Auger decay and the direct double ionization probability of a 2p inner-shell hole in a singly charged Ar+ ion

Single and double Auger decay processes of Ar+ 2p−1 hole levels belonging to the configurations of 2p53s23p5 and 2p53s3p6 are investigated in the framework of perturbation theory implemented by the distorted wave approximation. The single Auger decay channels and rates are determined and the predicted total rates can differ by more than an order of magnitude for the levels of 2p53s23p5, yet they are very close for levels belonging to 2p53s3p6. By combining the double photoionization cross sections of the neutral species, our theoretical Auger spectra of the single Auger decay process nicely interpreted a recent experiment [S.M. Huttula et al., Phys. Rev. Lett. 110, 113002 (2013)]. A configuration averaged branching ratio of 6.5% and 7.3% are predicted for the direct double Auger decay to the total probability for 2p53s23p5 and 2p53s3p6, respectively, which is smaller than that of Ar 2p−1 hole states.