Observation of the argon photoelectron satellites near threshold

The authors have studied near-threshold photoionisation of argon in the region of the valence satellites (32 to 49 eV) in two ways. They have measured photoelectron spectra for various constant values of photoelectron energy, from zero to 0.48 eV. Secondly, they have measured relative partial ionisation cross sections for many of the ionic states in this region, over the energy range from zero to 1.0 eV above their respective thresholds. The dominant contribution to these cross sections is observed to come from the decay of doubly excited neutral states or resonances.