A High-Resolution Beamline for In Situ/Operando Soft X-ray Spectroscopy and Scattering at HALF

Abstract A high-resolution soft X-ray beamline is being developed at the Hefei Advanced Light Facility for in situ and operando spectroscopy and scattering studies of energy and catalytic materials. The beamline covers an energy range of 180–3500 eV and features a dual-branch parallel configuration. It is designed to provide a theoretical resolving power above 15,000 at 244.4 eV, with an estimated photon flux exceeding 7 × 1012 phs/s at the sample. The beamline is equipped with two endstations. The Near Ambient Pressure Analysis endstation is dedicated to near-ambient pressure X-ray photoelectron spectroscopy and incorporates a compact, independently operated analysis chamber with a four-stage differential pumping system. This configuration enables windowless measurements over a pressure range from UHV to 100 mbar. A fast, compact sample manipulator facilitates the efficient handling of powder samples under diverse catalytic conditions, including environments containing highly contaminating gases. The Microscale Absorption Spectroscopy and Resonant Inelastic X-ray Scattering endstation combines X-ray absorption spectroscopy, X-ray emission spectroscopy, and resonant inelastic X-ray scattering. Its movable spectrometer provides a spatial resolution of 2.7 μm and a resolving power of 10,000 at 284 eV, enabling in situ/operando investigations under controlled gas, liquid, temperature, and electric field conditions. This study describes the overall beamline design, technical specifications, and simulated performance of the beamline and its two endstations. The complete system is expected to be completed and commissioned in 2028.