A Voxel Method for Correcting the Self-absorption Effect in Fluorescence X-ray Absorption Fine Structure Spectra

Partial fluorescence yield X-ray absorption fine structure (PFY-XAFS) spectroscopy in the soft X-ray region is important for obtaining information about the bulk region of a sample. However, the self-absorption effect is a serious problem that causes distortions to the fine structure of PFY-XAFS spectra. This self-absorption can be analytically corrected for flat surfaces but not for arbitrary shapes such as those of particles in powders. In this study, we propose a voxel method where we divide the sample with arbitrary shapes into small boxes (called voxel) to calculate the self-absorption effect. By comparing the O K-edge PFY-XAFS spectra of a CoO single crystal, a thin layer Li2CO3 on a NiO substrate, and a CoO powder sample, we investigate the validity of the voxel method, along with its merits and limitations.