X-ray-absorption fine structure in embedded atoms

Abstract

Oscillatory structure is found in the atomic background absorption in x-ray-absorption fine-structure (XAFS) measurements. This atomic XAFS (AXAFS) arises from scattering within an embedded atom, and is analogous to the Ramsauer-Townsend effect. Calculations and measurements confirm the existence of AXAFS and show that it can dominate contributions such as multielectron excitations. The structure is sensitive to chemical effects and thus provides a probe of bonding and exchange effects on the scattering potential.