Autoionization selectivity of Ne⁺ Rydberg states converging to Ne²⁺(¹S^e)

Indirect double photoionization processes of Ne have been studied in the photon energy range from 65.5 to 68.3 eV by using a thresholdphotoelectron- photoelectron coincidence method, where intermediately formed Ne⁺ states have been defined by the detection of threshold photoelectrons and fast electrons from their autoionizing decay have been analysed in coincidence. The present investigation revealed that each Ne⁺ Rydberg series converging to Ne²⁺(¹S^e) shows notable selectivity in the autoionizing decay to the final Ne²⁺ states.