Resonant multiple Auger decay after the2p3/2−14sexcitation in Ar studied with a multielectron coincidence method

Abstract

The multiple Auger electron emission processes after the $2{p}_{3/2}^{\ensuremath{-}1}$ 4$s$ excitation in Ar have been investigated with a multielectron coincidence method. We have observed the double, triple, and quadruple Auger decays of the resonant state, where both cascade and direct processes are identified. The cascade processes in the resonant double and triple Auger decays result mostly from the spectator behavior of the Rydberg electron in the initial core-hole decay: First Auger decay produces ion states with large internal energies, and subsequent electron emission leads mainly formation of ground Ar${}^{2+}$ and Ar${}^{3+}$ states. It is revealed that spectator behavior, which is known to be the dominant path in resonant single Auger decay, is also important in the direct paths of the resonant double and triple Auger decays. In contrast, the participation of the Rydberg electron is predominant in the direct path of the resonant quadruple Auger decay.