A setup for hard x-ray time-resolved resonant inelastic x-ray scattering at SwissFEL

Abstract

We present a new setup for resonant inelastic hard x-ray scattering at the Bernina beamline of SwissFEL with energy, momentum, and temporal resolution. The compact R = 0.5 m Johann-type spectrometer can be equipped with up to three crystal analyzers and allows efficient collection of RIXS spectra. Optical pumping for time-resolved studies can be realized with a broad span of optical wavelengths. We demonstrate the performance of the setup at an overall ∼180 meV resolution in a study of ground-state and photoexcited (at 400 nm) honeycomb 5d iridate α-Li2IrO3. Steady-state RIXS spectra at the iridium L3-edge (11.214 keV) have been collected and are in very good agreement with data collected at synchrotrons. The time-resolved RIXS transients exhibit changes in the energy loss region <2 eV, whose features mostly result from the hopping nature of 5d electrons in the honeycomb lattice. These changes are ascribed to modulations of the Ir-to-Ir inter-site transition scattering efficiency, which we associate to a transient screening of the on-site Coulomb interaction.

Band Gap Renormalization at Different Symmetry Points in Perovskites

“…However, for estimating the BGR energy shift, they focused on only the VB maximum. An alternative method that can resolve in both energy and momentum space fundamental excitations in solids is resonant inelastic X-ray scattering (RIXS), which is starting to be implemented in the time domain , but still awaits full implementation.…”