Data analysis in extended x-ray-absorption fine structure: Determination of the background absorption and the threshold energy

Two approaches for the determination of the background absorption (p0 ) in the extended xray-absorption fine structure (EXAFS) are presented. Both methods, experimental and computational, take advantage of the damping of the EXAFS amplitude resulting from the convolution with Gaussian functions of different widths. In the experimental method two or more spectra are collected with the use of different spectrometer slit widths, resulting in spectra of different resolutions for the same sample. In the computational approach the convolution is accomplished via a convolution algorithm. The intersection points of the resulting spectra are used to generate p 0 • At the absorption edge, the spectra intersect at a unique point, which is shown to be a measure of the threshold energy, E0• Illustration of the two methods for background removal is given for a copper-foil sample. The computational approach is superior to the experimental method of damping the EXAFS spectra to give Po·