AN ITERATIVE APPROACH TO ATOMIC BACKGROUND REMOVAL IN XAFS DATA-ANALYSIS

In standard XAFS data reduction there is often a spurious peak at low- r in the Fourier transform of the k-space data, which we attribute to features in the X-ray absorption spectrum that are not related to the backscattering of the photoelectron from the neighboring atoms. These features have been observed in the k-space range up to 6 Angstrom(-1), and can therefore interfere with the analysis of the XAFS oscillation s. We have developed an iterative method to extract the background. Fi rst we use a spline to obtain a rough estimate of the background and f it the XAFS data to a sum of standards in r-space. The resulting fit i s then subtracted from the raw data; the subtraction-corrected functio n is smoothed to extract a better background, which is used to re-redu ce the raw data. This process converges after only a few iterations. S ome examples of the extracted background structure are presented, and the ramifications for XAFS analysis are discussed.