Development of the Soft X-ray AGM–AGS RIXS beamline at the Taiwan Photon Source

We report on the development of a high-resolution and highly efficient beamline for soft-X-ray resonant inelastic X-ray scattering (RIXS) located at Taiwan Photon Source. This adopts an optical design that uses active grating monochromator (AGM) spectrometer (AGS) to implement energy compensation principle dispersion. Active gratings are utilized diminish defocus, coma higher-order aberrations as well decrease slope errors caused by thermal deformation polishing. The AGS is mounted rotatable granite platform enable momentum-resolved RIXS measurements with angle over wide range. Several high-precision instruments developed in house this briefly described. best resolution obtained from AGM-AGS was 12.4 meV 530 eV, achieving resolving power 42,000, while bandwidth incident soft X-rays kept 0.5 eV. To demonstrate scientific impacts RIXS, we present example high-temperature superconducting cuprate, La$_{2-x}$Sr$_x$CuO$_4$. reveal A$_{1g}$ apical oxygen phonons cuprates, opening new opportunity investigate coupling between these charge density waves.