A comparative study of the methods of speciation using X-ray absorption fine structure

Abstract

Determination of the chemical forms along with the relative quantity of the different species in a given sample, termed as speciation, can be done by analyzing X-ray absorption fine structure spectra. The different methods that can be used for speciation are: principal component analysis, target transformation, methods based on derivative spectra, method based on the relative position of the absorption edge, residual phase analysis, normalized difference absorption edge spectra analysis and linear combination fitting. An attempt has been made to make a comparative study of these different methods of speciation by recording the X-ray absorption fine structure at the copper K-edge in a mixture having cuprous oxide and cupric oxide in a specific ratio. The X-ray absorption fine structure spectra of the two oxides have also been recorded separately and the different characteristic X-ray absorption near edge structure features have been identified and their origins have been discussed. Speciation of the mixture has been done using these different methods and the results obtained have been compared and discussed.