Sparse Modeling of an Extended X-Ray Absorption Fine-Structure Spectrum Based on a Single-Scattering Formalism

We propose a new method for the analysis of extended X-ray absorption fine structures (EXAFSs), by the application of sparse modeling using simplified basis functions based on the single-scattering approximation. This method can overcome the following two issues of the conventional methods using the Fourier transform for EXAFS data analysis, and its validity is demonstrated by the EXAFS data analysis of polycrystalline copper foil. One is that conventional methods need prior assumptions of atomic-scale local structures to analyze the thermal and/or structural atomic disorder, namely the Debye–Waller factor. Our method, however, has accomplished the estimation of the Debye–Waller factor only from experimental data without assumptions of any atomic-scale local structures. The other issue of the conventional methods is that the radial structure function (RSF) shows a continuous spectrum with respect to the interatomic distance, despite the fact that neighbor atoms coordinate to the atom of interest at discre...