Quartz-based flat-crystal resonant inelastic x-ray scattering spectrometer with sub-10 meV energy resolution

Continued improvement of the energy resolution of resonant inelastic x-ray scattering (RIXS) spectrometers is crucial for fulfilling the potential of this technique in the study of electron dynamics in materials of fundamental and technological importance. In particular, RIXS is the only alternative tool to inelastic neutron scattering capable of providing fully momentum resolved information on dynamic spin structures of magnetic materials, but is limited to systems whose magnetic excitation energy scales are comparable to the energy resolution. The state-of-the-art spherical diced crystal analyzer optics provides energy resolution as good as 25 meV but has already reached its theoretical limit. Here, we demonstrate a novel sub-10meV RIXS spectrometer based on flat-crystal optics at the Ir-L$_3$ absorption edge (11.215$\sim$ keV) that achieves an analyzer energy resolution of 3.9$\sim$meV, very close to the theoretical value of 3.7$\sim$meV. In addition, the new spectrometer allows efficient polarization analysis without loss of energy resolution. The performance of the instrument is demonstrated using longitudinal acoustical and optical phonons in diamond, and magnon in Sr$_3$Ir$_2$O$_7$. The novel sub-10$\sim$meV RIXS spectrometer thus provides a window into magnetic materials with small energy scales

IRIXS Spectrograph: an ultra high-resolution spectrometer for tender RIXS

The IRIXS spectrograph represents a new design of a ultra high-resolution resonant inelastic X-ray scattering (RIXS) spectrometer that operates at the Ru L3-edge(2840 eV). First proposed in the field of hard X-rays by Shvyd'ko (2015), the X-ray spectrograph uses a combination of laterally graded multilayer mirrors and collimating/dispersing Ge(111) crystals optics in a novel spectral imaging approach to overcome the energy resolution limitation of a traditional Rowland-type spectrometer(Gretarsson et al., 2020). In combination with a dispersionless nested four-bounce high resolution monochromator design that utilizes Si(111) and Al$_2$O$_3$(110) crystals,we achieve an overall energy resolution better than 35 meV full width at half maximum (FWHM) at the Ru L$_3$-edge, in excellent agreement with ray tracing simulations

X‑ray Emission Spectroscopy of Biomimetic Mn Coordination Complexes

Understanding the function of Mn ions in biological and chemical redox catalysis requires precise knowledge of their electronic structure. X-ray emission spectroscopy (XES) is an emerging technique with a growing application to biological and biomimetic systems. Here, we report an improved, cost-effective spectrometer used to analyze two biomimetic coordination compounds, [Mn^IV(OH)₂(Me₂EBC)]²⁺ and [Mn^IV(O)­(OH)­(Me₂EBC)]⁺, the second of which contains a key Mn^IVO structural fragment. Despite having the same formal oxidation state (Mn^IV) and tetradentate ligands, XES spectra from these two compounds demonstrate different electronic structures. Experimental measurements and DFT calculations yield different localized spin densities for the two complexes resulting from Mn^IV–OH conversion to Mn^IVO. The relevance of the observed spectroscopic changes is discussed for applications in analyzing complex biological systems such as photosystem II. A model of the S₃ intermediate state of photosystem II containing a Mn^IVO fragment is compared to recent time-resolved X-ray diffraction data of the same state