Lifetime-broadening-suppressed/free XANES spectroscopy by high-resolution resonant inelastic x-ray scattering

The resonant inelastic x-ray scattering (RIXS) spectrum is uniquely related to the x-ray absorption oscillator strength distribution by the Kramers-Heisenberg equation via lifetime widths of the states involved. In this work it is shown that x-ray absorption near-edge structure (XANES), where the lifetime broadening of 1s core holes is suppressed and that of the 2p hole determines the resolution, can be analytically deduced from RIXS spectra. Furthermore, it is demonstrated that numerical procedures can provide lifetime-broadening-free (LBF) XANES, where the remaining 2p broadening is also eliminated. As examples, lifetime-broadening-suppressed (LBS) XANES and LBF-XANES of CuO and CuCl2·2H2O are derived from RIXS spectra measured by the use of a third-generation synchrotron source SPring-8 and are compared with XANES obtained by other methods to discuss the significance of LBS and LBF XANES spectroscopy