Properties of Resonant Interatomic Coulombic Decay in Ne Dimers

Properties of the interatomic Coulombic decay (ICD) process in Ne dimers have been obtained by tracking the formation of energetic Ne⁺ ions. The double photoionization cross section, deduced from the Ne⁺/Ne⁺ coincidence signal, is dominated by the ICD process and presents a threshold 280 meV below the atomic Ne⁺2s^-1 threshold. Rydberg excitation of a $2s$ electron in the dimer creates molecular Rydberg states whose Σ and Π symmetries have been resolved. These excited states decay by a resonant ICD process releasing an energetic Ne⁺ ion and a neutral excited Ne* fragment. Subsequent autoionization of the Ne* fragment explains a double photoionization threshold below the dimer $2s$ ionization threshold.