Determination of the exchange splitting of the shape resonance of O2 using the core hole decay spectrum as a "fingerprint."

Abstract

We have determined the exchange splitting of the 1${\mathrm{\ensuremath{\sigma}}}_{\mathit{g}}^{\mathrm{\ensuremath{-}}1}$3${\mathrm{\ensuremath{\sigma}}}_{\mathit{u}}$ shape resonance excitation of gas phase ${\mathrm{O}}_{2}$, which cannot unambiguously be identified using conventional absorption spectroscopy. By identifying the electronic decay spectrum of the shape resonance excitation we could separately monitor the decay of the ${\mathrm{\ensuremath{\sigma}}}^{\mathrm{*}}$ shape resonance and the Rydberg states. Using this fingerprint method we measured the pure core to 3${\mathrm{\ensuremath{\sigma}}}_{\mathit{u}}$ bound state absorption spectrum in partial secondary electron yield spectroscopy.