Auger electron yield XAFS measurement using synchrotron radiation. Application of element-selective analysis and chemical state analysis

Auger electron yield XAFS was applied to element-selective analysis and chemical state analysis for MoS2 and Na2S2O3. Mo L absorption edges appeared on a higher energy side of S K-edge in XAFS spectra for MoS2 measured by total electron yield and conventional Auger electron yield. They were obstacles to EXAFS analysis for S K-edge of MoS2. Therefore three-dimensional S KLL Auger electron spectra were measured by scanning both kinetic energy of electron and incident X-ray energy from synchrotron radiation. The Mo L-edges were removed from S K-edge XAFS for MoS2 by subtraction of background in the three-dimensional S KLL Auger electron spectra. EXAFS analysis for the S K-edge of MoS2 was successfully done. S K-edge XAFS spectra of S2- and S6+ in [S2--S6+-O3]2- were obtained individually by curve-fitting for Auger electron peaks corresponding to S2- and S6+ split by chemical shifts. Radial distribution functions around S2- and S6+ were obtained individually from the spectra. (author)