Configuration interaction in argon<i>KL</i>resonances

Abstract

Curious ``doublet'' resonances in the KL double photoexcitation spectrum of argon are explained as a strong admixture of 3${\mathit{d}}^{2}$ excited states to the principal [1s2p]4${\mathit{p}}^{2}$ excitation. A simulated ``ab initio'' KL photoabsorption spectrum including shake-up and shake-off contributions agrees well with the experimental data.