I21: an advanced high-resolution resonant inelastic X-ray scattering beamline at Diamond Light Source.

The I21 beamline at Diamond Light Source is dedicated to advanced resonant inelastic X-ray scattering (RIXS) for probing charge, orbital, spin and lattice excitations in materials across condensed matter physics, applied sciences and chemistry. Both the beamline and the RIXS spectrometer employ divergent variable-line-spacing gratings covering a broad energy range of 280-3000 eV. A combined energy resolution of ∼35 meV (16 meV) is readily achieved at 930 eV (530 eV) owing to the optimized optics and the mechanics. Considerable efforts have been paid to the design of the entire beamline, particularly the implementation of the collection mirrors, to maximize the X-ray photon throughput. The continuous rotation of the spectrometer over 150° under ultra high vacuum and a cryogenic manipulator with six degrees of freedom allow accurate mappings of low-energy excitations from solid state materials in momentum space. Most importantly, the facility features a unique combination of the high energy resolution and the high photon throughput vital for advanced RIXS applications. Together with its stability and user friendliness, I21 has become one of the most sought after RIXS beamlines in the world.

Laser-heating system for high-pressure X-ray diffraction at the Extreme Conditions beamline I15 at Diamond Light Source.

In this article, the specification and application of the new double-sided YAG laser-heating system built on beamline I15 at Diamond Light Source are presented. This system, combined with diamond anvil cell and X-ray diffraction techniques, allows in situ and ex situ characterization of material properties at extremes of pressure and temperature. In order to demonstrate the reliability and stability of this experimental setup over a wide range of pressure and temperature, a case study was performed and the phase diagram of lead was investigated up to 80 GPa and 3300 K. The obtained results agree with previously published experimental and theoretical data, underlining the quality and reliability of the installed setup.