On the interpretation of the NEXAFS spectrum of molecular oxygen

Calculations with extended basis sets and full intrachannel coupling of discrete and continuum states suggest an alternative interpretation of the NEXAFS spectrum of molecular oxygen. In this interpretation the roles of valence-Rydberg mixing and intrachannel discrete-continuum interaction are stressed at the expense of the exchange splitting mechanism. Calculations indicate that only the doublet-parent channel holds discrete strong transitions with sigma* character, while the quartet-parent channel contains preferentially Rydberg-like transitions.