Surprising similarities in the spectator decay of oxygen core-excited CO, CO2, and OCS

Abstract

De‐excitation electron spectra of oxygen core‐excited and core‐ionized CO, CO₂, and OCS are compared. The spectra for de‐excitation of the core‐ionized species are quite distinctive and show only broad similarities. Those for de‐excitation of the neutral core‐excited species to two‐hole, one‐particle states are, in contrast, strikingly similar to each other both in peak shapes and positions. Differences that are apparent in the normal Auger spectra largely disappear when an extra electron is added to the lowest unoccupied (antibonding) molecular orbital. It is suggested that the antibonding effect of the spectator electron is large enough to make the core‐excited oxygen weakly bound to the rest of the molecule in both the core‐excited and final states. As a result, the spectra are all similar to that of a core‐excited oxygen atom.