However, the f 1 value in the wide energy band is required for calculating the f 2 value using the Kramers–Kronig relation. The scattering factor f 2 is suitable for research of XAFS because f 2 is related to the absorption coefficient μ: f 2 = π / 2 C E μ, 6 where C = ( π r 0 h c ) − 1, h is the Planck’s constant, r 0 is the classical electron radius, and c is the speed of light. 5 applied the Kramers–Kronig relation to the atomic scattering factors f 1 and f 2 and determined the scattering factor f 2 to fit the DAFS data. They used XAFS standards to analyze the DAFS data by shifting the phase. 4 studied the DAFS as a new x-ray structural technique and demonstrated that the DAFS measurements provide the same local atomic structural information as XAFS. ![]() On the other hand, small oscillations are seen in the reflectance setup, referred to as the diffraction anomalous fine structure (DAFS). 1 (hereafter Clancy12) investigated spin-orbit coupling effects in a series of Ir- and Re-based 5 d compounds using XAS techniques and observed anomalously large L 3 / L 2 branching ratios in all Ir-based compounds, indicating a very large expectation value for the spin-orbit operator in these systems. The x-ray absorption edge spectra of iridium, which is one of the elements having high electron density, such as Au, Pt, etc., have been obtained to reveal the fundamental characteristics of the 5 d material 1 – 3. XAS is performed in a transmission setup, providing a direct measure of the linear x-ray attenuation coefficient μ ( E ). The x-ray absorption fine structure (XAFS) is often measured with x-ray absorption spectroscopy (XAS) to find useful information on the environment (geometry) and electronic structure of the absorbing atoms. The ground calibration to measure fine structures near the edges may potentially be simplified using f 2 estimated based on μ. Our measurements near L 3, L 2, and L 1 edges demonstrated a different technique to provide atomic structural information as XAS. The fine structure seen in L 1 also has two weak lines, which were seen in XAS at L 1-edge. The branching ratio ( L 3 / L 2) of the WL is >2, which reflects the initial core-electron states available for the L 2 (2 p 1/2) and L 3 (2 p 3/2) processes, and the ratio remains high to the energy of +7. The fine structures of f 2 of L 3 and L 2 can be represented by a strong sharp line referred to as a white line (WL) and two weak lines at center energies of ∼17 and ∼31 eV from each edge energy. ![]() The derived atomic scattering factor f 2 was similar to a shape of the absorption coefficient μ near L 3 and L 2 obtained by previous x-ray absorption spectroscopy (XAS) measurements. We measured the reflectivity of an Athena silicon pore optics sample coated with 10-nm thick iridium near the iridium L-edges ( L 3, L 2, and L 1) in a step of 1.5 eV.
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