Quantitative analysis of X-ray absorption spectra using a 2D map representation

A promising possibility for the quantitative analysis of X-ray absorption near edge structure (XANES) spectra of nanosized electrode materials is demonstrated. We used a 2D map representation technique, which utilizes the values of the first derivatives of the absorbance with respect to the inserted Li+ content plotted over the two-dimensional space defined by the inserted Li+ content (mole) versus photon energy (eV) as a single map. The technique was applied to XANES spectra of the LiyCoO system in the first Li+ insertion reaction for determining the structural and electronic variations associated with the change in Li+ content. The obtained show that the intensities of two peaks at 7725 and 7711 eV increased with the Li+ content and the difference of intensity change of these two peaks carried out for successive couples of spectra yielded the largest changes at 1.05 and 1.98 mol of Li content. This approach for quantitative analysis of XANES without using conventional simulation techniques enable us to interpret X-ray absorption spectroscopy (XAS) as a quantitative analytical technique with greater confidence.