Journal Article SACLA X-ray free-electron lasers Research Support, Non-U.S. Gov't SCSS+ X-ray free-electron laser accelerator beam tuning beamline instrumentation catalysts copper oxide crystal engineering environmental remediation free-electron laser low emittance low-emittance storage ring machine learning multiple-beamline operation next generation light source photon beamline self-seeding single-shot inline spectrometers single-shot spectrometers soft X-ray spectral-brightness optimization surface science sustainability two-color X-ray beams