ANALYTICAL THEORY OF NEXAFS FROM DIATOMIC-MOLECULES

Analytical expressions are derived for both the pi and sigma* resonan ces in near-edge x-ray-absorption finestructure (NEXAFS) spectra from diatomic molecules. A simple criterion is formulated for extracting st ructural parameters (e.g., the bond lengths) of such molecules from NE XAFS spectra. A universal curve for the positions of resonances is der ived from our analytical expressions. The predictions are confirmed by comparisons with computer simulations of NEXAFS spectra for gas-phase N-2 and O-2 molecules.