Postcollision-interaction effects in multistep Auger transitions following Ar 1s photoionization

Abstract

Post Collision Interaction (PCI) effects involving multi-step decay processes following Ar 1s photoionization has been studied by Auger electron spectroscopy. The experiment focused on LMM Auger electrons measured in small photon energy steps across the Ar 1s photoionization threshold. Decay pathways that we studied include 1) Ar + * 2p -1 →Ar 2+ 3p -2 LMMα Auger process due to a single L hole created by KL fluorescence, 2) Ar 2+* 2p -2 → Ar 3+ * 2p -1 3p -2 LMM1 Auger process following double L shell hole states produced by a KLL Auger processes and 3) the subsequent Ar 3+ * 2p -1 3p -2 → Ar 4+ 3p -4 LMM2 Auger transitions. Particularly pronounced PCI shifts and unusual line shapes compared to the ordinary one-step PCI process were found in the spectra of Auger processes following a KLL Auger first step. The experimental results were compared with calculations based on the semi-classical approach to PCI. Good agreement was found between the calculated and experimental PCI shifts. The result opens possibilities for further studies of the multielectron dynamics between Auger electrons mediated through the photoelectron in these and similar systems.