Threshold effects in Auger spectra of photoionized argon

The Auger spectra of photoionized argon have been studied around the threshold for ejection of a 2p electron. Above threshold the normal Auger line shape is distorted due to post-collision interaction. The line shape is well described using existing theories. Below threshold two high-resolution spectra have been recorded of resonantly excited inner-shell states. In these spectra the multiplet structure of the final state is partly resolved. Shake up of the excited electron appears to be an important exit channel. The authors find evidence that orbital and spin angular momentum of the excited electron are conserved during the shake up and shake down processes under the influence of the Auger decay.