Design of a time-delay-compensated monochromator for the ARPES endstation at SFEL.

The preliminary design and expected performance for the Angle-Resolved Photoemission Spectroscopy (ARPES) branchline at Shenzhen Superconducting Soft X-ray Free Electron Laser (SFEL) is presented. A time-delay-compensated monochromator (TDCM) in symmetric layout has been designed for spectral selection and pulse duration preservation. The TDCM is optimized using the six-dimensional K-matrix method and a start-to-end simulation of the beamline system using Fourier optics was performed. Numerical estimations indicate that the TDCM can achieve a time-bandwidth product approaching the Fourier-transform limit.