Unified picture of near-edge and extended x-ray-absorption fine structure in low-Z molecules

Self-consistent X+ multiple-scattering calculations for N2 and O2 reveal a close connection between the prominent multiple-scattering shape resonances found near threshold and the weak single-scattering extended x-ray-absorption fine-structure (EXAFS) oscillations at higher energy. The shape resonance may be interpreted as the first, enhanced, EXAFS wiggle while the valence electron potential is found to significantly influence the EXAFS, signifying a breakdown of the conventional picture. © 1991 The American Physical Society.