LAUSR

A new light source based on the electron storage ring, dubbed the “diffraction-limited storage ring” (DLSR) to keep the full intrinsic wave nature of X-rays had been proposed since the early stage of storage ring history and has finally been developed successfully, and an upgrade and a new construction programs have now chosen in the worldwide synchrotron facilities. The construction of the so-called “4th generation storage ring” (4GSR), which is a newly-coined term aiming in the same direction, was decided in Korea. The Korean 4GSR is expected to be 10–100 times brighter than the Pohang Light Source-II (PLS-II). Hard X-ray undulator beamlines will benefit from the 4GSR due to its low emittance approaching the diffraction limit. In the PLS-II, more than 10 hard X-ray undulator beamlines are currently in operation. We present a comparative study of the representative hard X-ray undulator beamlines by using the cutting-edge diffraction-spectroscopy techniques in the PLS-II and the 4GSR for better understanding the upcoming light source in Korea. The figures-of-merit of the two specific experimental techniques, resonant inelastic X-ray scattering (RIXS) and resonant X-ray emission spectroscopy (RXES), are discussed for comparison of the two light sources. Both RIXS and RXES are sometimes referred to as a “renaissance” in X-ray science and are, therefore, strongly expected to be adopted in the 4GSR beamlines.