Commissioning of a collimated plane-grating monochromator with ultra-high resolution and evaluation by resonant Auger spectra

Abstract We have upgraded a soft X-ray monochromator with moderate resolution at SPring-8 into a collimated plane grating monochromator with ultra-high energy resolution. This was achieved through the application of fundamental techniques, such as vibration measurement, optical metrology, and beam evaluation. The precise alignment of the collimating and focusing mirrors in the monochromator is critical for achieving high resolution, and this was accomplished using ray tracing. The energy resolution was estimated from the natural width free resonant Auger spectrum, which is known as the Auger resonant Raman effect. The estimated resolving power of 39,000 at 867 eV closely matches the design value.