The thickness effect is treated using a simplified form for the window function and the absorption edge. It is shown that for the low absorbing portion of the K edge the relative error caused by the tail of the window function becomes larger, rather than vanishing, in the limit of zero thickness foils. A means is described and experimentally demonstrated for separating changes in K absorption edge fine structure due to alloying from those due to the thickness effect.
Douglas M. Pease, "The Thickness Effect in X-ray Absorption Edges of Metals and Alloys," Appl. Spectrosc. 30, 405-410 (1976)