X-RAY-ABSORPTION K-EDGES OF SIMPLE METALS BEYOND THRESHOLD

The difference between threshold theory and X-ray absorption-edge data in the near-edge region of simple metals is indicative of a reduction in screening response beyond threshold. An empirical model in which t he edge exponent decreases linearly above threshold successfully repro duces the experimental Al K-edge absorption spectrum over an energy ra nge of 5 eV and confirms the previously determined threshold exponent. The K-edge exponent of Mg, determined using this model, is in agreeme nt with a prediction based on the singularity index and L-edge exponen t.