EUV RIXS at a seeded FEL on a KCoF 3 single crystal at Co M 2,3 -edge (62 eV). The instrument demonstrated 120 meV resolution and has great potential for high time-resolution RIXS studies ( Dell'Angela et al , 2016 ). Dean et al studied the ultrafast photo-induced magnetic dynamics in Sr 2 IrO 4 perovskite and discovered significantly different time scales for 2D and 3D antiferromagnetic ordering in the system on the order of a few picoseconds and few hundreds of picoseconds, correspondingly.…”

XUV-driven plasma switch for THz: new spatio-temporal overlap tool for XUV–THz pump–probe experiments at FELs

“…This is almost never the case in pump-probe experiments on solid-state samples, utilizing one of the XUV probing techniques [e.g. X-ray magnetic circular dichroism (XMCD) (Pfau et al, 2012;Willems et al, 2015) and resonant inelastic X-ray scattering (Dell'Angela et al, 2016)]. There, the spatio-temporal overlap between THz and XUV and in particular diffraction-limited focusing of the THz beam have to be achieved with the aid of versatile in-vacuum diagnostics.…”