Application of sparse modeling to extended X-ray absorption fine structure spectra of transition metals

Abstract

In various transition metals with different crystal structures, we have demonstrated the validity of sparse modeling (SpM) for the analysis of extended X-ray absorption fine structure (EXAFS). The target data are EXAFS oscillations of Ni, Co, and Fe foils, and these materials have face centered cubic, hexagonal close-packed, and body centered cubic structures, respectively. The SpM method provides the sparse radial distribution functions associated with the respective crystal structures. Although an assumption of crystal structure is required to extract insightful information concerning structural fluctuations in the conventional analysis method, the SpM method allows us to estimate more accurate Debye-Waller factors without such assumption.