Evidence of sequential interatomic decay in argon trimers obtained by electron–triple-ion coincidence spectroscopy

Abstract

Sequential interatomic decay, where the first step is an Auger decay with interatomic character and the second step is a pure interatomic Coulombic decay (ICD), is identified in Ar trimers Ar3. The 2p hole state in Ar3 decays via the L2,3M1M2,3 Auger to the one-site two-hole states Ar++(3s−13p−1)–Ar–Ar that couples to the two-site satellite states Ar+(3p−2nℓ)–Ar+(3p−1)–Ar. These states are subject to ICD to the states Ar+(3p−1)–Ar+(3p−1)–Ar+(3p−1), in which the nℓ electron fills the 3p hole in the same Ar site and one of the 3p electrons in the third Ar site is emitted as a slow ICD electron. This ICD process is identified unambiguously by electron–ion–ion–ion coincidence spectroscopy in which the kinetic energy of the slow ICD electron and the kinetic energy release among the three Ar+ ions are measured in coincidence.